4 APPENDIX. 



Dr CARSON endeavours to obviate the objections which 

 are made to the theory of SAUSSURE. He attempts to prove 

 that muscular exercise prevents the free return of blood to 

 the heart, and, therefore, when an individual rests in a 

 horizontal position, the blood is transmitted in its usual 

 way to the thorax, and consequently revives the sinking 

 powers of the system. This idea appears plausible, but, if 

 minutely examined, it can scarcely be allowed to be cor- 

 rect. Exercise alone seldom or never produces the peculiar 

 symptoms which are described by SAUSSURE and others 

 as occasioned by an ascent to Mont Blanc, and it has already 

 been observed, that the rarefaction of the air is alone insuf- 

 ficient to give rise to the same symptoms : it is, therefore, 

 manifest, that it is the combination of these two agents, co- 

 operating, as stated in the text, that tends to disturb the 

 whole of the sanguiferous system. 



In page 39 I allude to a small machine which I con- 

 trived for the purpose of inflating rabbits with warm 

 air. It was constructed as follows : A common syringe, 

 of about two inches and a half long, was placed 

 in the centre of a small tin box, an inch and a half 

 deep. A brass tube, about the size of a large crow- 

 quill, was connected with the syringe, in order to ad- 

 mit the egress of air from, and ingress into it. There 

 was also another brass tube, about one-fourth of the dia- 

 meter of the preceding, two inches long, soldered to the 

 end of the syringe, which protruded without the box, 

 and which was connected at pleasure to the tube inserted 

 into the trachea of the animal. The box was placed upon 

 four tin legs of two inches and a half long, and was also 

 covered by a lid. The box was filled with water, and af- 

 terwards a spirit-lamp was placed underneath, which very 

 soon heated the water in contact with the syringe, and as 



