4m 



Analyses of Books. 



[JuNEj 



iniles from Manchester, on the 4th of September, 1809. A 

 very loud explosion of tliuoder took place^ and the front wall of 

 the coal vault, containing about "^'OOO bricks, and weighing 

 about 26 tons, was gradually lifted up entire, and moved nine 

 feet forwards from its former position. Mr. Henry conipares 

 this to the thunder-storm at Coldstream, described by Mr. Bry- 

 done in the Philosophical Transactions for 17^7? '^^^ explained 

 in a very satisfactory manner by Lord Stanhope. He conceives 

 it to have been a case of the returning stroke. The lightning 

 issued out of the earth by the coal vault to restore the equili- 

 brium in the clouds over head. 



7- Tlieorems and Problems intended to ehicidate the mecha- 

 nical Principle called Vis Viva. By Mr. John Gough.] By vis 

 viva Mr. Gough means the whole force opposed by a body in 

 motion to a retarding force which impedes its progress; and 

 conversely, it is the whole force accumulated in a body by the 

 action of any motive force, which puts that body in motion. 

 These theorems and problems being mathematical demonstra- 

 tions could not be understood in an abridged form. I must 

 therefore of necessity refer the reader to the volume itself. 



8. On the Theories of the Excitement of Galvanic Elec- 

 tricity. By William Henry, M.D. F.R.S. &c,] Two different 

 explanations of the energy of the galvanic battery have been 

 given : the first entirely electrical, the second chemical. There 

 is a third, in which tbe two preceding agents are combined 

 together. 1. When zinc and coj>per are brought in contact, 

 the zinc becomes positive, and the copper negative. Hence 

 there is an accumulation of electrlcity.in the zinc. The imper- 

 fect conductor in contact with the zinc receives this redundancy, 

 and conveys it to the second plate of copper. In this manner 

 the electricity travels from one end of the battery to the other, 

 and accumulates as it proceeds in a geometrical ratio. Such was 

 Volta's original explanation. Mr. Cuthberton accounted for 

 the progressive motion i)y the chemical action of the liquid on 

 tlie zinc. But this explanation does not account for the prodi- 

 gious effects produced by some liquids when compared to others, 

 fior does it show us why all efiect ceases with the chemical action 

 of the liquid on the plates; nor why hydrogen gas is evolved 

 from the copper, while it is the zinc tiiat is chicfiy dissolved, 

 2. When a metal is oxydated it gives out electricity. Electricity 

 in a pure state can pass through perfect conductors; but it only 

 passes through imperfect ones when combined with hydrogen. 

 Hence the evolution of electricity depends upon tlie chemical 

 action of tlie metal on the liquid. Hence the hydrogen is 

 evolved from the copper. Hence the energy of the battery is 

 proportional to the member of pairs of plates. Such is the 

 chemical theory of Dr. Bostock; but it is founded on premises 



