APPENDIX. 
A. 
Description of a new Boiling-point Thermometer. 
On starting for Yarkand I took with me three boiling-point 
thermometers of the ordinary description^ two of which were 
used almost daily^ and the record of observations shows that 
the temperature of boiling water, if carefully taken^ and the 
thermometer be a good one graduated to tenths of a degree^ 
is almost, if not quite, as reliable as the mercurial baro- 
meter in estimating heights, and it is infinitely more trust- 
worthy than any aneroid, as the latter instrument is very 
apt to be put out of order by shaking and rough usage on 
the march, as well as by extremes of temperature. 
On my return to England I set myself to improve the 
ordinary boiling-point apparatus, as I found that for use in 
the field it was defective in many respects. 
Mr. J. Hicks, of 8, Hatton Garden, London, has carried 
out my ideas in a way which renders the instrument all but 
perfect. I think it might still be made considerably less 
bulky, however, and there is still some difficulty in getting 
the candle to burn without coating the bottom of the boiler 
with lampblack. These defects I would have remedied if 
I had not been obliged to leave England so soon. 
The ordinary apparatus is boiled by means of spirits of 
wine, and as few travellers when marching over a difficult 
country can keep up a supply of spirits or get it replenished 
when the original supply becomes exhausted, the only alter- 
native is to use a wood fire, which necessitates a supply of 
