TABLE FOR SADIYA.
Mean. >
Maxima »
Mean. >
Minima. \
Jan. Feb.
60-5 61
47-5 52-5
Mar.
69
•56
Apr.
73-5
66-5
May
78-5
70
June
83-5
76-5
July
83-5
76
Aug.
84
77
Sep.
85
76
Oet.
80
69-5
No*.
77
64-5
Dec.
0
0
Means. 54 56-7 62-5 70 74-2 80 79-7 80-5 80.-5 74-7 70-7
Mean annual temperature 67—2.
Taking the means of the tables of Mr. Reeves and of Mr. Davis, the mean annual temperature
of Canton will be very nearly 70 : the mean of the four hottest month? in the year
82-2, and of the four coldest months 54.
The mean annual heat of Sadiya, in upper Assam, will be 67-2.
The mean temperature of the four hottest months will b,e 80, and of the four coldest
months 57-8.
panton, Sadiya.
Mean annual temperature, 70 67-2
Mean temperature of 4 hottest months, 82-2 80
t- -- - —— ;■ -r . .,..——■ coldest months, 54 57-8
The greatest degree of cold which, so far as I know, has occurred at Sadiya, was in
January, 1887, when Major White observed it on one occasion at 6 A, M. to be so low as 320.
On another occasion it fell to 37 ; 42° is not uncommon. The highest range during the hot
month? was in 1836, 92°. It is singular that Captain Jenkins had never observed it so high as
this at Gowahatti, (90 being its highest range at that place) although considering its latitude
and situation, the contrary would be supposed to take place. In upper Assam, January is the
coldest month of the year; August and September the hottest and most oppressive.”
Were we to assume the climate of Assam as ,the most suitable for rearing this shrub, we
might find it difficult indeed to find a parallel one in southern India, but this cannot be
necessary as it is next to impossible that similar climates ,ean be conimon to the various and
widely separated countries where it is cultivated to so vast an extent.
Mr. CcClelland describes Assam as an extensive dekivial valley surrounded on all sides by
vast mountains ; those on the north extending backwards to the Himalayas which in this
portion of the range are covered with almost perpetual snow ; and travesed its whole length
by a vast river, fed by 5 or 6 others, the least of which nearly equals the largest river in
England. A valley so situated has its climate modified in a very remarkable degree by local
causes—Thus owing to the proximity of the snowy mountains a cool current of air blows from
the north-east at all season?. That meeting the south-west winds from the plains of Bengal
in the months of March, April and May, is productive of frequent showers bywhjch the air is
kept cool and moist during the season of heat and draught, again
“ Throughout the cold season, dense vapours arise from the Bramaputra about day-light, and
continue to increase until 8 A. M. when they begin slowly to ascend. They are then drifted
before the I*f. 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 qr less powerful dissipation, and exciting a movement in the general
mass towards the side op wjiich this action is taking place. The whole of the vapours are thus
attracted towards .the south, where unless entirely dispersed by noon, their broken masses linger
on the northern face of the Naga mountains, receiving daily fresh accumulations, until they
are precipitated in heavy rain, seldom however before they have served as an impenetrable
canopy to this side of the valley for several weeks.
This tendency of the mists to occupy the south side of the valley, is an interesting point if
considered with reference to what I have already stated regarding the absence of the tea plant
on the northern side.”
These mists are attributed to the inequality of temperature existing between the river and
surrounding air; that of the former amounting to about 15° higher than the latter, hence the
vapour rising from it, becomes partially condensed and has the effect of raising and equalizing
the temperature, while it preserves a constantly moist atmosphere. The striking effect of these
causes on vegetation is proved, by the fact of the tea plant being confined to the south side of
the valley or that protected by the mists from the cold wind blowing from the snowy mountains
The fact here stated is strongly corroborative of the view above taken, that this is truly a
tropical plant^ delighting in a mild humid climate with a moderate range of temperature and
not one suited Lor bearing exposure to frost and snow during one part of the year, and a’high
tropical heat at another and m so far, that the elevated of slopes the Himalayas, recommended
on that very account by Mr. Royle as a suitable locality for its cultivation, are in truth most un-
— V’f deep T 1 slle tered Tilleys h° " ^ e r of these- mountains may, and probably
Will be found, to present a combination of circumstances most suitable for its introduction *
... iTfhe °nly P^:ts. ,of th.e Indian Peninsula, so far as I am aware, which seem in any degree
fitted for the profitable- culture of this shrub are some portions of Mysore and Malabar especially
the mountain valleys ot the latter which partake of the proverbial humidity of its c imate
combined with such an abundance of forests, as would at once suffice by their density to afford
shade against too much light, shelter against cold blighting winds, and finally preserve an equal
and humid atmosphere over the plants at all seasons of the year. Whether such a union of
favourable circumstances can be found m combination with the peculiar light porous soil which
this shrub affects in its native country, is not easy to say, but in a country enjoying a range of temperature
rarely, if ever exceeding 85. or falling below 60°,withextreme humidity,* and abundance
fo,.
complete.senes of observations that h as perhaps ever been made in 1 ndia or e lsewhere It is h bwt vil- t ! h the. tlme occupy, th e most
are for Trivandrum in the extreme . South, they require to be sliehtly modified fo ; more nnrfhZi' Zl l observed.’ ™a t> registers
of rain, which in th a t p art of the coast between Cochin and Tellicherrv exceeds th a t fn r T r i Z , ! , ™ Rations, especially humid climate has been spoken of as the one best suited for the culture of th e Tea nlanT* by fr0.m 20 t0 30 inches and dry Bulb, Thermometer, will show, to exist in Malabar Mg|§|Hll as regards an M the fall
nually,
MM & d M w l h that coast,’ that at almost every season of the year, the depression'ora few d e ^ S S m 2 t ^ ^ ^ p « Tri? nd^T , th® ® s t i sta
mean ................Minimum neat tor any P?month DthJ ? never eve,r exceeds ■■.of that th a t of the dew point by bv above^ above i d V ^ r u ‘ a « I ' i y - a ae
falls below th a t of the dew point. The elevation o f temperature certainly exceeds what w h a f I hava have stated « “ tw i ™? .® le™1“ ?*’'err * r ““ r?,‘V of.1 eacbmc
eiluu “
° f t h e T - a n d r u m Observatory J of a e I suggested as th e most
iucai circumstances, ana me sicuauo
suitable for th e culture of this shrub
Register o f the Thermometer as observed at Trivandrum
The Max. Temp, o f each Month.
Minimum T emperature do.........
Extreme range of each do.........
Mean Maximum o f d o .....
Mean Minimum of do........
Mean iàngé o f
h o u r o f Max. Temp, of each M o n th .,
Mean hour of Minimum..
19. 6
•83.73
73.21
10.52
Sept.
88. 3
70. 8 71. 1 1
19. 2
84.09
HOURLY REGISTER—WET BULB THERMOMETER—1837-8 '
Table 1.1- Dontaming the DaUgand Monthly Dem Points (calculated from...the depression o f the We
Bulb Thermometer) from June 1837 to May 1838. J
Dec.
70.34
March I April May I
70-96 j 73.37 74.32 j
Hourly register- wet bulb tiierhometer_ i8S7 s
Table 2.H Sorting the Mean Dew Point o f each hour for each Month, from June 1837 I May 1838
and for the whole 12 Months. ' S'10**5
March
I 70.94
April
73.39
r > jy tj . , . M E M 0 R A N D U M.
Ofthe Quantity o f Ram mhwhfell at Trimndrum for each Month, from 3d .Tune 1837
until end o f July 1838.