HYDROSTATICS. 
open atmosphere which would fill the inte- 
rior of the tumbler. If the inverted tumbler 
were first placed at the bottom of an empty 
vessel, and that water were afterwards 
poured into the latter, the effect would be 
precisely the same. 
The air contained within the upper part 
of a diving-bell not only debars the ingress 
of water, but, like the rarified air in the 
balloon, gives the machine such a buoyancy, 
that, unless made very substantial, and duly 
laden at the bottom, or broadest part, it 
would sink with difficulty, and be apt to 
turn ori its side, so that the air would es- 
cape. Under the head of DiviNG-feeW the 
reader will find an ample detail of the in- 
ventions hitherto extant in that branch of 
adventure. 
With regard to the depth to which float- 
ing bodies become immersed in fluids, we 
may consider the following general prin- 
ciples, or propositions, to be sufficient for 
the purpose of our readers. Bodies whose 
bases, or bottoms, are angular, like the 
keels of ships, will be immersed deeper 
than those whose bases are flat, such as 
barges : hence sharp-built vessels necessa- 
rily (to use the technical term) “ draw more 
water” than those of a mote obtuse form : 
the reason for which is easily demonstrated ; 
viz. As every body floating on a fluid will 
be immersed in proportion to its weight, 
and will displace a quantity of water equal 
thereto, it follows, that as a triangle is equal 
to only half a parallelogram of equal base 
and altitude, a parallelogram (or flat-bot- 
tomed vessel) will, under equal pressure, 
sink only half the depth of a triangular 
shaped bottom of equal base and altitude. 
For the same reason, vessels that have sharp 
stems make an easier passage through the 
water than such as are more “ bluff,” or 
obtuse, “ at the bows the more acute the 
triangle, in that part, the less the resistance ; 
for the triangle displaces only half the quan- 
tity of water that would be removed by a 
parallelogram of equal base and altitude ; 
ergo, it would proceed twice as far within 
a given time as the latter, were not the 
friction in some degree increased. 
It must be obvious, that whether the 
vessel alone, or the circumstance of her be- 
ing laden, cause her to weigh more, than the 
quantity of water displaced by her whole 
bulk, up to the very gunwale, is not mate- 
rial; for in such case she cannot float, but 
must be depressed by the sum of specific 
gravity thus produced. This will appear in 
a very natural and simple manner, if we 
load a cup with small shot, &c. ; for, though 
partly empty, the cup will sink whenever 
the whole weight may exceed that of the 
water displaced. Both the cup and the 
shot are, however, specifically heavier than 
their bulk of water, and the former would 
sink if let in sideways ; but then it would 
only displace a quantity of water corres- 
ponding with its own bulk, which would be 
trivial when compared with that removed 
by its pressure as a floating body. On the 
other hand, we find that a ship may be laden 
with cotton, which is far lighter than water, 
so as to sink, at least to a level with the 
water, though not to precipitate to the bot- 
tom, unless forced by the adjunction, in 
whatever form or manner, of such other 
substances as are heavier than water, by 
which the levity of the cotton may not only 
be counterpoised, but exceeded. In India, 
where the principles of hydrostatics are 
absolutely unknown, the peasants make 
rafts of the straw, which they perceive to be 
lighter than water, and on them load the 
corn threshed from that straw, perceiving it 
to be heavier than water. Thus they act up- 
on the best principles merely from observa- 
tion ! 
Perhaps, among the most curious circum- 
stances that come Within the verge of our 
subject, nothing can more fully exemplify 
what has been advanced than the fact, well 
known, of some vessels sailing better upon 
than before the wind. We have no doubt 
that, if the forms of their bottoms were cor- 
rectly ascertained, they would be found to 
present such a surface in the former posi- 
tion, when “ keeled a little,” as created a 
more favourable position of the gravity of 
the vessel, though it must be at least equal, 
or indeed greater, if much pressed by the 
wind, than in the latter position. 
Before we quit this subject, it is necessary 
to inform the reader, that, except in cases 
relating purely to statics, few instances oc- 
cur in which the various matters appertain- 
ing to hydrostatics can be treated in a man- 
ner perfectly abstracted from pneumatics, 
or from hydrodynamics. Under the head 
of Fluids and of Hydraulics we have 
treated of the principles of fluids in motion, 
in such a way as may give a popular idea of 
those very intricate subjects ; recommend- 
ing to the student to read the whole con- 
tained under those articles with attention, 
and combining their several actions as de- 
rived from one great principle. 
HYDRO sulphuret, in chemistry, the 
combination of sulphuretted hydrogen, with 
