"^ 



HYSICAL AND LlTEkARY. 65, 



that It proceeds not from any unknowri 

 adlion of the rays upon one another, as has 

 been infinuated*, is evident from this, that 

 each particular ray, after paffing thro' the 

 focus, prefervljs its own colour .and its 

 own diredion^ in the fame manner as if it 

 were alone. 



QuER. VI. Ma'^ it not be inferred, that 

 the component parts of opaque bodies are 

 greater than thofe of tranfparent ones, as 

 theory requires -fj from this fimple obferva- 

 tion, that the former, fiich as metals, ftonesj 

 woodsy &c. when broken tranfverfely, fliew 

 a vifible - roughnefs and inequality at the 

 fradture ; whereas the latter, fuch as glafsj 

 chryftal, gems, ice, &c. appear as fmooth^ 

 almoft, as when they are poliflied ? 



QuER. VII. Do not Newton's experiments 

 with the ifland and rock chryftal fufticiently 

 prove, that the rays of light have different 

 permanent properties in their different fides, 

 relative to thefe two bodies ? Mufi we not 

 therefore conceive each particle of light to 

 preferve its pofition invariably while it moves 

 forward, at leaft fo as not to revolve round 



Vol. II. I its 



* I\iuJJchenlroeck\ Elementa phyfices, § 1040. 

 -j- Newton's Opt. Book 2= part 3. prop* 4. 



