102 Captain Newbold on the Temperature of 



greater extent, but a foot or two deep is less affected by the calorific 

 action of the solar rays than clear water. 



The transparent water of a large well at Bellary, lat. 15"^ 5' N., 

 and long. 76° 59' E., situate on a tableland elevated 1600 feet 

 above the sea's level, and containing 16 feet of water, I found, at 

 the depth of 9 feet from the surface, to vary but one degree during 

 the day, from sunrise to sunset, and this in several hundred experi- 

 ments. The minimum, 79°.5, took place a little after sunrise, and 

 the maximum 80°. 5, at 3 p.m., following those of the air. The 

 diurnal variation of the water an inch below tbe surface, amounted to 

 12°. During the commencement of the dry weather, as the heat 

 increased, the water gradually decreased, and the diurnal fluctua- 

 tions became greater, and increased at a greater rate than that of the 

 decrease of the water. 



Thermal Springs. — The thermal springs, both of India, the 

 Peninsula of Sinai and Egypt, are, with few exceptions, either 

 mineral or gaseous. Those near the shores of the Red Sea are sul- 

 phureous ; and, strictly speaking, perhaps, should not be classed as 

 thermal springs, from the great probability of their being connected 

 with the volcanic belt that passes under the bed of the Red Sea, 

 and bursting up from its watery fetters, appears in the semi-dormant 

 volcano of Gebel-Teer, and in the lavas of Aden, beyond the straits 

 of Babel-Mandel. The highest known temperature of the thermal 

 springs, is 102°, viz. that of El Kaor in the oasis of Dakhleh ; in 

 the Peninsula of Sinai 91°'6, that of the Hummam Mtisa, Hot Baths 

 of Moses (Wells of Elim ?) near Tor. It is probable, from reports 

 given to me by the Arabs, that the Hummam Pharaon, Hot Baths- 

 of Pharaoh, about 85 miles northerly from Tor, are of higher tem- 

 perature. The maximum attained by the thermal springs of India, 

 is 194°; at Jumnotri in North Hindostan (lat. 30° 52' N.), a tem- 

 perature almost equivalent, at that elevation — 10,849 feet above the 

 sea's level — to the boiling point of water, and 18° higher than that 

 of the hottest known thermal spring of Europe, unconnected with 

 present active volcanoes, namely, 176° Fahr., that of Chaudes Aigues 

 in Auvergne. The temperature of the hottest known thermal spring 

 in the world, according to M. Arago, is that of Las Trincheras, in 

 Venezuela, stated, on the authority of Humboldt and Boussingault, 

 to have increased 11° since 1806 to February 1823, viz., from 

 195° to 206° Fahr. Had M. Arago stated its elevation above the 

 sea, a better comparison between its temperature and that of Jum- 

 notri might have been formed. It would be interesting to observe 

 whether any similar increment of heat takes place in the chain of 

 thermal springs that rise abundantly along the great line of disloca- 

 tion at the southern base of the Himalaya chain, or whether the 

 temperature falls, as in some thermal springs, among the East Pyre- 

 nees. It is certain that the majority of the springs, strictly termed 

 thermal, occur in India, at or near lines of great faults, occasioned 



