96 Atmospherical Pressure on the Animal Frame. 



of a cubic inch, for the weight of an additional atmosphere. 

 Now as the body consists of solids and liquids of almost in- 

 compressible matter, and there is only a small part of the vo- 

 lume consisting of elastic fluid that is compressible, no mate- 

 rial change of volume can take place, but on the sudden tran- 

 sition from one atmospheric pressure to another; and unless 

 a change of volume take place, we cannot feel any pressure, 

 either inward or outward. The phenomena of the water ham- 

 mer shew, that the particles of water are hard, as they strike 

 each other like flint and steel ; and it is exceedingly probable 

 that other bodies, solids as well as liquids, are constituted in 

 like manner. A general pressure on the system, then, only in- 

 creases in a small degree the attraction of the ultimate particles, 

 and it is met by a corresponding increase of repulsion from the 

 atmosphere of heat ; so that the system remains as nearly as 

 possible the same, and unaffected by such pressure. 



I can scarcely forbear observing on the present occasion the ab- 

 surdity of those who remark, that all people might swim, and that 

 it is only from fear or ignorance of the art that some fail in the 

 attempt. When we see that some persons are heavier than water, 

 and others only .8 of that weight, it would be just as plausible 

 for a piece of deal to upbraid a piece of lignum vitae with the in- 

 ability to swim from fear, or from want of skill in the art, which 

 the deal considered of easy acquisition. — Manchester Memoirs^ 

 vol. V. New Series. 



Chemical Analyses of Sfinelf Gahnite, and Chrome Ore. 

 By Mr Hermann Abich. 



