440 



The P It //steal Condition of 



of Chinese, they might be employed in constant trials upon the leaves 

 afforded by the different colonies in order to detect what the nature and 

 degree of difference may be, between the products of the different soils 

 as well as of leaves of different size. The mode of manipulation adopted 

 with regard to each specimen, and how diversified, should be carefully 

 noted, and reports upon the subject forwarded to Calcutta by the per- 

 son in charge ; together with specimens of the prepared tea packed in 

 leaden boxes containing those aromatics upon which some of the fine? 

 qualities of teas may depend. 



Climate.-- The wind in Assam is N. E. at all seasons, and the whole 

 valley lies in the direction of its current. Descending from the 

 Himalaya the air derives an impetus from its low temperature, and 

 consequent greater specific gravity than the heated westerly wind. 

 It is not meant that the air in the upper atmosphere in contact with 

 the snow is heavier than the lower strata in the valley, which would 

 be contrary to certain well known laws ; but merely that the air in 

 the vicinity of the mountains above the line of congelation, is rendered 

 specifically heavier than the general air of the same altitude, in con- 

 sequence of the heat absorbed from it by the snow. It consequently 

 sinks, causing a motion in the warmer air to occupy its place. Thus 

 an upper current is formed while the lower one descends into the val- 

 ley where its diminished temperature renders it sufficient to overcome 

 the heated land winds which enter from the west, by Jthe great defile 

 of the Bramaputra. 



During those months when the westerly winds have greatest power, 

 and the influence of opposing currents from the N. E. extremity of the 

 valley most diminished, in consequence of the disappearance of a 

 larger proportion of snow in that direction ; the westerly winds then 

 extend with lessening temperature and velocity as high as Bishenath 

 in Middle Assam, beyond which they are .seldom known to reach ; 

 nor is their power even there sufficient to overcome the influence of 

 the N. E. current, more than for a few days at a time during the 

 hottest days of April and May. 



Throughout the cold season, dense vapours arise from the Bra- 

 maputra about day-light, and continue to increase until 8 a. m. 

 when they begin slowly to ascend. They are then drifted before 

 the N. E. wind, which from the diminished heat of the valley now 

 amounts only to a gentle movement, the direction of which is 

 modified by the action of the sun's rays on the upper stratum of mist, 

 causing a more or less powerful dissipation, and exciting a movement 



