Observations for Proving the Going of Mr. Ellicott's Clock, at St. Helena; by Mr. CharlesMasonAuthor(s): Charles MasonSource: Philosophical Transactions (1683-1775), Vol. 52 (1761 - 1762), pp. 534-539Published by: The Royal SocietyStable URL: http://www.jstor.org/stable/105664 .

Accessed: 25/06/2014 09:55

Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at .http://www.jstor.org/page/info/about/policies/terms.jsp

.JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range ofcontent in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new formsof scholarship. For more information about JSTOR, please contact support@jstor.org.

.

The Royal Society is collaborating with JSTOR to digitize, preserve and extend access to PhilosophicalTransactions (1683-1775).

http://www.jstor.org

This content downloaded from 91.229.229.162 on Wed, 25 Jun 2014 09:55:34 AMAll use subject to JSTOR Terms and Conditions

EXSXXJ0f ObAervvtions for provzng tbe Ga- iozg of f. Ellicott's Clock, at. St. Helena; by Mr. Charles Mafon.

ttad May 6} T N my rettlrn from the cape of Good I'62 1 Hope, the clock, uSed in the obServa-

tions made there, was fet going at Janles's fort, St. iTel^na, tlzv pendulum remainillg as at the Cape. Here I follud mySelf at a grseat lofs, to get obServa- tions to pl'0\Je sts motlon) the heavens belng almoR pe>rpetually covered with clouds. At length? conil- leting, that the place being fltuated in fuch a narrow deep valley, if the times of the deScent of the Itars, over the- F-eLlern ridge of rocks, (the altitude of WhoSe neaveLl fummit was about 3o°, and diRant about a quarter of a mile, at the obServatory) were ob- fcxved, it would give the time per clock, in a f1dereal day ; and the chances for fuch obServations would be greatera than by asly other method, as they might be .convinued the whole night. Accordingly, I began to obServe, by fixing the eye to a point: but this was foon improved) by the Reverend Mr. Maikelyne, by making the {lars defcend each rlight, in the fame part of the telefcope of the eqllal altitude inArument: atld it was srery beautiful to fee, how inRarltaneouily they difappeared.

The difference of the eicA of gravity at tlze wro places3 on the going of the clock, may be feen, by cotnparing the follon7ving with the obServations alade at the C8ape

l76I.

[ 534 ]

This content downloaded from 91.229.229.162 on Wed, 25 Jun 2014 09:55:34 AMAll use subject to JSTOR Terms and Conditions

tt

- . t

5 Stars of thc fXr#+ BecxindJ I or third magnitude, dcw I fcended thc hill, or raX iS tbe tidge of a keen ex t tenGte rock, that forms ,J one {}dc of the ralleyi

} Per Mr Mafkelync

Stan d-eScendedW

{IPE Mr. Mai1elyne4

l

Oftob. b 31.

Nov. S

e 6.

@ 8.

a 9.

@ IO

0 I5.

22 IT I0s 47 5

I 16 +

s7 l2x 23 T 57

573 e p

57X3

f ,

S73 r f g

57*7 r f

57*4

-

-

-

-

-

Z,ZZ

:

[ 535 ] Obfiervations of the Prom thc famc tter " bcmeassfthe ormp46 togetber. t-eEfurvatbnsD

thc clock loSc of fiderial w time per dar.

rimeperclsk. 176I.

h

I

2X

48 2

58 Star

-

Star - +. -

_

_ _.

_ _

_ _

fr - _ _

_ _

" _

*- _ _

_ _

. _ _

-_ _

jp _ _ ;

_ b

_

I4 -

_ _

a-

a

e

f

h i

-

-

2I 4 I2 21 57 57s

+ -22 IO . 50

54 f3 o

22 8 T2 48

SZ

34

48 4w

so

6 8

49 +

2s to 46

56 23 t

X IS AX wr

s6

3 * 5§ - g I

-

v

_ 3o + It -

' 4-F v

:

Vo ;. LII. 761.

This content downloaded from 91.229.229.162 on Wed, 25 Jun 2014 09:55:34 AMAll use subject to JSTOR Terms and Conditions

- -

h

536 Ol)fervations of the From thc fame letter to be mean of the col'npared together. obfervations,

the clock loSes of fiderial time per day.

I 76I. Time perclock.

Nov. } I6.

% I9.

Dec. 3

b 5

<3 6.

9

2 4I

44 5o 55

8 +

33 - 9

_

Star _ _

_ _

_ _

Sr -

_ _

_

f

h

h 22 4t 40 47 36tz 52 2tI

575

r

-

*

bt s

7 Thefe ate a i*¢t of diMereDt > flars, the others defcendw j ing in thc daylight.

23 45 so

51 52

53

44 44^ 10 -

I9

42

_ _ a b

c

_ d e

_ e 594

59@ I 23 SI 43 +

-

23 42 47 48 49

47 - 47 I2 +

a b

d e

5o44 + This day I difcoveled the wedges behind the clock, which was

put to make it flcand perpendicularX were loofe; {hrunk, I fuppofe, by the drynefs of the place. Auaere, If this vvas not the cauSe of the above diffierence.

