Notices respecting New Books. 71 



Dr. Hoppe divides his work into six Books, which deal with 

 different epochs in the history of Electricity, and which are, of 

 course, of very unequal bulk. The first gives us the history of 

 discovery from the earliest times to Franklin, and occupies 28 pages. 

 The second embraces the times of Franklin and Coulomb, 1747 to 

 1789,, 70 pages. Book III. gives us the history from Galvani's 

 discovery to the year 1819, treating chiefly of galvanic electricity 

 and the discoveries of Volta, Davy, Oerstedt, Zamboni, and 

 others, occupying 73 pages. Book IV. treats of the connection 

 between Electricity and Magnetism, and of the contributions to 

 electrical science of Oerstedt, Poggendorff, Schweigger, Ampere, 

 .Faraday, and Nobili, in the years 1820-26, and covers 60 pages. 

 Book V. extends from Ohm to the recognition of the law of conser- 

 vation of energy (1827-47, 260 pages), including, amongst others, 

 the researches of Ohm, Pouillet, Kohlrausch, Faraday, Schonbein, 

 Daniell, Grove, Bunsen, Poggendorff, Plante, Faure, Joule, Lenz, 

 Peltier, Kirchhoff, Gauss, Wheatstone, Weber; and Book VI. 

 treats of the technical applications of Electricity — of the electric 

 light, dynamo machines, the electric telegraph, and telephone, &c. : 

 this occupies 93 pages. 



It is not practicable, within the limits of a brief notice, to do 

 more than mention one or two points which may be of interest. 

 Dr. Hoppe discusses the question of the discovery of the Ley den 

 jar at some length, and, apparently, gives his verdict in favour of 

 Kleist as the actual discoverer ; at least he seems to adopt the 

 name " Kleist's jar " instead of the usual term. Von Kleist, Bishop 

 of Kammin, in Pomerania, on the 11th October, 1745, placed a 

 nail in a medicine-glass and held it to the conductor of an electrical 

 machine ; on touching the nail with the other hand he received a 

 shock, especially if the glass contained mercury ; and this appears 

 to be the first time the experiment was ever made. This result 

 was communicated by letter to at least three people, in Berlin, 

 Halle, and Danzig respectively, in November and December of the 

 same year. 



In January 1746 a similar observation was made, accidentally, 

 by Cunaeus, in Leyden, and repeated by Musschenbroek, Professor 

 of Mathematics and Physics at the University of Leyden, and 

 Gallamand, Professor of Philosophy at Leyden, who communicated 

 the discovery to the famous Abbe Nollet, in Paris, who, knowing 

 nothing of Von Kleist, accredited the discovery to the Leyden pro- 

 fessors. It would appear, then, to be due to the accident of the 

 general ignorance of the German lauguage, in comparison to the 

 widespread use of the French tongue, that this most important 

 discovery has been connected with Leyden and not with the name 

 of Von Kleist ; and there is some foundation for Dr. Hoppe's com- 

 plaint, that whereas every schoolboy knows what a Leyden jar 

 means, perhaps not one ever heard the name of Von Kleist. 



Some of our common appliances or observations seem to date 

 back further than is usually supposed, We note that the date of 

 the first lightning-rod is given by Dr. Hoppe as 1754, and that 



