408 



Proceedings of Learned Societies, 



[April, 



netic poles he conjectures, from similar 

 data, is in the Nortliern Ocean, and that 

 its position, in 1770, was 4° 11' from tiie 

 pole of the earth, and in longitude 

 101° 29' 30" E. ; and that it has a mo- 

 tion from west to east, amounting to about 

 25' per annum. — Philosophical Journal. 



While on this subject, we may add that 

 the explanation which was given by Mr. 

 Babbage of the magnetical phenomena de- 

 scribed by M. Arrago, has received the 

 strongest confirmation ; as in numerous ex- 

 periments recently instituted by the first 

 of these gentlemen, it has been found that 

 the same appearances take place from 

 electricity which he was led to point out as 

 probable, if the cause which he assigned for 

 the magnetical jihenomena were correct. 



Electro- Chemical Metal Preservers. — In 

 a paper by Sir H Davy in the last part of 

 the Philosophical Transactions, it is men- 

 tioned that, independently of the chemical, 

 there is a mechanical wear of the copper in 

 sailing, which on tlie most exi)osed part of 

 the ship, and in the most rapid coiu'se, 

 bears a relationtoit, ofiiearly2 to 4.55. As 

 the result of actual experiment, as to the 

 electro-chemical means of preserring the 

 copper sheathing of vessels, the President 

 is led to conchide, that the proportion of 

 protecting metal should be from l-90th to 

 l-70th ; that the most advantageous way 

 of applying protection, will be under and 

 not over the copper : the electrical circuit 

 being made in the sea- water passing tlirough 

 the places of junction in the sheets; and 



in this way, every sheet of copper may be 

 provided with nails of iron or zinc for pro- 

 tecting them to any extent required. By 

 driving the nail into the wood, tlirough 

 paper wetted with brine above the tarred 

 paper or felt, or any other substance that 

 may be employed, the incipient action will 

 be diminished ; and there is this great ad- 

 vantage, that a considerable part of the 

 metal will, if the protectors be placed in the 

 centre of the sheet, be deposited and re- 

 dissolved : so there is reason to believe, 

 that small masses of metal will act for a 

 great length of time. Zinc, in consequence 

 of its forming little or no insoluble com- 

 pound in brine or sea-water, will be prefer- 

 able to iron for tliis purpose ; and whether 

 this metal or iron be used, the waste will 

 be much less than if the metal were exposed 

 on the outside, and all difficulties with 

 respect to a proper situation in this last 

 case are avoided. The copper used for 

 sheathing should be the purest that can 

 be obtained, and in being applied to the 

 ship, its surface should be preserved as 

 smooth and equable as possible ; and the 

 nails used for fastening should likewise be 

 of pure copper, and a little ditference in 

 their thickness and shape will easily com- 

 pensate their want of hardness. In vessels 

 employed for steam navigation the pro- 

 tecting metal can scarcely be in excess, 

 as the rapid motiop of these ships prevents 

 the chance of any adhesions ; and the wear 

 of the copper by proper protection is 

 diminished more than two-thirds. 



PROCEEDINGS OF LEARNED SOCIETIES. 



DOMESTIC. 

 ROYAL SOCIETV. 



The following papers were read on the 

 2d of February ; " Observations on the 

 magnetizing power of the more refrangible 

 rays of light," by Mrs. Mary Somerville, 

 communicated by William Somerville, m.d., 

 r.R.s. ; " Commencement of a jiaper, on the 

 action of Sulphuric Acid upon Napthaline," 

 by M. Faraday, Esq., f.r.s. 



Feb. 9th. — The reading of Mr. Faraday's 

 paper was continued. 



16th. — Mr. Faraday's paper was con- 

 cluded ; and a paper was also read, " On 

 the circle of nerves which connects the 

 voluntary muscles with the brain," by 

 Charles Bell, Esq., f.r.s.e. 



LINN^AN SOCIETV. 



Feb. 6tb. — " A paper was read on the 

 Plectrophanes Lapiwnica, a species lately, 

 discovered in the British Islands," by Pri- 

 deaux John Selby, Esq., f.l.s., m.w.s. 

 Ed. &c. Read also, " Some account of a 

 collection of Cryptogamie Plants formed in 

 the Ionian islands, and brought to this 

 country by Lord G\iiIdfor(l," by Robert 



Kaye Grerille, li.-d., f.r.s.e., &c. Among 

 the species described in this paper the 

 followmg are new : Byssoideae, Gastromyci, 

 Algse, Fucoideae, Musci. 



21st. — The reading of Dr. F. Hamil- 

 ton's " Commentary on the Hortus Ma- 

 labaricus. Partiv," was begun. 



HORTICULTURAL AND AGRICULTURAL 

 SOCIETY IN JAMAICA. 



On January 10th, 1825, a society wa.s 

 established in Jamaica for the encourage- 

 ment of Horticulture and of Agriculture, 

 and of the Arts connected with them ; the 

 first, we imderstand, that has yet been 

 formed in the British West-Indies. The 

 following is a list of the officers and council 

 of this society -. 



Patron ; His Grace William, Duke of 

 Manchester, &c. &c. — President, Edward 

 Nathaniel Bancroft, m.d.. Fellow of the 

 Royal College of Physicians, &c- — Vice- 

 Presidents, Honourable John Mais, and 

 Samuel Murphy, Esq. — Treasurer, Robert 

 Smith, Esq. — Secretary, John Miller, m.d. 

 — Honorary IMembers of the Council, The 

 Right Reverend the Lord Bishop of Ja- 



