348 



BEN NEVIS OBSERVATORY.— LOG-BOOK. 



[1887. 



April 7. — Layer of thin stratus overhead all day, with 

 its lower edges often brushing the hills round; sun shining 

 through it in patches. At 17 h the sun's rays shining down 

 into the haze that rilled the valleys to westward light it 

 up: the rays below the sun were brick-red, those to S.W. 

 green, and those to N.W. bluish in colour. At 19 h the 

 clouds were coming lower and disappearing. At 20 h the 

 skv was cloudless. Faint brown colour under moon at 

 22 h . 



April 8. — Faint sunrise colours visible at 4 U . Stratus 

 fog in thin sheet on hills to N. and E. in early morning. 

 Broken cumulus on and over hills during the day. 



April 9. — Thin stratus fog on hills again this morning, 



and thick haze mixed with smoke from burning heather in 



the valleys during the day. The haze seemed to be higher 



than the level of Ben Nevis ; it showed above the horizon. 



Br wn Broken cum. over hills also to-day. Faint 



Blue upper glow at 5 h . At 8 h , 9 h , and 10 h colours 



Creamy white above haze to N.W., as noted in margin. 



Haze The brown extended almost all round the 



Horizon horizon 



April 10. — Thick haze in valleys all day, but hill tops 

 showing clear above it. The snow at the first gorge was 

 found to be overhanging the edge of the cliff by 214 

 inches. 



April 11. — No fog in valleys, but very thick haze ; in the 

 afternoon and at night the haze was higher, so that the 

 hills round could scarcely be seen through it. 



April 12.— At 5 h faint upper glow to eastward, and 

 earth shadow to westward about 10° high ; sky above it of 

 a reddish colour. Brown colour under sun at 6 h and 7 h . 

 Detached cumulus lay among and on the top of the haze 

 all to-day. Cum.-fog rising rapidly out of Glen Nevis, and 

 vanishing at ll h . At 18 h bright spot on each side of sun 

 like mock suns, but no trace of halo. Radius, 21° 48'. 

 Before 19 h thin fog was brushing across the top. At mid- 

 night the upper half of the dry bulb was covered with 

 small crystals of ice, while the bottom was quite clear. 



April 13. — At 5 h earth shadow seen to westward topped 

 by a brownish red glow ; also faint pink upper glow to 

 eastward. At 19 h bright red colour in valleys to westward, 

 with at times gaps in it due to cloud shadows. Clouds 

 forming above Glen Nevis at above 4600 feet height, indi- 

 cating ascending currents. At 20 h fog all round. 



April 14.— At 13 h a cum.-cloud lying 35° S.W. of sun 

 was seen to be very green on side next sun, and slightly 

 pink on the further side. No brown colour under sun to- 

 day, but haze mixed with smoke from burning heather 

 in the valleys all day. 



April 15. — Very small fine snow falling most of the 

 day, too little to affect gauge. 



April 16. — Aurora, single arch, no streamers, seen at 

 midnight. 



April 18. — Fog crystals forming all day, very hard and 

 icy at night. 



April 19. — Thermometer box shifted at 19 h 15 m . 



April 24. — The snow which fell to-day was mostly large 

 and rather hard — often conical in shape; the drift, there- 

 fore, did not rise high, though the top was thickly covered 

 with soft fresh snow. 



April 25. — Heavy shower of hard conical snow at about 

 It 1 ' 15 m . 



April 28. — Heavy masses of cumulus round Ben Nevis 

 and over the surrounding hills all day. Thermometer box 



shifted at 10 h 30 m . About a dozen peals of thunder heard 

 between 17 h 25 m and 18 h 20 m . No lightning seen, but 

 at from 35 to 40 seconds before most of them earth currents 

 moved the needle of telegraph instrument. 



April 29. — Sky well covered with loose detached cumu- 

 lus and cirro-cumulus all day. At 9 h these clouds were 

 observed to be coloured red, green, and blue, when passing 

 near or over the sun ; one cir.-cum. cloud lying a little below 

 the sun was red in its centre and blue all round towards 

 its edges. At 17 h there were two layers of cir.-cum., the 

 upper moving from W.N.W. and the lower apparently from 

 S.W. The cumulus or " lower clouds " were at the same 

 time moving from N.E. Sun set at about 20 h 5 m behind 

 the hills of Skye; horizon to N.W. rather hazy. 



April 30. — All lochs almost perfectly calm all morning. 

 Sky cloudy during the day, but air very clear underneath, 

 and especially to W. and S.W. except when loose cumulus- 

 fog rose from the glens near Ben Nevis. 



May 1. — At 4 h faint upper glow seen to north-eastward. 

 At 11 there was both cirrus and cir.-cum. in the sky, the 

 former being much higher than the latter, also a trace of 

 a halo. At the same hour fog lay over all the hills round, 

 and occasionally passed across Ben Nevis. Dark heavy 

 bank of cumulus, with a clear streak below it, to westward 

 all night. 



May 2. — At 10 h the dry bulb had fog crystals on its 

 windward (or south) side, and a film of ice on the north 

 side ; while the wet bulb had no crystals on south side, 

 but on the north side had long loose ones. (1 Eddy of 

 wind in box.) 



May 3. — Solar corona at 10 h ; colours Red 



as in margin ; no measurements got, Haze Blue 



in valleys and cum. over hills all morning;, „„ 

 , , . J , °' Yellow 



but air clear. White 



May 4. — The snow which fell this even- rt) 



ing was soft and in large flakes. 



May 5. — This morning the fog crystals were slightly 

 brown in colour. Loose cumulus fog rising all round in 

 the middle of the day, and very dark haze in the valleys 

 towards evening. 



May 6. — Fog crystals brown in morning. Very dark 

 haze almost hiding the nearest hills in afternoon. 



May 7. — This afternoon the depth of snow at the first 

 gorge was found to be 76 inches. The snow in the gorge 

 overhangs the edge by 243 inches. 



May 11. — Thermometer box shifted at 9 h 25 m . 



May 12. — At 3 h low strips of fog in valleys to north- 

 ward. 



May 13. — At 8 h fog was rising from Glen Nevis, and 

 getting blown away by the north wind. At ll h pink 

 coloured cloud, with upper part under sun coloured as in 

 margin. Length of cloud, 103°; breadth, «. 



6° 30'; radius of green (only distinct line Blue 

 of colour), 12° 36'. Cloud vanished sud- Green 

 denly, leaving a halo on cirrus much higher Red 

 up. Shortly afterwards the halo got more distinct ; it had 

 inside it another ring, as in fig. 14. The outer ring was a 

 distinct halo, with red inside and blue out; radius of red, 

 22° 12'. The inner ring had a faint trace of red inside; 

 radius of this red, 17° 54'. By ll h 15 m all had dis- 

 appeared. Coloured clouds were seen again several times 

 during the day; and at 17 h a halo was again observed. 

 The following measurements were got : — Radius of red, 

 21° 54' and 22° 12'; yellowish green, 23° 17' and 23° 17'; 



