Chap. 45.] MIIUIORS. 127 



thorn to undergo corresponding distortions : for, in 

 fact, the imago is nothing else but the shadow of the object 

 collected upon the bright surface of the metal. 



However, to finish our description of mirrors on the present** 

 occasion the best, in the. times of our ancestors, were those of 

 Urundisiuru,* 7 composed of a mixture of w stannum and copper : 

 jit a later period, however, those made of silver were pre- 

 ferred, l*asitelus w being the first who made them, in the time 1 

 of Pompeius Magnus. More recently, 2 a notion has arisen 

 that the object is reflected with greater distinctness, by the 

 application to the back of the mirror of a layer of gold. 3 



95 A subject to which he returns iu various parts of B. xxxvi. 



97 Sec H. xxxiv. c. 48. 



08 As to the identification of "stannum," on which there have been 

 great differences of opinion, see B. xxxiv. cc. 47, 48, and the Notes. 



*'> For some account of this artist, see Chapter 55 and the Xotcs at the 

 end of this Hook. 



1 " Silver mirrors were known long before this period, as is proved by 

 a passage in the Mostellaria of 1'lautus, A. 1, S. 3, I. 101, where they are 

 distinctly mentioned. To reconcile this contradiction, Meursius remarks 

 that Pliny speaks only of his countrymen, and not of the Greeks, who had 

 such articles much earlier, though the scene in Plautus is at Athens." 

 Beckmann, Hist. Inv. Vol. H. p. fi'2. Jtohn's Edition. 



2 ** Nupcr credi ca-ptum certiorem imuginem reddi auro opposite 

 aversis." " Of what Pliny says here I can give no explanation. liar- 

 douin (qy. if not Dalechamps ?) is of opinion that mirrors, according to the 

 newest invention, at that period were covered behind with a plate of gold, 

 as our mirrors are with an amalgam. But as the ancient plates of silver 

 were not transparent, how could the gold at the back of them produce any 

 effect in regard to the image? May not the meaning be that a thin plate 

 of gold was placid at some distance before the mirror, in order to throw 

 more lii^ht upon its surface ? Whatever may have been the case, Pliny 

 hinuelfacenii not to have had much confidence in the invention." Iteck- 

 rnann. lli>t. Inv. Vol. II. p. G2. 



3 Dr. Wat&on (Chemical Essays, Vol. IV. p. 24G) seems to think that 

 Pliny is here speaking of glass mirrors: "If we admit that I'liny was 

 acquainted with glass .mirrors, we may thus understand what he says 

 respecting an invention which was then new, of applying gold behind a 

 mirror. Instead of aii amalgam of tin, some one had proposed to cover 

 the back of the mirror with an amalgam of gold, with which the ancients 

 were certainly acquainted, and which they employed in gilding." Sec 

 Chapter 20 of the present I5ook. On the above passage by Dr. Watson, 

 Beckmann has the following remarks: "This conjecture appears, at any 

 rate, to be ingenious; but when I read the passage again, without pre- 

 judice, I can hardly believe that Pliny alludes to a plate of glass in aplace 

 where he speaks only of metallic mirrors; and the overlaying with amal- 

 gam requires too much art to allow lue to ascribe it to such a period with- 



