DESERTS OF THE UNITED STATES AND MEXICO 



713 



Some of the native animals, such as mice 

 and other small rodents, have been 

 known to live on hard seeds without 

 green food for periods of several 

 months, or even as long as two or three 

 years, and nothing in their behavior in- 

 dicated that they ever took liquid in any 

 form."^ 



Deer and peccary are abundant in des- 

 erts in Sonora in which the only avail- 

 able supply of open water is to be found 

 in the cacti. The endurance of the camel 

 is well known, and some of the best au- 

 thenticated evidence upon the matter 

 comes from Australia. The camels of 

 the Tietkins party in 189 1 and 1892 made 

 a march of 537 miles in 34 days without 

 a drink. These animals take water every 

 day when a supply is available, but it is 

 their capacity for accommodation that 

 has made them such a potent factor in 

 transportation in the deserts of Asia, Af- 

 rica, and Australia. Other animals, in- 

 cluding the common domestic sheep, are 

 also capable of making such changes in 

 their habits that they may go for weeks 

 without a drink. 



Man and his most constant companion 

 on the desert in America, the horse, are 

 comparatively poorly equipped against 

 the rigors of the desert. A horseman 

 may go from the morning of one day 

 until some hour of the next in midsum- 

 mer and neither he nor his horse will in- 

 cur serious danger ; experiences of this 

 kind are numerous. If the traveler is 

 afoot, abstinence from water from sun- 

 rise to sunset is a serious inconvenience 

 to him, and if he continues his journey, 

 the following morning his sufferings may 

 so disturb his mental balance that he may 

 be unable to follow a trail, and by the 

 evening of that day, if he has not come 

 to something drinkable, he may not rec- 

 ognize the friendly stream in his way. 

 Instances are not unknown in which suf- 

 ferers from thirst have forded streams 

 waist deep to wander out on the dry 

 plain to a grisly death. 



Some estimate may be made of the 



*F. V. Coville : Desert Plants as a Source of 

 Drinking Water. Smithsonian Reports for 

 1903, pp. 499-505. 



actual amount necessary from the fact 

 that a worker at the Desert Laboratory 

 during the course of an ordinary day in 

 May, at Tucson, consumed 16 pints of 

 water. A horse would have used 15 or 

 20 gallons in the same time. A walk of 

 3 or 4 miles was taken, but no special 

 muscular effort beyond this was in- 

 volved. A march across the desert in 

 midsummer would increase this quantity 

 by half. Under such circumstances, a 

 canteen of less capacity than a gallon is 

 a toy, and one of real usefulness should 

 contain at least twice that amount. 



The most notable example of en- 

 durance of thirst is that of a Mexican 

 prospector hunting for a ''lost mine" 

 near the old Camino del Diablo, or trail 

 from Sonora to Yuma, who made camp 

 safely after being out for eight days with 

 a supply sufficient for one. This experi- 

 ence is not likely to be duplicated soon, 

 although it is reported that Indians often 

 go as long as four days without water. 



The experience of the field expeditions 

 from the Desert Laboratory demonstrates 

 that saline or alkaline waters which con- 

 tain as much as one-fourth of i per cent 

 of salts may be used for periods of many 

 days without serious discomfort, but if 

 the proportion be increased to one-third 

 of I per cent only hardened travelers may 

 use it, while water which contains as 

 much as one-half of i per cent is inimi- 

 cal to health and comfort, although it 

 might suffice for a few hours or save 

 the life of a person who had been wholly 

 without water. 



All devices for allaying the discomfort 

 arising from the dryness of the mucous 

 membrane, such as carrying bullets or 

 pebbles in the mouth, chewing grass or 

 a piece of rubber, are wholly futile in 

 meeting the serious thirst problem. The 

 relative humidity often falls to 5 per cent 

 in the Southwestern deserts, and in a 

 temperature of over 100° the evaporation 

 from a vessel of water standing in the 

 open may be as much as an inch a day. 

 The amount thrown off by the skin is 

 correspondingly great, and if the loss is 



*W J McGee: Desert Thirst as a Disease. 

 Interstate Medical Journal, vol. 13, No. 3, 1906. 



