Easy lessons in natural philosophy, natural history, mechanics, chemistry, electricity, optics, and acoustics

8/14/2019 Easy lessons in natural philosophy, natural history, mechanics, chemistry, electricity, optics, and acoustics

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KASY LESSONSIN

NATURAL PHILOSOPHYNATURAL II I STORY

MECHANICS, CrilEMIBTRiELECTRICITY, OPTICS, AND ACOl's'iirs

\\TI1I NTMKKOrs ILI.rsTK.VI

LONDOLBTO5 AND \v li I


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GRANDFATHER WHITEHEAD'S CATECHISMS,

[.-NATURAL PHILOSOPHY.


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TO TEACHERS AND PUPILS.

THE object of every tutor should be to convey the knowledge the pupilrequires in as simple, clear, accurate, and concise a manner as possible.The object of every pupil should be to acquire the knowledge impartedby the tutor, not in words only, but in ideas ; so that the information

.1 should not be of a superficial character a mere catalogue ofscientific names but an acquaintance with the phenomena of Nature, and

net and comprehensive idea of the laws which regulate them..jitly remarked that " a tutor should not be continually

thundering instruction into the ears of his pupil as if he were pouring itthrough a funi :ter having put the lad, like a young horse, on a

.-fore him, to observe 1 : i,k- to perform,should, according to the extent ot his eai luee him to taste, todistinguish, and to find out things for himself ; sometimes opening theway, at other times leaving it for him to open ; and by abating or in-creasing his own pace, accommodate his precepts to the capacity of hispupil."

inquiry A\ill follow, and the consequencewill be a Lrratify that curiosity by acquiring knowledge. The.ignorant or m n quite as mm-li as theunproduet on the road-side. In the following Catechisms thepupil is led step by ste; -1 easy method, to acquire the

knowledge . is still further elucidatedby numerous diagrams nts.


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iv PREFACE.The experiments are so contrived, that the apparatus required is of the

most simple and inexpensive kind in most instances, and due regard liasbeen paid throughout to simplicity and usefulness, rather than mag-nificence

;the object being to render everything as plain and intelligibleas possible, commensurate with the subject.

The introductory narratives are all founded upon facts, or are the actualbiographies of eminent scientific men. The lessons have been constructedfor weekly tuition, it being desirable that the first five days should bedevoted to catechising, and the sixth to recapitulation, examination vivavoce, or essay writing upon the subjects contained in the week's courseof study.

Teachers are recommended to give additional illustrations of thesubjects under consideration, to perform the experiments given in thelessons before the pupil, and to adduce other familiar and simple experi-ments to elucidate them.

Pupils should perform the experiments themselves before studying thelessons, and repeat them again when master of the lesson. If possible,they should also perform other experiments bearing upon the question,and explain their analogy to those previously exhibited.

Each lesson has a few important questions appended, to assist theteacher in the examination of the pupils.


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GRANDFATHER W

INTRODUCTORY NARRATIVE.LESSON I.NEARLY a century and a half ago,

great distress prevailed in a certain dis-trict in England, where there were but afew houses, peopled by labourers in thehumblest condition of life ; and, as theland was unproductive, and marsheshemmed in by mountains were to be seenfar and wide, the earth did not bring forthsufficient to supply the wants of the peo-ple, so that many of them were oblip-,1to leave the home of their childhood, andsettle elsewhere. A poor lad, who hadonly received sufficient i-diuMtion toenable him to read, wa removed from

t' V


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6 INTRODUCTORY NARRATIVE. [Lesson I.school to assist his father in his employment of stuff-weaving. The love ofknowledge the ardent desire of becoming a scholar had taken possession of the youth,who devoted all his leisure moments, and even a portion of the time which his fatherrequired of him, to reading and writing. The father, instead of encouraging his son'sfondness for study, forbade him to open a book, behaved with great harshness, and atlength drove him from the house, telling him to go and seek his fortune where and howhe chose. "NVeary, and uncertain where to go, he threw himself upon the heath toreflect upon the course he must take; and, having refreshed himself at an adjoiningbrook, walked to the neighbouring village, and took up his abode in the house of atailor's widow, with whose son he had been previously acquainted. He contrived tosupport himself by industry and frugality, and to add to his stock of knowledge by care-ful observation and reading. Soon after his arrival, a pedlar, who combined fortune-teller and astrologer with his own trade, came to lodge in the same house ; and becomingintimate with Hallam for such was the boy's name instructed him in the various branchesof knowledge that he was acquainted with, while pursuing his own trade of pedlar anditinerant merchant From the astrologer-pedlar he obtained the knowledge of the firstprinciples of Natural Philosophy ; and his naturally active and intelligent mind, improvedby reading, extracted new and important facts from the incidents of every-day life withwhich he was surrounded.The time for the departure of the pedlar arrived, and previous to setting off on his

journey, he lent Hallam Cocker's Arithmetic, which had bound up with it a treatise onAlgebra, and a work upon Physics and Somatolosy. These he studied so thoroughlythat when the pedlar returned he was astonished to find his quondam pupil had almosteclipsed his tutor, and forthwith proceeded to draw his horoscope, as he termed it, inorder to discover the probable career of this wonderful lad.Having concluded his observations, the pedlar predicted that in two years Hallamwould surpass his tutor, and ultimately rise to bo a great man ; and the youth promised

that if such came to pass, he would not forget in his prosperity the instruction of thepedlar, and his kindness towards him.

Eighteen years have elapsed, and the prediction has been fulfilled : the lad abandonedhis trade of weaver, turned schoolmaster, and married his landlady the tailor's widow.He has passed through many phases in his journey through life, and, notwithstandingthe privations and hardships he encountered, has risen to considerable eminence as ascholar, has been appointed Professor of Mathematics, and elected a Fellow of the RoyalSociety.The few houses that were scattered upon the borders of the wild and desolate districtwhere Hallam's father formerly lived, have increased in number and size ; the marsheshave been drained, the land tilled, the mountains quarried, and the whole aspect changedfrom desolation to the busy hum of commercial activity. Jacqunrd-looms have beenerected, mills and factories built, and long lines of streets; BO that from being a villageat first, it has grown into a city. He seeks out the aged pedlar, who still instructs theyoung and labours for his bread; the old man has almost forgotten his pupil, but tearsof joy suffuse his eyes, as the remembrance of other days is recalled. At eve, the twostroll towards the brow of the hill, Hallam supporting his aged tutor, and as theyapproach a mill on the road-side, they halt, for the pedlar is wearied and wishes to resthimself.


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I.] NAT I- HAL PHILOSOPHY."This .spot," said Hallam, " is where I reclined when my father drove me from his

house; but how changed the prospect! The mountain's side is now peopled; andwhere the heath and furze grew amid marshy land, the golden-eared corn bends to thebreeze. Observe yon waggon as it moves along the road ; 'tis mine aye, and all thefactories beyond! So you must now leave off toiling, and share them with me; for tayour instruction I owe alL"" To mine ?" replied the pedlar."Yes! 'twas through the knowledge obtained from you, that I have risen to mypresent position. Your prediction ever before me, and with the desire of reaching thehighest pinnacle of fame and honour, I worked incessantly ; success crowned my efforts ;and now, surrounded with wealth and honours, I must not forget the pedlar-astrologer,and his gift-book of NATURAL PHILOSOPHY."

NATURAL PHILOSOPHY,BTIONfl AND EXPLANATIONS.

.vAt-r. WHAT is Natural Philo-sophy ?

Pupil. It is that branch of the naturalciences which treats of phenomena thatdo not depend upon a change of the con-struction of bodies ; and makes us acquaintedwith the nature, causes, properties, andeffects of the various objects and eventswhich surround us. It will enable us todiscover why a room smokes when thereare two fire? in it Why the handles ofcooking vessels are often made of wood.Why persons interpose a piece of woollenmaterial between their hand and the handleof an iron kettle. Why plunging thehands into water produces a sensation nfcold. Why water in fluid ; or why acracked bell makes a discordant SOUTH!.[The pupil should be required to give satisfactoryanswers to all these queries.]2. T. What is the term PhilosophyP. From the Greek philosophia

(cd as bodies ; thus v.solid body, and M

gaseous body. All these substances ex-cite certain sensations in our minds, andthe pov. M arc called

;n(ilitict or propertut.e me some examples of the

properties of boihas some i. quality : it is distin-


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NATURAL PHILOSOPHY. [Lesson II.guished from another. It is the propertyof glass to be transparent and brittle; offire to burn ; of charcoal to be inodorousanJ insipid ; of amber to be brittle, light,hard, and transparent ; and ofthe loadstoneto attract iron.[The pupil should be requested to give otherexamples of the properties of bodies.]9. T. You said that certain sensations

were excited in our minds by bodies : giveme some examples.P. One body excites the sensation ofgreen, another of blue, and a third is de-void of all colour, or may be said to bewhite, such as lime.

10. T. "Why is lime white ?P. Because the particles of matter ofwhich it is composed are piled so denselyone upon another, that they are able to

reflect all the coloured rays of light.1 1. T. What do you mean by the term

mattt-r ?P. The substance entering into the

composition of all bodies has received thegeneral name of matter, which possessescertain essential characteristic qualities.

