298 PERSONAL PREPARATION FOR RESEARCH. 



of the authors, and the titles and references of nearly every 

 scientific paper published in any language since that year, 

 down to a recent date. The most effectual way, therefore, 

 to obtain complete information of what has been previously 

 done in any particular scientific subject is first to refer to 

 the topic in all the English scientific books and periodicals ; 

 then from the names of authors mentioned in those to 

 refer to the catalogue for the titles and references of their 

 papers, and then to the papers themselves whether in English" 

 or foreign languages. In those original papers will pro- 

 bably be found the names of other authors on the same 

 subject, whose papers must be similarly found and referred 

 to ; and so on in this manner from one paper to another 

 until no more can be found. During the last few years 

 also the Chemical Society of London has published, in their 

 journal, abstracts of all foreign researches recently made 

 in physics and chemistry, and during a longer period the 

 6 Chemical News ' has contained somewhat similar abstracts 

 in a very brief form. In the German language a similar 

 plan has been carried out on a more extensive scale, during 

 many years, in a book entirely devoted to the object, and 

 entitled the ' Jahresbericht fur Chemie.' All these facili- 

 tate the search. 



The foregoing plan of finding published researches 

 necessitates some knowledge of the continental languages, 

 especially German and French. Even with the utmost 

 care a research may sometimes be missed in consequence 

 of being included under the title of a wider or different 

 subject, or from other causes. Once, in this way, after 

 I had discovered and made a long investigation of the 

 phenomenon of electro-magnetic torsion, 1 and published 

 an abstract of it, Professor Weidemann, to whom I had 



1 See Philosophical Transactions of the Royal Society, 1874, p. 529. 