The wEedges being again SecuredZ

O 13.

R tS

O I7 5: * 26 16 - -

O I5 7: * _ 24 zo - -

- g

.

- 2

g

g

| Thefe are different > fiars.

J Pex Mr. MaSkelynes

59*o 1761s

This content downloaded from 91.229.229.162 on Wed, 25 Jun 2014 09:55:34 AMAll use subject to JSTOR Terms and Conditions

-

-

[ 537 ] Obkrvations of thc From thc famG letter to be mean of thc compared together. obfervations, * - the clock loSis

of fiderial time per day.

t76t. lTimeperclock

k

r z

k

, I $,

m

n-

o

I m

n

o

I m

o

// s

S8*85

58.4

59.o

Dec. 3! ,6.

X 17.

b 19,,

O zo.

t 22.

I762. Jan.

& sw

0 2I

3 4

o zo 22

3

o 49 55

I s I 9

o 48

54 I I

8

o 46 52

I 6

//

47-: I 46

47 + 2

47 +

3I 21 +

s6W I 4aF

Star _ _

.

_ _

wr -

_

_ _

* _

_ . _

_ _

e _ _ _

_ _

_ _

Jj + - _ _

S _

33 23 + 8 ISX

35 + 25 - I8 -

I Per Mr. MaIkelyne.

J

It on, to ffiew the de- tes.

The cloclc was fropped, and an arch pu grees and minutes the pendulum vibrat

§ 6.

9

The apparent zenith- d;Rance of Aldebaran upon the meridian = 3I° 55' 2.o".

I 49 55 * _ _ p 52 3t + Archarnar q 55 27 + _ _ _ r

z 8 z8 _ _ _ pR f The pendutum vibra* 6 422 0 _ ^ _ _ _ - t ° 37t on each fidc d

t thc pctpcadicular. 58n4 sxs z

l762#

This content downloaded from 91.229.229.162 on Wed, 25 Jun 2014 09:55:34 AMAll use subject to JSTOR Terms and Conditions

: - - - - 5

[ 538 ] Obfersations of the From the faine letter to be mean of the coniparZd together. obServations,

the clock lofes of Jiderial time per day.

. .

Jan t) I0.

X II.

*§ I3;

762 Time perclock-

X lt

S9*o

.

5991

58t6

s849

h

2

s

48

5I

SA

7

56 32t- 295 3o

o

8

Star - _ Archarnar

, _

t _ _s

_ _ _

p q r

' - Vibration

* t F

F 34 °

Dkto - 2 34 4 56 o

I4 47 t

245 53 Dilato _ 2 55 t Per Mr..Makelyne..

O z ,,

V;bratton 2 S4 ° I6 20

4

3 4° 44

I6 39

3 39 43 51

4 23

I6 IX

3 9 16

37 4I

4 al

o

s 36 42

-

w7l

-

-

:

:tto

;

DittQ

- - - -

ip - - P

- - - 2;

- - b - y

<. a

_. _. _ _

- 2 59 o

- X 5t ¢

o

37 43 35 + 47

g Xs

k I6.

O 17v

X s8s

r

-

s

313 o

46 38 SQ

- - t

_ s t - - -U 1

_ - Z

_ _ y

_. a

_ _ _ Z

lPet Mn Matelyne

1 ° mIbratloh 2 5:3 Q t5 38 °

i 5t ° I3itto - 2 55 o

l762¢

This content downloaded from 91.229.229.162 on Wed, 25 Jun 2014 09:55:34 AMAll use subject to JSTOR Terms and Conditions

- - l: - l-

[ 539 ] ObSctvations of the From the fame letter to be mean of thc compared together. obServations

the clock Io;es of fiderial timc per day.

x76:. {Timeperclock.

* t t!

Yibration 2 58 o

Ditto - 3 4 o .

.

Ditto - 3 z o

Jan. t I9.

" 20.

% kI.

.

h r r

I 59 o

3 -s o 2 36k

3 4 II

32 4 I 4 4Q

2 35 3 3

IO 3I

4 o 5

4 5o

Star _

_ _

_

_

b Sr -

_ _

_ _

_

_ . _

..

5 o

38w 46 I4

o

6 + II -

39 47 + I5

57 -

s

t U

W

-

s

t

W

a

59.o

Ditto - 3 3t o

The-cloclc talren down, and the pendulum fecured, as at.the cape of GQod Hope, aft¢r tha diredclon given per Mr..Ellicott;. the maker.-

From the mean of a great num- 5 ber of obfervations,.takentat f November 68.7 5 from x sth different timesofthedayand in 4 December 70.3 > to nit, Fatenheids thernw | tvuary 7z.3J the I8th meter dcoud- at - - - - J

The tbermometer was hung bv the gide of the clock, and t never faw it hgher (from l2,th of November x76t to January xN8ths 176Z) than 74Z or-Iower than 67.

b 3

Thofe obServatiuns ma*ked: are a little dubious.

CharIeus Mafoni

This content downloaded from 91.229.229.162 on Wed, 25 Jun 2014 09:55:34 AMAll use subject to JSTOR Terms and Conditions