34S The adaptation of the Aneroid for surveying in India, [No. 4. 



turn, and so rids us of the tremor and vibration to which it is liable 

 when moved about. 



The improvements suggested are all too obvious to require to be 

 more than mentioned. They can be carried out without in any way 

 increasing the expense, size, or complexity of the instrument, and 

 ought to be insisted on by all those ordering Aneroids for survey pur- 

 poses or for service of any sort in India. 



Mr. Adie of Edinburgh states that below 28 inches he finds the 

 Aneroid uncertain, and untrustworthy in its indications. Mr. Patton's 

 experience is at variance with this ; but should Mr. Adie's views 

 prove correct, one set of instruments might be cut from 3 1 to 28 ; a 

 second from 28 to 24, and so carrying down the series as far as might 

 be considered desirable. The first set might serve for elevations 

 under 3000 feet ; the second commencing at 3000 might carry us to 

 6000 and so on. The instruments might easily be tested under the 

 receiver of an air-pump without any actual ascent, the barometer guage 

 with a good scale answering as well as the barometer itself. 



The neatly-glued, leather-covered, velvet-lined box in which the 

 Aneroid is enclosed is unsuited for India, a hot Dekhan wind will 

 warp, twist and split it into pieces, a wet monsoon atmosphere liquify 

 the glue, mould the cover and rot the lining. To meet the risks of 

 climate and rough usage it ought to be provided with a strong case of 

 copper, brass or zinc of nearly the form of the instrument. This 

 should be stuffed with hair, with scraps of cork, India rubber, gutta 

 percha, or fitted up with springs so as to diminish the risk of concus- 

 sion or vibration. It should be then enclosed in strong leather like a 

 powder flask or spyglass, with straps and buckles for convenient 

 carriage. 



