418 



BEN NEVIS OBSERVATORY. — LOG-BOOK. 



[J 892. 



Dec. 25. — Air very dry again to-day, the computed 

 humidity ranging from 9 to 19 per cent. Sky cloudless 

 except from 9' 1 till 13 h when a little cirrus moving from 

 N. or N.W. was observed. Haze in valleys and stratus 

 at horizon most of the day. A faint aurora was seen at 

 night, and a solar halo at 12 u . The earth shadow was 

 seen after sunset. At ll b the wet bulb was too dry at 

 the hour — the readings entered were made at 1 l b 9 m . The 

 S. or S.E. wind blowing last few days died out about mid- 

 day to-day and the afternoon was almost calm throughout. 



Dec. 26. — Sky quite cloudless all day. Air very dry, 

 extremes of humidity being 15 and 27 per cent. Thick 

 haze in valleys all day. This morning a faint grey 

 glimmering light was seen in N. sky not distinct enough 

 to say whether auroral or not. Fog was seen over the 

 haze on the Atlantic Coast in afternoon. 



Dec. 27. — Summit clear all day. Sky cloudless till 

 7 h , but some cirrus during the day. Thick haze in 

 valleys all day with fog to W. and S.W. in afternoon. 

 Air very dry — mean computed humidity 21 per cent., and 

 lowest 13 per cent. At 3 h , 4 h , and 5 h , the same peculiar 

 shimmering light was seen in N. and E. Sky as was 

 noted yesterday. It did not look like aurora, being more 

 like very thin filmy cirrus clouds lighted up. A solar 



halo was seen at 13 k , and a lunar halo at 23 h . At 23 h 

 and midnight thick dark str.-cir. clouds were seen low to- 

 N.W. 



Dec. 28. — Air very dry all forenoon. After ll b the 

 humidity increased, at 13 u it reached 100, and at 14 h fog 

 came on. Sky cloudy all forenoon and thick haze and 

 fog (to W. and S.W.) below. Top cleared again at 22 h 

 and hard detached masses of "rare" str.-cir. were seen 

 on sky. In early morning (3 h to 6 h ) the shimmering 

 light noted last two mornings was again seen in all parts 

 of sky, and apparently lighting up the edges of clouds 

 that lay near horizon. A bit of a lunar halo was seen 

 at l b . 



Dec. 29. — Air very dry, and sky cloudless except for a 

 few patches of hard str.-cir. till 7 h when fog came on and 

 did not clear during the rest of the day. Peculiar light 

 seen in E. and S.E. sky in early morning. Brown fog 

 crystals forming from the fog to-day. 



Dec. 30. — Fog till 15 h . Sky cloudy thereafter and 

 haze and fog below. 



Dec. 31. — Summit clear till 9 b , but fog below all round 

 which rose and enveloped summit at and after 10 h . 

 Thermometer box changed immediately after the 2 h 

 observation. Height above snow not altered. 



INSTRUMENTS ETC., 1892. 



Barometer. — No. 1385 was in use during the whole 

 year, No. 1252 being kept in reserve ; the latter is 

 supposed to have a trace of air in its vacuum. 



The following Dry and Wet Bulbs were used : Nos. 

 535541, 535542, 192677, and 192672 : and the following 

 self-registering thermometers max. 117293, min. 116918 

 in large screen from June 11th to Oct. 12th, and mins. 

 138533 and 138545 in small box during the rest of the 

 year. On Oct. 24th a new pattern of winter screen was 

 brought into use. It is much stronger than, but of the 

 same size as the old pattern. The louvres are stouter, 

 and are sunk into and kept flush with outside of corner 

 posts. The old pattern boxes have not been used since. 



The Tower screen and thermometer have been in 

 occasional use. 



The old 5-inch gauges were used till 11th Feb., and 

 since then a new pattern of 5-inch gauge without broad 

 base or screw-plug has been in use. 



The Campbell-Stokes Sunshine Recorder has been 

 in use throughout the year 



Black Bulbs. — Max. 186 and ordinary 484108 were 

 in use when possible — chiefly from June till Sept. 

 The former lies at Low Level Observatory since October. 

 The platinum points of the latter have been injured and 

 there is some air in its vacuum. 



The Direction and Force of the Wind have been 

 observed, as usual, on the roof of Observatory at the 

 hourly observations. 



The H.C. Anemometer was accidentally broken on 

 January 8th, and has not been used since. The Chrystal 

 Direction Anemometer has not been used. Its clock is 

 used as the standard G.M.T. clock in office. 



The Rainband observations have been continued with 

 the direct vision spectroscope. 



Several photographs have been taken. 



The Stephanome has been in use for the measuring 

 of glories, corona?, and halos. 



The depth of snow has been taken as usual at post A — 

 called "The snow gauge." 



The Barograph (Richards) has been in use all the 

 year. 



Except as regards the rainfall, the observations have 

 not been interrupted during the year. On January 17th 

 owing to the thermometer box door having been broken, 

 observations in it were not made for several hours, but the 

 temperature at these hours was interpolated from readings 

 of the Tower Storm Box. 



Dust observations have been made throughout the year 

 with the large Dust Counter in Tower — the small one is 

 still at the Low Level Observatory. 



