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IV. — On the Burning Mirrors of Archimedes, with some Propositions relating to 

 the concentration of Light produced by Reflectors of differ 'ent forms. By 

 John Scott, Esq., Tain. (Plate III.) 



(Bead 6th January 1868). 



As the reputed fact of Archimedes having burned the Roman ships engaged 

 in the siege of Syracuse, by concentrating on them the solar rays, has not only 

 been doubted but disbelieved by some of the most eminent scientific men, I shall 

 briefly give the evidence on both sides. 



The burning of the ships of Marcelltjs is mentioned by most of the ancient 

 writers who refer to the machines which Archimedes employed in the defence of 

 his native city, and their statements have been repeated by succeeding authors, 

 without any doubts having been expressed until comparatively recent times. 

 Our earliest authorities on the subject are Diodorus Siculus, Lucian, Galen, Dion, 

 and Pappus. At a later period the architect Anthemius, of Tralles, in a frag- 

 ment entitled -rrepi TrapaSoj-wv /j.t]-)(avrnuLaTwv (Wonderful Machines), not only dwells 

 particularly on the burning mirror of Archimedes, but adds, besides, that it 

 was universally admitted in his time that Archimedes had destroyed the Roman 

 fleet by means of burning mirrors. It is also mentioned by Hero, a writer on 

 military engines — about the middle of the seventh century— and by Eustathius, 

 Zonares, and Tzetzes, who flourished in the twelfth. Thelast two have transmitted 

 to us passages extracted from the work of Pappus on the siege of Syracuse, which 

 was then extant, but has since disappeared. We give that by Tzetzes as the more 

 definite and circumstantial :— " When Marcellus had placed the ships a bow-shot 

 off, the old man (Archimedes) contrived a hexagonal mirror. He placed at 

 proper distances from the mirror smaller mirrors of the same kind, and which 

 were moved by means of their hinges and certain square plates of metal. He 

 placed it in the midst of the solar rays at noon both in summer and winter. The 

 rays of the sun being reflected by this, a dreadful fire was excited on the ships, 

 which reduced them to ashes at the distance of a bow-shot." 



In the sixteenth century mirrors similar to that of Archimedes seem to have 

 engaged the attention of Leonhard Digges, and of Baron Napier of Merchiston. 

 At a subsequent period Father Kersher took up the same subject, prosecuting it 

 with such assiduity that he travelled to Sicily to examine the coast in the vicinity 

 of Syracuse, and came to the conclusion that Archimedes might have oppor- 

 tunities of placing his mirror within 30 yards of the ships. He also mentions 

 in his "Magica Catoptrica," as the result of experiments which he had performed, 

 that the superimposed rays reflected from five plane mirrors at the distance of 

 vol. xxv. part i. 2 I 



