SCIENCE. 



[Vol. XVI. No. 40 r 



battery. The magnet was made by Mr. Nesbit. . . . The 

 greatest weight sustained by the magnet ia these experi- 

 ments is 12f hundredweight, or 1,386 pounds, which was 

 accomplished by sixteen pairs of plates, in four groups of 

 four pairs in series each. The lifting power by nineteen 

 pairs in series was considerably less than by ten pairs in 

 series, and but very little greater than that given by one cell 

 or one pair only. This is somewhat remarkable, and shows 

 how easily we may be led to waste the magnetic powers of 

 batteries by an injudicious arrangement of its elements."' 



At the date of Sturgeon's work the laws governing the 

 flow of electric currents in wires were still obscure. Ohm's 

 epoch-making enunciation of the law of the electric circuit 

 appeared in " Poggendorf s Annalen "' in the very year of 

 Sturgeon's discovery, 1825; though his complete book ap- 

 peared only in 1827, and his work, translated by Dr. Francis 

 into English, only appeared (in Taylor's '"Scientific Memoirs," 

 vol. ii. ) in 1841. Without the guidance of Ohm's law, it 

 was not strange that even the most able experimenters should 

 not understand the relations between battery and circuit 

 which would give them the best effects. These had to be 

 found by the painful method of trial and failure. Pre- 

 eminent among those who tried was Professor Joseph Henry, 

 then of the Albany Institute in New York, later of Prince- 

 ton, N.J., who succeeded in effecting an important improve- 

 ment. In 1828, led on by a study of the " multiplier" (or 

 galvanometer), he proposed to apply to electro-magnetic 

 apparatus the device of winding them with a spiral coil of 

 wire "closely turned on itself," the wire being of copper 

 from one-fortieth to one-twenty-fifth of an inch in diameter, 

 covered with silk. In 1831 he thus describes^ the results of 

 his experiments: — 



"A round piece of iron about a quarter of an inch in 

 diameter was bent into the usual form of a horseshoe; and 

 instead of loosely coiling around it a few feet of wire, as is 

 usually described, it was tightly wound with 35 feet of wire 

 covered with silk, so as to form about 400 turns. A pair of 

 small galvanic plates, which could be dipped into a tumbler 

 of diluted acid, was soldered to the ends of the wire, and the 

 whole mounted on a stand. With these small plates, the 

 horseshoe became much more powerfully magnetic than 

 another of the same size and wound in the same manner, by 

 the application of a battery composed of 28 plates of copper 

 and zinc, each 8 inches square. Another convenient form 

 of this apparatus was contrived by winding a straight bar of 

 iron, 9 inches long, with 35 feet of wire, and supporting it 

 horizontally on a small cup of copper containing a cylinder 

 of zinc. When this cup, which served the double purpose 

 of a stand and the galvanic element, was filled with dilute 

 acid, the bar became a portable electro- magnet. These 

 articles were exhibited to the institute in March, 1829. The 

 idea afterwards occuiTcd to me that a sufficient quantity of 

 galvanism was furnished by the two small plates to develop, 

 by means of the coil, a much greater magnetic power in a 

 larger piece of iron. To test this, a cylindrical bar of iron, 

 half an inch in diameter, and about 10 inches long, was bent 

 into the shape of a horseshoe, and wound with 30 feet of 

 wire. With a pair of plates containing only 2^ square inches 

 of zinc, it lifted 15 pounds avoirdupois. At the same time a 



' Sturgeon'3 Seientlflc Researches, p. 188. 



2 Silllmaa's American Journal of Science, Jauuarj-, 18)1, x\x. p. 400. 



very material improvement in the formation of the coil sug- 

 gested itself to me on reading a more detailed account of 

 Professor Schweigger's galvanometer, which was also tested 

 with complete success upon the same horseshoe. It consisted 

 in using several strands of wire, each covered with silk, in- 

 stead of one. Agreeably to this construction, a second wire, 

 of the same length as the first, was wound over it, and the 

 ends soldered to the zinc and copper in such a manner that 

 the galvanic current might circulate in the same direction 

 in both ; or, in other words, that the two wires might act 

 as one. The effect by this addition was doubled, as the 

 horseshoe, with the same plates before used, now supported 

 28 pounds. 



"With a pair of plates 4 inches by 6 inches, it lifted 39 

 pounds, or more than fifty times its own weight. 



" These experiments conclusively proved that a great de- 

 velopment of magnetism could be effected by a very small 

 galvanic element, and also that the power of the coil was 

 materiallj' increased by multiplying the number of wires 

 without increasing the number of each." ' 



NOTES AND NEWS. 



The well known writer on vegetable paleontology. Professor 

 E. Weiss of Berlin, died on July 5 last. 



— The annual meeting of the American Folk-Lore Society will 

 be held Nov. 38 and 29, 1890, at Columbia College, New York. A 

 Ijreliminary meeting for the purpose of organizing a local com- 

 miltee of arrangements was held at Rooai 15, Hamilton Hall, 

 Columbia College, 49tli Street and Madison Avenue, on Wednes- 

 day, Oct. 8, at 4 p.M 



— We learn from the Medical and Surgical Reporter of Oct. 4 

 that there were registered in the second tiimester 908 foreigners 

 who were studying medicine in France, of whom 822 were in 

 Paris. Of the latter there were, from Russia, 361; the United 

 States, 159; Roumania, 85; Turkey, 71; England, 51; Spain, 34; 

 Greece, 34; Switzerland, 35; Servia, 20; Portugal, 18; Egypt, 13; 

 Italy, 13; Bulgaria, 8; Austria, 7; Belgium, 7; and Holland, 60. 



— By the death of Professor Carnelley the science of chemistry 

 in England has suffered an irreparable loss. It appear.*, as we 

 learn from Nature, that some little time ago Dr. Carnelley had 

 been suffering from an attack of influenza, and it was while re- 

 turning to Aberdeen after a journey to the south, made with the 

 object of reoniiting his health, that he was seized with sudden 

 and severe illness, which was due, as his medical attendants dis- 

 covered, to the formation of an internal abscess. Surgical aid 

 proved unavailing, the patient's strength gradually gave way, and 

 Dr. Carnelley passed away at mid-day of Aug. 27, at the compara- 

 tively early age of thirty-eight. 



— The report of Dr. Eitel, inspector of schools in Hong Kong, 

 for the past year, contains some interesting details. According to 

 Nature, the total number of educational institutions of all descrip- 

 tions, known to have been at work in the colony of Hong Kong 

 during the year 1889, amounts to 211 schools, with a grand total 

 of 9,681 scholars under instruction. More than three fourths of 

 the whole number of .scholars, viz., 7,659, attended schools (106 

 in number) subject to government supervision, and either estab- 

 lished or aided by the goveinjment. The remainder, with 3,023 

 scholars, are private institutions, entirely independent of govern- 

 ment supervision, and receiving no aid from public funds. The 

 total number of schools subject to direct supervision and annual 

 examination by the inspector of schools amounted, in 1389, to 104, 

 as compared with 50 in 1879, and 19 in 1869. The total number 

 of scholars enrolled in this same class of schools during 1889 

 amounted to 7,107, as compared with 3,460 in 1879, and 943 in 

 1869: in other words, there has been an increase of 31 schools and 

 3,518 scholars during the ten ytars from 1869 to 1879, and an in- 

 ' Scientific Writings of Joseph Henry, p. 39. 