12. T. What do you mean by the ex-pression general name ?P. A general name is one that is usedto express a large genus or class of thingsof similar character ; thus, fiats may in-clude straw hats, gutta-percha hats, corkhats, silk, beaver, or felt hats, and manyother kinds ; and when we say apples, weuse an indefinite term, if we allude to anyparticular kind, such as crab-apples, orgolden russet, and only employ the generalname to express the class. Generalisationof facts can only be accomplished by per-sons of experience, well acquainted withscience. The vast and heterogeneous massof phenomena which puzzle ignorant peo-

ple, are compared, classified, and gene-ralised by the philosopher, and renderedfamiliar and useful to mankind.

13. T. What do you mean byphenomena ?P. They are all extraordinary appear-ances in the works of Nature; the \\oid

phenomenon being derived from the Greekword phaino (to appear), and signifying,literally, an appearance.

14. 7\ Give me some illustrations ofnatural phenomena.

P. Heat applied to ice drives the par-ticles entering into its composition furtherasunder, and changes it from a solid to aliquid form ; and if the temperature is in-creased, and the process prolonged, thewater or liquid is converted into a gaseousfluid or steam, because the component par-ticles are driven still further apart. Heatrarefies air and causes it to expand ; forexample, [Experiment 1,] let a bladder,half full of air, be tied tightly at the neckand then laid before a fire, or held over theflame of a spirit-lamp sufficiently high toprevent the flame injuring the bladder, andthe air will expand and fill the bladder.[The pupil should give some further illustra-tions of natural phenomena.]

GENERAL QUESTIONS UPON LESSON I.1. What is the derivation and meaningof the term Philosophy ?2. How is Philosophy divided ?3. Name the senses by which the exist-ence of bodies are made known to us.4. What is the quality of a body ?5. What constitutes the composition ofbodies ?6. What is matter ?7. What is a natural pnenomenon ?8. Prove that the same cause may pro-duce various effects.

LESSON II.*WE have an excellent example for the youth ofthe present age to follow, in the caseof the poor boy Hallam, who, by untiring zeal in study, and perseverance, raised him-self from obscurity to affluence, and an honourable position in the scientific world. Thechief points in the story are true, but some little incidents have been introduced for

* Grandfather Whitehead requests that the Pupil will commit to memory the ideat of each lesson,and endeavour by experiments of a different character from those given here, to demontlrate to theTeacher that he has thoroughly mastered the subject.


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Lesson H.] NATURAL PHILOSOPHY.especial reasons. It is founded upon the career of Thomas Simpson, the celebratedmathematician, who was born in the town of Market- Bosworth, in Leicestershire, inthe year 1710. By studying the books given to him by the pedlav-astrologer, the boy

i ibled to comprehend many of the laws of nature; and the Blowledge he thusacquired was applied to the daily purposes of life, for Natural Philosophy explains theprinciples of the various arts which are practised, elevates and improves the mind, andextends man's power over nature. It unfolds to us the magnificence, order, and beautyof construction in the material world, and adduces the most powerful evidence of thewisdom and beneficence of the Creator. It was the knowledge of its laws that enabledHallam to change the desolate tra|^>f land into a populous and productive district.We can understand the manner ^hich bodies act upon each other, and the reasonthey do so, by means of its laws ; for example : [Experiment 2,] take a sheet of glassand place some water upon it ; the glass will be wetted. You know this already fromdaily experience ; but you require to know Natural Philosophy to explain the reason.If we wipe the glass dry, and place some mercury upon it, [Experiment 3,] the sameeffect is not produced, the glass remains dry ; and Natural Philosophy explains whythe glass is differently affected. Suppose we substitute a thin sheet of lead or tin,[Experiment 4,] and use the mercury as we did with the glass, the effect will bedifferent ; the metal plates will be wetted with the mercury, and if there is sufficientmercury, the plates will be dissolved in a short time. Again, take a lump of sugar,[Experiment 5,] and place it upon the glass plate we used a short time ago ; examineit carefully, and you will observe how compact it looks ; place a teaspoonful of waterupon the glass and allow it te flow towards the sugar, you see it falls to pieces, and hasnow disappeared ; and when you know more of Natural Philosophy the reason will beobvious.

QUESTIONS.15. T. From what you have shown re-

specting the manner in which some bodiesact upon each other, it would appear thatthe phenomena we have witnessed alwayshappen under similar circumstances, andtherefore, that there must be a natural lawto govern the action of bodies. Do youthink that this is the case?

Yen, undoubtedly. It is a naturallaw that bodies always act in the sameimiiM-r under the same circumstances, and>dy has its own law. Pure water

will always dissolve sugar, but does notaffect gold in the same manner, because itis not its nature to do so.

16. T. Do you understand what ismeant by a natural law TP. It is tl. ..f thephrnmnen* < It' we apply heat towater it converts the water into steam, coldwill not ; thm-fnre we .ty it is a naturallaw that gov< 1 1 is a natural

.: all bodies at the earth's sin

left to themselves, descend in straight linestowards the surface.17. T. Do you think that I can dissolvesand in water ?/'. No; I know you cannot, because it

is contrary to its natural law.18. 7\ How have these laws been dis-cover.

P. By experiments and observ.v19. T. What is the use of expei :/'. Experiments verify oliserv.it ions and

truths, elicit facts, establish ipress the principles more strong!.our minds, and exemplify thw .i|>]of gener.il principles to the demonstrationof individual facts.

. rdth.it sail.!.and other bodies .ire insoluble, or

uith water, you say thatit is a natural law that p'"-'"" '>as it would he impossible fo:to observe and experiment upon all (he

ii .5


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10 NATURAL PHILOSOPHY. [ Lesson III.bodies by which he is surrounded, how canwe obtain the knowledge we reqii :P. From the experience of philo-sophers, who have observed and experi-mented upon the many and various bodiesaround them, and left their knowledge tous. Galileo was the first to test theoriesby practical experiments, and Lord Baconshowed that this was the only method ofacquiring a knowledge of the laws ofnature.

21. 7*. Where can the recorded ex-perience of philosophers be found ?P. In works upon Natural Philosophy,in which the nature and properties ofbodies, the laws which govern them, andthe phenomena of nature are explained.

22. T. As bodies differ materially onefrom another, the comprehension of thenature of their individual properties appearsto be almost impossible.P. So it would be, if there were notgeneral properties which we observe toexist in all bodies, whatever other differencesthey exhibit. Thus, it is essential to theexistence of a body that it possess thepower of extension, occupy a limited space,and be impenetrable ; but in addition tothese properties, without which we cannotform any idea of matter, there are other

properties which we observe, .MS divisibility,extensibility, compressibility, porosity, in-ertia, and gravity.

23. T. Can you always re-cognise theseproperties in bodies ?P. Yes ; some arc essential to theexistence of a body, others are not, as Istated before.

2-t. T. How do you expect to under-stand all the phenomena that occur whenexpcrMting upon bodies ?studying Natural Philosophy.

GENERAL QUESTIONS ON LESSON II.1. What is the object of Natural Phi-

losophy, and to what purposes is it applied ?2. What is meant by a natural law ?8. What is the use of experiments ?1. What is essential to the existence of

a body ?5. Do all bodies possess peculiar cha-

racteristic properties ?[The pupil should be required to state the pro-

perties of various bodies in a concise mannerExample : Lead is solid, heavy, soft, mal-leable, deficient in tenacity, and readilyfusible. Water is fluid, inodorous, clear, andtasteless. Carbonic acid is gaseous, colour-less, pungent, insoluble in water, and acid-ulous, &c.J

LESSON III.HALLAM learned from the bogk on Natural Philosophy that the pedlar-astrologer

lent him, many of the laws of nature and their application, and by reading, reflection,and observation, he was enabled to add much to his store of knowledge, and apply hisexperience in such a manner, that he not only enriched himself, but benefit ted hisneighbours. The only source from whence we can derive our knowledge of nature isthe perception of the senses, practical experience and observation ; the facts observedand collected are arranged, and inferences drawn cither from analogy or induction ; butwe derive all the certain and accurate knowledge of the laws of nature from the latter.Having mastered certain points, his next object was to apply his experience, and thishe did so effectually that he drained the marshy lands, and made the mountain streamsmove machinery. We trust our pupils will all endeavour to be Hallams.

