36 REPORT — 1887. 



February 1886. The month with the largest number of days on which 

 less than O'Ol inch was recorded was 18 in June last, and the smallest no 

 days in July 1886. 



It is expected that the hourly observations, given in e.vtenso, of the Ben 

 Nevis Observatory to the end of 1886, and those of the sea-level station at 

 Fort William, referred to in the Committee's last report as in the press 

 as an extra volume of the ' Transactions of the Royal Society of Edin- 

 burgh,' will be ready for delivery at the end of the year. 



In preparing new isothermal and isobaric charts of the globe for the 

 ' Challenger ' Expedition Report, Mr. Buchan has constructed tables of 

 corrections for height above the sea up to 8,000 feet for the diflFerent air 

 temperatures and sea-level pressures that occur, which are based on the 

 results arrived at regarding the rate of diminution of temperature, and of 

 pressure with heights for different air temperatures and sea-level pres- 

 sures. TJie results of charting from these tables offer the strongest cor- 

 roboration of the great value in practical meteorology and in physical 

 geography of this piece of work already accomplished from the data 

 lurnished by the Ben Nevis and Fort "William observations. 



In the meantime, and in addition to the regular work of the observa- 

 tory, Mr. Omond, superintendent ; Mr. Rankin, first assistant ; and Mr. 

 Dickson, who lias repeatedly relieved the regular observers at the obser- 

 torv, are engaged in carrying on original researches. Of these the 

 following may be mentioned : — 



Mr. Omoxd. — 1. A second paper on the rainfall of Ben Nevis in 

 relation to the winds, in which the observations of 1886 are dealt with. 

 The most important result is in corroboration of the results deduced from 

 the observations of 1885, viz., of all winds N.W. winds are much the 

 wettest while they blow ; and he can now state explicitly that the rule 

 holds good both as regards cyclonic and anti-cyclonic winds, which is a 

 valuable contribution to the theory of storms. 



2. The diurnal variations in the direction of the summer winds on 

 Ben Nevis. 



3. On a peculiarity of the cyclone winds of Ben Nevis (which is to be 

 read at the meeting). 



4. Glories, halos, and coronje seen from Ben Nevis Observatory, being 

 in continuation of a paper on the subject published in the ' Proceedings of 

 the Royal Society of Edinburgh ' of last year. The new facts brought 

 forward in these papers, for which the observatory affords peculiar 

 facilities for observing, necessitate important modifications of the ex- 

 planations hitherto given of these phenomena. 



5. Temperatures at different Jieights above ground at Ben Nevis 

 Observatory. 



Mr. A. Rankin. — 1. The thermic wind-rose at the Ben Nevis Obser- 

 vatory, to be read at the meeting. For the coming year Mr. Rankin 

 has undertaken the laborious work of prosecuting the inquiry still 

 further by sorting the winds and the temperatures in cyclonic and anti- 

 cyclonic areas, and also into the two opposite sides of these areas. 



2. He has also recently detected a connection between an increased 

 darkness of one of the lines of the spectrum and a mass of air of an 

 unusually low temperature over the observatory, and no opportunity will 

 be lost next year in accumulating observations bearing on the point. 



Mr. Dickson. — 1. A continuation of his hygrometric work, to be 

 read at the meeting. 



