56 Mr. W. G. Rhodes on a Theory 



As such an hypothesis, if true, would be of fundamental 

 importance to chemical and physical philosophy, it is to be 

 desired that it should be thoroughly tested by experiment. 

 Indeed it appears that the present need on the experimental 

 side of thermochemistry is the determination of the heat of 

 formation of all the typical organic compounds, and of the 

 first few members of the homologous series derived from 

 them, with some reliable estimate of the probable error of 

 each value. The first grand general survey of the experi- 

 mental region of thermochemistry has been carried out by 

 such experimenters as Favre and Silbermann, Andrews, 

 Berthelot, Thomsen, Stohmann, Louguinine, and others, to 

 whom we owe the fine existing body of thermochemical data; 

 but it is now time that those who wish to carry on their work 

 should take up the details and establish for the thermo- 

 chemical constants of bodies as reliable determinations as the 

 skilled analyst can give of their percentage composition. 



The existing data for the heat of combustion of a large 

 number of organic compounds as liquids and solids, such 

 as have been determined by Stohmann and his pupils, and 

 Louguinine and others, could be made available for the theo- 

 retical study of their heats of formation as gases, by the 

 calculation of their latent heats of vaporization, according to 

 the equation given in the introduction to the present paper, 

 and the use of approximate values of their specific heats as 

 vapours, if it is desired to reduce all results to a temperature 

 of 18° C. But the discussion of such results will probably be 

 more profitable after the fundamentals of the subject have 

 been more thoroughly investigated. 



Melbourne, July 1894. 



II. A Theory of the Synchronous Motor. 

 By W. G. Rhodes, M.Sc* 



1. OEVERAL foreign writers, notably Steinmetzf, have 

 O given theories of the synchronous motor, but most of 

 them, by failing to see how the analysis could be simplified, add 

 to the difficulties of the theory by mathematical intricacies 

 which are apparently quite unnecessary. The author offers the 

 following attempt to present a theory of the synchronous motor 

 in as simple a way" as possible, and as the mathematics for the 

 most part consists of simple algebra, the difficulties are reduced 

 to a physical conception of the subject. Many of the results 

 have already been obtained, and the part for which the author 



* Communicated by the Physical Society: read April 26, 1805. 

 t Trans. Am. Inst. Elec. Eng., December 1894. 



