138 Altitudes of Mountains, &c. visible from 
thermometer being on an average of 29 observations from 105 0™ 
to 19% 20"; 14° highest at Pendle Hill. 
Barometer at 10- 0 28-911 Hygr. —5° 
Do. 13: 0 28°856 —4° 
Do. 18:20 28-830 —6° 
Beamsley Rock, June 14. 
h. m. a a Therm. Do, at Bolton. 
12 © © Pendle Hill elev. 9 31 59 58 
12 40 ee 9 26 62 59, 
14:10 e 9 27 582 58 
15 15 ae 9 8 o4t 574 
17 10 =. 9 10 53 562 
18 10 9 15 522 554 
The Hiermnigeten. at Bolton was 913 feet lovee than on the 
Rock, at 14°35 the hygrometer was —14°. The barometer 
reatiaiell stationary at 28-925. 
Beamsley Rock, June 27. 
Dy is Therm. 
16 35 Pendle Hill elev. 8 56 Hye 
17 20 ete 92°0 55: 
18 15 “he ae ai, 52 
19 35 aie 8 54 AT 
19 50 ar 8 54 ~ 46 
At 17 20 the hygrometer was —10°, Barometer about 
28:80. 9’ 3” will be the apparent angle which will best agree - 
with other observations. 
Symon Seat, agust 29. 
h. m. Therm. 
15 45 Gt.Almias Cliff, depr. 46 58 WindS.E. 53 
16 40 Do. ae AN violent 52 
September 8. 
14 10 Gt. Almias Cliff, 47 29 S.W. 56 
Observations of other stations made on both days agreed within 
a few seconds. The mean of the above three angles is the nearest 
to the true one. 
The mean refraction in terms of the are is ascertainéd by re- 
ciprocal observations of the angles of elevation and depression. 
The observations should however be made at the same instants 
of absolute time, and during the existence of the diurnal varia- 
tion, it is almost superfluous to add that they must include the 
extremes, otherwise the greatest errors may be committed. The 
instruments should moreover be free from any constant error 
(such as those of collimation, &c.) or the refraction will be no 
longer correctly obtained in terms of the arc. When the tear 
rica 
