Fig. 17, 



Sheffieth a fmall piece of OaJ^ cut a-- 

 thwart. 



b The juft bignefi of it^ as it ap- 



peareth to the naked eye. 

 hhhb The appearance thereof 



through a Microfc&fe. 

 aaaa. The greater Inlertions vifible 



to the bare eye. 

 The white Lines are the finaller In- 



iertions only vifible by the M- 



crofcope, 

 cccccc The greater Pores vifible to 



the bare eye. 

 eeeeee The middle fized. 

 The black Spots are thefmalleftof 



all^ and boththefe latter vifible 



only through the Microfcope. 

 € The THh of every great Pore. 



Fig. 



