30 Proceedings of the American Philosophical Society. 



York, 4h. 56m. 3.7s. Mr. Paine, in the American Almanac, makes the 

 same 4h. 56m. 4.5s. ; and Mr. E. I. Dent, by transportation of four chro- 

 nometers from the Greenwich observatory to New York, and again to 

 Greenwich, finds for the same 4h. 56m. 4.42s. The mean of the three 

 determinations is 4h. 56m. 4.2s. 



March 6. — Mr. Saxton exhibited additional medals obtained by the 

 galvanic process of Prof Jacobi; and likewise pieces of charcoal and 

 anthracite, which he had used as substitutes for the forms of fusible me- 

 tal ordinarily employed. These were perfectly coated with copper, a 

 fact which shows it to be but necessary, that the substance at the nega- 

 tive electrode should be a conductor of electricity. 



March 20. — The committee, consisting of Prof Henry, Dr. Patterson, 

 and Mr. Walker, to whom was referred a paper entitled, "Observations 

 of the Magnetic Intensity at twenty one Stations in Europe, by A. D. 

 Bache, LL. D., President of the Girard College for Orphans, d&c," re- 

 ported in favor of the publication of the paper in the Society's Transac- 

 tions. The report was adopted, and the publication ordered accordingly. 



Ths stations at which the observations recorded in this memoir were 

 made, were twenty one in number : three in Great Britain, and the others 

 on the continent of Europe. They include Edinburgh, Dublin, London, 

 Brussels, Berlin, Paris, Vienna, the Flegiere, Brientz, the Faulhorn, Ge- 

 neva, Chamberi, Chamouni, Lyons, Milan, Venice, Trieste, Florence, 

 Turin, Rome and Naples. The author remarks, that the magnetic dip 

 and intensity are so well known at some of these places, that he produces 

 his results for them in order that by comparison with those of other ob- 

 servers, the value of his determinations for other places may be judged 

 of The observations were of the horizontal intensity and dip, except 

 in the comparison of the intensities at London and Paris, where, in addi- 

 tion, the statical method devised by Prof Lloyd was used. At three of 

 the stations the dip was not observed. The horizontal intensities were 

 generally compared by oscillating two different needles in a rarefied me- 

 dium, according to the method described by the author in a former paper, 

 (Am. Philos. Society's Transactions, Vol. V.) At London and Paris two 

 additional needles were employed. The dip was observed in the usual 

 way, with an instrument by Robinson, by whom also the needles for 

 Prof Lloyd's method were made. The corrections required for tempera- 

 ture in the horizontal needles had been previously obtained. The cor- 

 rection for loss of magnetism by the needles, was ascertained from obser- 

 vations at Philadelphia, London, and Paris, and curves traced represent- 

 ing the loss, from which the specific correction, to be applied at any epoch, 

 was readily obtained. The curve for one of the needles showed a ten- 

 dency towards a permanent state, and for the other was nearly a straight 

 line. Irregular changes took place in neither needle. The author's 

 experience with these needles, induces him to give a preference to the 



