June 6, 1878] 



NATURE 



143 



A word in explanation of this strange appearance from some 

 of your learned contributors would, I think, be interesting. 

 Model School, Waterford, June i Henry P. Dowling 



Classes for Women at University College 

 ■ In view of the new charter enabling the University of London 

 to confer degrees on women, and the increased demand for a 

 higher education of women, the council of this college have 

 determined to provide for them systematic instruction in regular 

 college classes. 



In most subjects the junior classes for women will be distinct 

 from those attended by male students. The senior classes will 

 more generally be open to both sexes, and these classes, which 

 are already open to both, as fine arts, philosophy of mind, &c., 

 will remain so. 



Prospectuses embodying the results of this change will be 

 ready by the i8th inst. Talfourd Ely 



University College, London 



[Our St. Petersburg correspondent, " C. S." must send us his 

 name (in confidence), before we can publish his last communi- 

 cation.] 



PROF. JOSEPH HENRY, LL.D. 



p ROF. HEN RY was born December 17, 1 797, at Albany, 

 New York, where also much of his early life was 

 passed. The year of his birth seems, however, uncertain, 

 some authorities placing it in 1 799, or even later. He had at 

 first the advantages of only a common school education. 

 A parish library supplied him with boyish reading, and 

 his early tastes were in the direction of romance and the 

 drama. He was nearly grown when the accidental 

 possession of a copy of Robinson's "Mechanical 

 Philosophy" turned his thoughts towards natural 

 philosophy. After two years of work as a watchmaker, 

 he came under the training of the Albany Academy, 

 where he developed a degree of mathematical talent 

 which, in 1826, led to his selection for the duties of in- 

 structor in mathematics in that institution. Prior to 

 this, having had some experience in the field as a 

 surveyor, he was associated with Amos Eaton in the 

 Geological Survey along the line of the Erie Canal, pro- 

 jected and sustained by General Stephen van Rensselaer. 

 Failing physical health led to his taking this step. He 

 returned home with a' robust constitution, which never 

 failed him throughout his life. 



While occupied with his duties as mathematical in- 

 structor in the academy— then in charge of Dr. T. 

 Romeyn Beck — he commenced that line of investigation 

 in electricity which resulted in the important discoveries 

 that have made his name famous. He attended the 

 lectures on chemistry of Dr. Beck, and assisted in the 

 preparation of his experiments. At this time he devised 

 and published an improved form of Wollaston's sliding- 

 scale of chemical equivalents, in which hydrogen was 

 adopted as the radix^a contrivance which is hardly 

 known, even by name, to the present generation of 

 chemists. Thus, while Prof. Henry's original contributions 

 to science were chiefly physical, his first scientific work 

 was in the department of chemistry. His work with Dr. 

 Beck enabled him, after his removal to Princeton — where 

 he became professor of natural philosophy in 1832, — to 

 take up the duties of the chemist, Dr. John Torrey, when 

 that well-known teacher was disabled for a time by ill 

 health. 



It was in the interval between 1828 and 1837 that the 

 most important work of his life was accomplished in the 

 line of strictly scientific research. 



If we compare the poverty of his apparatus and the 

 poverty of his means for research and publication with 

 the importance of the results which he reached, we may 

 accord him a place by the side of Faraday as an experi- 

 mentalist. He became the sole discoverer of one of the 



most singular forms of electrical induction, and was 

 among the first, perhaps the very first, to see clearly the 

 laws which connect the transmission of electricity with 

 the power of the battery employed. One of the problems 

 to which he devoted himself was that of producing 

 mechanical effects at a great distance by the aid of an 

 electro-magnet and a conducting wire. The horse-shoe 

 electro-magnet, formed by winding copper wire round a 

 bar of iron bent into the form of a U, had been known 

 before his time, and it was also known that by increasing 

 the number of coils of wire greater force could be given 

 to the magnet, if the latter were near the battery. But 

 when it was removed to a distance the power was found 

 to weaken at so rapid a rate that the idea of using the 

 electro-magnet for telegraphic purposes seemed hopeless. 

 Henry's experiments were directed toward determining 

 the laws of electro-motive force from which this diminu- 

 tion of power resulted, and led to the discovery of a 

 relation between the number of coils of wire round the 

 electro-magnet and t'oe construction of the battery to 

 work it. He showed that the very same amount of acid 

 and zinc arranged in one way would produce entirely 

 different effects when arranged in another, and that by 

 increasing the number of cells in the battery there was no 

 limit to the distance at which its effects might be felt. 

 It only remained for some one to invent an instrument 

 by which these effects should be made to register in an 

 intelligible manner, to complete the electro-magnetic 

 telegraph, and this was done by Morse. Henry himself 

 considered the work of an inventor as wholly distinct 

 from that of a scientific investigator, and would not pro- 

 tect the application of his discoveries, nor even engage 

 in the work of maturing such applications. He never 

 sought to detract from Morse's merits as the inventor of 

 the magneto-electric telegraph, but did on one occasion, 

 under legal process, give a history of the subject which 

 was not favourable to Morse's claim to the exclusive use 

 of the electro-magnet for telegraphic purposes. Some 

 feeling was thus excited ; but Henry took no other 

 part in the controversy than to ask an investigation of 

 some charges against himself contained in an article 

 of Morse's. 



The results of these researches are chiefly recorded in 

 the Transactions of the Albany Institute, the volumes of 

 the American Jojirnal of Science and Arls for the period, 

 and the Transactions of the American Philosophical So- 

 ciety. His " Contributions to Electricity and Magnetism " 

 were collected in a separate volume in 1839. The analysis 

 of these important researches, and the discussion of the 

 questions of priority connected with them, will be the duty 

 of the academician to whom shall be assigned the prepara- 

 tion of a memoir or eulogy of the distinguished author. 



The memoir in the American yourtial gives a list 

 of twenty-two memoirs and discoveries by Prof. Henry. 

 To these papers should be added an important series 

 of communications, made chiefly to the National 

 Academy of Sciences during the past four or five 

 years, upon the laws of acoustics as developed in the 

 course of investigations conducted for the Light-House 

 Service in order to determine the various conditions in- 

 volved in the transmission of fog-signals. These 

 investigations have been carried forward mainly in 

 government vessels, and occupied Prof. Henry's close 

 personal attention during many weeks of each season. 



Besides these experimental additions to physical 

 science. Prof. Henry is the author of thirty reports, 

 between the years 1846 and 1876, giving an exposition of 

 the annual operations of the Smithsonian Institution. 

 He has also published a series of essays on meteorology 

 in the Patent Office Reports, which, along with an expo- 

 sition of established principles, contain many new sugges- 

 tions, and, among others, the origin of the development 

 of electricity, as exhibited in the thunderstorm. 



In 1837 he visited Europe and made the acquaintance 



