1885.] 



BEN NEVIS OBSERVATORY. — LOG-BOOK, 



331 



Red and haze in valleys, and cloud fog on hills 



Blue-green to soutU ward. Double corona at 21 h . 



Yellow Colours as in margin. Heavy dew at 



3) night. 



Aug. 24. — Fog, level-topped, to 4000 feet all round, till 

 1 1 hours ; rain and fog reported from Fort William. At 

 noon fog covered the hill top and lasted till 22 h , getting 

 gradually wetter. Slight drizzle at times. At 22 h fog 

 began to sink, and top was clear about midnight. Double 

 lunar corona from 22 h to midnight. Rather misty looking 

 colours, same as last night. 



Bed Aug. 25. — Double lunar corona observed 



Blue at l h . Colours as in margin. Radius of 



Yellow outer red about 9° 4'; of iDner red about 



Whitish 5° 14'; of yellow about 3° 36'. Bather 



J) too misty looking to measure accurately. 



Aug. 26. — At 23 h tied Robinson anemometer up. To- 

 day water was carried up from Buchan's well. 



Aug. 27. — Robinson anemometer set agoing at 13 h , but 

 tied up again at 20 h . At 20 h black bulb radiometer taken 

 in. White fog crystals forming at night. 



Aug. 28 — Robinson set agoing at 14 h , but tied up 

 again at 20 h . At 15 h and 16 11 heavy cloud bank over 

 Mull. 



Aug. 29. — Very slight showers of snow in afternoon 

 and evening. 



Aug. 30. — Robinson anemometer set agoing at 13 h . 

 Thick haze, mixed with fog, in valleys all round at night. 



Aug. 31. — Thick haze all round in forenoon, fog on 

 hills to S. and W. at times, clearer in afternoon, but thick 

 haze again at night. 



Sept. 1. — Thick haze in valleys all morning, and fog on 

 hills round in forenoon. Faint upper glow at 5 h ; before 

 sunrise. 



Sept. 4. — At 20 h earth currents observed on telegraph 

 (needle) instrument. Constant in direction, keeping the 

 needle over to right. 



Sept. 7. — In the afternoon a sharp shower of rain fell, 

 the hill top remaining clear. At 17 h 30 m a rainbow was 

 seen over the east end. of the hill; about 250° of arc 

 being visible. The colours of the primary bow were in- 

 tensely bright, and inside was one strong spurious bow, 

 and a second distinctly marked. The secondary bow was 

 also bright. What appeared to be faint traces of an outer 

 secondary bow were seen on the north side, but these are 

 doubtful. 



Sept. 9. — At 22 h a very heavy shower of hail fell, the 

 hailstones being of considerable size. During the shower, 

 the tips of the lightning conductor, and the point of the 

 vane of Chrystal's anemometers, were tipped with St 

 Elmo's fire. At 22 h 15 m the shower was over, and the 

 fire had disappeared. 



Sept. 17. — Hill top clear. After 10 h thick fog all 

 round, and sky covered with cum.-str., which cleared off 

 gradually in afternoon. Fog sank after 18 h . Sky pale 

 yellow to westwards at sunset, with rosy afterglow high 

 up. Greenish blue colour to southwards, and faint lunar 

 corona formed by very thin almost invisible scud. At 22 h 

 7 m a meteor was observed to eastwards, described about 

 10° of arc. Not very bright. 



Sept. 24. — Snow fell nearly all day, drifting slightly. 

 Exposed (radiation) thermometers could not be read or 

 set. Snow about 4 inches deep at night. 



Sept. 25. — Showers of snow occasionally, about 6 inches 



TRANS. ROY. SOC. EDIN. VOL. XXXIV. 



deep at night. Exposed thermometers still immovable. 

 Top clear in afternoon, and after 22 h . Ross-shire hills 

 seen coated down to about 2500 feet level. 



Sept. 26. — Readings of rain-gauge doubtful all day, as 

 snow was drifting considerably. 



Sept. 27. — Sun rose above a heavy bank of stratus at 

 6 h 15 m . At 5 h 40 m rosy coloured streamers were seen. 

 These disappeared at 5 h 50 m leaving rosy glow all over 

 eastern sky. At 6 h 5 m rosy colour disappeared from 

 eastern sky, and was seen to westwards, lower edge being 

 sharply denned by dark earth-shadow. 



Sept. 30. — Very stormy after 4 h . Barometer pumping 

 heavily, and mercury surfaces much disturbed owing to 

 shaking of the house. 



Oct. 1. — At 5 h St Elmo's fire seen on tips of lightning 

 conductor, and on Chrystal and Robinson anemometers. 

 It was accompanied by a sound similar to that of an 

 electrical machine, which continued after 5 h 3 m , when fire 

 ceased. This sound was again heard on lightning con- 

 ductor, &c, and also on top of snow post (A), at 14 h . 



Oct. 4. — At 12 h the rain-gauge was found almost buried 

 in drift. At 15 h it was found with the snow cut away 

 from under it by the wind, and lying over about 20° to 

 windward. All the measurements are vitiated by drift. 



Oct. 6. — New small thermometer box put on ladder- 

 stand at 15 h 20 m . The dry and wet in large box were so 

 hard frozen that they could not be got in. 



Oct. 11.— Thermometer box shifted at 13 h 10 m . 



Oct. 12. — At 5 h glow in sky to eastward about 15° high. 

 At 9 h needle-shaped crystals of snow falling. 



Oct. 15.— Thermometer box shifted at 13 h 10 m . Top 

 clear in afternoon, no fog in valleys. The increase in 

 depth of snow as measured at gauge (31" at 10 h and 33" 

 at 22 h ) is due to the fog crystals on the post falling off 

 with the thaw. 



Oct. 16. — At 2 h and 3 h faint white glare at northern 

 horizon, possibly auroral. At 6 h bright sunrise colours ; 

 fog on hills and haze in valleys. The haze remained all 

 day in the valleys, but the fog cleared off the hills as the 

 day went on, except to S.W., it looked dark and gloomy 

 all day over Mull. Blood-red streak at W. and N.W. 

 horizon at sunset. 



Oct. 17. — At d h faint white solar holo, no colours seen. 

 At same hour thin flat sheets of cloud observed forming 

 and vanishing over adjacent hills, and on west end of top 

 of Ben Nevis. 



Oct. 18. — In afternoon level- topped fog all round, rising 

 to about 4000 feet. Sky very blue and clear, with no un- 

 usual colours. Afterglow broken by curious gaps observed 

 at 18 h . 



Oct. 19. — At 6 h eastern horizon red below and intensely 

 green above, faint pink glow at about 20° altitude. At 

 8 h the fog had risen to the level of the hill top, three- 

 ringed glory seen. At 10 h no trace of rain-band visible 

 from zenith to horizon. Dry white fog crystals forming 

 all afternoon and evening. 



Oct. 20.— At 7 h fog on hills to 3000 feet. At 10 h 

 broken fog rising from valleys everywhere. During the 

 afternoon and evening fog all round, coming over the top 

 of Ben Nevis at intervals. At 22 h double Ked 

 lunar corona, with faint traces of outer blue Green 

 margin, formed on this fog. Colours as in Red 

 margin. Radius of inner red, 1° 45' ; outer Yellowish white 

 red, 3° 52'. 



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