the Trigonometrical Station on Rumbles Moor, Yorkshire. 14\ 
~ The thermometer on the mountain, however carefully shaded, 
is more suddenly and materially affected by the sun than the one 
at its base. On the approach of a shower, it will, for instance, 
suddenly fall several degrees. 
When the thermometers differ but trivially, rain is generally 
the consequence. 
Rumbles Moor and the Observatory are not upon the same 
isothermal curve; the mean temperatures of the latter will cons 
sequently require a small reduction. 
M. temp. of Near Ilkley. at Cowper Cross. 
3 obs. at 10" in Dec. 1820... 31-3 5:0 low 
26 Jan. 1821 P 38:6 3°8 
20 se Feb. af 37°1 37 
23 ae Mar. ¥: 41:7 4-4 
15 Lid April bis 50:2 AD 
17 aa May ¢2 51-1 3°3 
13 ae June aie 55°6 34 
7 ie July ve 5Y-4 4:4 
7 - Aug. ee 62°7 4-4 
2 oe Sep. as 65°5 4°5 
4 4 Dec. 47.0 4:6 
11 obs. at 14" O™ to 185 45™ Apr. 9 53:6 51 
7 9 30—12 30 Apr. 17 49:4 37 
13 10 30—12 30 July 25 60-5 (rain) 2.4 
Cowper Cross is about three quarters of a mile W.N.W. of 
the station on Rumbles Moor, and is 1250 feet high. likley is 
two miles north of the Moor, and 296 feet high. If we exclude 
the last set of observations, the mean difference of the temperz- 
tures will be about 4°, and that of the altitudes 954 feet, which 
is equal to an ascent of 240 feet for a diminution of tempera- 
ture of 1°. 
Mean temp. of 1821. Near Ilkley At Rumbles Moor. 
10 obs. 10°45 to 13°0 Apr. 25 66°9 ee 3-2 low" 
12 845 —140 — 30 52°5 oe 
18 11-0 —19:30June 2 62-0 ee 
7 11-15 — 12°45 July 13 66°9 ee 
y 10°15 — 12°15 — 21 62.6 oe 
10 10:30 — 12:0 — 27 61:9 “i 
13 110 —13-0 — 28 60:3 2 57 
15 11°30— 15-0 Aug. 7 63°0 oe 6°2 
The station at Rumbles Moor being 1029 feet higher than the 
one near Ilkley, the ascent appears to be about 210 feet for a 
fall of 1° of the thermometer. 
Mean 
