s, was about to abandon the subject altogether, when
the following circumstance suggested to his discerning and prepared mind
a train of thought which led to the solution of the difficulty. Stepping
into his bath one day, as was his custom, his mind doubtless fixed on
the object of his research, he chanced to observe that, the bath being
full, a quantity of water of the same bulk as his body must flow over
before he could immerse himself. He probably perceived that any other
body of the same bulk would have raised the water equally; but that
another body of the same weight, but less bulky, would not have produced
so great an effect. In the words of Vitruvius, "as soon as he had hit
upon this method of detection, he did not wait a moment, but jumped
joyfully out of the bath, and running forthwith toward his own house,
called out with a loud voice that he had found what he sought. For as he
ran he called out, in Greek, 'Eureka! Eureka!--I have found it! I have
found it!'" When his emotion had sobered down, he proceeded to
investigate the subject calmly. He procured two masses of metal, each of
equal weight with the crown--one of gold and the other of silver--and
having filled a vessel very accurately with water, he plunged into it
the silver, and marked the exact quantity of water that overflowed. He
then treated the gold in the same manner, and observed that a less
quantity of water overflowed than before. He next plunged the crown into
the same vessel full of water, and observed that it displaced more of
the fluid than the gold had done, and less than the silver; by which he
inferred that the crown was neither pure gold nor pure silver, but a
mixture of both. Hiero was so gratified with this result as to declare
that from that moment he could never refuse to believe anything
Archimedes told him.

Travelling in Egypt, and observing the necessity of raising the water of
the Nile to points which the river did not reach, as well as the
difficulty of clearing the land from the periodical overflowings of the
Nile, Archimedes invented for this purpose the screw which bears his
name. It was likewise used as a pump to clear water from the holds of
vessels; and the name of Archimedes was held in great veneration by
seamen on this account. The screw may be briefly described as a long
spiral with its lower extremity immersed in the water, which, rising
along the channels by the revolution of the machine on its axis, is
discharged a