144 



BEN NEVIS OBSERVATORY.— INSTRUMENTS, ETC. 



[1889. 



dug out, and a wreathe Hush with the roof of the coal 

 cellar. 



Dec. 22. — No raingaugo was out till 9 h , owing to the 

 heavy drift, but apparently little or no snow fell before 

 that hour. Drizzling rain began to fall at ll h , and 

 continued most of the day after. The temperature at ll h 

 was 28° - 8, and it never rose above 31°'0. 



Dec. 28.— Thermometer box shifted at h 20 m . 

 Height above snow not altered. Air dry till 8 h , the 

 humidity being below 40 at 7 h and. 8 h , but at 9 h the 

 temperature had fallen 11°*3, and the air was saturated. 



The sun was first seen at 8 h 55 m . Fog lay in detached 

 masses over the hills to E. in forenoon, and from 10 h 

 onwards was mostly on Ben Nevis also. There was also 

 haze in the valleys. 



Dec. 29. — After 4 h the fog cleared off, but the sky was 

 overcast with cum. -stratus till 18 h , and detached fog lay 

 among the hills at about 3000 feet height. After 18 h the 

 sky cleared, but at 21 h and 22 h showed small high cum.; 

 after that fog again covered the top. Misty lunar corona 

 seen at 19 1 ', 21 h and 22*. 



INSTRUMENTS, ETC., 1889. 



Barometers. — No. 1385 was in use throughout the 

 year; No. 1252 being kept as a reserve instrument. 



For Dry and Wet Bulb Thermometers.— Nos. 192660, 

 192672, 192671, 192677, 50850, and 50852 were used. 

 Max. 117293 and min. 116918 were used in the large 

 box in summer, and mins. 138533 and 138545 in the 

 small box in winter. Up to midnight of May 13th, and 

 at and after 18 h on Nov. 1st, a small louvred box on 

 ladder stand No. 2 was used to hold the thermometers. 

 Between these dates the large box (old clock box) was 

 used. 



The usual 5-inch raingauges, either rain or snow 

 pattern, have been in use. 



The Campbell-Stokes Sunshine Recorder has been used 

 all through the year. 



The max. black bulb in vacuo No. 186 has been 

 observed when feasible ; and since Aug. 31st black bulb 

 No. 484108 — common thermometer not max. — has been 

 in occasional use. 



The direction and force of the wind was estimated as 

 usual on the roof of the office at the hourly observations, 

 and the Robinson and Chrystal anemometers used when 

 the weather allowed. The damage to the Robinson 

 anemometer mentioned last year was not, however, 

 repaired till July 16th, since when it has continued in 

 good order. On July 24th the clock which works the 

 tracing point of the Chrystal anemometer was disconnected, 

 and shifted into the office to serve as a temporary 

 standard clock while the original standard clock was sent 

 to Edinburgh for repairs ; and it is still there. The 

 standard clock began to stop frequently after the middle 

 of June, and on July 22nd was sent to J. Ritchie, 

 Edinburgh, for repairs. It was returned to the Observa- 

 tory on Aug. 17th, but has not gone well since then. 



On the 30th and 31st July a staff of post office work- 

 men laid a new earth-wire from the Observatory to below 



Buchan's Well, which has greatly improved the action of 

 the telegraph instrument in dry weather. Except re- 

 charging the battery by the lineman, no other repairs or 

 alterations were made on the telegraph apparatus. 



The Rainband was estimated daily, with few excep- 

 tions, by a direct vision spectroscope. 



The Stephanome was used for measuring halos, glories, 

 coronae, etc., as usual. 



Several photographs have been taken at all times of the 

 year, including various cloud forms, a luuar corona, 

 different kinds of post work, etc. 



The Barograph was in use throughout the year except 

 from April 29th to May 11th, when it was dismounted, 

 one of the levers being sent to Adie and Wedderburn, 

 Edinburgh, for alteration. The effect of this alteration 

 has been to bring the scale more nearly in accordance with 

 the true barometric reading, it being now only necessary 

 to add a constant to the barograph readings, to reduce 

 them to the true barometric values. 



The Thermograj)h has not been used. 



The depth of snow has always been measured at post A. 



The ozone test papers were frequently blown away or 

 bleached, and the rain-fall returns occasionally invalidated 

 by drift. With the above exceptions, the hourly observa- 

 tions have been carried on completely, though the 

 observation or part of it was on a few occasions from 1 to 

 5 minutes late. 



The staff of the Observatory consisted of R. T. 

 Omond, superintendent ; Angus Rankin, 1st assistant ; 

 and J. Miller, 2nd assistant; also up to April 17th 

 Alex. Drysdale, and since Oct. 23rd Wm. Wilson. 

 Messrs R. C. Mossman, J. Macdonald, R. Turnbull, and 

 J. Duncan took the places of some of the observers at 

 various times. Mr C. E. Gray acted as telegraphist and 

 occasional observer from July 4th to Oct. 1st. 



