1886-87.] 



BEN NEVIS OBSERVATORY. — LOG-BOOK. 



343 



bow, 34° 44' ; inside, 32° 20'. The first and last measure- 

 ments give the radii of the two reds. Misty glory seen at 

 15 h ; colours as in fig. 9 ; the central part a confused mass 

 of colour. Radius of red, 1° 53'. Earth shadow seen to 

 eastward at 16 h , and a very faint afterglow at 16 h 5 m . 

 Fog on hills to about 4000 feet all day. 



Dec. 31. — Distinct icy hail fell in forenoon. At 13 h 

 the rain-gauge contained round icy particles like frozen 

 rain drops. The rain covered everything with a coating 

 of ice, three or four inches thick in some places. 



Instruments in use during 1886. 



Barometer No. 1385 was in use during the whole of 

 1886 ; No. 1252 being occasionally read as a check. 



For the Dry and Wet Bulb Thermometers, No. 192660, 

 192672, 192677 and 192671, all by Adie and Wedder- 

 burn ; and also No. 50850 and 50852, by Negretti and 

 Zambra, but fitted with glass scales by Adie and Wedder- 

 burn, were used. 



The Black Bulb in vacuo used was No. 186 by Hicks. 



Up to July 4, 5-inch rain-gauges were used, but after 

 that date 5-inch gauges with higher rims were in use 

 except when only rain was falling. All gauges made by 

 Alexander Kemp, from drawings supplied by Mr Omond. 



The Chrystal (Direction) Anemometer worked fairly well, 

 and the Kobinson (Velocity) Anemometer occasionally. 

 On Oct. 7 it was taken down for the winter. 



From July 1 to July 24 the brass- work of the Sunshine 

 Recorder was under repair, and the papers were mounted 

 in a temporary frame, which, however, worked well. 



On Sept. 18 a new Chrystal Hygrometer arrived at the 



Observatory, but there have been as yet very few oppor- 

 tunities of testing its working. 



From July 6 to Nov. 5 inclusive, the Thermometers in 

 use were placed in the large louvred box ; for the rest of 

 the year in small boxes on ladder-stand. Max. 117293 

 and min. 116918 were used in large box ; and mins. 1 38533 

 and 138545 in small boxes. The depth of snow was 

 always measured at post A. 



The measurement of the rainfall was interrupted several 

 times by drifting, and the ozone papers were occasionally 

 blown away. Temperature readings were not got at 6 h 

 and 7 h on Dec. 8, owing to the high wind and dangerous 

 drift. Otherwise the record is continuous, though once 

 or twice the observation was a few minutes late. 



Professor Ewing of Dundee sent during the summer a 

 Seismometer, which was mounted on the stone slab in office, 

 but which is not yet in satisfactory working order, owing, 

 it is believed, to want of steadiness in the slab. From 

 Aug. 14 to Sept. 4 the Cosmic Dust Collector was out. 



The Barograph has worked most of the year, but its 

 scale is seriously in error, a deflection of 2*25 inches on it 

 corresponding to l'OO inch on the Mercurial Barometer. 

 It seems also to have been strained a little during the low 

 pressure on Dec. 8. 



The Thermograph has not been used. 



The Hair Hygrometer has not been used. 



The permanent staff of the Observatory consists as 

 before of R T. Omond, A. Rankin, and J. Miller. 



From July 15 to Sept. 28 Mr Cray (telegraph clerk) 

 was also at the Observatory. 



Messrs H. N. Dickson, J. T. Morrison, W. Hay, and J. 

 Duncan took the places of some of the staff at various 

 times. 



1887. 



Jan. 1. — At 7 h a very few large flakes of snow falling, 

 each covering about one inch square. 



Jan. 2. — At 18 h triple corona seen. Red outside in all 

 three rings ; outermost ring faint and evanescent. At 

 times a fourth red was seen inside these surrounding white 

 space near moon, but it was too small to measure (less 

 than 50'). It was formed on scud ; diameters seemed to 

 vary. The following measurements were got : — Radius of 

 innermost red, 1° 22' ; middle, 2° 5' ; outermost, 4° 23'. 

 When no scud was passing a blue corona was seen. 

 Radius, 3° 2'. Lunar fog-bow seen also at 18 h . Radius 

 was about 38° 40'. 



Jan. 3. — At l h rain-gauge was found undercut and 

 leaning over. None was put out till 4 h- At ll h it was 

 again found undercut, and none was out till 17 h . Faint 

 halo seen at 19 h ; also triple corona. Red outside in all 

 three rings. The following measurements were got : — 

 Radius of first red, 0° 54'; 0° 56'; 1° 0'; second red, 1° 

 48' ; third red, 3° 36' ; 3° 15'. Thermometer box shifted 

 at 22 h 20 m . 



Jan. 4. — At 6 U narrow auroral arch seen, top about 11° 

 above horizon. No streamers. At 9 h a bright golden- 

 coloured corona round sun. No fog or haze in valleys, 

 but a pink colour, like very thin haze, under the sun in 

 the valleys. No gauge was out at night, but apparently 



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



no snow fell. Though the wind was high (force 7-8) there 

 was little drift. Red 3 



Jan. 5. — Solar corona seen at 13 h ; Green 

 colours as in margin. Radius of red 1 , Red 1 

 3° 7'; red 2 , 6° 12'; extreme outer edge wl » te 

 of red 1 , 4° 13'. Lunar corona seen at " 



22 h ; colours as in margin. Radius of inner red, 3° 20'; 

 outer red, 6° 29' ; inner yellow, 2° 36' ; 

 outer yellow, 5° 22'. Yellow bands narrow, Yellow 

 but green broad, and badly-defined. Green 



Jan. 6. — Thermometer box shifted at Red 

 9 h 30 m . Solar halo at ll h and 13 h . Red Yellow 

 inside. Radius, 22° 24' and 22° 6'. Misty ™ e 

 badly-defined lunar corona at night. To- 

 day the snow at the first gorge was measured, and found 

 to be overhanging the cliff about 63 inches. 



Jan. 8. — Halo seen at l h . Three measurements got. 

 Radius to inside edge of halo, 21° 36'; 22° 0'; 20° 51'. 

 Solar corona seen at 1 l h (double). Radius of inner red, 

 3° 31'; outer red, 6° 7'. At same hours glory seen with 

 four rings; larger than usual, and the colours broad and soft- 

 looking. The innermost red was only seen occasionally. 

 Radius of second red, 4° 46' ; third red, 8° 43' ; fourth 

 red, 12° 6'. While measuring the glory a cloud passed to 

 southward of Ben, and its shadow blotted out part of the 



3 Y 



