1891.] 



BEN NEVIS OBSERVATORY.— LOG-BOOK. 



315 



temperature, below 32° for the rest of the day. Air very 

 dry at 7 U and 8 h , humidity being 39 and 41 per cent, 

 respectively. Aurora seen in early morning. Thermo- 

 meter box shifted at 6 h 20 m . Height above snow not 

 altered. 



Feb. 14. — Temperature below 32°, but mist and drizzle 

 forming ice on all surfaces all day. 



Feb. 15.— Mist till 8 h , with drizzle at times. Top 

 clear for the rest of the day except for a few hours at 

 night, when fog prevailed. Fog or detached cumulus on 

 hills and haze in valleys. Motionless brown pieces of 

 cir.-s. (rare) seen to N.E. at 15 h . Thermometer box 

 shifted at 9 h 15 m . Height not altered. 



Feb. 17.— Fog till 9 h , a little cirrus on sky at 10 h , but 

 clear and cloudless till 22 h , with fog all round below 

 to 4000 feet, rising at times to level of summit and 

 blowing over it, and after 22 h enveloping it continuously. 

 During the afternoon this fog was pouring down into 

 the northern corry all along from first gorge to Cairn 

 Dearg. Rapid rise of temperature in forenoon. At 9 h 

 it was 27° - 8, and at noon 40°-4. A set of temperature 

 readings was made by Sling Thermometer. (1) on top, 

 in fog, and in clear air; (2) on way down to M'Lean's 

 Steep and on way back ; and (3) on top of tower. 

 The readings were highest on top of tower and lowest 

 in the fog. At times the top was covered in fog, 

 when the top of tower was quite clear of it. The read- 

 ings at the thermometer box varied very much during 

 the evening, being high and rising when the top was 

 clear, but low and falling when the fog was on or passing. 

 Lunar coronse were seen at times on passing fog at 21 h 

 and 22 h . 



Feb. 18. — Mist covered the summit till 9 b , but after 

 that hour it sank below level of top, and left the sky 

 entirely cloudless during the rest of the day. The mist 

 sank to about 3000 feet, and, in the afternoon, began to 

 break up till at 19 h it was all gone, and only left haze 

 in the valleys to about 2000 feet. Dark brown colour 

 under sun all afternoon. At 14 h 10 m the thermometer 

 box was placed one step higher on ladder stand. 



Feb. 19.' — Except for two small cumulus clouds that 

 were to be seen to W. about 4000 feet above sea-level, 

 at 15 h there was not a speck of cloud above or below 

 Ben Nevis all day, but thick haze was all around below to 

 3000 feet in the early morning, and to 4000 feet at night. 

 Brown colour around the sun to-day, strongest between 

 sun and horizon. 



Feb. 20. — Air warm and dry all day. Thick haze be- 

 low all around. Some cirrus in sky from 5 h till 18 h , but 

 cloudless during the rest of the day. 



Feb. 21. — Cloudless, but thick haze all around below 

 till 9 h , fog till 18 h . Top clear, but sky overcnst for the 

 rest of the day. Fog crystals, slightly brown, forming 

 in afternoon. A lunar halo was seen at 20 h — 22 h . A 

 hare was seen on summit at midnight. 



Feb. 22. — Overcast sky till 7 h , mist till 16 h , and over 

 cast again till midnight. At l h the haze was thinning 

 all around and rising, being then up to the clouds 

 apparently ; there was no definite top to it as on the 

 previous days. 



Feb. 23. — -Top clear and air dry all day. Haze all 

 round reaching up to the clouds, and in afternoon show- 

 ing peculiar bands and streaks to S. of a green colour. 



having well defined, cleanly cut upper surfaces, but no 

 well marked lower surface. To-day there appeared to be 

 a constant downward motion of the clouds, the high 

 cirrus at one hour being a middle cirrus at the next 

 hour, and a lower cloud an hour afterwards. The ther- 

 mometer box was lowered one step at 18 h . 



Feb. 24. — Thick haze below all round. At l h the 

 clouds were lowering and thickening quickly. At 2^ 

 they were touching all the hills around, and at 3 h nothing 

 could be seen for cloud but the summit. The lower 

 surface of cloud seemed to be of the same shape as Ben, 

 but kept a little clear of it. The lowest of these strata 

 of clouds at 14 h was (rare) str.-cir., and motionless, while 

 the middle layer moved from S.W., and the top one 

 from W.N.W. 



Feb. 25. — No lower clouds, but varying amounts of 

 upper clouds on sky. In early morning there were some 

 (rare) str.-cir., and at 3 h patches of cum.-cir. that appeared 

 to be motionless as regards position, but showed an 

 internal drift of particles. Thick haze all around. 



Feb. 26. — Sky cloudy with upper clouds only till 17 u , 

 cloudless thereafter. Thick haze all round below. The 

 zodiacal light was seen at 20 h , and a faint aurora at 

 midnight. Haze was very thick at midnight, dark blue 

 to N., milky to S., while there was a wonderful mistiness 

 all around and above, and very faint flashes of light were 

 seen to N. above and in haze. Remarkable and very 

 beautiful colours were observed before sunrise in the 

 eastern sky. 



Feb. 27. — Very thick haze all day — so thick at 2 h 

 that nothing could be seen but the hill top. All day 

 the haze was white on the side of the observer next the 

 sun, and dark blue on the opposite side. Sky cloudless 

 till after 22 h , but a little fog was passing at 20 h . Except 

 at 20 h the air was dry throughout. After 22 h clouds 

 formed rapidly almost close over summit in thin sheets 

 of stratus, which showed a long fibry, streaky texture. 

 These sheets of clouds moved quickly, but to the S.E. 

 Over the Moor of Rannoch there was a thick heavy cloud 

 that was quite motionless. 



Feb. 28.— Thick fog till 5 h , clear but cloudy till 9 k , 

 and fog or mist thereafter. Heavy snow showers and 

 some drift from ll h till 15 h , and very heavy rain at 16 h , 

 17 h and 18 h ; the total for these three hours alone being 

 1T02 inch. Owing to drift the amount of fall at 12 h 

 was lost, the rim of gauge being flush with surface of 

 snow. Brown fog crystals forming in morning, and an 

 icy covering on everything in afternoon. 



March 2. — St Elmo's Fire seen at 21 h 

 pencil, on anemometers, on the tower, 

 chimney. 



March 3. — St Elmo's Fire was seen at 2 U . 



March 4. — Heavy drift at and after 



on observer's 

 and on the 



17 1 



making 

 measurements of amount of snow very doubtful. Drizzle 

 and rain falling in forenoon, and hail at 16 h . This hail 

 was of three sizes : — 1st, small glassy hail quite round 

 and transparent ; 2nd, larger hail — conical snow-hail 

 with an icy glaze on outside ; 3rd, still larger hail 

 showing the middle to be the usual dry snow-hail 

 (conical), but having the outer surface covered all over 

 with small round glassy particles like the 1st kind. 



March 5. — Note book blown away at 3 h . St Elmo's 

 Fire seen at 21 h , bright and strong. Snow falling heavily 



