﻿62 Notices respecting New Books. 



to the enunciation of laws much more general in their applica- 

 tion than those with which we are at present familiar. 

 Manchester. 



P. S. —Since this paper was read, it has occurred to me that 

 a comparison might be attempted to be drawn between the con- 

 trolling power of the magneto-electric current over the rotations 

 of a number of armatures, and that of the voltaic current over 

 the oscillations of a number of pendulums. Beyond the fact 

 that synchronism is produced in both cases through the agency 

 of an electric current, there is no further resemblance between 

 the two actions. In the case of the armatures the synchronism 

 is produced by the mutual action of several rotating bodies upon 

 one another, or by the dominant influence of several bodies upon 

 one; whereas in the case of the pendulums the synchronism of 

 the system is produced by the influence of one body alone upon 

 several. Again, the synchronism of a number of pendulums is 

 only accomplished by the skilful adaptation of means to an end, 

 while the synchronous rotation of a number of armatures is a 

 phenomenon which exhibits itself without the exercise of any 

 ingenuity whatever ; and, so far as I have studied this peculiar 

 electromechanical action, no amount of ingenuity can produce 

 the synchronous ro cation of the armatures by means of the vol- 

 taic current, as magneto-electric currents and circuits seem ab- 

 solutely essential to the attainment of this result. 



IX. Notices respecting New Books. 



A Manual of Elementary Chemistry, Theoretical and Practical. By 

 George Fownes, F.R.S., late Professor of Practical Chemistry 

 in University College, London. Tenth Edition. London, Churchill : 

 1868. (Pp. xxviii & 1020.) 

 The Elements of Heat and of Non-metallic Chemistry . Especially 

 designed for Candidates for the Matriculation Pass Examination of 

 the University of London. By Frederick Guthrie, B.A. (Lond.), 

 Ph.D., F.R.S.E., F.C.S., late Professor of Chemistry and Physics, 

 Royal College, Mauritius. London, Van Voorst : 1868. (Pp. x 

 & 210.) 

 npHE different chemical manuals which appear from time to time 

 ■*■ seem to be written from two distinct points of view — the author 

 desiring either to display some original mode of considering his sub- 

 ject, or to make an average statement of the chemical knowledge 

 which is accepted, in a given year, as useful to the student. Manuals 

 of the former class are, from their nature, not very frequently 

 written ; while those belonging to the latter constitute the great 

 majority of such publications. To each kind a special merit apper- 



