96 Steam- Engine Indicator. 



as for every individual instrument, a b d are constant quan- 

 tities; then -— = a;, a constant number by which to multiply 

 da 



the average distance obtained from a diagram, for the average 

 pressure in pounds upon each square inch of the steam piston. 

 Mr. Button, of the Anderston Foundry, near this city, now 

 makes these instruments upon a very convenient plan, and as 

 he attaches to each the constant multiplier by which the result 

 is obtained, their application is rendered perfectly simple. 



Art. IX. A Review of some of the General Principles 

 of Physiology, with the practical Inferences to which they 

 have led. By A. P. W. Philip, M.D.,F.R.S., Edinb. 



It is not my intention in the following observations, to 

 attempt a general view of the state of our knowledge respecting 

 the vital powers of the animal system, but to confine myself 

 to those parts of the subject to which my attention has been 

 particularly directed, embracing what is known respecting the 

 nature of these powers, and their relation to each other. This 

 is far from comprehending the whole of the subject, but forms 

 the basis on which the whole must rest. 



As there are few of the general principles of physiology 

 which have not given rise to much difference of opinion, it is 

 only by a tedious investigation, for which the members of our 

 profession seldom find leisure, that we can arrive at the truth ; 

 yet every one will admit that a knowledge of these prin- 

 ciples is always useful and in many instances essential in 

 the treatment of disease. I cannot help thinking, therefore, 

 that I shall perform an acceptable task if I lay before them a 

 simple statement of the facts we possess on the subject, with 

 references to the means by which they have been ascertained ; 

 so that those who wish to recur to the original sources may do 

 so without trouble, and with such a general knowledge of the 

 subject, as will enable them to form a correct judgment of its 

 several parts. 



