652 Miscellaneous. [Dec. 



night, when the sudden immersion into the column of air next the ground, 

 cooled by its contact with the radiating earth at the bottom of the valley, strikes 

 one with a sudden chill. As a consequence of the same cause, the lower valleys are 

 frequently filled with a dense fog, while the stratum of air immediately above is 

 perfectly clear and transparent. 



" So powerful is this effect of radiation from the earth, that a cup of water or 

 milk, placed on the ground, even in the higher situations, instantly freezes, while 

 a thermometer, elevated three feet above it, will only indicate a temperature of 38°, 

 39o, or 40°. This fact leads to some important conclusions both as to the situa- 

 tion of houses, and of ground selected for horticultural or agricultural purposes. 

 In a clear bright day, the thermometer generally attains its maximum at about 2 

 or h. past 2 p. m., but this is, to the feelings, by no means the hottest part of the 

 day, owing to the constant current of wind prevailing, from one quarter or ano- 

 ther, at that time. About \ past 8 or 9 a. m. is the time when the sun's rays 

 appear to have most power, the air being then still, and its capacity for heat 

 having been diminished by the increase of density arising from the cold of thepre- 

 ceeding night. This it is important for invalids to observe, as well as the sudden 

 chill produced by the sinking of the sun below the horizon in the evening, when 

 the column of rarefied air next the surface rises aloft, and is rapidly replaced by 

 a colder stratum from above. 



' ' The minimum generally occurs about half an hour before sun-rise, when as be- 

 fore observed, the lower valleys are generally filled with fog. 



" During the monsoon season, when the sky is covered with clouds, at once 

 diminishing the power of the sun's rays, and obstructing the effect of radiation 

 from the ground, the temperature is remarkably equable, the range seldom ex- 

 ceeding 12° or 14° in the open air, while in rooms without a fire, it is under 4 or 

 5°. The thermometer attached to one of my barometers, kept in a small sleeping 

 room, without a fire-place, (though the house itself was rather exposed,) during 

 the months of May, June, July, August, and September, 1831, never fell below 

 59°. 5, nor rose above 62°. This is therefore, notwithstanding many drawbacks, 

 much the most favourable season for invalids, and should be selected, when a 

 power of choice exists, as the period for ascending the hills." 



Moisture. — " The air during the month of January, February and March, is 

 intensely dry, the point of saturation, (or temperature to which the air must be 

 reduced to deposit any part of its moisture,) being occasionally as low as 13°, 

 the temperature of the air being 60°. In April it begins to fluctuate, and in 

 May, the quantity of moisture increases very perceptibly, being accompanied by 

 rapid changes of the electrical condition of the atmosphu't., indicated by thunder- 

 storms and heavy showers, but of short duration. During June, July, and August, it 

 is nearly charged with moisture ; in September, it is again fluctuating ; in October 

 and November, moist ; and in December, it begins to re-assume its dry state, 



" In close connection with the above statement, we find, that there is little or no 

 rain in the first three months, some showers in April and May, a good deal of 

 drizzle and light rain in June, July, and August ; the month of September varies, 

 as does that of October ; in November there are heavy falls, and in December 

 the weather again becomes dry. This will be more distinctly seen in the table 

 in which is given the fall of rain in each month during the greater part of four 

 years, as observed by my friend Dr. Glen, of the Bombay Establishment ; the 

 meanannualfall,as deduced from this table, is 4488 inches, or 13. 58 inches great- 



