1876.] The Book of the Balance of Wisdom . 499 
one to know what is a genuine precious stone, such as a 
hyacinth, or ruby, or emerald, or a fine pearl ; for it truly 
discriminates between these and their imitations or simili- 
tudes in colour, made to deceive. 55 
Then follows the theory of the water balance; and in the 
fourth section some account of its early history and the well- 
known narrative of King Hiero's crown. 
“ It is said that the [Greek] philosophers were first led to 
think of setting up this balance, and moved thereto, by the 
book of Menelaus* addressed to Domitian, in which he says : 
O King, there was brought one day to Hiero, King of Sicily, 
a crown of great price, presented to him on the part of several 
provinces, which was strongly made and of solid workman- 
ship. Now it occurred to Hiero that this crown was not of 
pure gold, but alloyed with some silver ; so he inquired into 
the matter of the crown, and clearly made out that it was 
composed of gold and silver together. He therefore wished 
to ascertain the proportion of each metal contained in it, 
while at the same time, he was averse to breaking the crown 
on account of its solid workmanship. So he questioned the 
geometricians and mechanicians on the subject, but no one 
sufficiently skilled was found among them, except Archimedes 
the geometrician, one of the courtiers of Hiero. Accordingly 
he devised a piece of mechanism which, by delicate contri- 
vance, enabled him to inform King Hiero how much gold 
and how much silver was in the crown, while yet it retained 
its form. This was before the time of Alexander. After- 
wards Menelaus [himself] thought about the water-balance 
and brought out certain universal arithmetical methods to 
be applied to it ; and there exists a treatise by him on the 
subject. It was then four hundred years after Alexander. 55 
Al-Ivhazini takes pains in this sketch of the early history 
of specific gravity, to establish dates by reference to con- 
temporaneous individuals, but his chronology is evidently at 
fault. The Hiero alluded to is Hiero II., who died 216 B.c., 
while Alexander the Great lived more than a century earlier 
(356 b.c— 323 b.c.) 
This Arabic version of the anecdote of Hiero’s crown lacks 
the piquancy and interest of the narrative as originally given 
by Vitruvius, and is moreover not an accurate transcription ; 
the words “ devised a piece of mechanism ” convey the 
impression that Archimedes constructed some peculiar form 
of apparatus with which to solve the problem. Indeed this 
* A celebrated mathematician who lived in the reign of Trojan, g8— -117 A. D», 
and author of a treatise on Spherical Geometry, 
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