Encyclopaedia Britannica > Volume 3, Anatomy-Astronomy

430 A R C
Archi- thematicians, was born at Syracuse in Sicily, about the year
niedes. 287 before the Christian era. Hiero, king of Syracuse,
v—v—deemed it an honour to have this philosopher for his rela¬
tive and friend. History does not inform us by whom he was
instructed in the rudiments of literature, but he flourished
about 50 years after Euclid. It is reported that he was in¬
debted to Egypt for much of his knowledge ; but other ac¬
counts indicate that he conferred more knowledge than he
received from that celebrated nation; and, in particular,
Diodorus mentions that Egypt was indebted to him for the
invention of the screw-pump for drawing off water : and the
same author narrates that he was the inventor of several
other useful machines, which conveyed his fame to every
quarter of the globe. The following passage from Livy
proves that he was celebrated both for the invention of war¬
like machines, and also for his accurate observation of the
heavenly bodies: “Unicus spectator cceli siderumque, mi-
rabilior tamen inventor ac machinator bellicorum tormento"
rum,” &c. lib. xxiv. cap. 34. It appears also that, in Cicero s
time, his skill in solving problems had become proverbial.
In a letter to Atticus, he informs him that he is now freed
from a difficulty, which he termed an Archimeden problem,
Ep. xiii. 28.
Vitruvius mentions a fact which proves Archimedes s
knowledge in the doctrine of specific gravity. Hiero, the
king, having given a certain quantity of gold wherewith to
make a golden crown, and suspecting that the workmen had
stolen part of the gold and substituted silver in its stead, he
applied to Archimedes to employ his ingenuity in detecting
the fraud. Ruminating upon this subject when he was in
the bath, he observed that he dislodged a quantity of wa¬
ter corresponding to the bulk of his own body; and in¬
stantly quitting the bath with all the eagerness natural to
an inventive mind upon a new discovery, he ran into the
street naked, crying, EvprjKa! Evpr/Ka! / have found it ! I
have found it! Then taking one mass of gold and another
of silver, each equal in weight to the crown, he carefully
observed the quantity of fluid which they alternately dis¬
placed when introduced in the same vessel full of water.
Next he ascertained how much water was displaced by the
crown when put into the same vessel full of water; and, upon
comparing the three quantities together, he ascertained the
exact proportions of gold and silver of which the crown was
composed.
Archimedes’s knowledge of the mechanical powers is fa¬
miliar to every one. His celebrated saying with regard to
the power of the lever has been often repeated, “ Give me
a place to stand upon (irov cttw), and I will move the earth.’
In order to show Hiero the effect of mechanical powers, it is
said that by means of ropes and pulleys he drew towards him
a galley which lay on the shore manned and loaded. The dis¬
plays of his mechanical skill at the siege of Syracuse, men¬
tioned by Marcellus,were long deemed incredible, until the
subsequent improvements in mechanics had demonstrated
their practicability. He harassed the vessels of the besiegers,
both when they approached and kept at a distance from the
city. When they approached, he sunk them by means of long
and huge beams of wood ; or, by means of grappling hooks
placed at the extremity of levers, he hoisted up the vessels
into the air, and dashed them to pieces either against the
walls or the rocks. When the enemy kept at a distance, he
employed machines which threw from the walls such a quan¬
tity of stones as shattered and destroyed their vessels. In
short, his mechanical genius supplied strength and courage
to the city, and filled the Romans with astonishment and
terror. The account of Archimedes's instrument for burn¬
ing ships at a great distance by means of the rays of the sun
was deemed fabulous and impossible, until Buffon invented
and framed a burning glass, composed of a multitude of plane
mirrors, capable of setting fire to wood at the distance of 200
ARC
Archi-
medes-
Screw
Archi-
mimus.
feet, of melting lead and tin at 120 feet, and silver at the
distance of 50 feet. . . Screw
But, however eminent for mechanical invention, he uas pr0pejjer
still more eminent for the investigation of abstract truths, n
and the deduction of conclusive demonstrations in pure geo¬
metry. Plutarch also mentions that Archimedes himself
esteemed mechanical inventions greatly inferior in value to
those speculations which convey irresistible conviction to
the mind. His geometrical works afford numerous proofs
of his success in this field of science. It is reported that
he was often so deeply engaged in mathematical specula¬
tions, as both to neglect his food and the care of his person ;
and at the bath he would sometimes draw geometrical figures
in the ashes, and sometimes upon his own body after he was
anointed according to the custom of that time. He valued
himself so much upon the discovery of the ratio between
the sphere and the containing cylinder, that he ordered his
friends to place upon his tomb a cylinder containing a sphere,
with an inscription explanatory of its nature and use.
When Syracuse was taken by storm, Archimedes, igno¬
rant of the fact, was run through the body by a soldier,
while engaged in drawing a geometrical figure upon the
sand. As Marcellus had given express orders that both his
person and his house should be held sacred, this appears to
have happened through ignorance, and therefore removes
a great part of the odium from the Roman name. I his
event happened in the 142d Olympiad, or 212 years before
the Christian era. Marcellus, in the midst of his triumph,
lamented the death of Archimedes, conferred upon him an
honourable burial, and took his surviving relations under his
protection; but greater honour was conferred upon him
when the philosopher of Arpinum, 140 years after, went in
search of his long-neglected tomb. “ I diligently sought,”
says Cicero, “ to discover the sepulchre of Archimedes,
which the Syracusans had totally neglected, and suffered to
be overgrown with thorns and briers. Recollecting some
verses said to be inscribed on the tomb, which mentioned
that on the top was placed a sphere with a cylinder, I looked
around me upon every object at the Agrigen tine gate, the
common receptacle of the dead. At last I observed a little
column which just rose above the thorns, upon which was
placed the figure of a sphere and cylinder. This, said I
to the Syracusan nobles who were with me, c this must, I
think, be what I am seeking.’ Several persons were imme¬
diately employed to clear aw'ay the weeds and lay open the
spot. As soon as a passage was opened, we drew near, and
found on the opposite base the inscription, with nearly half
the latter part of the verses worn away. Thus would this
most famous and once most learned city of Greece have re¬
mained a stranger to the tomb of one of its most ingenious
citizens, had it not been discovered by a man of Arpmum.”
The following works of this celebrated mathematician
have escaped the wreck of time: 1. On the Sphere and
Cylinder : 2. On the Dimension of the Circle, or the Pro¬
portion between the Diameter and the Circumference. 3.
On Obtuse Conoids and Spheroids: 4. On Spiral Lines:
5. On the Quadrature of the Parabola : 6. On Equipon¬
derants and Centres of Gravity : 7. On Bodies floating on
Fluids : 8. The Arenarius : 9. Lemmata ; but the genu¬
ineness of this last has been doubted.
The existing works of Archimedes were printed at Basle,
in a folio volume, Greek and Latin, in 1544. This is the
editio princeps. Another edition was printed at Paris in
1615. The most complete and best is that of Torelli, printed
at Oxford in 1792, folio. There is a French translation of
his works by M. Peyrard ; and an English translation of the
Arenarius, by G. Anderson, London, 1784.
Akchimedes-Screw Propeller. See Steam Navi¬
gation.
ARCHIMIMUS, in Antiquity, the chief mimic actor or