Description of a Burning Mirror. 181 
Anthemius, who flourisbed at the commencement of the 
‘sixth century, informs us that it was unanimously allowed 
that Archimedes burned the enemy’s vessels by means of 
the solar rays. 
Eustathius, in his commentary on the Iliad, says that 
Archimedes, by an invention in catoptrics, burned the fleet 
of the [Merits at a distance equal to the isht of an arrow 
from a bow. 
«© Archimedes,” says Zonaras (Aznal. lib. ix.) ¢* burnt 
the fleet of the Romans in an admirable manner; for he 
turned a certain mirror towards the sun, and which received 
its rays. The air having been heated on account of the 
density and smoothness of this mirror, he kindled an im- 
mense flame, which he precipitated on the vessels which 
were in the harbour and reduced them to ashes.’”’ 
‘< When the fleet of Marcellus was within bow-shot,”’ 
says Tzetzes, “the old man (Archimedes) brought out a 
hexagonal mirror which he bad made. - He placed at pro- 
per distances from this mirror other smaller mirrors which 
"were of the same kind, and which were moved by means 
of their hinges and certain square plates of metal. “He 
afterwards placed his mirror in the midst of the solar rays, 
precisely at noon day. The rays of the sun being reflected 
by this mirror, he kindled a dreadful fire in the ships, which 
were reduced to ashes at a distance equal to that of a bow- 
shot.....Dien and Diodorus, who wrote the life of Archi- 
medes, and several other authors, speak of this fact; but 
chiefly Anthemius, who wroie on the prodigies of me- 
chanics ; Hero, Philo, Pappus, and in short all who have 
written id ancient mechanics: it is in these works that 
we read the history of the conflagration occasioned by the 
mirror of Archimedes.” 
Such are the authorities on which the history of the 
burning mirrors of Archimedes is founded, and these au- 
thorities are in my opinion of great weight, The silence 
of Polybius, of Livy, and of Plutarch, however, who relate 
at preat Jengib ‘atin Archimedes did’ for the defence of 
Syracuse, seems to warrant a doubt as to the fact of the 
burning the fleet of Marcellus. But whet! her Archimedes 
did or did not burn the fleet of Marcellus, it is certain that 
be contrived a burning mirror, and that this mirror was an 
-assemblage of plain mirrors. 
But what was the burning mirror of Archimedes? I 
shall endeavour to answer this question, after I shall have 
made some observations on the different kinds of parabolic 
mitrors composed of plain glasses. 
M 3 Take 