QUESTIONS.25. T. You have said that one of the

properties of matter was divisibility. Now,do you think that there is any limit to this ;divisible, being capable of division intosmaller and still smaller portions ; and, pro-vided the instruments of division are fine

thn.t is to say, can it be infinitely divided ? | enough, there is no limit as far as ourP. As far as we know, all bodies are j senses arc concerned. Yet, as all particles


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Lesson III. ] NATURAL PHILOSOPHY. 11of matter must be possessed of a finite

ade, we should rather say that it is. though too small to be seen evenwhen maguilicd by the most powerful

microscope.26. T. Give me some examples of the

ILITY of matter?/'. One of the best examples of extreme

divisibility of matter is musk, which willcontinue to diffuse its odour year afteryear without any perceptible loss of weightIt is stated* that "a clean cork, whichstopped a phial in which there was musk,which it seemed never to have touched, in

melled of musk more than twentyyears after;" and Fee says that one part ofmusk will communicate its odour to 3,000parts of inodorous powder. It is veryevident that some particles of the muskmust have been diffused, otherwise theodour would not have been discovered bythe sense of smelling; touch and visioncould not assist in the perception of itsexistence. Again : the silk, spun by thesilk-worm, is about the 500th part of aninch thick; but a spider's line is, perhaps,six times 6ner, or only the 3,000th part ofan inch in diameter ; insomuch that asingle pound of this attenuated substance

>>c sufficient to encompass our globe.Another remarkable instance of the di-ly of matter is seen in the dyeing of

ilk with cochineal, where a pound of silk,containing eight score threads to the ounce,each thread seventy-two yards long, andthe whole reaching about 104 miles, whendyed with scarlet doet^iot receive above a

weight ; so that a drachmolouring mattrr of the cocliactually extended through more than 100

tliis minute quan-to give an intense colour

to the silk with which it is combined. I h

/'. Cinnabar, which is composed of sul-phur and mercury, may be separated intothese constituents ; but we cannot di-tin-

'!< particles of sulphur from thoseunder the microscope./.Do you consider that the di-.ty of matter is wholly unlimited fP. No; to adopt such an assuhe to ndmit th.it the ni*c

ultimat. s null ; whileit is evident, that if the ultimate particle


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NATURAL PHILOSOPHY. [Lesson IV.have no extension, it cannot enter into thecomposition of a body occupying space.

31. T. What do you gather from allthe facts and observations you have stated ?

P. That all bodies are composed ofminute particles, which cannot be furtherdisintegrated, but are undivisible.

/'. What name have these particlesreceived from natural philosophers ?

P. Atoms. If, however, we speak ofthe particles of a mass, without wishingactually to describe them as the ultimateportions, we employ the term molecules.

33. T. Then it appears that a moleculeis not the same as an atom ; will you ex-plain the difference ?P. A molecule is supposed to beformed of several atoms, arranged accordingto some determinate figure, and generallysignifies the component parts of a body toosmall for sensual perception.

:;i. 7'. -Has the knowledge of the con-stitution of bodies thus formed been ap-plied?P. Yes. Natural philosophers andchemists have universally embraced thehich has received the name of theatomic theory, or theory of atoms.

GKXF.RAL QUESTIONS ON LESSON III.1. Are all bodies divisible ?2. Give some examples of the divisibilityof matter from the organized world.3. C;ui you give a familiar example of

the divisibility of matter ?4. Can we always prove the divisibilityof matter by our senses ?5. Is there any limit to the divisibilityof matter ?0'. What is the difference between an

atom, a molecule, and a particle?7. "What name has the fundamental view

of the constitution of bodies received ?

LESSON IV.RECAPITULATION, &c. THE study of the laws of Natural Philosophy enabledHallam to discover that matter was capable of division, and he applied his knowh

to many useful purposes. The mountain on the borders of the marsh where he hadtaken up his abode, was barren, and he therefore rented a portion of it for a small sum :on this he built a hut, and formed lime. The lime he sold to the fanners ; and by fru-gality and industry, was enabled to purchase a plot of ground on which to build hishouse. The house he now built was formed of stone, procured from the mountain'sside, united with mortar made from lime he manufactured himself. To procure thisstone, he was obliged to have recourse to Natural Philosophy as his assistant, and bymeans of judiciously conducted experiments and observations, he was enabled to accom-plish ten times the amount of work he otherwise could have done, if unacquaintedwith Natural Philosophy. QUESTIONS.

.',3. T. I remember that you said oneof the essential properties of a body was

- n. 11. IT Y. Pray what do you meanby the term ?

P. Every body must occupy a certainamount of space, which space will, of course,be in proportion to its magnitude. Exten-sibility is the property observed in bodiesto have their volume enlarged without in-creasing their mass.

36. T. What do you mean by thevolume of a body?

P. It is the bulk or size of a body,being the quantity of space included withinits external surfaces.

37. T. How do you estimate the bulkor volume of bodies?

P. By the quantity of their dimensions ;or in other words, by their length, breadth,and depth.

38. T. You have just said that a bodymay have its volume enlarged without in-Qg its mass; how is this possible?


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Lesson IV. J PHILOSOPHY./'. -I will prove it to xpcri-

eriiiK'nto'.] Take ,1 glass tube(a, &,) with a bulb at the end (6);let the bulb (6), and part ofthe tube be filled with some

i of logwood, solutionof indigo, or other colouredfluid, as far as c. Plunge thebull) into hot water, and if youobserve, you will see the decoc-tion of logwood, which is in thistube, rapidly rising towbecause the fluid has dilated orextended under the influenceof the increased temperature,and is occupying a greater spacethan before, therefore its volumeis increased. We will now allowthe fluid to cool, and you will *V *observe that it will return to the level at c,therefore we prove that the mass is the sameas before. If you repeat the experimentwith the bladder, [Experiment 1], you willhave another illustration of extensibility.In both these experiments the elevation ofthe temperature produces an incrvolume, which will be easily comprehendedby examining these two diagrams.

CC.

:*

r,g. 4.

5 represents a cubic inch of roldich we will suppose contains six-teen atoms of nir, but vsame space only contains nine atoms, (as

the vo! > the size ofbut when the air again '

it will return to the original size. i:nch of air contains the same

r of atom*, ii* the sameas before.

39. T. You have on ::ie twoillustration*, the one relating to a fluid,the other to a gaseous body. Can youillus" v a solid bo

P. \canter has become firmly fixed, s >

cannot easily be withdrawn witln.probability of breaking the decanter, if aflannel is dipped into hot water, and appliedto the neck of the bottle, it will cause theglass to expand [Experiment 7], and whenthe neck is enlarged the stopper can beeasily extracted.

40. T. Has the volume of a body anyrelation to i/'. No. Bodies Inviiu? very different

volumes may have the same figure; andbodies with different figures may havj thesame volume. Thus, a box may be tenia large as a die, or another box,but yet have the same figure ; and a squareand a sphere may, though of dilferuit

figures, yet have equal volumes.41. T. Do you think that bodies canbe diminished in bulk, without diminishing

their mass 1P. Yes ; all bodies possess the propertyof compressibility as well as extensibility.42. T. What do you mean by COM-PRESSIBILITY ?P. It is that quality which all bodies

possess of having their volume diminishedwithout decreasing their43. T. Can you furnish me wit::

familiar examples of the compressibilityOf bod:

P. The most elastic, and therefore themost compressible bodies, siml the most familiar of these is the

iieric air, which varies in bulk, ac-cording as it is near or remote from theearth's surface. It may appear v. i ,

. tli.it tli hulk of the atmshould . 'is the case,and 1 will . xplain

iagsofseed or flour, nn.lplacc tin :above tin-

i will easilyhowthose at th.torn of the pileas those at thotop.

illustrated by inrrn^n^ thr i.bags, urn! employing 1. It inon account : of the bap abovo

ment.


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li NATURAL PHILOSOPHY. [Lesson IV.pressing upon the lower ones. So it iswith the particles of nir at the surface ofthe earth : they are pressed upon hy thoseabove them, at a pressure of about 15 Ibs.to every square inch. If you examine thebags, you will perceive that a is very muchcompressed, b not quite so much, c less,and d almost uncompressed ; so that as weascend you observe the pressure is less, thesame as it is with atmospheric pressure.4K T. Can you compress gases thesame as you do atmospheric air ?P. Yes ; all gases can be compressed ;and one of the most familiar illustrations

of the truth of this, is the compression ofcarbonic acid gas in the manufacture ofsoda-water.45. T. Are fluids or liquids compres-

sible ?P. Yes ; but in so slight a degree that,

in a hydrostatic sense, they are consideredincompressible ; yet they are not abso-lutely incompressible, but only yield slightlyto very intense pressure.

46. T. Are you certain that liquidshave been compressed ?P. Yes. Canton proved this by ex-periment in the year 1761. He placed atube with a bulb, similar to the one weemployed [Experiment 6], in a condenser,and submitted the surface of the liquid toa very intense pressure of condensed air.The result was, that the level of the liquidfell perceptibly, and rose again to itsoriginal height upon removing the pressure.

47. T. Can solids be compressed?P. Yes. You observe this piece of

lead is round, in fact, it is what is called abullet; now immediately that it receives astroke of this hammer it will be partiallycompressed. [Experiment 9.] You seethat it is somewhat flattened, and now thatit has received six strokes, the size of it isdiminished, but its weight is the same. Inthe same manner, iron, steel, gold, andother solids may be compressed.

48. T. How can you account for this ?P. All bodies have interstices betweenthe different particles of matter, and it is

therefore very evident that the atoms arc-not in immediate contiguity wi:i,other. The spaces between the atoms arecapable of being compressed or extended,and therefore the volume of the body maybe diminished or increased.

49. T. What do you call the spacesbetween the particles of bodies ?P. They are called pores.50. T. Have all bodies spaces or poresbetween their particles ?P. Yes ; every body is porous.51. T. Then the property of being

porous is a general one ?P. It is ; and the quality of being so iscalled POROSITY.

GENERAL QUESTIONS ON LESSON IV.1. When bodies have their volume en-

larged without increasing their mawhat term do you express this prop.2. What is the volume of a body ?3. How is the volume of a body es-timated ?4. Prove by experiments that the volumeofa body may be enlarged without increasingthe mass.5. Are all bodies capable of being ex-tended ?6. What relation has the volume of a

body to its figure ?7. Can bodies be diminished in bulk

without decreasing their mass ?8. What term has been applied to

this property of diminishing the bulk ofbodies?9. Are all bodies capable of being com-pressed ?

