9 6 SCIENCE PROGRESS. 



faction of the air alone, and the consequent diminution 

 of the oxygen in the blood, was the only influence tending 

 to weaken the heart. 



During such periods of rest, the comparative regularity 

 of the tracings is against the likelihood of failure of the 

 heart at such times, and this is pretty well all one can say 

 about them. They do not, and they cannot, enable us to 

 decide definitely whether the heart is overstrained during 

 the exertion, which is a necessary part of mountain climbing. 

 I know of only one means by which this important question 

 can be definitely decided, and that is by using a stethoscope, 

 and learning whether or not a heart-murmur accompanies 

 the first sound of the heart during exertion. If it does, we 

 may diagnose functional incompetence of the mitral or 

 tricuspid valve, or both, and therefore the failure of one or 

 both ventricles ; if the murmur be not present under these 

 conditions we must in the meantime exclude heart-failure. 



Conway's observation that more distress was experienced 

 in hollow places than when walking on an arete, confirms 

 what has been noted by others. This may be due to the 

 fact that water takes up more oxygen than nitrogen from 

 the air, so that when, on a high peak, the sun falls upon the 

 snow, melting a certain part of it, the neighbouring air is 

 robbed of some of its oxygen. The wind on a ridge need 

 not have passed over fields of melting snow, and may there- 

 fore contain a larger percentage of oxygen. The difference 

 in the amount of oxygen compared with nitrogen which 

 water obtained from melting ice takes up is not very great, 

 and the fact is probably not of much importance, but seeing 

 that the two gases will not be dissolved in the proportions 

 in which they exist in the atmosphere, but will each be 

 dissolved as if it were the only gas present, we may have, 

 even if the melting snow takes up equal volumes of oxygen 

 and nitrogen, a very serious lowering of the percentage of 

 oxygen in the air which rests or passes over the melting 

 snow. This offers to my mind a very probable explanation 

 of the increased distress felt by Conway in hollow places, 

 especially when the sun was shining on them. 



Conway does not, in his notes, refer to variation in the 



