1891.] 



BEN NEVIS OBSERVATORY. — LOG-BOOK. 



319 



was passing over Ben Nevis. For the last three days 

 there has been a good deal of slight haze. 



June 19. — Mist or fog till 15 h , after which it sank down, 

 leaving sky clear except for a little cirrus moving from 

 W.S.W. The fog covered the hills round till 21 h , but 

 after that broke up and dissipated, but haze and streaks 

 of fog lay among the hills, especially to N., all night. 



June 20. — Air hazy all day — thickest towards evening. 

 Low streaks of fog in valleys and over water, including 

 upper Lochiel, till 7 h . In early morning the haze was 

 distinctly low down, not rising above 4000 feet, but 

 during the day and at night it extended far above the 

 height of Ben Nevis. 



June 21. — The. fore-glow was seen at 3 h . The sun was 

 not seen till 3 h 35 m owing to the thick haze which filled 

 the air to a considerable height above the level of Ben 

 Nevis all day. 



June 22. — Sun first seen at 3 h 15 m . At 3 h the fore- 

 glow was seen. Fog in valleys to N.E. from 5 h to 7 h . 

 No fog below during the rest of the day, but haze at 

 horizon. 



June 23. — Sun rose at 3 h 15 m . Fog lay in the valleys 

 to northward as far as Loch Lochy till 9 h , but after that 

 dispersed. Air rather hazy all day. The after-glow was 

 seen at 22 h . Fog gathered again in valleys to N. at 

 night. 



June 27. — Fog most of the day, but when clear, masses 

 of cum.-fog and haze seen on hills round. Solar halo 

 seen at 18 h . Three measurements of radius gave — 21° 

 22', 22° 2', and 21° 53'; mean 21° 46'. 



July 1st. — Top clear in afternoon ; no fog in valleys, 

 but sky cloudy. Some cirrus seen moving from S. 

 Haze to W. and S.W. in evening. Solar halo seen at 

 18 u . 



July 2. — Misty or cloudy sky, and mist hanging about 

 hills round all day. Thunder was heard at 13 h 45 m , at 

 \b h 30 m , and at 16 h 55 m . Heavy showers of rain all 

 afternoon and at night. A rainbow was seen at 18 h . At 

 21 h St Elmo's Fire — nothing could be seen as it was 

 daylight, but post A and the anemometers were hissing 

 loudly — could be heard 20 yards off, and a tingling 

 sensation was felt in observer's face when turned 

 upwards. 



July 8. — Thin wet mist till 21 h . Summit clear after- 

 wards, but other hills all covered, and high cum.-s. on sky. 

 At midnight the northern sky was pretty free from 

 ■cloud, and the spectrum colours were very distinct and 

 pure. The air over the fog was very clear. 



July 9. — Fog on hills below 3000 feet most of the day 

 and iu the evening blowing over summit also. Cirri 

 forms on sky, on which from 9 h till 13 h a solar halo was 

 visible. At 5 h fog was observed pouring down on the W. 

 and S.W. sides of Aonach More. At 23 h pearly cirrus was 

 seen in the northern sky for the first time this summer. 

 At 23 h 5 m the highest point of the pearly cirrus was 5° 

 18' and the lowest 3° 14' above the horizon. Photographs 

 were taken of the phenomenon and several measurements 

 made of certain bright streaks iu the cloud. At midnight 

 the cloud extended along the northern horizon from 

 N.W. to N.E. 



July 10. — A photograph was taken of the pearly cirrus 

 which was partly obscured by cum.-cir. or cir.-s. clouds 

 at h 35 1U . These dark clouds gradually increased, and at 



l h covered the whole northern sky so that no pearly cirrus 

 was seen thereafter. Pearly cirrus was not seen at night 

 though the sky was clear. Fog all round below, rising in 

 the afternoon to level of summit and occasionally passing 

 over it. A rainbow was seen at 7 h and a glory at 20 h . 



July 11. — Fog all round to level of summit till 8 h . 

 After this it rose and enveloped the hill top for the rest 

 of the day, changing to mist at 18 h , from which at and 

 after 20 h drizzling rain fell. 



July 13. — The summit cleared after 10 h , and remained 

 clear, except for a little fog passing at times for the rest 

 of the day. Broken fog on hills till 21 h , none thereafter. 

 Pearly cirrus seen to N. at midnight, stretching from 

 N.W. to N.E., its highest point being then 14° 16' 

 above horizon, and its lowest limit 7° 8' above same. 

 A light of dazzling brightness was seen to S.W. by S., 

 about ou a level with Observatory at 10 m past midnight. 

 It appeared to be stationary, was seen for about 30 seconds, 

 then it vanished, and in a few seconds it was seen again 

 as a faint red speck in the same place. This red speck 

 lasted for a few seconds, when it vanished in an intensely 

 white flash. 



July 14. — The pearly cirrus continued visible till 

 after 2 h . Two photographs were taken of it at l h 15 m to 

 l h 26 m , and several measurements were made to compare 

 with photographs. At 3 h it was not to be seen, but 

 the N., N.E., and E. sky was full of faint, filmy dust 

 streaks. Fog lay on the lower hills around most of 

 the day, and at times passed over the summit also. 

 Pearly cirrus was again seen to N. at 23 h . Its upper 

 limit was then 17° above the horizon. At midnight 

 there was only a trace of it in the sky. 



July 15. — At l h a little pearly cirrus was seen to N. 

 and N.E., but at 2 h none. Haze and broken fog below 

 3000 feet most of the day. At 15 h some cum. clouds 

 close overhead were moving quickly from the E., while 

 at the Observatory there were only very light variable 

 airs. The air over 3000 feet was very clear to-day. 

 Very fine sunset. 



July 27. — Heavy rain fell between h and 1\ and 

 at l h several flashes of lightning were seen. 



July 31. — Summit clear all day. Air warm and very 

 dry. Fog below from 3000 to 4000 feet all morning, 

 breaking up about the middle of the day, but continuous 

 again at night. Sky somewhat cloudy with cir.-c. types. 

 Solar halo seen at 14 h . 



Aug. 3. — Summit clear and air slightly dry till 16 h . 

 Mist and saturation thereafter. Heavy shower of hail 

 at noon, and heavy showers of rain, and at times, sleet 

 all afternoon. Several peals of thunder heard between 

 17 h and 18 h ; no lightning seen, but before each thunder 

 peal the telegraph needle gave a sharp click. 



Aug. 6. — Air dry till 14 h : very dry from 4 h till 6 h . 

 Cloudy in forenoon, and fog below all round, which rose 

 covering the top at ll h with occasional breaks after. 

 Solar halo seen at 8 h . 



Aug. 16. — Summit clear almost continuously from 6 h 

 to 22 h . No fog below when summit was clear. 



Aug. 22. — Clear for the most part between 9 h and 17 h 

 with fog passing at times. Between l h and 2 h some 

 animal, probably a weasel, was heard behind partition in 

 passage between kitchen and office. 



Aug. 23. — Summit clear from ll h to 22 h . A great 



