Till 



PREFACE. 



of snow on the summit ranges from nothing in summer to occasionally as much as 12 

 feet by the end of winter, and the aspect of the Observatory at the two seasons is well 

 seen in figs. 1 and 2. In the latter the raised piece in front is not a part of the 

 building, but is the end of a snow tunnel leading down to the doorway on the ground 

 level. 



On the top of the tower of the Observatory are placed a wind vane and a Robinson 

 hemispherical cup anemometer (see fig. 1.) The former works fairly well, but the Robinson 

 anemometer is useless in winter. The cups and arms get so encrusted with fog-crystals, and 

 the bearings of the shaft so clogged with ice, as to make its readings quite untrustworthy. 



Fig. 5. — the instrument stands at ben nevis observatory. 



For a record of the wind on Ben Nevis, as of the temperature, we are dependent on the 

 hourly observations made by the observers, and great care has been taken to insure 

 uniformity in the estimation of the direction and force of the wind by the different 

 members of the staff. 



The Observatory in Fort- William was opened in July 1890. The building was 

 erected by the Directors, the expense being met by a donation of £957, lis. 2d. from 

 the surplus funds of the Edinburgh International Exhibition of 1886, and by a mortgage 

 on the building. This Observatory was equipped with self-recording instruments by the 

 Meteorological Council of London, which give continuous records of pressure, dry and 

 wet bulb temperature, rainfall and sunshine. A brief description of the method of 



