INTRODUCTION. 31 



south-west monsoons ; but the former is the regular 

 trade — the latter alone is the anomaly, and needs 

 explanation. The cause usually assigned is, the 

 rarefaction of the air on the continent of Asia 

 during the summer months, when the sun is north 

 of the equator ; the air from the Indian Ocean 

 flowing in to supply its place. This would suffi- 

 ciently explain why the wind should be southerly, 

 but leaves its westerly inclination entirely unac- 

 counted for ; and this seems the more inexplicable, 

 because one would suppose that the air over the 

 burning deserts of Arabia and North Africa would 

 be much more heated, and that the direction of the 

 supplying current would be south-east. Strange, 

 however, as the fact is, it is perfectly uniform in 

 its occurrence, and is obviously a very gracious 

 ordination of God's beneficent providence, in di- 

 minishino- the uncertainties of navigation. 



There i% yet another phenomenon connected with 

 the wind, in the climates of which we speak, that 

 requires notice ; it is the alternation of the land 

 and sea-breezes. Every one who has resided near 

 the coast in tropical countries is aware of the eager- 

 ness with which the setting in of the sea-breeze is 

 looked for. Usually about the hour of ten in the 

 forenoon, when the heat of the sun begins to be 

 oppressive, a breeze from the sea springs up, in- 

 vigorating and refreshing the body by its delight- 

 ful coolness, and continues to blow through the 

 whole day, gradually dying away as the sun sinks 

 to the horizon. Then, about eight in the evening, 

 an air blows off the land until near sunrise ; but this 



