1835.] . On the Temperature of Wells. 229 



XII. — On the Temperature of Deep Wells to the west of the Jamna. 



By the Rev. R. Everest. 



During the last cold weather and the present, I have paid some 

 attention » the temperature of wells in the country to the west of 

 the Jumna. They nre not usually more than 30 or 40 feet deep 

 within a few miles of the river, hut beyond Rhotak, about 50 miles 

 to the west of this, on the road to Hansi, they are not less than 110 

 ox 120 feet deep, and, in one instance I have met with (that of the 

 fort at Hansi) 160 feet. Farther than that I cannot speak from exami- 

 nation, hut all accounts agree in stating those in the Bikanir country 

 to,«be the deepest, probably not less than 350 feet. I have almost 

 invariably found the temperature to increase with the depth, but the 

 increase is modified by three circumstances. 



1st. By the locality, as in the case of a pool of water being near, 

 or the mouth of the well being broad in proportion to its depth, both 

 which causes tend to lower the temperature in the cold weather. 



2ndly. By the season of the year at which the observation is 

 made. The tendency of the rains is to reduce all wells to the uniform 

 temperature of 78°, which is about that of the rain-water when it 

 fulls. From this cause the deep wells are at their minimum about 

 the autumnal equinox, and get warmer during the cold weather. On 

 the contrary, the more superficial ones become colder during the same 

 period. 



3rdly. By the quantity of water that is drawn from them. Those 



that are not used are usually the lowest, and those where oxen are 



working for the purpose of irrigation by a great deal the highest. I 



have only to premise further that the mean temperature of the year 



here, according to Major Oliver's observations, is 76°. The general 



results I have obtained are as follows : 



No. of wells. Depth to bottom. Temperature at the bottom. 



1. Mean of 10 observations 

 made at nearly equidistant pe- feet, 



riods throughout the year, 42 78*6 



5 observations, 60 79-2 



6 ditto, 80 to 100 79-0 



5 ditto, .110 to 120 79-8 



1 ditto 160 80-0 



The increase in Europe is said to be 1° centigrade, or 1°- 8 Farht. 



for every 35 or 37 metres (about 105 or 110 feet English), of depth. 



Were I to select from my observations those made where bullocks 



were working for the purposes of irrigation, the increase would be 



much more rapid than what I have above stated. Thus : 



No. of wells. Depth to bottom. Temperature. 



81 



81-9 



827 



2 



.. . 60 



3 



90 



o 



120 



