kept for some time in large Reservoirs. 27 



the brine of a terrace yielding salt : and believing the hottest 

 water to be therefore near the bottom I tried the temperature 

 there about a month afterwards by immersing an empty bottle 

 at the end of a bamboo, fixing the mouth so that it would be 

 filled about a foot from the ground. The contents when 

 poured out were at the temperature of 120°. A similar ex- 

 periment made on the same day in a circular brine reservoir 

 at Narainpore (120 feet diam. and about 16 feet deep) gave 

 104°. But on a subsequent visit to Narainpoi'e on the 29th 

 October, I was startled to observe that a pump fixed against 

 the wall of this reservoir, for the pui'pose of feeding the boilers, 

 was actually bringing up water of the temperature of 130° 

 from a depth of about 12 feet. This very unexpected disco- 

 very determined me to contrive an instrument that should 

 serve as a probe to ascertain both the temperature and the 

 specific gravity or saltness of the water at different depths. An- 

 nexed is a drawing of the instrument employed : it consisted 

 of a split bamboo with bamboo buckets fixed between at di- 

 stances of one foot from centre to centre, the mouths of the 

 buckets being corked, but the corks having small air-holes ; 

 and the mode of using the machine was, to let it down with 

 the mouths of the buckets downwards, and then turn it round, 

 after which the air bubbles indicated the progress of filling ; 

 and in ten minutes or a quarter of an hour, when these disap- 

 peared, the machine was quickly drawn up and the tempera- 

 ture of the water in the buckets was tried rapidly in succes- 

 sion with a small thermometer, leaving the specific gravity to 

 be tried afterwards. 



On the day of the first trial of this probe I was favoured 

 with the company and assistance of Dr. Huffnagle, who took 

 a lively interest in the experiment. The following particulars 

 are the results of all the trials I have yet made with it, the 

 buckets being numbered from the bottom of the machine. 



First Experiment, 5th November, 9 a.m. 



Open long reservoir at Balya Ghat. Probe immersed at an angle of 

 45° or 50°. 



