358 .Mechanics, Physics, and Chemistry.

Summary of Abstracts of the Steam Logs of the U. S. Steamer Susquehanna. From June l,t, 1851, to March 31st, 1855~WlTrr OLD BOILERS.

l)ays. Hrs. Vsys.IHours./Days.lZ[ours Z)ays.lZ~rs. L~ ~ ~ ]~ = ~ 1~'~ I~ ~ ~1~ ~ t P- ~ I~ "~[~ ~ ,' ' ' i , , . ~ ® , . ~ z , ~ . 1 ~ - ~ ~ i ~

From May 1st to September3Oth, 1856--WITH NEW BOILERS.

From May 1st to J~ly 31st.

I 15 I I9 I It I t5 I 1 I I I it.4 I 11.3 [8'3 ] 2596 I 1.404 I 8715 :] I 8715

From August 5lh to September 30th. Frigate Congress in tow.

8[ 4 [ 84 I ] [ J I I I 1 2 I 11 [6.6 12860[ 318 ]124.8 [ [ 12~

Total average with "new boilers."

521 ]9 1 8~" I 18 I 15 I I I I I 11.3~ I al .25 1 s 1 2~'52 1 1722 19063 I [ 9963

By reducing these abstracts to one common standard of speed, by means of the ordinary rules applied for that purpose, with the view of obtaining the relative economy of fuel, and by taking the " logs" of the ship with "old boilers" as the basis of calculation, having special refer- ence to speed and coals, we obtain the following comparative results:

The performances of the ship under ordinary circumstances, (with the ship alone,) is found to be as 100 : 182, or 45 per centum in favor of the new boilers.

With the Frigate Congress in tow, it was as 100 : 87, or an expendi- ture of only 13 per cent. more fuel whilst the ship was performing dou- ble duty.

A general mean of performances with "new boilers," is as 100 : 134, or 25 per cent. in their favor under all circumstances (including time of towing, &e.)

The Atlantic Submarine Cable.*

The projected telegraphic communication between this country and the United States is of such vast importance, that any suggestions tending to its successful completion are worthy the consideration of the directors of the scheme.

The object of this letter is to draw attention to the probable effect of the immense pressure to which the insulated wire will be exposed when sunk in the Atlantic. Supposing the gutta percha coating to be perfect, no injury can be sustained by this pressure ; but in case of there being any "Mows" (air holes) that have merely a skin of gutta percha over them, the water under so enormous a pressure would soon find its w a y

to the wire and destroy the insulation, and so render the cable useless. Tlaue defects would not be perceived by ordinary testing, such as ira- tootling the cable in a few feet of water.

l'he plan of testing I should propose, is to construct large east iron • F r o m the Prac t ica l M e c h a n i c ' s J o u r n a l , Feb . , 1857.

Proceedings of the Franklin Institute. 359

tanks in which some hundred miles of cable can be placed, with stuffing boxes where the wire enters and leaves the vessel, and then subjecting it to hydrostatic pressure; the insulated wire to be connected through a galvanometer with one pole of a powerful intensity battery, and the iron of the tank, in which the cable is enclosed, with the opposite pole.

Chester, January, 1857. J . H .

Westley's Expanding Spikes.* Mr. William Westley, of Wellington, Derby, has patented the im-

proved nail or spike shown in the an- hexed engraviugs. The body of the nail or spike is split into two legs or fangs, a b, fig. 1, which are chamfered or bevel- ed at their ends, the said beveled ends constituting two edges, the inclined i:aces of which are turned towards each other. In driving the nail or spike into wood or other substance, tile wedge-shaped ends, in consequence of their inclined faces being turned towards each other, cause the two halves, a b, to open, in the manner represented in fig. 2, and thus fix themselves firmly in the material.

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* From the Lond. Mech. Mag., Nov., 1856.

F R A N K L I N I N S T I T U T E .

Proceedb~gs of the Stated .Manthly J~leeting, ./]pril 16th, 1857.

John Agnew, Vice President, in the chair. John F. Frazer, Treasurer. Isaac B. Garrigues, Recording Secretary. Letters were read from the K. K. Geological Society, Vienna ; Smith-

sonian Institute and the Metropolitan Mechanics' Institute, Washington City, D. C.

Donations to the Library were received from The Royal Astronomical Society, London ; K. K. Geological Society, Vienna ; L. A. H. Latour, Esq., Montrea/, C. E.; United States Coast Survey ; Prof. A. D. Baehe, Washington City, D. C.; Hon. Job R. Tyson, U. S. Congress ; Regents of the University of the State of New York ; State Lunatic Asylum, Al- bany, New York ; Academy of Science of St. Louis, Missouri ; C. M. Saxton & Co., New York ; Railroad Company, the Coal McKean & Elk Land and Pennsylvania Institution tbr C. Cresson, Dr. B. H. Rand,

Donations to the Cabinets

Philadelphia, Wihnington, and Baltimore Run Improvement and Railroad Comp.,

hnprovement Company ; Girard College ; the Blind ; Prof. John F. Frazer, Prot. J. and F. de B. Richards, Esq., Philadelphia. from Ellwood Morris, Esq., Cold Spring~