Trigonometrical Survey, 



721 



importance. I did not, however, lose any opportunity which the 

 subsequent season offered; the first was, when the instruments were 

 at White Horse Hill and Whiteham Hill ; the second, when one was 

 stationed at Brill and the other at Arbury Hill; and the third op- 

 portunity offered itself, when one party was stationed at the latter 

 place and the other at Wendover. 



On these occasions, the instructions which I communicated to 

 Mr. Woolcot, and by which I governed myself, were to observe 

 the elevation or depression of the corresponding station at the expi- 

 ration of every hour, beginning at six A. M. and to have the watch 

 well regulated from observed altitudes of the sun's limb. I requested 

 him also to be very minute in entering on his book the state of the 

 weather; to keep the instrument properly sheltered from the wind ; 

 to be always cautious to adjust his level ; and also to insert the state 

 of the air, as to temperature and density, by noting the thermometer 

 and barometer. 



During the time we were at the two first stations, White Horse 

 and Whiteham Hills, there was only one day when the air was suf- 

 ficiently clear for the purpose ; this was the 6th of June. On that 

 day, the following observations were made at the same time as shewn 

 by signal.. 



Whiteham Hill. June 6th, 1799. 



Hours. 



Wh Horse H. 



Barome- 



Thermo- 





Elevated. 



ter. 



meter. 





/ t 



In. pts 



Degrees. 



3 



6 4 



29,730 



60,3 



4 



6 24 



29,724 



62,5 



5 



6 14 



29,728 



58,7 



6. 



6 10 



29,732 



58,5 



7 



6 11 



29,728 



57 >5 



8 



6 21 



29,732 



57 



* 9 



5 37 



29,736 



55>7 



•10 



5 39 



29,740 



55>5 1 



Remarki. 



Light airs at SW. 

 Ditto. 

 Ditto. 

 Ditto. 

 Ditto. 



Sun not shining; remarkably clear. 

 Ditto ditto. 



Ditto ditto. 



Ditto ditto. 



Ditto . ditto. 



Very calm, and cloudy, but clear. 



Ditto. Lamp at Shotover very bright. Dew falling. 

 Ditto. Ditto. 



