23*1 Proceedings of the Royal Society 
Polybius, Livy, and Plutarch, are silent respecting the burning 
mirrors, although they describe some of the other contrivances 
employed by Archimedes against the assailants. In reply to this 
objection, it has been stated, as an admitted axiom in estimating 
historical evidence, that the silence of one author is not sufficient 
to disprove an event of which another, even subsequent in point 
of time, has given a plain and consistent narrative. Besides, 
similar omissions by ancient historians are not unfrequent ; and 
in this instance, it is the less surprising, since the invention had 
perished with the fall of Syracuse, and the death of the illus- 
trious inventor, who, in the peculiar circumstances, must have en- 
deavoured to keep from his contemporaries the secret of its con- 
struction. 
Returning to Buffon’s experiments, Peyrard appends to his trans- 
lation of the works of Archimedes a memoir of his own, pointing 
out the defects of Buffon’s combination of reflectors, viz. : — That 
the number of assistants required to adjust so many mirrors were 
apt to confuse one another — the operation itself was a tedious 
one, taking about half an hour for one hundred and sixty-eight 
mirrors — and, after all, the superposition of the light was imperfect. 
Again, after a short interval, a readjustment would be rendered 
necessary by the angular deviation of the rays, arising from the 
varying position of the sun. Peyrard suggests “ that each mirror 
should be furnished with a telescope, and a somewhat complex 
apparatus, to render the adjustment more speedy and accurate, and 
by this means to diminish the number of assistants required. This 
remedy is admitted to be only partial. It is proposed, in what 
follows, to obviate the forementioned defects, by producing a solar 
reflecting machine, capable of being directed by one eye, guided by 
a single hand, and coinciding in its construction with the descrip- 
tion in the fragment preserved by Tzetzes from Pappus. 
It is stated that Archimedes contrived a hexagonal mirror, and 
placed at proper distances from it other smaller ones of the same 
kind. This peculiarity has no parallel in that of Buffon. Articles 
11, 12, and 13, in the memoir, show how burning mirrors can be 
constructed, corresponding to the above description, free from the 
defects of Buffon, and capable, moreover, of darting the consuming 
rays instantaneously in any given direction, thereby affording a 
