Royal Physical Society. 17 



depth of rain noted to have fallen in twenty-four hours, is from 1-J to 2^ 

 inches. At Kendal, in 1792, 4^ inches fell. Our longest continued rains 

 usually begin on the south and west of Great Britain, and proceed north- 

 wards. This occurs when an easterly and south-west current both prevail 

 in the atmosphere. In these cases it sometimes takes several days before 

 the dry east wind becomes saturated with moisture, and rain begins to fall 

 on the eastern coasts. Hence the popular idea that our greatest rains 

 come from the east, whereas, in reality all the deposited moisture comes 

 with the southerly current, and the cold east wind acts merely as the con- 

 densing agent, 



In the end of the year we generally have a south-west wind prevailing, 

 often with great violence, somewhat in the form of a monsoon. About a 

 month or six weeks after the autumnal equinox, when the sun has pro- 

 ceeded so far in its south declination, the atmosphere of the whole northern 

 part of Asia, hemmed in on the south by the highest barrier of mountains 

 in the world, becomes cooled down to a very low pitch. This highly con- 

 densed atmosphere then begins to make its way southward by the east of 

 Asia, and forms, in fact, the north-east monsoon of the Peninsula of Hin- 

 dustan and the Eastern Archipelago. To supply this eastward current, 

 a south-west current rushes from the equatorial regions, and sweeps over 

 the North Atlantic, passing over Britain and the middle of Europe. This 

 continues more or less during the months of November and December, 

 and is accompanied by a great deposition of moisture. An equilibrium of 

 the northern atmosphere is brought about in our mid-winter, and then 

 commences the season of our northerly and easterly winds. In so far the 

 laws of our apparently inconstant climate may be wrought out. The 

 average direction of winds, and the temperature and fall of rain, in a 

 series of 15 or 20 years, will be found to be remarkably constant. There 

 are, however, occasional irregularities either of mild or severe, of dry and 

 wet seasons, which are not so easily referable to any known or defined 

 laws. It has been beautifully demonstrated by Professor Dove, that as 

 respects the temperature of the whole globe, and also the respective hemi- 

 spheres, there is a perfect uniformity year after year; Thus, that the 

 same amount of warm currents passes yearly from the equator to the poles, 

 while this is balanced by equivalent currents of cold air from the poles to 

 the equator. These respective currents, however, as regards our northern 

 hemisphere, may pass in varied lines of longitude. So that while in the 

 meridian of Europe we may have for one or more successive years an ex- 

 cess of the southerly currents, these currents in other years may pass 

 along the meridian of America, or of the Atlantic or Pacific Oceans, 

 That such variations actually take place, there can be no doubt, and more 

 extended observation is daily more precisely defining and recording these 

 occurrences ; but the laws which regulate these variations yet remain un- 

 solved, and are perhaps of too refined and complicated a nature to come 

 within the grasp of man's limited observation, 



vol. i, c 



