22 k Z 



BEN NEVIS OBSERVATORY. — LOG-BOOK. 



[1890. 



March 27. — A lunar halo was seen at 22 h . 



March 28. — Thermometer box shifted at h 15 m . 

 Height above snow not altered. A lunar corona was seen 

 faintly at 22 1 '. 



March 30. — Thermometer hox shifted at 23 h 15 m . 

 Height above snow not altered. A lunar corona was seen 

 at 21 h . 



March 31. — Shadow of Ben seen above the horizon at 

 sunrise. Great " visibility " in all directions till 8 h , and 

 to N. and N.E. till 16 h . At 14* \b\ and 16 h , a thick 

 bank of haze was seen to W., and S.W. approaching. At 

 17 u it reached Ben Nevis and at same time the summit 

 was enveloped by very thick fog. 



April 1. — A lunar corona was seen at midnight. Thick 

 haze all round below to-day. At ll h the distance be- 

 tween the edge of cliff and post at " first gorge " was 

 measured, and showed that the snow overhangs about 

 26 feet. 



April 3. — Summit clear all day, and except for a little 

 cirrus, about midday sky cloudless. Thick haze all round. 

 Air very dry to-day. At 7 h and 8 h the humidity was 31 

 per cent. 



April 4. — Summit clear and air dry till 15 h , fog after- 

 wards. In early morning there was some cirrus on sky, 

 and at l h its radiating points were N. and S., but at 2 h , 

 N.E. and S.W. At 2 h a lunar corona was seen. 



April 5. — Top cleared after 4 h and air was dry, except 

 at 9 h , till 22 h ; lowest humidity 26 at 6 h . Part of solar 

 halo seen at 15 h . Haze all round, but not so thick as 

 during last few days. 



April 6. — Top clear at 6 h and 7 h . At these hours a 

 solar halo with two mock suns was observed. Radius 

 from centre to outside edge = 24° 5T. 



April 8.— Thermometer box shifted at 20 h 10 m . 

 Height above snow not altered. Between 20 h and 22 h , 

 there was a peculiar fall and rise in temperature. The 

 barometer readings at those hours were the same, 25 - 294, 

 but at 21 h it was 25*248. The temperature readings were 

 20 h , 19°-9; 21 h , 19°-8; 22 h , 19°-5; but the minimum, which 

 was put out at 20 h , gave 17°-1 at 21 h and 13°-1 at 22 h . 

 The barograph shows that at about 20 h 5 m there was a 

 sudden rise and fall of about "050 inch (a mere kick up 

 and down again), and at 20 h 55 m a fall, which continued 

 till 21 h 15 m to 20 m , of about -080 inches, and then a more 

 gradual rise till after 22 h . Previous to this the curve was 

 somewhat shaken. At 21 h the wind was N.E. force (2-4), 

 while the sky was ^ covered with strato-cumulus, the 

 appearance to N.W. being exceedingly gloomy, while to 

 S. the sky was open and clear. 



April 11. — The zodiacal light was seen at 22 h . 



April 12. — Ben clear of fog and air dry except at 22 h 

 and 23 h . Between hotel and first gorge depth of snow 

 was found to be 167 inches, and nearer bucket stage 181 

 inches. Thick haze to S.E., S., and S.W. in distance 

 all afternoon, very little to N. 



April 13. — Shadow of Ben seen above the horizon at 

 sunrise. The humidity was very unsteady in forenoon, 

 at 7 b it was 36, and at 9 h the air was saturated. Passing 

 showers were seen in various directions during afternoon. 



April 15. — At 17 h a glory was seen. At 20 h and 21 h 

 the sky was covered with the hard detached (rare) form 

 of cirro.-str. cloud. Its radiating points being S.W., 

 N.E., not well defined. 



April 20. — Brown fog crystals forming to-day. A 

 little drizzling rain fell at night. 



April 21. — The summit was clear from 3 h to 6 h , but 

 sky was partly covered with hard detached sheets and 

 lumps of cir.-s. or str.-cir. ("rare" type). Fog or mist 

 during the rest of the day. In forenoon heavy rain and 

 hail fell, but the raingauge measurements were rendered 

 useless by heavy surface drift ; at times the drift seemed 

 to be all pieces of ice torn from the surface by wind. 



April 24. — Thermometer box shifted at 4 h 15 m , put 

 one step higher on ladder stand than it was before. 



April 26. — At 13 h to-day a sound was heard in neigh- 

 bourhood of kitchen chimney similar to that made by 

 St. Elmo's Fire. It lasted for about 2 minutes. 



April 27. — A mock sun brightly coloured seen to N. 

 of sun (about 22°) from 19 h 40 m till after sunset 

 (20 h + 4™ or 5 m ). It was formed on a thin horizontal 

 streak of cir.-s. Lunar halo with mock moons seen at 

 23 h and midnight. 



Radius to inside of mock moons 25° 13'. 

 „ „ halo 22° 36'. 



There were gaps in the halo (or inside edge of halo) 

 where the mock moons were seen. Immediately inside 

 the halo all round there was a band of darkness {i.e., this 

 band was distinctly darker than any other part of the 

 cirro-stratus film on which halo was formed). The cirrus 

 on sky at night radiated from N. by W. and S. by E., 

 and took the form of long filmy bands through which 

 the stars could be seen, and stretching at times right 

 across the sky from radiating point to radiating point. 

 The depth of the snow wreath to N.W. of hotel near 

 bucket stage was to-day found to be 218 inches. The 

 snow at first gorge was overhanging 23 feet. 



April 28. — The air was dry except at 10 h , ll h , 23 h , 

 and midnight. From 4 h till 9 h the humidity was very 

 low and steady, being 25 or 26 the whole time. Part 

 of a solar halo was seen at 12 h ; and a lunar corona 

 at 23 h . 



April 30. — Fog or mist all forenoon but clear after 

 13 1 ', sky being overcast, or nearly so with cumulo-str. 

 and scud till 6 p.m., and afterwards with str.-cir. and 

 cir.-c, the latter at 23 h being uppermost and moving 

 quickly from S.S.W., and the str.-cir. motionless. At the 

 same hour a cloud of the " rare " str.-cir. type was seen to 

 S.W. From a mere speck it quickly increased and then 

 gradually faded off, being gone 6 minutes after it was 

 first noticed. It kept the same position all the time, but 

 its growing in one direction and fading in the opposite 

 gave it an apparent motion first in one way and then iu 

 the other. 



May 4. — Passing showers were seen to N. in forenoon. 

 Haze all day, not so thick in afternoon as in morning. 

 The thermometer box was shifted down one step on 

 ladder stand after the midnight observation. 



May 5. — Thin fog on hills to N. and N.E. in forenoon, 

 clinging close to hills and showing on its upper surface 

 the shape of the hills and valleys it covered. At 4 h aud 

 5 h cumulus shaped clouds formed to E. in distance and 

 advanced W. quickly. Each cloud had a thin stratus 

 cap which moulded itself to shape of upper surface of 

 cum. cloud, but did not touch the cloud. Peculiar forms 

 of ascending currents were observed in corrie to N. at 8 h . 

 A click in telegraph instrument at 15 h 15 m was followed 



