'Transactions of the Bombay Geographical Society, from January 1847 to May 1849. Edited by the Secretary. Volume VIII.' [‎82] (98/496)

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the cylinder,, when both decreased rapidly by evaporation : but strange to tell,
after continuing to descend from noon till daybreak, it commenced imme
diately to rise again till 11 A. M., remaining motionless till 1 p. m., when it
began to sink, and so continued descending till about an hour after sunrise,
when it commenced immediately to rise, and so continued till the same hour as
during the preceding day. This had gone on regularly for four days—each day
it sunk from two to three inches, and only rose half as much ; the fluctuation was
in all respects most perfectly regular and symmetrical.^ For the purpose of deter
mining the amount of evaporation from the surface of wetted earth, the water in
the tube was intended to be kept as nearly as possible at the same point, but it
was also desired to be ascertained to what extent capillarity acted beneath the
surface of the ground. Even now, after six months of uninterrupted heat, when
a thermometer on the surface of the ground would generally rise to 140, a foot
under the soil was found to contain from sixteen to twenty-two per cent of water
capable ot being drawn off by a few hours’ exposure to the sun, four or five per
cent more being capable of expulsion by a temperature of 300°. It was clear from
this that capillarity and conduction ceased to operate at a very short distance
downwards. In reference to the latter, much information had already been ob
tained, and it was hoped that some new light might be thrown on the former by
making the experiments under consideration—determining how many grains of
vapour passed off daily as the water sank, or the rate at which reascension in the
tube progressed.
It was added that these were to be considered as merely casual remarks: thi
perplexity might vanish, or the apparent wonder turn out to be no wonder at all
the next step that was taken—or perhaps it might be a thing perfectly well known
lliose engaged in physical research in the colonies, and more especially in India
laboured under the disadvantage of want of books, and ignorance of what was do
ing, or had been done, by others. They had only to choose betwixt making at
tempts, of which the worst that could be said was that they were useless, bavin,
een successfully per formed before, or proved hopeless or visionary altogether o
rest in indolent despondency of accomplishing anything, when numberless tasks o
importance were around, for fear of doing what was superfluous, or being reproach
ed for an ignorance there were no means of remedying. No tolerably indnstriou
man would under the circumstances hesitate which course to pursue, for fear of be
nig reproved for the want of knowledge, which was not his fault, but the misfor
tune ol his position.
samtr“'Thetw 0 th r am ! SiZ ? nd f0rmhaS ^ the “ been *tecL„ P) with exactly t:
morn in" the 15th A •) ^ ° getber Wle a I ,air of well-going chronometers. On Sunil
movemL was s ^^ra? 6 / airWaS <3*mp> and a strong south wind blew,
heenTw , ^ “ 10 °' cl °ek_ the fall during the preceding night h
ly bavin" nlV Snia 1 ’ aUlle ll0llr i ust n ‘' | med the water in the tubes ofboth began to riserapi
scende l n " CheS 1 0 ’ Cl ° Ck 5 ^ « paused in both for a little, and then d
and a nie'ce < ' ekllty allover tlle afternoon and night. Anyone who has an old map-ea
•ri -ki ^ lSS U 6 ma ^ re P eat; the experiment for himself; it does not seem to require ai
era e c e 0 ree of caie. Probably a cask or tub, or any kind of water-tight vessel of two
nee ee m length, with a hollow bamboo inside, and piece of ccrk as afloat, might suit
as le contrhance already made use of. It would be interesting to know if the same thii
occurre with instruments of different forms, soil of different kinds, or in localities widely apar