AND METEOROLOGY OF DUKHUN. ]65 



dredths of an inch of water less than the smaller in the first tenth of an inch of rain. 

 Subsequently they coincided in their indications even to the hundredth of an inch. 



With Gary's Englefield barometers, I received three thermometrical barometers, 

 for determining heights by the difference in temperature of boiling water at different 

 levels. Owing to faultiness in their construction, they proved complete failures, and 

 were sent back to England. I satisfied myself there was a good deal superfluous in 

 the apparatus accompanying them, which made them moreover expensive, and I effi- 

 ciently supplied the place of these barometrical thermometers by two good common 

 thermometers with metaUic scales and a tin shaving-pot with a slit in the Hd, in which 

 the thermometer was placed, being moveable in a collar of cork. Pure water and 

 dry sticks were always found, an attendant carried a light, and my boiling-operation 

 was concluded in a quarter of an hour without the aid of tallow, lamp, sulphuric 

 acid, phosphoric matches, trimming-scissors, tweezers, hanging-screw to fix into 

 trees, water-bottle, &c. &c., involving the outlay of several pounds. Accuracy in the 

 indications of the instrument also was risked, owing to three fourths of the stem of 

 the thermometer being exposed to the wind or cold air during the time of the im- 

 mersion of the bulb in the boiling water, which checked the rise of the mercury. 



Having for several years practised the barometrical and thermometrical methods 

 to determine heights, I have no hesitation in expressing my opinion, that a good 

 thermometer and a boiling-pot may efficiently supply the place of the expensive and 

 delicate barometer where great accuracy is not required. In many instances I found 

 the results by the two processes almost identical. 



My electrometers consisted of two balls of pith suspended in small glass jars capped 

 with brass, having an elevated point on the plane of one cap, and a wire projj^cting 

 from the apex of the other, which was bell-shaped. They were in fact Cavallo's 

 pith ball bottle electrometers, with Saussure's addition of pointed wires, but without 

 a graduated scale on the bottle to measure the divergence of the balls. Owing to 

 some peculiarity in the instruments, they feebly indicated the presence of electricity 

 in the atmosphere, although at certain seasons it was so rife as to be painful to the 

 feelings. When first received, they were sensible to artificial electricity, but latterly, 

 without having been injured, they lost all susceptibility. I never could make a record 

 of their indications. Even had they been available, the want of a scale rendered it im- 

 possible to give any positive idea of the extent of the electric state of the atmosphere 

 at any time. A scale, in case it did not measure definite quantities, would neverthe- 

 less be highly useful to determine the electricity of any particular period relatively to 

 that of any other period. 



In placing the instruments for measuring the pressure and heat of the atmosphere,. 

 I was particularly careful to secure them from the operation of causes capable of 

 producing partial and unsatisfactory results. They were always in the shade, and 

 always guarded from direct or reflected heat, but with a free admission of the external 

 air. Annually, from October until May inclusive, they stood, for the most part, 



