former calls them balls or globes of glass, or crys- 

 tal, which exposed to the sun, transmit a heat suffi. 

 cient to set fire to cloth, or corrode away the dead 

 flesh of those patients, who stand in need of caus. 

 tics, and the latter, after Clemens Alexandrians, 

 takes notice, that fire may be kindled, by interposing 

 glasses filled with water, between the sun and the 

 object, so as to transmit the rays to it. 



h 



