66 ESSAYS AND OBSERVATIONS 



its center perpendicularly to the direction of 

 its motion ? Would it not be proper to try 

 how light is infleded in paffing clofety by 

 the feveral angles and fides of thefe foflils ? 



QuER. VIII. Is it not pofTible to prove by 

 experiment what Sir Jfaac Newton takes for 

 granted as a reafonable fuppofition, that thin 

 tranfparent plates, of aiiy uniform colour, 

 divided into fmaller fragments, would com- 

 pofe a powder of like colour * ? And would 

 not this tend to flrengthen the analogy be- 

 tween the colours of fuch plates and thofe 

 of natural bodies ? For this purpofe, I have 

 tried to freeze foap-bubbles j but could ne- 

 ver make any ftand till they were turned to 

 ice, except fuch as were too thick to have 

 lively colours : however, I doubt not, but^ 

 with due care, the thing might be done ; 

 efpecially, if the foap-water, infliead of be- 

 ing blown- with a pipe into bubbles, were 

 drawn out intp a plain plate upon any wooden 

 or metalline frame : for, the fides of a plain 

 furface bearing a greater proportion to its 

 iirea^ than a bafe of a fpherical fegment to 

 its furface, the froft would be fooner. com- 

 municated 



Kewton's Opt. book 2. part 3. prop. 5. 



