252 Mr. T. Hopkins on the Vapour Atmosphere at Bombay. 



many parts of the world ; but the following account given by 

 Hutchison of Glasgow, contains a description of that which 

 oi'dinarily takes place in localities similar to that of Bombay, 

 although the distance of the mountains from the places of 

 observation in the two cases, and the influences of the trade- 

 winds may modify the process. Mr. Hutchison says that 

 " the formation of clouds is finely illustrated by the phaeno- 

 mena daily exhibited during the dry season over what are 

 called the Liguana, or Port Royal Mountains in the island 

 of Jamaica. These mountains are situated about four or five 

 miles to the north-east by east of Kingston, the principal port 

 in the island, and their height above the level of the sea is 

 about 4000 to 5000 feet. During the dry season, from the 

 beginning of November till the middle of April, the sea and 

 land breezes alternately succeed each other with an interme- 

 diate interval of atmospheric stillness, in the following manner. 

 From sun-rise till about ten o'clock in the forenoon it is usually 

 perfectly calm. About ten o'clock, the sea breeze, blowing at 

 Kingston from the east, or a little to the south of east, com- 

 mences and continues till about half-past thi'ee in the after- 

 noon, when it gradually and entirely subsides." Again, 

 " About eleven o'clock every forenoon, or between that and 

 mid-day, the summits of the Port Royal Mountains begin to 

 be covered with clouds, which, though thin, fleecy and trans- 

 parent at first, gradually increase in density till about one 

 o'clock. By this time the upper portions of the mountain, 

 when viewed from Kingston, seem to be wholly enveloped in 

 dense clouds, rain is apparently falling in torrents, flashes of 

 lightning are seen, and the sound of distant thunder is heard. 

 About half-past two o'clock in the afternoon, the clouds, gra- 

 dually diminishing in density, begin to quit the mountains; 

 so that their summits again become visible, as in the morning, 

 and so continue till about eleven o'clock the following day. 

 The clouds after quitting the mountains rise gradually to a 

 greater altitude and float very slowly westward, assuming as 

 they proceed the appearance of large heaped-up cumuli." 

 See Hutchison on Meteorological Phaenomena, p. 64. 



The general trade-wind about Jamaica was from the east, 

 and it bore the ascending clouds to the west in the afternoon : 

 the trade-wind at Bombay was ordinarily from north of west, 

 and it would doubtless modify the influence of the mountains 

 on the clouds formed in the part. Were meteorological in- 

 struments corresponding with those kept at Bombay placed 

 to the east of that place at the rise of the hills, and registered 

 in the same way as at Bombay, it would probably throw fur- 

 ther light on the daily atmospheric disturbances in this part 



