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XLIV. Notices respecting New Books. 
Formulaire pratique de V Electricien. Par E. Hospitaller, Inge- 
nieur des arts et manufactures, Professeur a Vecole de physique et 
de cliimie industrielles de la ville de Paris. 
r PHE aim of this book, as given in the preface, is to 
-*- amateurs and those who are engaged in electrical engineering 
by throwing together in a convenient form for reference the 
formula? connected with its various branches, and the guiding 
principles underlying the various operations that an electrician 
may find himself called on to conduct. It is designed, in short, as 
a practical handbook on electrical subjects. 
The first part treats of the definitions and general laws of 
electricity and magnetism. It may be noted that the custom of 
English writers is followed in naming the poles of a magnet, the 
north pole being the north-seeking pole of the magnet. The 
second part treats of units, and contains several useful tables, such 
as are to be found in the " Report of the Committee on Electrical 
Standards appointed by the British Association," and in ' Illus- 
trations of the C.Gr.S. System of Units ' by Professor Everett. 
Among the units is included the " watt," which, however, is taken 
to be an amount of work and not a rate of working. This is not 
the meaning attached to the watt by its originator. It is to be 
hoped no confusion will ari&e as to the meaning of this convenient 
term, for it would be a pity if, after its use had become general, it 
had to be abandoned to avoid ambiguity, as in the case of the 
" weber." 
Brief descriptions of various forms of apparatus and methods 
employed in maldug electrical measurements form the third part 
of the book. This contains diagrams of the various circuits 
employed in the ordinary tests ; and it may be noted that the con- 
ventional sign here used for a battery is just the reverse of that 
ordinarily employed in English text-books. The fourth part, 
comprising nearly half the book, treats of applications of electricity 
to useful purposes, and gives some accounts of the results already 
achieved. Details such as algebraical and trigonometrical formula?, 
specific gravities, resistances of metals and alloys, &c. &c, which 
are frequently required in practical work, are presented in a 
tabular form, and the values of various quantities (such as the 
E.M.E. of cells, accumulators, and thermopiles) are duly recorded. 
Probably the sections dealing with generators and motors will be 
found of considerable interest, giving as they do in a tabular form 
the results claimed for various machines. The concluding pages 
of this part treat very briefly of telegraphy and telephony : this 
portion of the work might well be amplified, and illustrated with 
diagrams of the circuits in common use, in a future edition. 
Gf. A. Care, Lieut. R.E. 
