68 



BEN NEVIS OBSERVATORY.— LOG-BOOK. 



[1888. 



the whole, smaller in size, none exceeding ^ inch diameter. 

 Faint lunar halo seen at 20 h , 21 h and 22 h . It was 

 difficult to distinguish between upper and lower clouds at 

 night, they seemed to pass into each other without any 

 marked plane of separation. 



March 26. — A slight shower of snow, consisting of 

 small rough pellets of hardish texture, fell at 15 h , diameter 

 about tt\j- inch. Stars and small pellets mixed about ^ 

 inch diameter fell at 19 h . Neither of these showers were 

 sufficient to affect the gauge. 



March 27.— Thermometer box shifted at 9 h 40 m . At 

 9 h cum. fog on hills to about 4000 feet. The cum. fog 

 continued to hang about the hills round most of the day, 

 but at 18 u had risen and joined cum. clouds above the 

 hills, which gradually disappeared later in the evening. 

 At 23 h and midnight lunar halo seen, faintly tinged with 

 red inside. At 23 h it was measured. 



Radius to inside of halo . . 23° 58' 

 Radius to outside of halo . . 29° 4' 

 No low fog in valleys all day. 



March 28.— The lunar halo still visible at l h and 2 h . 

 At 4 h a lunar corona was seen occasionally. Before 

 sunrise at 6 h the earth shadow and shadow of Ben Nevis 

 were seen. When clear to-day there was no fog in valleys, 

 but cum. fog on and over hills. The great amount of fine 

 drift going made the raingauges useless ; most of the 

 snow that fell a few days ago was swept off the hill top 

 and the old icy surface exposed. 



March 29. — Raingauges useless in early morning 

 owing to drift, and measurements by them in forenoon 

 doubtful from same cause. 



March 30. — At 10 h a few star-shaped crystals were 

 falling mixed with the snow-flakes. At 19 h the snow 

 consisted of small pellets not flakes. 



April 1. — Thermometer box shifted at 2 h 20 m . No 

 fog in valleys in morning, except a little patch of stratus 

 fog over Fort- William at 6 h and 7 h . At 7 h fog on hills to 

 W. At 8 h fog blowing across Ben Nevis and on hills 

 round. The snow that fell this afternoon was icy, in 

 small pellets rather than flakes. Measurements of amount 

 of snow at night rather doubtful owing to drift. 



April 2. — Aurora, single arch without streamers, seen 

 at 22 h and midnight. 



April 3. — Aurora still visible at l h and 2 h . At 8 h 

 cum. was seen to N., and at 9 h it was over Ben Nevis, 

 and fog brushing the hill top. 



April 4. — At 17 h fog on hill top, but sky seen above 

 covered with cum.-s. The fog on the hill seemed local and 

 distinctly below the level of the cum.-s clouds. 



April 5. — Thermometer box shifted at h 15 m . At 2 h 

 very faint aurora seen low down to N.N.W. At 4 h faint 

 sunrise colours were observed. At 5 h the upper glow 

 and earth shadow were seen. Fog over hills to E. to 

 4000 feet. This fog gradually broke up into cumulus in 

 the forenoon. At ll h the sky was clear, but there was 

 cum. fog rising out of Glen Nevis ; before 12 h the sky was 

 overcast with cumulus, but the air under remained very 

 clear till the clouds sank and formed fog on the hill top 

 at 15 h . The beginning of the fog was not accompanied 

 by any change of temperature. 



April 6. — Faint aurora, single arch, no streamers, seen 

 at l h . At 7 h a little fog lay over Loch Lochy and cum. fog 

 hung about the hills all forenoon. In the afternoon 



this fog rose and formed detached cumulus clouds above 

 the hills. No fog in valleys all day. At 18 h the cloud 

 that had formed above Ben Nevis sank down and became 

 fog. 



April 8.— At 5 h the sky was covered with cum. 

 and fog lay over the hills round to 4000 feet. In the 

 forenoon the fog broke up and formed cumulus clouds ; 

 these, in the afternoon, were specially heavy to W., but 

 there was no fog in valleys. No unusual colours in sky 

 all day. A few faint and evanescent glories seen between 

 18 h and 19 h on fog blowing across the hill top. 



April 9. — Till 4 h , though the sky was cloudless there 

 was str. fog on hills to N. and E. to about 3500 feet. 

 After this the fog broke up into detached portions. The 

 earth shadow was seen at 5 h . At 15 h small needle-shaped 

 crystals of snow were falling, and at 16 h besides these there 

 were flakes composed of agglomerations of these crystals 

 without any order or arrangement. The needles were about 

 Jy inch long and the flakes up to -f^ diameter. Small icy 

 particles fell mixed with the snow in the evening. 



April 10. — The snow that fell this afternoon was small, 

 hard, and rather icy. Louvres of thermometer box 

 choked with ice all evening. 



April 12. — At l h a light was seen to N. through breaks 

 in the fog — probably auroral. At 6 h 10 m thermometer 

 box shifted. Portions of solar halo were seen at 7 h and 

 9 h . At 9 h there were two small arcs, one on each side of 

 the sun, coloured red, yellow, green, blue, the red being 

 inside. No fog in valleys in forenoon, but detached fog 

 on the hill tops all round. 



April 14. — A solar halo, red inside, blue outside, was 

 seen to-day between 17 h and 18 h . 



April 16. — Thermometer box shifted at 5 h 15 m . 



April 18. — No fog in valleys all day, but cum. fog hang- 

 ing about the hills in heavy masses and haze below it. 

 Thermometer box shifted at 15 h 10 m . 



April 19. — Dense masses of cumulus all round during 

 the day, with dark haze below in valleys. 



April 20. — Very squally and heavy drift in forenoon. 

 At 1 l h the raingauge was found blown over and lying 

 about ten yards to leeward of its proper place. The door 

 of the thermometer box was also torn from its hinges, 

 while reading the thermometers at the same hour. No 

 gauge was used all forenoon, but apparently no snow fell 

 except a few crystals. At night though the top was 

 sometimes clear of fog the air was evidently saturated, so 

 the box was not shifted though slightly coated with drift. 



April 21.— Thermometer box shifted at 19 h 10 m . No 

 fog in the valleys, but cum. fog hanging about the hill tops 

 round all day. Though fog was mostly brushing the top 

 of Ben Nevis, the sky above seemed pretty clear. Some 

 star-shaped snow crystals fell several times during the 

 day. Fleeting lunar coronse were observed at night. 



April 24. — No fog in valleys to-day, but considerable 

 haze. No unusual colours in sky during the day, but 

 usual sunset colours and after glow at 20 h . Solar halo 

 seen at 19 h — red inside. Radius of red = 21° 36' (rough 

 measurement). A lunar halo also seen at 21 h and mid- 

 night. 



April 25. — Lunar halo still visible at l h and 2 h . At 

 \ h , 2 h and 3 h cum. fog to E. on hills. At 5 h cum. fog had 

 formed on the hills to W., but no fog in valleys all day, 

 though haze at night. A solar halo was seen at 16 h . 



