316 EEPOET — 1889. 



in last year's Report, as rapidly as the means at the disposal of the 

 Directors of the Observatory will admit. 



This season (1889) the snow disappeared from the summit of the 

 mountain in the middle of May, being about a month earlier than in any 

 previous year, and seven weeks earlier than in 1885 ; and during the 

 mouth of June the spring near the Observatory, and about 60 feet lower 

 down, frequently ran dry, so that for some time water had to be carried 

 on horseback a distance of two and a half miles. 



The Directors have had under consideration a proposed systematic 

 observation of the numbers of dust particles in the atmosphere with the 

 instrument recently invented by Mr. John Aitken, and they are of 

 opinion that the Ben Nevis Observatory is the best place for making the 

 observations in the most satisfactory manner. Mr. Aitken will himself 

 superintend the construction of the two instruments which are required, 

 and will see to the placing of the stationary one in the Observatory, and 

 its connections with the atmosphere outside, in suitable positions, and 

 give directions as to the portable one designed as a check instrument, 

 and for observations made at various distances from the Observatory. 

 Application has been naade for a grant from the Government Research 

 Fund to aid in carrying on this novel and important research. 



Mr. Aitken recently visited the Observatory, and ten observations of 

 the numbers of dust particles on the top of the mountain were made by 

 Mr. Omond and himself, with the result that the numbers per cubic 

 centimetre rose from 350 at noon to 500 at 3 p.m. This result of the 

 iirst observation is interesting and suggestive. The purest air previously 

 obtained by Mr. Aitken anywhere was on the Ayrshire coast, and on 

 that occasion the numbers were 1,260 per cubic centimetre. It may be 

 also observed that the numbers on Ben Nevis rose from noon to 3 P.M., 

 the observations being made at the time of the day when aerial currents 

 from lower levels ascend along the heated sides of the mountain to the 

 Observatory. 



In January last the Directors accepted an oSer from the Meteorologi- 

 cal Council that on being satisfied that provision had been made for the 

 maintenance of a Low Level Observatory at Fort William, they would 

 supply and erect in the Observatory the self- registering instruments and 

 otherwise complete the ordinary outfit of meteorological instruments, and 

 make an annual grant of 250Z. towards its maintenance, and also continue 

 the grant of 100^. yeai-ly under the present arrangement. 



Since last Report, the Directors have received a legacy of 5001., 

 bequeathed to the Observatory, by the late R. M. Smith, Esq., who was 

 one of the directors ; and a grant of 1,000Z. from the Association of the 

 Edinburgh International Exhibition of 1886 from the Surplus Fund of 

 the Exhibition. A suitable site for the Low Level Observatory was pro- 

 cured in Fort William, and plans of the buildings were prepared by their 

 architects, Messrs. Sydney Mitchell and Wilson, which were submitted to 

 the directors and the Meteorological Council and approved of. The 

 building is now well advanced, and it is expected that the Observatory 

 will be opened towards the end of the autumn. 



The Directors of the Observatory and your Committee in their succes- 

 sive Reports from 1884! insisted on the absolute necessity of combining 

 the double observation for all forecasting purposes, and inquiries in 

 connection therewith ; in other words, of combining with the observa- 

 tion at the toD of Ben Nevis that made at the same instant near sea-level 