10. Give some familiar examples of thecompressibility of bodies, and illustratethe fact by experiments.

11. How do you account for the com-pressibility and extensibility of bodies ?

12. What term has been applied to thespaces between the particles of bodies?

13. What is the name of the generallaw, " that all bodies have spaces betweentheir particles? "


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\\.\L PHILOSOPHY. II

SOX V.ve learned how bodies may be extended, and how

compressed, and hare also ascertained that all bodies are porous. Now these facts areall tery important, especially when they are associated with other matters which we shallconsider hereafter. They are intimately connected with the affairs of every-dav life, andare therefore of great consequence. Hallam had become conversant with the laws whichregulate them, and was led on step by step until he applied the knowledge he thusacquired to useful purposes. He learned that even solid bodies may be made to expandor contract without diminishing their mass, and he also learned that solid bodies havepores or interstices between their particles. Hallam had yet to learn more of thoprinciples of Natural Philosophy ; so have we.

QUESTIONS.52. T. You said that all bodies have

pores or interstices between their particles ;now do you know this ?P. It has been discovered by experi-

ment, and I know it by reading. Morethan two centuries ago it was proved lu-

cent, at the Academy !)! Cimento,.11 Florence, that gold was porous ; the ex-perience was the result of accident, but itestablished the fact that water may be madeto pass through gold.

53. T. Then you would imply, thatbecause all bodies arc compressible, thereare interstices between tlu-:r j>:irticles.

P. Certainly, but the sire of the poresvaries in different substance-.substance may contain 10,000 pores in asquare inch, and another 100,000 pores inthe same space. In the former case, thepores are considerably larger than in thelatter.

54. 7 i the effect of the portsof a body being closer together IP. The substance itself is rendered

inon- di-r.s.-.55. T. What do you mean by being

den,.- ?P. '} !. -ponds uponthe pr . of any sub-

tancc, the less will be the porosity. Thedensity of a body ia the relation of itsweight to its volume, and therefore in-dicates its specific gravity, a property wehall consider on another occasion.

56. T. How can you prove that bodieshave pores ?/'. By a very simple experiment. [Ex-periment 10.] 1 have here a piece of wood,with a wire fastened to it, and a tumbler of

water. I will plunge the wood into thewater, and keep it at the bottom of thetumbler by means of the wire [performingthe experiment]. You sec tintbubbles of air are rising to the surface, theyhave escaped from the pores of the wood.which are bein-j filled with water i:If there were not any int. rst ices it wouMbe impossible for the air to be in the sub-stance of the wood, because it is contraryto one of the established general laws ofNatural Philosophy.

/'.Is the knowledge of the porosityof bodies applied to any useful or scientific^es?P. Yes; filtration is based upon, ami

electrotyping is under obliga:58. T. Can you adduce any further

proofs of the jHiroiity of bodies fP. Yes ; many bodies are capable ofcompression merely by merit.mi.Mand this I will explain by a simple

ill 1 1|

I li.ivebasin of water, and a piece of cork floating

I will take an- (n* it i* commonlyfilled with air) and invert it orcr

the cork, so that the edge shall just ..the water; the air is now confined withinthe tumbler and occupies a given space,


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16 NATURAL PHILOSOPHY. [Lesson V.but if I plunge the tumbler below the sur-face, and keep it tbere.it will be found thatthe water rises to a certain height above thelevel of the brim, and the deeper that it isplunged the more the cork rises in the tum-bler : but as the pressure is removed and thegoblet rises, it will be found that the waterdescends and the cork with it, because theair expands. Thus you will see that air iscapable of being compressed a sufficientproof of its porosity.

59. T. Why did not the water fill thetumbler when you plunged it below thesurface ?P. Because, as the air was in the tum-

bler, the water could not occupy the samespace at the same time, and, therefore, theexperiment also proves the IMPENETRA-BILITY of the air.

60. T. What do you mean by impene-trability rP. By the impenetrability of bodies ismeant, that no two particles of matter canoccupy the same identical portion of spaceat the same moment.

61. T. How can you prove this ?P. By experiment. [Experiment 12.]I have here a piece of clay, and a bullet,which 1 will enclose within the clay. Nowit is quite impossible to make another bulletoccupy the cavity that contains the firstbullet as long as it is there. This you willreadily understand, because it is like trying

to pour a pint of water intoa pint measure already fullof water. Again, if I drivea nail into a piece of wood,the effect is only to compressthe wood, because it is im-possible that the wood andnail can be in the sameidentical space at the sameprecise time.

62. T. Has this know-lodge of the impenetrabilityof bodies been usefully em-

ployed ?P. Yes ; the principle of the wedgeis founded upon it. In the above diagramyou will see the explanation of the law ; thepoint of the wedge has been inserted into

a block of wood by a blow from a ham-mer, and has displaced the wood by com-pression. The substance of the woo;l isdividing, because it cannot be compressedany more.

03. T, If you remove the wedge, doesthe wood resume its former shape, andoccupy the space it did before the wedgewas driven in ?

P. No; because, unlike the air in thetumbler, it is not elastic, otherwise it wouldresume its former dimensions.

64. T. Are not all bodies elastic ?P. No ; lead or iron may be com-

pressed or diminished in size, but theycannot resume their former volume; andtherefore we learn, that elasticity does notalways accompany compressibility.

65. T. Then am I to understand thatelasticity is the power by which a bodyresumes its figure or volume, after thatfigure or volume has been altered by theaction of any force ?P. Yes, undoubtedly, after the forcethat caused the alteration of the figure hasceased to act ; not otherwise, and tintpower is found in solid and fluid bodies.

GENERAL QUESTIONS ON LESFON V.1. How do you know that all bodies have

pores between their particles ?2. What is the result of the greater

proximity of the pores of bodies ?3. What is meant by the density of

bodies ?4. Can you prove the porosity of bodies?5. Is it possible for two bodies to occupythe same space at the same time ?6. What do you call this natural law ofbodies ?7. How can you prove the impenetra-

bility of bodies ?8. Has the knowledge of the impenetra-

bility of bodies been practically applied ?9. Do all bodies possess the property of

resuming their former volume after beingcompressed ?10. What is this property of matternamed ?


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Lesson VT.] NATURAL PHILOSOPHY. 17

LESSON VIVPITI-LATION, &c. WHEN Hallam commenced the study of Natural Philosophy,

he learned that there were certain laws relating to bodies, called Natural Laws, whichhave been in force since the creation ; and having stored his mind with the information

iL-d in the gift-book of the pedlar-astrologer, having reflected upon the variousapplications of the principles he ha.l learned, and experimentally proved the practicaluse of his knowledge, he was enabled to overcome the many difficulties with which hewas surrounded. He discovered that the stones in the vicinity of his hut were fit forbuilding, and by means of the application of the wedge, he was enabled to separatelarge masses from the parent rock. Thus, he applied the knowledge of the impenetra-bility of bodies to a useful purpose. He read, that all bodies near the earth's surface, ifleft to themselves, descend in straight lines towards that surface, and that the direc-tions in which they fall in different places of the earth, tend nearly to the centre of it.This is a general natural law, and is seen daily. He also learned that philosophers had

red by observation, that matter is incapable of spontaneous change, a fact ofgreat importance.

QUESTIONS.CG. T. Do bodies possess the power of

spontaneous action ?/'. No; all bodies, when at rest, must

rfmain passive or inactive, unless influ-; >y some external force.

67. T. What does this prove?P. That mere matter is void of life ;for spontaneous action is the only test ofthe pretence of the living principle.

/'.Then it is impossible for anybody of itielf to commence to move froma slate of rest.

P. It is. A body cannot be in a stateof motion and rest at the same instant ; and,as I have explained before, all bod;.remain pasMve unless put in motion I

/'. Can you tell me the name ofthis quality of mv

/'. It is called INKRTIA, or i've that it exists,hat are the sources of heat?.it illict docs it produce upon

hr.it cominunici action

ami r.ulia'.ion of heat?t xamples of the repulsion ofbodies.

[Tli* pupil should gire other example! thanm iheo lmiUr bodies, like wood, to

prove that heat is latent, *c. ftc.J

LESSON X.rm LATIOX, &c. WE have learned that heat possesses remarkable properties ;and although it is unequally distributed over the sui t has a con-

y to preserve , .-,> in all fixations. When we know mote


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24 NATURAL PHILOSOPHY. [Lesson X-respecting heat, we shall be able to understand how the heat-measurer or thermometer isconstructed, and in what manner it acts, and many other phenomena connected with it.ll:ill:un observed, that when all the forces acting upon a body counteracted each other,it remained in a state of equilibrium, or was balanced; and having gained a knowledgeof the properties of matter, he applied it to the study of the laws of motion and forces.

QUESTIONS.121. T. What is MOTION ?P. It is the very reverse of rest, andmeans the change of place, which may beuniform or variable, according to its rate

or relative velocity.122. T. What do you mean by rest;because it appears a direct contradiction

to the laws ot nature ?P. There is no such thing as absolute

rest, because the earth upon which we standis always in a state of motion, therefore theterm is only relative, and not positive.

