170. As a matter of course, if the above principles are
correct, no solid can float on the surface of a liquid, if it

of water, what will be the effect ? How is it shown that it would remain at rest beneath
the surface ? How much greater is the upward than the downward pressure 1 Why^
then, will not the block rise to the surface 1 If the block were heavier than an equal
Tolumc of water, what would be the effect 1 If lighter, what would be the result 1
IVhen a body floats in water, how will the weight of the water displaced compare with
the weight of the body 1 17(^ If a substance heavier than water, bulk for bulk, will




105



r AT URAL PHI LO SOPH r.
be heavier than its own bulk of the liquid ; but, as the
bulk of most or all substances can be increased without
increasing their weight, it may be formed, however
heavy, so as to float. Thus, vessels made of brass, iron,
and other heavjr substances, readily float upon the surface
of water. So iron steam- vessels are not now uncommon.
In consequence of their form, they displace just as much
water as if they were solid ; but their weight is very
much less. If they are filled with water, therefore, they
immediately sink.
