340 The adaptation of the Aneroid for surveying in India. [No. 4, 



The following observations were made at Poona in July and August. 



The Standard Barometers employed were Nos. 1 and 2, the finest 

 sent out by Mr. Adie, the way they kept together was quite admirable. 

 The Mountain Sympiesometer referred to was a very elegant instru- 

 ment procured for Col. Campbell, whose indications were also very 

 accurate, and in most perfect harmony with those of the other instru- 

 ments. 



On comparing the instruments at Sewree, about 70 feet above the 

 level of the sea, they stood on the 22nd July at 10 a. m. as under, the 

 Thermometer being 84°, the correction for temperature of the Baro- 

 meter here applied .149 — the Standard at the Observatory at this date 

 was 29.667, the instrument being 32 feet above the level of the sea. 



t, , Mountain A . , 



Barometers. Sympiesometer. Aner0lds « 



I. II. 5821 5822 2244 



29.676 29.662 29.750 29.765 29.790 29.780 



The following were the readings of the instruments respectively at 

 Poona at 10 a. m. on the 27th — the Observatory Standard had be- 

 twixt these two dates sunk from 29.667 to 29.587 or by 00. 080 :— 



Temperature at Poona 76° — Barometer corrected 



I. II. Symp. Aneroid. Aneroid. Aneroid, 



27.713 27.713 27.830 27.800 27.802 27.650 



Difference betwixt Poona and Bombay. 



1.963 1.949 1.920 1.965 1.988 2.13a 



The coincidences here betwixt the barometer and mountain sympie- 

 someters, and Mr. Treacher's Aneroids, are as close as may be. 



These experiments were performed at Col. Grant's at the extreme 

 end of the Artillery lines, his house is pretty nearly on a level with the 

 church, the top of the spire of which is set down in the Trigonometri- 

 cal Survey at 2038 feet above the level of the sea. Mr. Treacher's 

 instruments were only cut to 27.5 inches, and that belonging to the 

 Society cut to 23 was unserviceable. I took our own Aneroid to the 

 top of Bap-dieu Ghat along with me — the following were the results ; 

 but as already stated the instrument was unserviceable, so that no con- 

 clusion from its indications, can in this case be drawn — the perfection 

 of the Mountain Sympiesometer is very remarkable : 