123. T. What do you mean, by sayingthat rest is only relative ?

P. If I let a stone fall from my hand,it will remain in the same place and inthe same position where it fell, until re-moved by some applied force ; and, there-fore, we say it is now at rest, but we meanto say that it is at rest only as regards theearth, because we know that there is nosuch thing as absolute rest in creation.The earth, the planets, and the sun move ;in fact, all creation moves.

124. T. Which is more natural, for abody to be in a state of rest or motion ?

P. Rest, of course ; because bodiesmust be arrested in their progress byatmospheric pressure, friction, the attrac-tion of the earth, or their own gravity.

1 25. T. What causes motion ?P. Its causes are various, but it is cer-

tain that all bodies must continue at restunless acted upon by some force or forces-ed upon them. In the animaleconomy it is produced by a principle oflife, which we do not quite understand;inanimate bodies are put in motion orarrested by certain forces or powers.

126. T. Is motion variable or constant ?P. It is variable, and must ever be so,

although its degree of velocity is in accord-ance with the force applied. Thus, if Ipush a cart with one hand, it will moveslowly ; with two hands faster, but if six orseven men all push at once, and with con-

siderable force, its velocity will be aug-mented.127. T. What do you mean by velocity?P. It is the degree of speed that bodies

possess, which is increased by the space ordistance passed over.128. T. But does not this speed vary ?P. Unless any impediment is presentedto moving bodies their velocity is uniform,and their speed is calculated by the time

they take to pass over a given distance orspace. Thus, any body that takes thirtyseconds to pass over sixty feet, is said topossess a velocity of two feet per second.

129. T. Is motion always uniform ?P. No ; it may be retarded or accele-rated.

130. T. Explain these terms.P. If it decreases gradually, it is saidto be retarded ; if it increases, it is accele-rated, and the force that governs or regu-lates this, is called the retarding or accele-rating force.

131. T. How are forces distinguished ?P. They are called instantaneous or coa-

tinued forces.132. T. What is the difference ?P. An instantaneous force is an im-

pulse ; it is sudden, like a blow, but acontinued force has always the same degreeof power, and is called a constant forcewhen it has no intermission.133. T. Can forces varyT. Yes ; of course they vary when the

power is not constant, or when there isintermission.134. T. What is meant by absolutemotion ?P. When any body moves towards an-other body at rest, or passes it, or movesfrom one point of space to another, it isinfluenced by absolute motion.135. T. What do you mean by relativemotion ?


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Lesson XI.] NATURAL PHILOSOPHY.P. It is the motion of one body con-sidered in relation to that of another body ;thin : suppose I roll two balls, one ofwoodand the other of lead, along a table, and

>th move in the same direction, theice between their motions is the

relative motion.136. T. If I let a bullet fall at the samemoment as cork, but of the same s

there be any great difference in the descentof tlv/'. Yes ; because it will depend uponthe momentum.

T. What do you mean by themomentum ?P. It is the raotal force of a body. All

. whether light or heavy, may movewith the same speed, but the momentumof a body being proportionate to its in issand velocity, it is very evident that thedifference will be relative.

138. T. How can you estimate themomentum of a b. T '-'' ' do you mean by the the influence of gravitation in, as it were,con and upon which a bod.P. It is that point in all bodies at which rest if it be freely suspended ; it is


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NATURAL PHILOSOPHY. [Lesson XI.quently the central point of parallel andequal forces.

141. T. If a body is not suspended withclue regard to the centre of gravity, whatwill be the result?

P. It will move until it settles in a po-sition in which the centre of gravity cannotfall lower.

142. T, What is the use of finding outthe centre of gravity ?P. When we know the weight of bodiesand their centre of gravity, we can substi-tute the weight for all the forces actingupon the body, and a single point (thecentre of gravity), for the collective pointsforming the body.

143. T. Have all solid bodies a centreof gravity ?P. Yes ; the centre of gravity is sureto be in the centre of all round, square, andregular bodies of the same density ; andno mattr what form a body has, it is sureto have a centre of gravity. In irregularbodies it is situated at that point whichwill place the body in a state of equilibriumwhen fixed or suspended from it.

144. T. Can I stand an egg, or placeit in a state of equilibrium, upon its narrowend?P. Not without following the exampleof Columbus. Because, if there is not any-

thing to supportthe egg, it will as-sume such a posi-tion, that a linedrawn from thecentre of gravityto the point below,where the body

Fig. 12. comes in contactwith the surface, will be the shortest thatcan be drawn from the centre to any otherpart of its superficies. If you observe thisdiagram carefully, you will see that the eggcould not remain in the position it is inthe figure; it would roll over, and insteadof the line a c being perpendicular to theline d t, it would be the line c b.

145. T. If the centre of gravity of abody be a fixed point, the body itself willalways be in a state of equilibrium, nomatter how we turn or place it. Is thisso?P._Yes; the only thing that is actually

necessary to the equilibrium of any bodyis, that the centre of gravity should besuppn:

146. T. How will you find the centre ofgravity of an irregulartigure ?P. Very easily ; orthat of any body. Ifyou suspend the body ata point a, (Fig. 13,) thedirection of the stringsupporting it will passthrough the lower partof the body at l>, andtherefore it is very evi-dent the centre of gra-vity is in the directionof the line a b. Again,suppose we suspend thesame body at the pointd (Fig. 14), the centreof gravity is still in thedirection of the sus-

pending string de, and therefore the ci litreof gravity lies where the two lines a b andd e cross one another at c. Although itis easy to determine the centre of gravityof some bodies of regular form and uniformdensity by geometric principles, yet there

Fig. 13.

Fig, 14.are certain bodies in which it is difficult toascertain the line of direction exactly.

147. T. What do you mean by the lineof direction?P. It is the imaginary line drawn fromthe centre of gravity of a body toward the

centre of the earth ; therefore it is evidentthat, if the line of direction fall within thebase of any body, it will stand ; if not, thebody will fall over, or, what is generallytermed, over-balance itself.


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Imim XII. NATURAL PHILOSOPHY. 27T. Where is the centre of gravitylight line?

I'. In the centre of the line, so that itwill be maintained in a state of equilibrium ?

T. How would you find the centreof gravity ofa homogeneoustriangle ?P. By draw-ing straightlines from twoof its angles tobisect the op-posite sides, andthe point of in-tersection, d, ofthese two lines,

is the centre of gravity. Thus, the pointe is the centre of gravity of the line b, c,and any line drawn parallel to 6 c in thetriangle must be bisected or divided bythe line a e, which proves that the cen-tre of gravity lies upon the line a, e, as re-gards all lines parallel to be, and, by thetame reasoning it would lie in the line a b.

T.ls the centre of grav:'body always in its substance ?

P, No ; because in a circle or ;is in the centre of the circle, and in a drumit is in the axis of the drum.

[The pupil should give some other illustra-tion* of the situation of the centre of ^such as coaches heavily laden upsetting:attitudes of men and women dancing uponthe tight-rope, tendency of trees to grow ina direction perpendicular to their base, &c.]

l~>\. T. If I attempt to stand upon oned fall down, is it because I cannotkeep the centre of gravity ?P. Yes; the equilibrium is not pre-served, and therefore you fall over.

HAL QUESTIONS ON LESSON XI.1. What is the centre of gravity ?

hy do bodies fall down when in-o one side ?... Have all bodies a centre of gravity ?4. How can you find the centre ofof a body ?5. Give some examples of the directionof the centre of gravity >6. Are the animal and vegetable king-doms subject to its 1..

ive some examples of other bodiesbeing affected by it.

LESSON XII."RECAPITULATION, &c. IK Hallam had not known anything about the centre of gravity,

it is possible that he might have built his house in such a position tint it would havefallen down, or he might have overloaded his waggons, and then there would have beena probability of 'their upsetting when they ran over any urn-ven Around. The onlyrequirement for the equilibrium of any solid body is, that its centre of gravity shouldbe supported, which may be done in various ways. A body attached to an axis maycither be in a state of stable, unstable, or iiuiii! lihrium, according towhether the centre of gravity is below, above, or within the axis.

QUESTION&152. T. What do you mean by the term,stable brium, because it must fall. When a mancarries a weight he must change his posi--ht and the rnan-

. otherwise t 1of thebody and the load would be beyo;base, and he would fall. For iiut..he carries a bale of cloth, or any load upon


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28 NATURAL PHILOSOPHY. [Lesson XII.his back (Fig. 1(5) he must bend lorward ;and if he carries a load in his left hand

Fig. 18. Fig(Fig. 17), he must bend the upper part ofhis body to the right.

154. T. What do you mean by in-different equilibrium ?

P. When any body is balanced in allpositions it is in a state of indifferentequilibrium. For example, when the wheelof a carriage is raised from the ground towash it, we have a body in a state of in-different equilibrium, upon a fixed axis.The common balance is an excellent ex-ample of this state, when both scale-pansare of equal weight.

]')">. T. We will try an experiment[Experiment 21]. I have here a bulletwith a hole in it, through which a stringpasses, and you will see that when thebullet is drawn out of the perpendicularand let go, that it will swing backwardsand forwards. [Performs the experiment.]You observe that it swings or oscillates, asit is termed, and in doing so describesa segment of a circle, which is called itsarc. Can you tell me what is the causeof this?

