54 Lord Napier' $■ different Contrivances 



'^ Foitrthly, The invention of a round chariot in metal, 

 made of the proof of double musquet, whose motion shall 

 be such, that those that be within the same shall be more 

 easy, more light, more speedy, and more safe in battle, than 

 any hitherto contrived. The use hereof in moving, is to 

 break the array of the enemy's battle, and to make passage, 

 as also in staying and abiding within the enemy's battle. 

 It serveth to destroy the environed enemy, by continual 

 charges and shot of the arquebuss, through small holes; 

 the enemy in the mean time, being amazed, and altogether 

 uncertain what defence or pursuit to use against a moving 

 jnoulh of metal. 



** These inventions, besides devices of sailing under the 

 water, with divers other devices and stratagems for harming 

 of the enemies, by the grace of God, and work of expert 

 craftsmeuj I hope to jpefform. 



John Napier, of Mcrchiston, 

 .Amio Domini I096, June 2. 



Remarks on the above, 

 I. The accension of combustible bodies by the solar rays 

 concentrated in the focus of a concave mirror, was well known 

 to the anticnts, it being the 31st, and concluding proposi- 

 tion, of the Treatise on Catoptricks, generally ascribed to 

 Euclid*: and it was by such mirrors, according to Plutarch, 

 in the life of Numa, that the vestal fires were rekindled. 

 Tiiere can be no doubt that the Magi, who were equally scru- 

 pulous about their sacred lire, renovated it by the same means. 

 The anticnts also knew, that if a number of plane mirrors 

 were so disposed as that each of them should reflect the 

 image of the sun to the same spot, a combustible substance 

 placed there would be set on fire. It was precisely in this 

 way, according to the Grecian poet Tzetzes, that Archi- 

 medes, ^t the distance of a bow-shot, projected the rays of 

 the sun on the fleet of Marcellus, before Syracuse, and re- 



* Dr. Rutherford, in his Syst, of Nat. Philos. vol. i. p. 448. says, 

 tliat the author of tliis piece on Catopn^ics, who, we ni:iy be certain, was 

 not Euelid the geomerrician, has erroneously supposed the burning pcint, 

 or focas of the -sun's rays, in a concave mirror, to be in the centre of the 

 Si here, whereof it is a portion. And VVoifiuf, in his Efcm. Muihes. 

 TJni-jer. t. iri. p. 1S7. charges not Euclid only, but all the antients with 

 this error. But how then, it may be asked, could they be acquainted, 

 as they certainly were, with the rtf/«fl/ :/jf of such mirrors ? Hcrigon, 

 • n thj; Catoptrics, which he gives as Euclid's, without mentioning tli';: 

 »rrror of his author, places the focus where it ought to be, namely veiy 

 Tiearly, or, as to sen;e, exictly, in the middle <d the axis, between the 

 centre vn-i ths concnve reflecting', surficc, ■ 



duced 



