Porta, on the Refection of Cold o#c. 1 73 



cimals to measures in his Practical Geometry, published 

 early m the se.venteenth century *. I s.iv tlie first European • 

 tor, according to father Noel, the dccin.al division of sseWhil 

 and measures has long been established in Cliina f. "^ 



I am. See. 

 . *D. 



P. S. Having little prospect of addressing voti again for 

 some time, I shall take the liberty to subjoin a' short'^extract 

 from the Mag'ia Naturalis of J.' Baptista Porta, first pub- 

 lished in the year 1504 ^ Though I have proved in my 

 former letters, { believe to general satisfactinn, that this 

 learned ItaHan did not invent^thc telescope, I bv no i/ieans 

 insinuated that he was destitute of original o-enius. This 

 work shows the contrary, and that he both eiTcouracred and 

 praciiscd physical experiments with great success ;"fyr his 

 Magia contains nothing of what we now call maaic, but 

 the name, and somwhat of the legendary spirit. 



" Calorem, frigus et vocem. specula vovcavo re fleet eve. 



" Si quis candelam in loco, ubi spectabilis res locaji 

 debet, apposuerit, accedet candcla per aerem usque ad ocu- 

 los, ut illos calore et lumine oft'endet. Hoc aute^i niira- 

 bilius erit, ut calor, ita frigus reflectitur, si eo loco nix ob- 

 jiciatur, si oculum tetigerit, quia sensibilis, etiam frifuis 

 percipiet. Sed res admirabilior est, qu.jd idem snecuhun, 

 non soIun» calorem et frigus, sed vocem refring'et, atoue 

 echi officio fungitur; reflectitur enim vox a polita', tersaque 

 speculi superficie, rectius et integrius, quam a quovis pa- 

 nete." (J. B. Forlce, Mag. Nat. lib. 17. cap. 4. edit. 

 Bothomagi {Rouen) 1630, p^^S?.) The literal translation 

 of this passage (which it will be remembered was written 

 before the thermometer was invented) is as follows : 



_*' To reflect heat, cold, and the voice, from a concait 

 TJurror. 



" If any one put a candle in the situation where a thincr 

 to be viewed ought to be placed, the candle will come') 

 through the air, to the eyes, so as to offend them with light 

 and heat. But it is more wonderful, that as heat is reflected, 

 «o IS cold, if snow be exposed in that place, and touch the 

 eye, this organ, because sensible, will also perceive coJd, 

 It IS, however, still more wonderful, that the same specu- 

 lum will not only reverberate heat and cold, but the voice, 



• If^olfii. E/tm. Gfutut. § 27, ed. 2. Huiion's Diet, articles Dfdmah, 

 M'llln, ?iirt>nch, Su-.m 



t Ohinv. Maihcrrj. Phvs. in Ifitlia ft China, fuctis. c. vii. p. loj^- 

 1 btf S.'one't Maihcrn. Diction, an. Tf/euulf. 



ani 



