224 REPORT — 1897. 



August 9) been mostly anticyclonic, being the type of weather so mucli 

 desired for the observations needed in carrying out the important inquiries 

 referred to above. 



During the past year much of the time of the office in Edinburgh, 

 aided by Mr. Ormond and the staff on Ben Nevis, has been spent in pre- 

 paring for the press the whole of the observations, hourly and otherwise, 

 made at the two Observatories from January 1888 to 1896. These obser- 

 vations, now ready for press, will fill two large quarto volumes. A dis- 

 cussion of the observations from December 1883, when they commenced, 

 to December 1896, is in progress, which, it is expected, will be finished in 

 the spring of next year. 



Among the separate parts of this large discussion, already completed, are 

 the mean hourly variation of the barometer, and the temperature, for the 

 months and the year, at each of the two Observatories for the same terms 

 of years, from August 1890 to December 1896, or six years and five months. 

 The two sets of curves are therefore strictly comparable, being calculated 

 for the same time. The results are given in the four Tables, V., VI., 

 VII., and VIII., at the end of this Report. 



The hourly observations made by the Swedish expedition at Jan 

 JVIayen in 1882-83, particularly the hourly barometric obsei'vations in 

 clear and clouded weather respectively, together with the observations 

 made on the open sea of the Arctic Ocean by the same expedition. The 

 results, in clear and in clouded weather, are of the greatest possible interest 

 in their relation to similar inquiries made with the observations of the two 

 Ben Nevis Observatories, and of other observatories in different parts of 

 the world, and reported on by your Committee in their Annual Reports 

 for several years past. 



" But an equally great interest attaches to the discussion of these 

 barometric observations made on the open sea of the Arctic regions in 

 1882-83, together with similar observations made by Professor Molin 

 in the Arctic Ocean in the summer months of 1876-77-78. From the 

 observations made on this ocean at a season when the sun is constantly 

 above the horizon, it is shown that there is only one daily maximum and 

 one minimum of pressure closely agreeing with the diurnal curve of 

 temperature. At the same season the small island of Jan Mayen presents 

 in its diurnal curves of pressure the usual double maxima and minima. 



The same discussion opens up important inquiries as to the different 

 effects on the diurnal curves of pressure according as the terrestrial 

 radiation from the earth's surface towards space, proceeds from extended 

 fields of snow, bare rock or soil, grass, or sheets of water. 



The hourly observations of the rainfall and snowfall at the two 

 •Observatories have been discussed, from which it is shown that the diurnal 

 ■curves have two maxima and two minima, and that the summer and 

 winter curves present striking differences. 



The work of preparing maps, showing for each day the amount of the 

 rainfall at 120 stations well distributed over Scotland, is steadily progress- 

 ing. As the work proceeds it becomes more and more apparent that as 

 regards large rainfalls with west wind — (1) over all Scotland ; (2) over 

 western districts only ; (3) north of the Grampians only ; (4) south of the 

 Grampians only ; or with east winds — (5) over all Scotland, an exceedingly 

 rare occurrence ; (6) over eastern districts only ; (7) over only a narrow 

 strip on the coast ; (8) over the foreshores only of the Firth of Forth, the 

 Moray Firth and the Pentland Firth, these inquiries receive much elucida- 



