lOO Vr. Falconer on the Knovoledge 



according to the aflronomical ideas that i\\tn 

 prevailed, but alio made to move in their orbits 

 according to their different degrees of velocity. 

 The meridians, the zodiac, with its figns, and 

 other great circles of the heavens, together with 

 the rife and fettingof the ftars, were all exprefied. 

 The v/hole of this curious mechanifm, was in- 

 clofed in glafs, and feems to have been in form 

 of a fphere. Whether the celeftial circles, to- 

 gether with the fixed ftars, were delineated on 

 tlie outer glafs covering, which might be made 

 to revolve round the reft of the planetary fyftem, 

 like that defcribed in the firft volume of Dr. 

 Long's Aftronomy, and the print of it prefixed 

 to the title of that book ; or whether it was 

 conftructed in any other manner, is not clear. Ic 

 muft, at any rate, have been a furprifing piece 

 of mechanifm. 



Lucretius was undoubtedly well 

 ^* acquainted with glafs, and its pro- 

 perties. In his fourth book, he remarks the 

 difference between founds, and the images of 

 objei5ls. The former paffing through any open- 

 ings however curved or winding, * whilft the 

 latter are broken and confufed, if the paffagesj 



* .- -'Vox per flexa foramina reruin 



Incolumis tranfire -poteft, fimulacra renutaiu. 

 Perfcinduntar enim, nifi re£la foramina tranant, 

 ■ Qualia funt vitrl, fpecies qua: travolat omnis. 



Lucret. L. IV. Lin. 605. 



through 



