1888.] 



BEN NEVIS OBSERVATORY. — LOG-BOOK. 



65 



zon. At 20 h the aurora was very bright, and double, and 

 sometimes triple-arched, but its upper limit did not extend 

 higher than Vega and Benetnasel — Ur. Maj. Each arch 

 had streamers. At 19 h and 20 h there was no 'dark 

 segment,' but at 21 h there was, and from the ragged 

 appearance of its upper edge it seemed to be due to a 

 bauk of cloud. At 21 h some red was seen in aurora. 

 At 22 h the body of auroral light was faint, but the 

 streamers then seen were very long, reaching in some cases 

 from horizon to 25° altitude. At this hour dark broken 

 clouds were seen to N. At 23 h it had neither streamer 

 nor arch, and was greatly obscured by dark clouds. At 

 midnight it was very faint and low, and had neither 

 streamer nor arch. At 19 h 30 m there was a steady cur- 

 rent in telegraph cable, keeping needle almost hard over 

 to dash side (current up the wire), and at 21 h 15 m , when 

 sending report, there was a steady current, keeping needle 

 over to dot side (current down wire). At 20 h dew was 

 observed on thermometer box, and hoar frost on snoic and 

 roof. A like observation was made at 22 h . At 18 h , 19 h 

 and 20 h the zodiacal light was observed. 



Jan. 14. — The aurora continued faintly visible till 5 h 

 to-day. At 2 h mist was passing summit, but during the 

 rest of the day the summit was clear, but fog covered the 

 lower hills. At 15 h the shadow of the cir. clouds in 

 sky was seen in the air as dark streaks. At 16 h shadow 

 of Ben was observed with its apex above horizon. From 

 18 h till midnight an aurora was observed. At 18 h it had 

 two arches — the lower just visible above horizon. At 19 h 

 and 20 h it w T as faint and streamerless. At 21 h it con- 

 sisted of a single arch, low to N., with streamers occasion- 

 ally. At 21 h 30 m it was double — the lower arch shooting 

 streamers — at same time the ' dark segment ' was sharply 

 defined. At 22 h there were two well-defined arches, the 

 lower one being sharply defined beneath. At 22 h 10 m it 

 suddenly brightened up, lighting the hill top, and broke 

 up into many streamers, which moved quickly horizontally, 

 its lowest limits and the base of each streamer were red. 

 At 23 h there was no definite arch, only patches, but there 

 were numerous streamers. Its altitude was not above 12°. 

 At midnight it was but faintly seen. Alter 18 h the 

 zodiacal light was visible in W. sky ; at 20 h and 21 h it 

 was very distinct, stretching up through Pisces to near 

 Aries. It continued visible till after 22 h . 



Jan. 15. — Summit clear all day. From l h till 6 h the 

 aurora was faintly visible. Eog in valleys all day to 

 the height of about 2500 feet. In afternoon glimpses of 

 the lower hills and moors were got through breaks in the 

 fog, and it was observed that the Moor of Rannoch was 

 white with hoar frost, as were also the hills to S. and 

 N.E. of Ben, but these only to a height of about 2500 

 feet, all above this having no hoar frost. From 13 h to 

 16 h a small arc of solar halo was seen, coloured red, 

 yellow and blue, and at times red, yellow and green. 

 At 15 h two small arcs were seen at opposite ends of almost 

 horizontal diameter. The colours were very bright. 

 The following measurements were got per stephanome : — 



13 h Radius to red . 



14 h Radius to red . 



14 h Radius to yellow 



15 h Radius to inside of red 



15 h Radius to outside of red 



15 h Radius to middle of yellov 



15 h Radius to outside of blue 

 ROY. SOC. TRANS. EDIN. — VOL. XLII 



. 22° 



57' 



. 22° 



24' 



. 23° 



3' 



22° 



12' 



22° 



49' 



w 23° 



17' 



. 23° 



44' 



At 16 h shadow of Ben was seen above horizon to N.E. 

 At 23 h there was a pale grey light in N. sky. At 

 midnight the S., N. and E. skies to 20° altitude were 

 much brighter than zenith — as bright as 'Milky Way.' 

 At 7 m past midnight an aurora burst into view low to N. 



Jan. 16.— Till 4 h the sky to E., N. and S. to 15° altitude 

 was much brighter than the part above this. There 

 was fog in the valleys all round till 6 h ; mist passing at 

 7 h ; but at 8 h the N. hills and valleys were clear of fog. 

 The top was enveloped in fog at 16 h and again from 

 18 h till midnight. At 14 h and 15 h glories with three 

 and four rings were seen from roof on passing fog. 

 Snow crystals •were forming from fog at night. A weasel 

 was seen at ll h running from S.E. side of summit 

 towards hotel. 



Jan. 17. — The fog cleared away after 4 h , and for the 

 rest of the day the sky was absolutely cloudless, from 

 zenith to horizon all round, but fog lay on E. and S. 

 hills, and in afternoon haze was observed in valleys to 

 N. and W. Fog crystals forming in early morning. 

 The wet bulb reading at ll h (that on daily sheet) being 

 somewhat doubtful, owing to the bulb having been partly 

 dry. The following observation was made at ll h 15 m , 

 viz., — dry bulb 25"8 and wet bulb 21"1. 



Jan. 18. — Faint aurora seen at 4 h 50 m . Fog passing 

 at 12 h , and fog crystals forming then. Fog on E. and 

 S. hills till about 16 h , after which it vanished, but dark 

 haze filled valleys all round. A little cir.-s. was seen at 

 l h low to N.E.j this was the only cloud above horizon all 

 day. 



Jan. 19. — Fog on Caledonian Canal and Loch Eil all 

 morning. Hoar frost was seen on low grounds about midday. 

 Thick haze filled valleys to-day to about 3000 feet, the 

 tops of the higher hills showing clear above it. Fog was 

 seen to S.W. at ll h . It steadily increased E. and N, 

 till at midnight it was all round, and rising to S. higher 

 than Ben. At 22 h faint aurora was seen, and also a broad 

 white ill-defined lunar halo. In afternoon the cir. clouds 

 were lying S.W. to N.E., and moving from N.W. 



Jan. 20. — Fog passing at l h , but sky above cloudless 

 till 4 h , after which, however, and till 14 h it was overcast or 

 nearly so with cirrus types, which at ll h were observed to 

 be lying W.S.W. and E.N.E. Mist on at 15 h and for 

 rest of day. 



Jan. 21. — Double and triple corona were observed at 

 19 h and 20 h , and an aurora suspected at 21 h . A fog-bow 

 was seen at midnight. 



Jan. 22. — At 2 h and 3 h aurora was seen, single arch, 

 bright, but no streamers. The thermometer box was 

 shifted one step down on ladder stand after 4 h . A corona 

 was seen at 19 h . 



Jan. 24. — At 8 h and 17 h the readings of thermometer 

 were taken from 1 to 3 m late, owing to the door of box 

 being tightly frozen. 



Jan. 25. — A lunar corona was seen at midnight. Very 

 large, white snow hail fell between 21 h and 22 h . 



Jan. 26. — Lunar corona were observed at l h and 3 h , 

 and at the latter hour a fog-bow was seen. 



Jan. 28. — Thermometer box was shifted at h 35 m . 

 From 4 h till 23 k the sky was cloudless, except for 

 occasional whiffs of fog passing summit. Fog covered 

 N. and E. hills mostly all day, and haze was observed to 

 W. and S.W. At 6 h and from 19 h to 2 1 11 lunar 

 corona were seen on passing fog, double and triple at 



I 



