HOT SPRINGS, ARKANSAS. 93 



is almost imperceptible in half a century. In one instance, that of 

 the Alum spring, there is a very marked decrease in temperature, 

 and as this is the only spring on the west side of the creek, there is 

 no doubt of its identity. In 1804 this had a temperature of 132°. 

 In 1S59 its temperature was 133°, according to Owen, and to-day it is 

 but 114.8°. 



Amount of outflow. — The comparison of outflow is more difficult. 

 According to Dunbar and Hunter the largest spring had an outflow of 

 11 quarts in eleven seconds in 1804, corresponding to 22,100 gallons 

 per day, and the four largest springs had an outflow of 165 gallons per 

 minute, or 237,600 gallons per day. Dr. Owen gives no measurements, 

 but Glasgow gives the discharge of each spring — a total of 317 gallons 

 per minute, or 450,480 gallons per day, as compared with 850,000 gal- 

 lons per day at the present time. As the writer has shown elsewhere, 

 the spring water is of meteoric origin, like most spring water, and prob- 

 ably varies somewhat from year to year, corresponding to variation in 

 annual rainfall at some previous } r ear, so that no definite comparison 

 can be made with the early records, except to state that the volume of 

 water discharged is very much greater. Supposing a practically con- 

 stant amount of heat applied, this of itself would mean a slightly low- 

 ered temperature. In this connection attention should be called to the 

 well put down by Major Torney, U. S. Army, in the Army and Navy 

 Hospital, which is capable of yielding the amazing amount of 350,000 

 gallons per day without affecting but one very small spring (No. 40 

 of the list). 



From a consideration of all these facts it is concluded that the springs 

 are losing their heat so slowly that the loss is almost inappreciable. 



Amount of mineral matter carried in solution by the waters. — No 

 essential difference in the composition of the waters can be detected 

 by a comparison of the analyses made for Owen or Larkin (1859) or 

 for Dr. Branner, of the State geological survey, in 1889, with the elab- 

 orate and careful analyses made by the National Government. The 

 waters are remarkable more for their purity than for their mineral 

 contents. The material in solution consists mainly of bicarbonate of 

 lime, which is so easily precipitated by the loss of carbonic acid gas 

 that a deposit forms in pipes, and rather rapidly where the spring 

 waters drip, as in the walls about the bowl of the Cave spring. The 

 total mineral matter for all the springs amounts to 1,367 pounds a 

 day, equivalent to 249.5 tons a year. This amount of material carried 

 by the hot water from the earth's interior to the surface must leave a 

 very considerable cavity in the course of time. 



SOURCE OF HEAT. 



While there have been many theories advanced to account for the 

 source of the hot waters, the only hypothesis that stands the test of 

 scientific inquiry is the one which ascribes the heat of the waters to 

 still hot but concealed bodies of igneous rock. It seems scarcely nec- 

 essary to call attention to the absurdity of the idea that either slaking 

 lime in the depths of the earth or chemical reaction of the waters with 

 the atmosphere could be the cause of the heat. That the waters come 

 from a depth sufficient for their heating by the normal increment of 

 earth heat (1° for every 50 feet) seems unreasonable, since it would 

 necessitate a depth of nearly 5,000 feet to give the waters their pres- 

 ent temperature, even assuming that they were not cooled in their course 



