134 Daniell on a new Hygrometer, 



My opportunities of trying experiments upon heights have 

 still been very limited ; so limited, indeed, that I dare not at^" 

 tempt to draw any inferences from their results. I shall content 

 myself, therefore, with noting the particulars of the few that 

 have been within my power. 



On the 3d of April I had an opportunity of ascending Leith- 

 hill, in Surrey, which is about 800 feet above the level of the 

 valley of Mickleham, the place from whence I set out. The ba- 

 rometer, at the lower station, stood at 30.296, the hygrometer 

 denoted the temperature of the air 60°, and the point of deposi-r 

 tion 51°. On the top of the hill the barometer stood ^ 2^.406, 

 and the hygrometer marked 55° and 46° ; making a difference 

 in the pressure of the whole atmosphere of 0.890, and in the 

 pressure of the vapour 0.060. 



On the 22d May, I again ascended the same hill. 



Barometer at first station .... 30.178 Hygrometer. . 71-56 



second station 29.348 • — .. 66-47 



Difference of barometric pressure 0.830 



Ditto of hygrometric ditto , 0.1 19 



A third time, on the 14th of August. 



Barometer at first station .... 29.948 Hygrometer.. 72-61 



second station 29.055 .. 70-52 



Difference of barometric pressure 0.893 



Ditto of hygrometric ditto , 0.141 



On the 4th of April I ascended to the highest point of Hedr 

 ley-heath, a hill in the same vicinity, about 600 feet above the 

 valley. 



Barometer at first station ... 30.050 Hygrometer 58-34 



at second station 29.370 59-32 



Difference of barometric pressure 0.680 



Ditto of hygrometric ditto 0.014 



On the 7th April the same stations gave as follows : 



