192 REPORT— 1895. 



It being felt that more assistance was required to expedite this 

 work of discussion than it is in the power of the directors to give, 

 application was made to the President and Council of the Royal Society 

 for a grant of 100^. from the fund placed at their disposal by the Goveni- 

 ment Grant Committee. The application was granted, and the money 

 will be applied in paying assistants for doing portions of the routine 

 work of the offices in Edinburgh and Fort William, in order to give 

 Dr. Buchan and Mr. Omond time for cai-rying on the inquiries sketched 

 out above. 



The examination of the Hourly Barometric Curves during fine, clear 

 days and during cloudy days respectively, have been continued, on 

 account of their very high value in connection with the work of the two 

 Observatoi'ies. To our last report six tables were appended, giving the 

 hourly values for each month for the top of the mountain for Fort 

 William, and for Trieste, near the head of the Adriatic, for clear and 

 cloudy days respectively. 



During the year Mr.Omond has continued these most laborious calcula- 

 tions, so that your Committee are in a position to add four Tables to the 

 above. The two new stations are Magdeburg, in Germany, selected because 

 its comparatively dry climate forms an admirable contrast to the rather 

 wet climates of Fort William and Trieste, and San Jose, situated in lat. 

 9°-56' N., long. 84°-0 W., and at a height of 3,756 feet above the sea. A.s 

 its height approximates to that of Ben Nevis, the observations made at 

 this Observatory, which is situated only ten degrees from the equator, 

 form an excellent comparison with those made at the top of Ben 

 Nevis. 



Tables V.-VIII. give the departures in thousandths of an inch from the 

 daily means of the barometer at each hour of the day at Ben Nevis, Fort 

 William, Trieste, Magdeburg, and San Jose, on fine or sunny days, and 

 on cloudy or overcast days. In each case, three years have been taken, 

 though not the same years at each station, the figures being 'bloxamed,' 

 as in last report. San Jose is chiefly interesting as showing how a tropical 

 station in a steady climate, where every reading of the barometer during 

 the three years lay between 26'000 and 26"400 inches, with rain falling 

 only at certain seasons, and then almost wholly confined to the afternoon 

 hours, differs from the recoixls of a temperature zone-station with a vari- 

 able climate. 



This is not the place to enter on any adequate discussion of the results, 

 but it is of importance to point out that the characteristically low morn- 

 ing maximum, and very high evening maximum during cloudy days at 

 Ben Nevis, Fort William, Trieste, and Magdeburg, in all seasons, do 

 not occur at San Jose in similar weather. It is, however, diflferent as 

 regards the two daily minima at San Jose, the morning minimum being 

 distinctly larger on cloudy than on sunny days, and the afternoon minimum 

 less. There are also marked characteristics, in cloudy weather, of the 

 barometric pressure at Fort William and Trieste, suggesting that in such 

 weather the temperature of the atmosphere, taken as a whole, falls to n 

 greater extent than when the sky is clear, and tension is consequently 

 more reduced ; but that the temperature of the lower strata of the 

 atmosphere rises to a less extent than it does in sunny weather, when the 

 surface of the earth is screened by clouds, resulting in a reduced ascending 

 current from the heated ground. 



