XXIV 



METEOROLOGY OF BEN NEVIS. 



7 P.M., . 



Dry. 

 . 21°-8 



Wet. 

 14°-8 



Dew- Point. 



-32°1 



Humidity 



7 



8 „ . 



. 21°0 



14°0 



-34°-3 



6 



9 „ . 



. 19°-2 



13°0 



- 32°3 



8 



During these two days the sky was cloudless throughout, the wind south- 

 easterly, blowing at first with force 5 (scale to 12), then gradually falling to 

 3 at 9 a.m. of the 11th, about which it remained till 4 p.m. of the 12th, when it 

 fell to a calm, or only the lightest airs from the north-east at the time the 

 greatest dryness took place. On these days the extremes of temperature 

 were 24° 3 and 13° 3 ; and it may be noticed that at 8 a.m. of the 12th, while 

 at the Observatory the temperature was 23°9, at Fort-William it was 19°-2, 

 or 4° 7 lower than on the top of the mountain. Mr Wragge's observations of 

 1882, made at different heights, clearly show that such extraordinary dry states 

 of the atmosphere are restricted to the higher parts of the mountain. 



For each of the four years the maximum temperatures recorded at the 

 Observatory were 60° 1, 60° *0, 55° '8, and 66° 2 ; and the minimum tempera- 

 tures 9 0, 9, ll°'l, 8 0, 4, and 9°0 respectively. Thus the highest temperature 

 recorded in these three years was 66 0, 2 in June 1887, and the lowest 8°*4 in 

 December 1886, giving 57° "8 as the absolute range. 



Atmospheric Pressure. 



The mean monthly atmospheric pressures at the Observatory (at 32° only), 

 and at Fort- William (at 32° and sea-level) are these, the means being calculated 

 from the hours 9 a.m. and 9 p.m. 





Jan. 



Fell. 



Mar. 



April. 



May. 



June. 



July. 



Aug. 



Sep. 



Oct. 



Nov. 



Dec. 



Year. 





Ben Nevis Observatory. 



1883, 

 1884, 

 1885, 

 1886, 

 1887, 



in. 



25-174 

 25-150 

 24-942 

 25-159 



in. 



25-i'lO 

 24-863 

 25-398 

 25-494 



in. 



25 : 184 

 25 360 

 25-234 

 25-390 



in. 



25 : 291 

 25-189 

 25-273 

 25-374 



in. 



25-319 

 25-153 

 25-322 

 25-472 



in. 



25-499 

 25-467 

 25-417 

 25-680 



in. 



25-386 

 25-594 

 25-319 

 25-424 



in. 



25-440 

 25-475 

 25-382 



25-424 



in. 



25-405 

 25-193 

 25-395 

 25-358 



in. 



25-377 

 25-130 

 25-201 

 25-445 



in. 



25'-438 

 25-233 

 25-213 

 25-086 



in. 

 25-390 

 25-056 

 25-390 

 24-953 

 25-089 



in. 



25'-302 

 25-267 

 25-259 

 25-366 





Fort- William. 



1883, 

 1884, 

 1885, 

 1886, 

 1887, 



29-751 



29-758 

 29 544 

 29-753 



29-704 



29-422 

 30-071 

 30-124 



29-759 

 30-004 

 29-875 

 30-032 



29-859 

 29-759 

 29-867 

 29-992 



29-842 

 29-718 

 29-880 

 30-044 



30-018 

 30-001 

 29-940 

 30-168 



29-844 

 30-099 

 29-810 

 29-902 



29-896 

 29-986 

 29-865 

 29-911 



29-886 

 29-692 

 29-916 

 29-875 



29-932 

 29-702 

 29-780 

 30-046 



30 063 

 29-775 

 29-776 

 29-655 



30-011 

 29-636 

 29-978 

 29-558 

 29-698 



29-849 

 29-825 

 29-824 

 29-933 



Mean B. N. 0., 

 „ F.-W., 



Difference, . . 



25-106 

 29-701 



25-216 

 29-830 



25-292 

 29-918 



25-282 

 29-869 



25-316 

 29-871 



25-516 

 30-032 



25-431 



29-914 



25-430 

 29-914 



25-338 

 29-842 



25-303 

 29-865 



25-243 



29-817 



25-176 

 29-776 



25-300 

 29-862 



4-595 



4-614 



4 626 



4-587 



4-555 



4-516 



4-483 



4-484 



4-504 



4-562 



4-574 



4-600 



4-562 



This table gives for Ben Nevis a mean annual pressure of 25-300 inches. 

 The maximum monthly pressure is 25-516 inches in June, and the minimum 



