ADVERTISEMENT 



vM 



TO THE SECOND EDITION. 



'THE favourable reception winch this work "has ex~ 

 perienced from the public having rendered a fecond 

 edition neceffary Jooner than was expefted, but lit tie time 

 has been afforded for new difcoveries in philojophy ; yet 

 the additions and alterations in this edition will be found 

 tonfiderable, and I flatter myfelf they will be thought im- 

 provements. 



A very long chapter has been added on the Mechanic 

 Powers, and two whole chapters on the Reflexion and 

 Refraction 'of Light , intended to make the Jcience of 

 optics plain and intelligible to readers unacquainted with 

 mathematics. 



Whatever of novelty has occurred in Jiience fince the 

 ft? -ft publication of the work has been carefully added-, 

 many omijjions have been Jupplied \ and by the kind at" 

 tention of feveralfcientific friends, Jome errors, which had 

 efcaped in the fir ft imprejfion, have been corrected. 



G.G. 



Chapsl-ftreet, Bedford-row, 

 Feb. 1798. 



857313 



