1887.] 



BEN NEVIS OBSERVATORY. — LOG-BOOK. 



347 



were useless after 15 h as they were found always either 

 nearly buried or else undercut and lying over. 



Mar. 11. — A rain-gauge was put out at 8 h , and they con- 

 tinued to be shifted till 15 h ,but the readings were obviously 

 worthless. No gauge was out after 15 h . Sky clear, but 

 banks of curn.-fog all round higher than Ben Nevis at 

 night. Dry and wet bulbs shifted at 22 h 10 m . 



Mar. 12. — Faint brown colour under sun in afternoon. 

 Cum. at horizon all day, especially to westward. 



Mar. 13. — At 4 1 ' faint brown colour under moon. The 

 recent fall of snow has been almost entirely swept off by 

 the wind, leaving only patches or wreaths here and 

 there. 



Mar. 14. — Some passing showers were observed to-day 

 near the horizon, and a little snow may have fallen on 

 Ben Nevis, but the gauges were quite useless, owing to the 

 light whirling drift brought up by the northerly wind from 

 the cliff. 



Mar. 15. — Masses of cum. -fog round Ben Nevis most of 

 the day. A light — probably auroral — seen above this to 

 northward at 21 h and 23 h . 



Alar. 16. — Aurora, single arch, no streamers, seen at 2 h 

 and 3 h . At 5 h red, green, and blue sunrise colours seen. 

 At 6 h faint pink upper glow above yellowish sunrise 

 colours to eastward. After 6 h dark arch of shadow seen 

 to westward about 10° broad at thickest part, and about 

 20° above horizon. The sky above and below this was 

 distinctly brighter than itself. By 6 Jl 32 m this arch had 

 sunk down towards the horizon, and become the earth 

 shadow ; the sky above it was bright red. The sun rose 

 about 6 h 35™, and at G h 37 m the shadow was still seen to 

 westward, with the shadow of Ben Nevis showing still 

 darker in it. At 6 h 40 m the earth shadow was gone, but 

 the shadow of Ben Nevis was still visible above the horizon. 

 Views very clear in forenoon ; Jura, Colonsay, and Oronsay 

 clearly visible. Distinct brown colour under sun. At ll h 

 two mock suns, with faint trace of white horizontal circle 

 outside them, seen on apparently perfectly clear sky. No 

 trace of 22° halo. Radius of eastern mock sun, 25° 13'. 

 At ll h 15 m , however, a trace of cir.-str. was observed 

 round and near the sun. After noon cum. -fog began to 

 form on southern and western hills, and very loose fog 

 to rise out of Glen Nevis. 



Mar. 18. — Low fog in valleys not rising above 1000 feet, 

 except in a few places in morning and on till 10 h , after 

 which it broke up and rose as cum.-fog. Thin uniform 

 sheet of cloud over the Ben most of the day. Thermometer 

 box shifted at 15 h 10 m . 



Mar. 19. — Air very clear at sunset, Jura, Mull, and 

 islands beyond being all visible. At 1 9 h dark purple belt 

 to eastward about 15° above horizon, with streak of sky 

 below it above the haze near the horizon. Dark haze all 

 round horizon at night, with auroral light above it to N. W. 

 and N. 



Mar. 20. — Very dark haze at horizon in early morning. 

 At 14 h a few hard rounded flakes of snow were falling, 

 though the gauge recorded nothing; similarly at midnight, 

 but the flakes then were soft. White fog crystals forming 

 in afternoon. 



Mar. 21. — Very thick haze in valleys in early morning, 

 Locheil and Loch Liunhe invisible at 6 h . At 6 h faint 

 pinkish upper glow above red streak at eastern horizon. 

 At 6 h 7 m earth shadow seen ; at 6 h 18 m the top of it was 

 about 15° above horizon to westward. Sun appeared at 6 U 



TEANS. EOY. SOC. EDIN. VOL. XXXIV. 



Red 

 Blue 

 Red 

 White 



22 m , and was all up at 6 h 26 m . At 9 h solar corona seen 



colours as in margin ; no measurements got. 



Haze and cum.-fog all round all morning. 



A few soft snow flakes fell in afternoon. 



Probably no snow fell at night, though the 



gauge recorded a little, as there was a good 



deal of surface drift. 



Mar. 22. — Fog crystals in morning loose and dry, and 

 slightly brown in colour. 



Mar. 23. — Several showers of hardish solid snow fell 

 in the forenoon. Fog crystals at night hard and icy. 



Mar. 24. — Louvres of thermometer box considerably 

 choked with drift and crystals both yesterday and to-day. 



Mar. 26. — Thermometer box shifted at 4 h 15 m . Solar 

 halo of 22° seen at 8 h , red inside and bluish white outside ; 

 no measurements got. The snow at the first gorge was 

 found this afternoon to be overhanging the edge of the cliff 

 by 217 inches. Icy fog crystals forming in afternoon. 



Mar. 27. — Very variable winds most of the day, and 

 especially towards nightfall. 



Mar. 29.— Thermometer box shifted at 22 h 15 m . 



Mar. 30. — At 6 h , after the sun was up, the shadow of 

 Ben Nevis was visible above the horizon to westward. At 

 7 h thin haze filled the lower parts of the valleys, but 

 to S.W. there was above this another distinct streak of 

 haze just touching the tops of the hills in Mull and Jura 

 with quite clear air between. This streak was distinctly 

 haze and not cloud. At 8 h the clear space had vanished, 

 and stratus was beginning to form in the haze. At 8 h 7 m 

 the sky was overcast. At 9 h the cloud formed an arch over 

 Ben Nevis, moving with the northerly wind, and hanging 

 down both to N. and S. 



Mar. 31. — Strong back-swirls of wind in early morning 

 and very heavy and sharp squalls coming in hammer4ike 

 blows. 



April 1. — Strong back-swirls again to-day. Thermo- 

 meter box shifted at ll h 25 m . A single-arch rather faint 

 rainbow seen at 15 h [Temp, dry, 25° 1'; wet, 23° 9'J. 

 Icy fog crystals forming all night. 



April 4.— Thermometer box shifted at ll h 30 m . At 12 h 

 and 13 h hard snow falling in conical pieces having spherical 

 bases ; diameter of base from 2V to £ inch ; angle at vertex 

 90°. Fleeting double lunar corona formed on scud at 

 night, usual type, inner circle yellow and outer blue-green ; 

 no measurements got. 



April 5. — At h 10 m thermometer box put one stage 

 higher on ladder-stand. At 3 k double lunar corona seen ; 

 colours as in margin. Radius of red 1 , 2° 

 10'; yellow 1 (about) 1° 38'; red 2 , 4° 13'; 

 yellow 2 , 3° 58'. Fog-bow seen at same time, 

 rather faint. At 4 h light seen to E.N.E., 

 possible zodiacal. At 20 h wind very squally 

 and variable. The lamp was blown out 

 twice, and the sling note-book blown away. 

 Lantern in jacket was used at 21 h and 22 h . 

 door of the thermometer box was found torn off its hinges 

 and lying on the snow ; it had probably not been properly 

 secured at 21 h . The dry and wet were, therefore, for that 

 hour (22) exposed partly to radiation. 



April 6.— Thermometer box shifted at 9 h 30 m . At 10 h 

 solar corona seen occasionally. At 19 h stratus pallium 

 overhead, but rosy and hazy light to westward below its 

 edge. This reddish colour was also seen on the westward 

 side of the hills to S. and S.E. 



3 z 



Red- 

 Yellow 2 

 Blue 

 Red 1 

 Yellow 1 

 Bluish white 



D 

 At 22 h the 