P. Gravity, which causes bodies to fall.15(5. 7\ What is the name applied to a

rod of iron with a weight at the lower part,like my bullet and string?P. A pendulum ; which hangs perpen-

dicularly when at rest. The uppermostpart is called the axis or point of suspen-sion, and the part where the ball is placedis called the point of rest

157. T. You have not explained to \\\


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Lesson XIII. 1 N VI IKAL PHILOSOPHY. 29T. What is the use of a pendulum

to a c!/'.On account of its uniform vibrationotion, for without it thewheels would go very irregularly.

T. As pendulums are required- ite only sixty times in a minute,. neither slower or quicker ; how is

Managed ?P. By adjustment of the length.

GENERAL QUESTIONS ON LESSON XII.1. How many kinds of equilibrium are

there, and how are they distinguished ?2. What is a pendulum .'3. "Wh.it causes its oscillation?4. Why does the sweep of a pendulum,

left to itself, decrease in length each time ?hy does the length of the rod affectthe vibrations of the pendulum ?

LESSON XIII.RECAPITULATION, &c. IT is quite as natural for a body to be in a state of motion

as rest, according to the laws of Natural Philosophy, because it has been shown thntis passive, and must therefore be influenced by some external force to make it

change its condition from a state of rest to that of motion, or vice versa. Sir Isaaci laid down three propositions, which have been called the " laws of motion."

They are as follow :1st " Every body must persevere in its state of rest, or of uniform motion in a

straight line, unless it be compelled to change that state by forces impressed upon it."2nd. " Every change of motion must be proportional to the impressed force, and

mutt be in the direction of that straight line in which the force is impressed."3rd. " Action must always be equal to and contrary to reaction ; or the actions oftwo bodies upon each other must be equal, and directed towards contrary sides."

.1 he our duty to consider these laws, and examine the phenomena theypresent We have already found that bodies cannot possibly continue in a stateof motion for any length of time upon or near the earth ; for the attraction ofgravitation, atmospheric resistance, and friction, would operate so powerfully, that thebodies would be arrested in their course. It is therefore evident, that permanency oruniformity of motion can only be fully demonstrated by the heavenly bodies, whichhave continued to move, with uniform force, since the time the Creator launched theminto space.

QUI164. r. Suppose that there are two

equal forces acting upon one point fromoppOM .-, what is the result .'

l>ody acted upon willin a stateof equilibrium.

two forces act in thesame direction, what inP. i ill he equalto that of a double load, and so on forevery additi',H that;st class

of vertebrate animals. We have now to, or howliof monkry

find out to which of the nine orders ofMammalia it belongs ; and without runningthrough all the peculiarities of each. Iknow that it should be placed in theorder, among the four-handed animals, orqiindruiHtinu, which are divided into threegenera the monkeys, marmosets, andlemurs. It therefore belongs to the mon-keys.

50. T. How do you know that t!cimen you have does not belong to thelemurs or marmo-P. Because these two genera presentsuch distinct peculiarities that it is impos-sible to make a mistake.[The pupil should explain what these pecu-liarity* are.]51. T. How is it that the vertebrate

animals have been subdivided into so manyparts, if they all agree in respect to theirgeneral character;-'

/'. Because, as I have explained before,[ (Jm'-:ion -JliJ they diller in some impor-tant particulars.

52. T. Explain this more fully.P. If we examine the sub- kingdom

ita, we shall find that tinthree distinct divisions of animal-adapted for the earth, the air, and thewater.

5-?. T. I thought that the vertebrateanimals were subdivided into four classes;how is it that you only make three .'/' I do not make three classes. In

divisions; and, as those that are a.iion the earth are divided intotwo Mammalia and llcptilia. tin ;

still four classes of animals ; viz. 1, Mam-malia; 2, Aves; 3, Reptilia; 4, Pisces.

64. T. Give me the reason that therate animals are arranged thus.

P. The first group Mammalia, or ani-mals that suckle tlieir young i- rangedfirst, because the an n thisclass are superior in organization to theother t!r are formed for an espe-cial purpose residence upon I'while the liinls and fishes nave !.- tuition withuc. cuwrmg tiictu.

injured during progression or other mo-tions. By a peculiar arrangement ofmuscles they are enabled to retract or drawback their claws, the same as a cat does ;so you see that we are enabled at once, byexamining the foot of an animal that canretract its claws, to decide that it belongsto a certain class of animals.

63. T. Explain how the lion is enabledto retract the claws.P. You will understand the manner inwhich they are retracted much better by

referring to this diagram, than by a mere

description. When the retraction takesplace, the ends of the two bones (/) are

.i pon the ground, between which andthe hones, a pad of thickened skin is in-terposed. I cannot explain the itfthe projection of the claws better than bydrawing my hand forcibly backwards andcurving the fingers, and then suddenlythrowing it downwards, the arm beinghorizontal at the time.

/'.Does not the perfectionorgans of touch influence us in cln-

iltfPig 4. Thtmtcl

* I* rtractedK'mlanx.

whirli ii K ri't in (i retracted f tli )a%t phalanx> uowu at g and k,


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44 NATURAL HISTORY. [Lesson VI.P. Yes, it forms an important part in

classification.65. T. How is the perfection estimated ?P, By the power of prehension or

grasping possessed by the animal.66. T. Then all the Mammalia have

not the power of grasping.P. Certainly not, the lower we descend

the more it is wanting.67. T.lf this be correct, we ought to

divide the class Mammalia into two parts.How should we do this ?P. Into animals having claws Un-

guicitlated; and animals with hoofs Un-gulattd.68. T. Give me an example of each.P. The orang-outang is a very good

Fig. O.f

example of the former, and the ox or deerof the latter division.69. T. How can you determine the

habits of an animal by examining its teeth ?P. Uecause they vary in structure andarrangement, according to the food of theanimal ; and therefore the character of theteeth and extremities generally guides natu-ralists in determining the habits of animals.

70. T. Does not the food exert its in-fluence on other parts of the body ? that isto say, can the naturalist ascertain thehabits of animals by other parts of thebody?

P. Yes ; the organs of the senses anddigestion exhibit its habits in common withthe teeth and extremities.

71. T. Can you distinguish an herbi-vorous animal by its teeth !

P. Yes ; they have flat-crowned grind-ing teeth, with irregular ridges on their

j surface, for triturating their food.72. T. How can you distinguish, bymeans of its teeth, an animal that eat?

various kinds of food .'P. The tops oftheww/arteeth orgrinders

!are raised into flattened masses, like theend of a pestle, and are intended for bruis-ing and crushing, as in man.

73. T. How are carnivorous animalsdistinguished by their teeth ?P. By the size of their cmiine teeth,which are very large, to enable them toseize firmly upon their prey.

[The pupil should give ex;tni|.les of the variouiteeth, Mu-h as those ot" (he lion, hoar, monkey,sheep, horse, &c. ; and state the numuer, andClasses of each.]

GENERAL QUESTIONS ON LESSON V.1. Why does Cuvier consider Mammaliashould be placed first among the vertebrateanimals I2. Can you learn anything of the habitsof an animal by examining its extremitiesor teeth ?3. How can the knowledge of the formof the extremities of animals inform us of

their habits ?4. \\ hat other reasons have we for clas-

sifying certain animals together ?5. Have all mammalia the power of

grasping ?6. Describe the difference between un-

guiculated and ungulated animals.7. Describe the diilen nee in the struc-

ture of the teeth of herbivorous and car-I nivorous animals.

LESSON VI.WE have seen that naturalists are guided by certain peculiarities in their classification

of the Mammalia, and indeed of all objects of Natural Uistory. Our purpose is not *oenter into the peculiarities of the various orders of each class, but rather to show the

Fig. 5. Hand of Orang-outang. t Fig. 6. Foot of Orang-outang.


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Lesson VI.] NATURAL HISTORY.principles of classification. The characteristics of each order, genus, and species, willbe given in the Catechism on ZOOLOGY ; and the remaining portions of Natural History,in those on BOTANY and (M:>I.(H.Y. Our present object is to consider the second classof vertebrate animals Aves, or birds.

In classifying the birds, naturalists attend to the form of the extremities and the bill.In some birds, we see the bill and claws sharp, hooked, and powerful ; as in the eagleand Egyptian neophron, adapted for tearing the flesh and holding the prey ; in others,

Kt. T. fit- S.f Fig. 9.1the beak is short and thick, suited for crushing hard seeds, as in the parrots and loriets ;while some have long slender bills, or soft short ones, fitted for feeding upon insects.The bill varies in length, breadth, and direction, as well as shape. The feet also differmaterially: thus we have perching, climbing, wading, and swimming foot. In additionto these means of classifying the birds, the naturalist has to call to his aid the appear-ance of the crests, eyes, ears, mouth, feathers, wings, and tail. The whole structure ofthis class of animals is peculiarly adapted for motion in the element the mass of them

QUESTIONS.74. T. Is there anything peculiar in the

structure of birds ?P. Yes; the general adaptation of the

. .trk to the purposes of life,and the covering of the body./' Why is the body covered with

feath.P. Because they are bad conductors of

rapidly, tlbodies is not decreased too suddenly.76. T. Do they possess a completeP. Yes, and are called warm-blooded

animals./' How is the bo ; light?

