274 ANNUAL OF SCIENTIFIC DISCOVERY. 



tions, and so situated that the natural drainage of the soil should 

 not convoy any deleterious matters into the water used or earth 

 occupied by man or animals. 



RESPIRATION VS. TUE TEMPERATURE OF THE BLOOD. 



One of the results of Dr. Lombard's experiment?, with a tlier- 

 mo-clectric a])paratus capable of indiealins: a difference of 

 temperature of one two-thousandth of a degree centigrade 

 (described in the "Annual of Scientific Discovery" for 18(39, p. 

 '2S5), is, that, although the air taken into the lungs and thence 

 into the blood be cold and dry, it does not lower tiie temper- 

 ature of the blood suflicicjitly to be appreciable l)y this (U'li- 

 cate thermometer, as compared with the temperature when 

 the respired air is hot. In the "Quarterly Journal of Sci- 

 ence" for April, 1869, we find the following: "We must all 

 have noticed tiie feeling of heat in the lungs on a cold, frosty 

 day, — a sensation which is not experienced in warmer weather, 

 and which is the very reverse of what we should expect from 

 the greater coldness of the inspired air, M. Brown Sequard sug- 

 gests that the explanation may be this, — the lower the temperature 

 of the inhaled oxygen the greater will be the amount absorbed, 

 according to a well-known law of physics, and hence possibly, 

 there being a larger absorption of oxygen, there may be increased 

 oxidation, and increased heat accordingly. The tension of the 

 vessels aff<'Cted by cold air may have some connection with the 

 sensation in the lungs. 



ASCENT OF HIGH MOUNTAINS. 



According to carefully made experiments of Mr. Lortet in the 

 valley of Chamounix, up to a height of al)out 3,900 metres the 

 respiration is but little troubled, if the precautions are taken of 

 walking with the head low to diminish the orifice of the air-i)as- 

 sages, of keeping the mouth shut and breathing through the nose, 

 and of sucking some small substance, as a nut or stone, to 

 increase the salivary secretion. Above this iieight, the respiration 

 becomes hurried, even to 3G a minute, and difficult; it seems as if 

 the pectoral muscles became stiff and tlie ribs were encased; the 

 amount of air which passes through is much less than in the val- 

 ley, and the amount of oxygen for purification of the blood 

 very small. 



The pulse increases from G4 to IGO, according to altitude, and 

 is febrile and weak, the arteries feeling ahnost empty. The 

 rapid circulation of the blood in the lungs adds to the insufficient 

 oxygenation arising from rarefaction of the air ; tiie veins become 

 swollen, and all experience a heaviness in the head and sleepi- 

 ness, due to imperfect aeration of the blood. The weakness of 

 the pulse is accompanied by a general refrigeration of tiu; body. 

 Between l,OoO and 4,810 metres, the lieat of the body may 

 descend 6 to 8° C. during the muscular efforts of ascension, a 



