286 
Experiments on Evaporation. 
[Octr. 
the transportation of the coal. That a mine shall be opened on a cheap and simple 
plan, where the best coal is to he found, and carried to the bank of the river, during 
the dry season. That immediately upon the opening of the river, the new boats 
shall drop down, and the hired ones go up and load with coal as quick as possible, 
and proceed down with it to Amptha, and unload there; return empty, or take grain 
or other articles up, which would pay freight ; load again, and continue in the same 
manner during the period which the river should continue navigable -. and when 
the Dauiuda become not so, the whole of the boats should then load at Amptha, 
and be employed during the dry season in transporting the coal to Calcutta. By 
this method, the boats would be employed the whole year, and I believe they might 
make six at least, if not seven trips annually'. 
X would dispose of the new boats at Calcutta whenever a good price offered, and 
replace them from the building establishment. 
The business ought by all means to commence upon a simple and cheap plan, and 
if found profitable, many useful contrivances may be introduced to facilitate the 
business of loading and unloading; and also in that of land carriage, which after a 
little lime, may, in a great measure, be obviated. 
Note by the Editor. 
Mr. Jones appears to have been deficient chiefly in technical knowledge, the want 
of which may possibly occasion the scientific reader to undervalue the preceding paper, 
although it contains many hints which by the practical man will be duly apprecia- 
ted. The result of the proposal, with which the paper concludes, was the opening of 
the coal mine at Raniganj, described in our preceding number, from which, and 
anothe mine in the vicinity since opened, Calcutta derives her whole supplyof coals. 
II . — Experiments on Evaporation, made in the Vicinity of Calcutta. 
The amount of aqueous evaporation from the surface of the earth in different cli- 
mates and situations has long been a subject of interest and experiment : but it has 
been fairly doubted whether much confidence can be reposed in experiments on such 
a minute scale as they have usually been confined to. The sun has more power upon 
a vessel of a few inches diameter and an inch or two (or less) in depth placed on a 
dry surface of wood, masonry, or sand, than upon a large surface of water, whether 
deep or shallow ; the wind less, perhaps, except in so far as the larger body of water 
may affect it liygrometrically. 
The enclosure of about 100 bigalis of dilute sea water cut off from the Lake at 
Ballyaghat a few months since for the manufacture of salt by' soiar evaporation, 
seemed to give opportunity for obtaining results more satisfactory. Having for 
another object registered almost daily the speciGe gravity of the water there and in 
several subdivisions of the ground, with the depth by' estimate or fixed measure, I 
have thought it worth while to make them available for ascertaining the evaporation 
which occurred at Ballyaghat during the period they embrace. 
Water marks were not fixed till the first week in April. Tire best and easiest 
method (measure ot height,) is therefore only' applicable during eight weeks of April 
and May. Comparing the specific gravities of the same spaces at different periods 
when the water in them remained undisturbed, I find an averarre addition of In. 1, 0 
to the depth by mark requisite to make the increase of density' correspond with 
the diminution of volume during those two months. This might be partly owing 
to errors of measure, but is sufficiently accounted for by the water contained in the 
very loose soil below, which must, to a certain degree, intermix with and affect that 
above it. Considering however that on digging three feet below the surface in No- 
vember, I found water of the specific gravity of 1028 in the middle of the ground 
then laid dry, and that few of the flooded spaces were raised to that density' before 
April, it is probable, the ground influence was minus in January, null or balanced in 
February, and at most one inch in March. For the last month I make this allow- 
ance accordingly in the following table, which gives the evaporation for the first five 
months oi the year with more or less accuracy, as the spaces and days of trial were 
many or few. * J 
