49 



Tables of Barometrical and Thermometrical Observations, made in Aff- 

 ghanistan. Upper Scinde, and Kutch Gundava, during the years 

 1839-40. By Dr. Griffith. 



A copy of these Tables was furnished to the Surveying Officers of the 

 Army of the Indus, as their Barometers ceased to be effective soon 

 after leaving Quettah. No other register was I believe kept. 



Columns 8 and 9 require some explanation, they contain the readings 

 off of the Thermometer, Barometer invented by Dr. Woollaston, but 

 with the substitution of an ordinary Thermometer for his delicate one. 

 Of these I have had several in India, but never met with one that was 

 in working order. The great weight and thinness of the bulb, likewise 

 renders them very liable to be broken. 



After adjusting the new tubes, and marking on them zero marks 

 corresponding to the zero of the scale, I formed a scale of valuations of 

 each degree from comparisons with the Barometers. I had similar 

 Thermometers in use in Bootan, and have had ample opportunities of 

 knowing that they will intimate altitudes to within trifling differences 

 of travelling Barometers, than which they are much more portable. 

 Ordinary thermometers for ascertaining altitudes by boiling water, vary 

 a good deal, and are not to be depended upon. My instruments are 

 now in Captain Sander's possession, and if they have escaped unbroken, 

 after comparing them with the best barometers in Calcutta, I shall do 

 myself the honour of presenting the results to Government. 



These Barometrical observations were made with an Englefield's 

 Barometer, and though made in a dry climate, and with every care, as 

 to drying the inside of the tube with a silk sponging- wire, as well as to 

 allow no air-bubbles to remain, can only be considered as approxima- 

 tive. The mercury was not as pure as it might have been, and none of 

 the Chemists in Calcutta could supply me with fresh distilled mercury. 



There is also considerable laxity in the columns of attached and 

 detached thermometers owing to breakages, occasional reduction to one 

 instrument, and the general place of observation, a tent, in different 

 parts of which very various temperatures are to be found. 



As I found that screwing, however lightly, the ordinary cistern to the 

 tube (to fix it) occasioned some of the tubes to break, I subsequently, at 

 Cabool, abandoned the plan altogether, and used a wooden box as cistern, 

 sufficiently large to enable the inverted tube, closed by the forefingers, 

 to be inserted under the liquid ; the float was adjusts as usual. I can 

 recommend this plan as a practical one, and much easier than the use of 

 the ordinary cistern. 



The instrument was put up afresh every day, even during halts, — 

 the tables shew that with care, and using one tube, the readings of vari- 

 ous days do not differ very much. 





