90 



BEN NEVIS OBSERVATORY. — LOG-BOOK. 



[1893. 



was white in colour, and the streamers occasionally tinged 

 with green. The earth currents in telegraph wire were 

 intermittent, but it was not noticed whether they 

 coincided with brighter displays of the aurora or not. 



March 29. — Aurora seen at 2 h , single arch, no streamers. 

 Lunar corona formed on high cir.-cum. at 3 h , small and 

 badly defined. Thick haze all day. Solar halo visible 

 from 8 b to 13 h . Mock sun at ll h . It was distinctly 

 outside the halo. 



March 30. — Top clear 17 h to 19 h , but sky covered 

 with cirro-stratus. Solar halo seeu at 17 h . 



April 3. — Top cleared after 20 1 ', leaving cloudless sky 

 and fog on hills. The moon rose shortly after 22 h , and it 

 was then seen that the valleys were full of stratus fog at 

 about 2000 feet. Faint aurora seen at 22 u and 23 h . 



April 4. — Horizon hazy all day. Fog in valleys at 

 about 2000 feet till 9 U ; none after that. Sky cloudless, 

 except for some cirrus in afternoon and evening. Some 

 of these clouds near the horizon looked like detached 

 elevated patches of haze. 



April 5. — Thick haze all day ; in forenoon so thick 

 that the hills at the other side of Glen Nevis were barely 

 visible, but sky almost cloudless and air dry. 



April 6. — Haze all day. At 15 h 37 m a peal of thunder 

 was heard, aud thunder clouds at about 4000 feet height 

 were evidently hanging about the hills to E. From 

 18 h 30 m to 21 h 20 m there were frequent peals of thunder 

 and flashes of lightning, and rain fell heavily, especially 

 from 19 h to 21 h . St. Elmo's Fire was seeu on kitchen 

 chimney at 20 h 35 m and at 21 h . Rain was falling heavily 

 at the time, and the summit was free of fog. The storm 

 was accompanied by strong earth currents in telegraph 

 cable, a click of the needle occurring simultaneously with 

 each flash. The flashes followed each other at intervals of 

 from one minute upwards, and in some cases only about 

 two seconds intervened between the flash and the follow- 

 ing thunder. No discharge took place inside the Observa- 

 tory, and no damage was done. No outside observations 

 were taken at 19 h , 20 h , and 21 h ; the rainfall for this 

 period was measured at 22 h , and divided by estimation 

 over these hours. 



April 7. — At 5 h fog lay over the hills to N. and E. at 

 from 3000 to 4000 feet. This continued all day, and 

 frequently it rose and covered Ben Nevis also. 



April 8.— Fog on hills round till 9 h . From 10 h to 13 h 

 detached fog rising out of valleys to S. ; after that no fog- 

 in valleys, but haze, the latter due partly to burning- 

 heather. 



April 9. — Sky cloudless, except for occasional scattered 

 clouds at horizon ; but slight haze all round. No fog 

 below. 



April 10. — Cirrus gathered on the sky at 3 U , lying in 

 ' : Noah's Ark" form, pointing E.N.E. and W.S.W. A 

 solar halo was seen at 7 h . No fog in valleys till 5 h ; but 

 after that, detached fog among hills till noon and fog on 

 summit all afternoon. Slight drizzle of snow after 15 h . 



April 11. — Fog cleared off summit at 5 h , but continued 

 in detached portions on the hills round till noon, after 

 which it rose clear of them and formed cumulus till 

 Minset, but from 20 h onwards the sky was clear. Air 

 very clear except to S. in afternoon. Aurora seen 22 h , 23 1 ', 

 and midnight, a single, badly-defined arch, no streamers. 



April 12. — Sky cloudless, except for a little cirro-cum., 



till 7 h ; but fog in valleys, which rose and enveloped 

 summit ; thereafter slight showers of snow fell during the 

 evening. Aurora seen at l h , 2 h , and 3 h . 



April 13. — Top clear after 2 h , leaving sky cloudless, 

 and fog on hills all round to 4000 feet till 10 h , after which 

 it rose and formed cumulus overhead, but in the after- 

 noon the clouds came down again and enveloped the 

 summit after 16 h , though clearing at times in the evening. 



April 19. — Summit cleared after 4 h , but sky overcast, 

 or nearly, all day, with cir. and cirro-stratus and loose 

 scud and fog passing frequently over the hill top in the 

 evening. Thick haze all round in the afternoon. A solar 

 halo seen at 12 1 ' 30 m . 



April 20. — Sky cloudy, but fog on or over hills all 

 round, and at times rising and enveloping summit. At 

 21 h and 22 h sky was cloudless, but thin fog passing. Air 

 dry all day, except at 3 h and midnight. St. Elmo's Fire 

 seen at 2 h on kitchen chimney and tower. Thunder peals 

 heard from 16 h 15 m to lG h 50 m down to south-east. 



April 21. — Thick haze all day. Fog lay over hills 

 all round till noon, and breaking up into detached cum. 

 fog to W., N. and S., and in the evening fog was all 

 gone. Sky nearly cloudless all day. In early morning 

 thermometer box and roof of Observatory were completely 

 saturated with dew. At h 15 m , thermometer box was 

 lowered one step. Height above snow, 48 inches. A 

 robin redbreast was seen on office roof at 5 h . 



April 22. — Temperature high all day; highest hourly 

 reading, 52 0, 5 at noon. Sky cloudy after 2 h and till 21 h ; 

 cloudless thereafter. Hazs around all day. No fog in 

 valleys. 



April 23. — Sky cloudless down to horizon all day, 

 except for a little cirrus on E. horizon at 17 h and 18 h . 

 Haze all day, thicker to W. in the forenoon. 



April 24.— Light S. and S.S.W. airs till 1 p.m., and 

 calm the rest of the day. Sky cloudless all day, except 

 for a little cirro-cum. from 18 h till 21 h ; haze all day. No 

 fog below. 



April 25.— Sky cloudless till 7 L , but some cirrus above 

 horizon to E. and S.E. ; sky cloudy thereafter till 18 h ; 

 almost overcast till 20 h , and fog the rest of the evening, 

 but moon seen gleaming through the fog at times. Fog lay 

 over Loch Eil, and in valleys to N. in the early morning. 

 Calm till 9 h , but light variable airs thereafter, chiefly 

 southerly. Thermometer box was lowered one step on 

 ladder at h 15 m . 



April 26. — Fog or overcast sky till 21 h , but sky 

 cloudless since, leaving detached cum. fog on hills around. 

 At midnight humidity was 47 per cent. A solar halo 

 seen at ll h and a corona at noon. An aurora seeu at mid- 

 night, a well-defined and complete arch extending from a 

 point E. of N.E. to W. by S. No streamers were seen. 

 Judging from the appearance of the arch, this would be 

 a magnificent aurora, but sky being very bright (nearly 

 full moon), details could not be distinguished. 



April 27. — Sky cloudless till 4 h , but cloudy thereafter, 

 with cum., cir.-cum., and cir.-s. till 16 h . Mist and fog 

 the rest of the day. Air very dry and clear in the early 

 morning. Lowest humidity was 38 per cent, at 3' 1 . 

 Detached fog lay over hills all day. Slight showers of 

 sleet fell after 23 1 '. Aurora seen at l h , with single arch 

 and streamers shooting to the zenith. A halo at 13 h and 

 14 h . 