/*. By the interior of th,hollow, and containing air, which lenemtheir specific gravity.

78. 7*. Can y- sh a water-bird from another, and '

P. Yes: by the form of its feet, andother peculiarities.[Tho pupil should name them.]79. T. Is then at difference

in the form of a ,1's feet fromthose of a swimming-bird .'

I'. Yes. Tin- former h.ivc long slenderlegs, bare ot md long straighttoes ; while the lat;>

! by a web, which formsabroad surface \\!.. hat the' legs, arm

powerful, sharp, and hooked talcil

front ; and th- perching birds have threehind, anil '

:ies arc united by a very short mem-the toes are long, with long claws

I

lave natura'Ity in the subdivision of the

class Avc-s ?I. S. U.d of llarpjria dt.tructoc.

I /'; 9. II vail of Pesopor .. fortMSW.


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NATURAL HISTORY. [Lesson VELP. Yes, because there is a general con-

formity of type, and therefore it is difficult

Fig. 10.to decide what characters are of greater orlesser importance ; because there are notthose prominent distinguishing charac-teristics that we find in the other classes ofvertebrate animals.

81. T. Are there any orders of this classpossessing marked peculiarities ?

P. Yes, there are six; 1, ACCIPITRES,or birds of prey ; 2, INCESSORES, or perch-ing birds; 3, SCANSORES, or climbingbirds ; 4, GALLING, or scratchers ; 5,ORALLY, or stilt birds; 6, PALMIPEDES,or web- footed birds.

82. T. Give me an example of the firstorder.

P. The golden eagle, or condor vulture.83. T Give me examples of the secondand third orders.P. In the second order we find the

humming-birds, fly-catcher, thrush, jay,

raven, sparrow, &c. ; and in the third order,the cuckoos and macaws.84. T. Give some examples of thefourth and fifth orders.P. The fourth contains such birds as

pigeons, pheasants, fowls, peacocks, \c. ;and the fifth, the rail, snipe, heron, crane,and ostrich.85. T. Give examples of the sixthorderP. Here we find gulls, penguins, ducks,

geese, swans, &c.86. T. Is there anything very peculiar

in the anatomical configur-ition of birds,that assists naturalists in their classifica-tion ?

P. Yes ; the form of the sternal appa-ratus, and the modifications ef the diges-tive organs.

87. T. Is there anything else ?P. Yes, many things; but especially

the modifications of the vocal organs.

GENERAL QUESTIONS ON LESSON VI.1. What peculiarities have naturalists

paid attention to in the classification ofbirds ?

2. Is there any great difference in thebeaks or bills of birds ?3. Why do the bills of birds differ ?4. Is there any difference in the feet of

birds? If so, why ?5. Does the osseous, or bony structure

of birds, differ from that of mammalian*?6. Why have birds feathers ?7. Are birds warm, or cold-blooded

animals?8. How are the various orders of birds

distinguished?9. How many orders are there of the

class Aves?10. What additional peculiarities assist

the naturalist in the classification of birds I

LESSON VII.WE have now to consider the third class of vertebrate animals the Reptiles. There

is this peculiarity in the class, that their form is more varied than that of any other.As their blood is imperfectly aerated, they only maintain a low degree of animal heat,Fig. 10. a, foot of Egyptian neophron ; b, foot of nuthatch ; c, foot of thrush ; d, foot of solan gooM.


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Lesson VII.] NATURAL HISTORY. 47and are therefore termed cold-blooded animals. Their peculiar characteristics areoviparous reproduction ; low power of making heat ; peculiarity of protecting-surface.by means of scales, or hard plates, and a heart with three cavities, one of whichreceives the blood from the lungs ; another from the system generally ; and the thirdpropels the blood which is mixed in it partly to the body and partly to the lungs ; so

hen each contraction of the heart takes place, only part of the blood is aflectedby the air, and the consequence is, that their motions are sluggish, their sensationsdull, and their digestion slow.

QUESTIONS.88. 7". What is the chief reason rep-

re separated from other animals ?P. Because the conformation of theirbody is different, and also the circulationof their blood.

A Is not the blood perfectly oxy-genated

I1. No; because the nutritive functionsand power of circulation are feeble.

90. T. Is it possible for reptiles tosuspend their respiration?I'. Yes ; because the smallness of the

pulmonary vessels enables them to do sowhile submerged ; and thi> i> dom- withoute circulation of the blood./'.Why are reptiles covered with

scales, or hard plates ?se, as they are not warm-blooded animals, they are only coveredwith a naked skin, which is not caj

retaining heat like those animals coveredwith fur92. T. How are reptiles sutxlivi

(ling to , :!

in the second order ofBony Fishes called I

/'. MALACOPTERYGII;t lins under

the abdomen.100 T. How many families are theyinto ?

P. Five. 1, the Car Pikes;3, the Sheat-fishes , 4. 'ho Salmon orTrout family : and 5. the Herrings.

1 10. T. What is the third orderof Bony/'. Ihe MALA ton,

rill ATI. or sot'.- r;i> i-il t.the ventral tins under th.> ];ee'o.-als. andthe pelvis suspended to the shoulder bones.

111. T. What do you mean by the termP. Jointed- fins.112. T. What families arc contained

in the third order ?P. I, the Cod family: 2 the Flat-

fish ; .v ventral finsformed into a su


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50 NATURAL HISTORY. [Lesson IX.rows, like the teeth of a comb, are arrangedin small rounded tufts ; the body is coveiedwith hard plates instead of scales ; the jawsare united, except at the very end, so thrtthey appear to have a tubular snout ornose, especially in the sea-horse ; and themale is provided with a pouch, in whichthe female deposits the spawn, where theyoung are hatched, and retreat whenalarmed.

119. T. What is the sixth order of theBony Fishes called?

P. PLECTOGNATHI, or fishes with sol-dered jaws; so named because the bonesof the jaw are immovable. The gills andgill-covers have a covering of thick skin.120. T. What is meant by CHON-DROPTERYGII ?

P. Fishes with cartilaginous, insteadof bony skeletons.121. T. What is the first order of this

division called?P. CHONDROPTERYGII BRANCHIIS LI-

BERIS, or fishes with free gills, such assturgeons.

1 22. T. What is the name of the secondorder ?

P. ClIONDROPTERYGII BRANCHIISFIXIS, or fishes with fixed gills. Thesefish have the edges of the gills fixed, insteadof being free at the edges, and the waterenters through a number of small holes oneach side of the head, as in the shark tribe.

GENERAL QUESTIONS ON LESSON VIII.1. How are fishes divided ?2. What is the most important object toattend to, and guide us in the classificationof fishes ?3. How are the young of fish and the

species reproduced ?4. What do you mean by spinous rays ?5. What is the ray of a fin ?6. How many orders of Bony Fishes arethere? Name them.7. Explain the meaning of the variousterms applied to each order ?8. Give some examples of each order ?9. How many orders of Cartilaginous

fishes are there?10. Name the orders, and their pecu-

liarities ?

LESSON IX.WE have now to consider the second great division of the Animal Kingdom theAMMALIA MOLLUSCA, or soft-bodied animals. These animals present many pecu-

liarities, being without an articulated skeleton, or back-bone, and without brain orspinal marrow. Their blood is of a bluish tinge, or white ; and their muscles areattached to the integuments instead of to bones. Cuvier says, " that their organs ofmotion and of the senses have not the same uniformity in number and position as inthe vertebrated animals; and the variety is still more striking with the viscera, par-ticularly in relation to the position of the heart and respiratory organs, and even in thestructure and nature of the latter ; for some mollusca breathe the free air, and othersthe fresh or salt water." Some of the molluscous animals have naked bodies, whileothers are protected by shells. Cuvier divided the molluscous animals into six classes,which we have now to examine.

123. T. What Ismolluscous animals?

P. The CEPHALOPODES,footed animals.

QUESTIONS,the first class of

or head-

124. T. Why are they called thus ?

P. Because the animals in this classpropel themselves by means of appendagesconnected with the head.

125. T. Name some examples of thisclass of animals.


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Lesson IX.] NATURAL HISTORY.P. The nautilus, and cuttle-fish.[The pupil should name the peculiarities ofboth these example*.]126. T. Wh.it is the second class called ?P. PTEROPODES, or fin-footed animals.127. T. State the peculiarities of thisP. Cuvicr says that, like the cepha-

lopodes, they " swim in the ocean, but canneither fix themselves to any object, norcrawl on the ground, because they arewithout feeL They move from place toplace by means of tins, placed like wingson each side of the mouth."

128. T. Name the third class.P. They are called GASTEROPODES, oranimal* that move on their stomachs, such

as snails and .-lugs.T. State something more about

this class.P. It is divided into nine orders,

containing many species, some of whichare entirely naked; others have a concealedshell ; but the greater number a completecovering as snaiK, which shelterfrom the .vt .( kx of other animals. Mostof those that live in the water have anoptrctilum, or little door, attached, whichprotects the animal when it has retreatedwithin the -

130. T. What animals with shells ared in this class ?

/'. ! : I ivalvft; or mollus-cous animals with shell* in one \ .

do you call the fourthelass?P. ATI. IMI u.rs. or animals withoutheads. Thin is n-*' rcct, as theyhave heads.

