60 Notices respecting New Books. 
will appear electrical ; that whose natural attraction was in- 
creased by contact, having” received an addition to its quantity 
of electric fluid, will be positively electrified ; and that whose 
attraction was lessened, having lost a portion, will be negative.”” 
The action of the electrical machine is explained very satis- 
factorily by this theory. Its effect is to bring successively in 
contact with the rubber different parts of the surface of the glass, 
which are as suddenly separated from that contact, and carry 
with them the electricity they have acquired by the change of 
capacity it produces. 
The same theory is applied very naturally to all the usual ef- 
fects of electric motion and the action of different conductors in 
transmitting electricity: the explanation of points appears to 
us novel and appropriate. It is stated to consist in promoting 
the* recession of the particles of electrified air, by protruding a 
part of the electrical atmosphere of the conductor into a situation 
more exposed to the action of the ambient unelectrified medium, 
and thereby producing a current of air from the electrified point 
to the nearest uninsulated body. 
The phenomena of electric light are treated at some length, 
and explained in a very simple manner; the Leyden jar, the 
condenser, and the electrophorus, are referred to the action of 
one principle, that of electrical influence, which has been so well 
illustrated by Volta in his excellent paper in the Ixxiid volume 
of the Philosophical Transactions. The explanations differ 
essentially from those of most preceding writers. The author 
uniformly avoids the use of repulsion as a principle of electri- 
eal action, but he does not adopt to any extent the opinions 
of those who have preceded him in this idea. 
The second part of the work treats of the mechanical and 
cliemical agencies of electricity, and contains three chapters. 
Chap. 1. describes the instruments required for the applica- 
tion of the electric power to the purpose of experiment. 
Chap. 2. the mechanical agencies of electricity. 
Chap. 3. chemical effects of electricity. 
The description of instruments is concise ; it ineludes only 
those which are really necessary; it contains much useful infor- 
mation, and concludes with the following very just remark: 
* Tubes of glass, wires of different metals, corks, and a few 
other materials, are adequate to the construction of an endless 
variety of electrical machinery, and the proper direction of such 
resources is constantly followed by useful discovery. Mechanical 
dexterity is therefore essential to the character of an electrician, 
since his progress will be in proportion to the facility with which 
he can adapt the objects around him to new inquiries. He 
cannot 
