94 Mr Adie on the Register of the Thermometer, 



spheric temperature was supposed to be 60° ; let it now be sup- 

 posed that the loss of heat caused by evaporation is equal to 

 10°. The mercury in the tube a will then point to 50, and 

 that in the tube b to 10 on their respective scales ; and then 

 10 -f 50 = 60°, which was the temperature of the air at the 

 instant the globule quitted the open extremity of the tube b, 

 when the instrument received its horizontal position. 



The way in which the instrument may be placed in a hori- 

 zontal position, at any given instant during absence, was for- 

 merly described, (see vol. iii. p. 251) — a pocket time-piece, 

 and a small additional but simple piece of mechanism, being 

 all that is requisite. A vessel for containing the evaporating 

 fluid, fitted with a valve, and a capillary tube terminating in 

 one or more small and soft hair brushes, completes the ap- 

 paratus, and which can obviously be made of such small di- 

 mensions as to be easily portable. 



If the bulb e, at the upper extremity of the tube b, Fig. 2, 

 be made of the bent form represented in Fig. 4, the instru- 

 ment does not require tc be moved from a horizontal position. 

 In this case, the globule of mercury is made to quit the open 

 extremity of the tube d, and fall to the bottom of the bent 

 bulb i, Fig. 4, in consequence of the tube d, on a separate 

 piece of ivory, being made to turn half-way round on itself, 

 the centre of motion being a line drawn through the centre of 

 the tube, and the extremity of the bent portion being thus 

 made to describe the half of a circle. 



Art. XIX. — Abstract of the Register of the Thermometer, 

 Barometer, and Rain-Gage, for the years 1824 and 1825, 

 kept at Canaan Cottage. By Alexander Adie, Esq. 

 F. R. S. Edinburgh. Communicated by the Author. 



As the individual observations, of which we propose at pre- 

 sent to give an abstract, are regularly recorded in every num- 

 ber of this Journal, and the circumstances under which they 

 are made distinctly described at the head of each quarterly 

 table, it is unnecessary to enter into any farther details upon 



these subjects. 



n 



