MR JOHN SCOTT ON THE BURNING MIRRORS OF ARCHIMEDES. 149 



of two thousand years, by the light of modern science, and pass with credit 

 through the ordeal, the pretended discoveries of comparatively modern times, 

 when subjected to the same test, fall to pieces. 



An instance may be given without digressing from the subject of our paper 

 Thomas Digges, who republished in 1591 a work by his father, Leonhakd 

 Digges, entitled " Pantometria," would make us believe, in the preface to this 

 edition, that he had seen his father at sundry times fire gunpowder and discharge 

 ordnance at a distance of half-a-mile or more, by means of the sun's beams. 

 Had he been aware that to accomplish such a feat would require at least four 

 thousand square feet of reflecting surface, we may venture to affirm that he 

 would not have overstepped so far the Archimedean range. 



We may observe, in conclusion, that the experiments of Buffon, taken in 

 connection with the preceding deductions, are calculated to produce a strong 

 conviction that, in clear and comparatively warm climates, the sun's rays may be 

 made, at a small expense, to supersede in some respects the fires employed in 

 culinary operations. Further, when it is considered with what ease a combina- 

 tion of plane mirrors, or a series of conical reflecting zones, can be constructed, 

 capable of producing a heat exceeding that of the most intense furnace (Art. 16), 

 we infer that the solar beams may also be turned to account by the chemist 

 and metallurgist. For these purposes, one reflection only is required, as the 

 reflected light can be made to fall always on the same spot, by directing the 

 axis of the reflector to the centre of the sun's disc, and causing it to follow the 

 sun's motion in the heavens, by revolving round a fixed axis parallel to that 

 of the earth. 