T. Give me an example of this-, mussels, and all bivalve

oca.133. 7*. What do you mean by bivalve

Soft-bodied animals, with shells intwo pieces,mny orders are tl

/' IA i. .irrpkalaUttactai and 2,Acrphnln nn,in

7'. What is the difference 1

P. The former have protecting shells;and the latter are naked, or without shells.136. T. What is the name of the fifth

class of the Mollusca?P. BRACHIOPODES, or animals with

arm-feet ; but we do not know much aboutthem, except that they have two fleshyarms, furnished with numerous filaments,which they can protrude from and drawwithin the shell when they please; themouth is situated between these arms.137. T. What is the sixth class called ?P. CIRRHOPODES, or animals with hair

feet, like the barnacles (Lrpat), which at-

tnrh thnmclves to ships and posts by longfleshy M. ms In c \^ class we also have

in-shells (balantu). The principalpart of the shell consists of a haiwith sn opening at the narrower pai .or leas closed by two or lour valves.

KAL QUESTIONS ON LE89O1 Vfhatbl ft he second great

n of the uniinal IV- Bunch of LtjMuAt

to part of a j.ir.


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5-2 NATTRAL HISTORY. [lesson X.2. I low do the Molluscous animals differ

from the Vertebrate ?o. Name the \arious classes of Mollusca.4. (Jive examples fro-ii each class.5. State the peculiarities of the Mollus-cous animals.

i. What is tin- meaning of the termsapplied to each class .'

7. What is an ti/ii'rculuni ?8. Kxplaiu uli.it is meant hy a univalveand bivalve.

LESSON X.EACH great division of the Animal Kingdom presents some generality of form. We

have observed the peculiarities of the first t\\o divisions, and we have now to noticethose presented by the third ANIMALIA AKTICULATA, or animals with articulatedbodies. That great naturalist, Cuvier, observed that "this third general form is aswell characterised as that of Vertebrata ; the skeleton is not internal, as in the latter;neither is it wanting, as in the Moliusca. The articulated rings which encircle thebody, and frequently the limbs, supply the place of it ; and as they are usually hard,they furnish all the necessary support for the muscles by which the body is moved ;so that among the animals, as is the case of the Vertebrata, those which have limbsare able to w.tlk, to s^im, or to Hy. Thus they have some general resemblance, moreparticularly in their internal organisation, although in most respects they differ fromeach other to the utmost degree."

QUESTIONS.138. T. In what respect do all articu-

lated animals resemble each other most?P. In their nervous system.MO. T. Is there anything peculiar

in it ?P. Yes, the brain, which is very small,

///. 14.

is placed over the oesophagus or gullet, and* t'iy. H. Nervoua iyiniof Carubus Clftibnt-

..MII! the ci.Hiii of g;iii;:ll;i Connected bydouble chord.

supplies nerves to all the parts near to thehead, and two chords whi'-h encircle the; oesophagus are continued along the abdo-1 men, and connected at intervals by ganglia,j

from which the r.ervcs are sent to thevarious parts of the body and limbs.

j140. T. What oflice does a ganglion

perform ?P. It seems to act like a brain, con-

ferring sensibility on the parts with whichit is intimately connected.HI. T. Are there any other pecu-

liarities to be observed in the Articulata .'/'. Yes, their jaws arc invariably lateral,and shut together like a pair of scissors

that is, horizontally, and not upwards anddownwards ; and besides this, we observethat they have not any distinct organ ofsmell.

142. T. How are the articulated ani-mals classed ?

P. Into four principal classes ; 1. TheANNELIDES, or red-blooded worms. 2. TheCRUSTACEA, or hard-coated animals ; 3.'l ^ AEACHDA, r animals like spiders ;4. The INSECTA, or insects.


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Lesaon X.] NATfUAL HISTORY.1 13. T. Why have the Annelides been

separated from (he other three classes ?P. Because they have red blood, and

are the only invertebrate animals that have.The circulation is douhle, consisting ofarteries and veins; almost all of them livein water, except the earth-worms. Thebody, which is more or less elongated, isalways divided into little rin^s, whencethe name (the Latin word annetltu signify-ing a little rinp), and they respire bywhich are either spread over theof the body, concealed internally,

ioped externally.m. T. How are the Annelides di-P. Into three order*, the first of which

is called the Tt'Blcot^E, or worms inhabitingtubes. Some of these animals form tubesof fragments of shells, sand, and mud,which are lined by a membrane; othersform an uniform calcareous tube ; and o:h< rshave their tubes composed of membraneonly.

T. What is the name of thesecond order ?

/' The DORSIBRANCIIIATA.- ime their peculiarities./'.They have their bronchia or gills

distributed about the body, espe-cially the middle portion. The Arhave beautiful little gills in tufts upon the

middle part of ti ry fifth ringlarger than the others, and the feetand gills attached to it. In the same or-der we have the Nereids, and many other

1 curious and interesting genera.

1 17. 7' -\\ h t is the name of the thirdorder of Annelidrt fABHANCHIA. This order of animals

is destitute of external respiratoryand they M-CIM tsurface of the skin, or, a* in the letc

intern*! some have bristles,jand others ar. f them, they

moving. I di.-idnl into t --\^fffmlm Contorlnplicata, with a portion of the body protrudtd from UM

* tub* of *nd n I fr.imrnt of (hells.4. \l. ArrnKoin fUcatotmm, . \ lul


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54 NATURAL HISTORY. [Lesson XI.148. T. What are these two families ?P. The ^bronchia setigera, providedwith silky bristles, as the earthworm

Fig. IS.*tribe ; and 2, the Abranchia nuda, or the^bronchia without bristles, such as the leechtribe.

C.I.XF.RAL QUESTIONS ON LESSON X.1. What is the name of the third greatdivision of the Animal Kingdom ?2. What are articulated animals ?3. How many classes of articulatedanimals are there ?4. Describe the peculiarities of the first

class, and give examples of each order andfamily?

5. Why have the Annelides been se-parated from the other classes ?

b'. Is there anything peculiar in thenervous system of the Articulata ? If so,state the peculiarity.

LESSON XLLINNJEUS classed the Crustacea, Aractmida, and Insecta together, under the generalname of Insects ; but other Zoologists have thought

proper to divide them. The second class of articulatedanimals is, properly speaking, the crustaceous or hard-coated animals. They have a great many genera andspecies, articulated legs, respire by branchiae, or a kindof gills, sometimes enclosed, and in other speciesexternal to the shell ; the circulation is double, andresembles that of the Molluscous animals; and thenervous system is of two kinds, which will be noticedin another Catechism.

QUESTIONS.149. T. How are the Crustacea divided?P. Into the MALACOSTRACA and ENTOMOSTRACA.150. T. Describe the peculiarities of the former.P. The shell of the animals is hard and calcareous;

they have ten or fourteen legs, hooked at tlie tip ; andsome have fixed eyes, while others have theirs placedon a moveable piece.

151. T. What is there peculiar in the seconddivision ?p._The shell is slender, and generally in two parts ;the eyes are fixed, and frequently there is only oneof these organs. The legs vary in number, have onlyone hook at the extremity, and appear more suitedfor swimming than anything else.

d

distributed

* Fig. 18. ffirudo nflicinalis, or leech.t Fit. 19. A vertical longitudinal section of the common

lobtter (AstacHs marinus). a. mandibles and palpi ; b, theotoinach ; c c, intestinal prolongation of the same ; d, the outlet;e, the heart ; / g h i. a system of KI eat blood-vessels distributed to19-t the posterior portion of the animal ; kl m, great blood-vessels

to the sternal or anterior aspect of the body; n n n, lobes of the liver.


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XIL] NATURAL HISTORY. 55T. How many orders are there in

the first division ?p._Five. The first is called Decapoda

or ten-footed, all of which have ten feet,furnished with nippers; and the commonlobster, which is included in the secondfamily, is an excellent example of the order.

153. T. What is the name of thesecond order?

P. There is very little of interest in thesecond, third, fourth, or fifth orders, whichare called Stomopoda, Amphipoda, Lcemo-dipoda, and Itopoda.

T. How is the second division ofa divided ?P. Into the Branchiopoda and Pcecilo-

poda, which have each certain peculiarities.T. What is the third class of

latafP. The Arachnida, or spiders.

ite the peculiarities and rea-sons why they have been classified bythemselves.

P. They are destitute of wings, do notundergo any changes of form like insects,and differ in their nervous system.

157. r. Howare they divided ?

P. Into two.orders. 1. T'.ietrue spiders andscorpions, and 2,The Miiall animalsknown as

scorpions, such as the book-scorpion, andthe mites.GENERAL QUESTIONS ON LESSON XI.1. How are the Crustacea divided?2. Describe the peculiarities of each

division, and give examples from them?3. Name the various orders of each

division, and the reason they are dividedfrom the others ?4. How is the Arachnida, or third class,

divided ?5. Give examples from each order?

LESSON XII.Tiir. fourth class comprises those creatures called Insects whose peculiar and beautiful

form, colour, and instincts, have captivated all enthusiastic naturalists. In a treatiselike this, we can only take a glance at them a mere transient glance. They undergovarious changes during their brief existence, wonderful to behold, and yet \\man's existence and future state. They are divided into twelve orders, each charac-terised by C- .. here, but will be particularised inthe Zoological Catechism.

QUESTIONS.r. What iniects are f

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