lis MifceUanea Curio/a. 



tract the entring Light towards the farther part 

 of the Room \ which, as I (aid, will thereby be 

 difFuled into an oblong coloured Image. Then 

 place a Lens of about three Foot Radius (fup- 

 pofea broad Object-glafs of a three Foot Tele- 

 fcope,) at the diftance of about four or five Foot 

 from thence, through which all thofe Colours 

 may at once be tranfmitted, and made by its Re- 

 fraction to convene at a farther diftance of about 

 ten or twelve Feet. If at that diftance you in- 

 tercept this Light with a Sheet of white Paper, 

 you will fee the Colours converted into whitenefs 

 again by being mingled. But it is requifite, that 

 the Prifm and Lens be placed fteady, and that 

 the Paper, on which the Colours are caft, be 

 moved to and fro; for, by fuch motion, you 

 will not only find at what diftance the whitenels 

 is moft perfect, but alfo fee how the Colours gra- 

 dually convene, and vanifti into whitened ; and 

 afterwards, having croffed one another in that 

 place where they compound whitenefs, arc again 

 diffipated and fevered, and in an inverted order 

 retain the fame Colours, which they had be- 

 fore they entred the Compofition. You may al- 

 fo fee, that, if any of the Colours at the Lens 

 be intercepted, the whicenefc will be changed in- 

 to the other Colours. And therefore, that the 

 Compofition of whitenefs be perfect, care muft 

 be taken that none of the Colours fall befides 



the Lens. | r 



In the annexed Defign, Tab. 3; Fig. z, 01 this 

 Experiment, ABC expreffeth the Pnfin fct end- 

 wife to fight, clofe by the hole F of the Window 

 E G. Its vertical Angle ABC may convenient- 

 ly be about 60 Degrees: M N defigneth the 

 Lens. Its breadth ai or 3 Inches. SF one ot 

 the ftreight Lines, in which difform Rays may 



