104 Mifcellanea Curiofa. 



lifhing, proper for Metal, whereby, as I i ma- 

 gin' d, the Figure alfo would be corrected to the 

 laft ; I began to try what might be effected in 

 this kind, and by degrees fb far perfected an In- 

 ftrument (in the effential parts of it like that I 

 fent to Lender. ,) by which I Could difcern Jupiter 's 

 four Concomitants, and (hew'd them divers times 

 to two others of my Acquaintance. I could alfb 

 difcern the Moon-like Phafe of Venus ^ but not 

 very diftin&ly, nor without fbme nicenefs in di- 

 ipofing the Inftrument. 



From that time I was interrupted, till this laft 

 Autumn, when I made the other. And as that 

 was fenfibly better than the firft (efpecially for 

 Day-Objects,) fo I doubt not but they will be 

 ftill brought to a much greater perfection by their 

 Endeavours, who, as you inform me, are taking 

 care about it at London* K 



I have fometimes thought to make a Micrcfcope, 

 which in like manner fhould have, inftead of an 

 Object-glals, a reflecting piece of Metal. And 

 this 1 hope they will alfo take into Confideration : 

 For thofe Inftruments feem as capable of improve- 

 ment as Telefcopes, and perhaps more, becaufe 

 but one refleSive piece of Metal is requifite in 

 them, as you may perceive in Plate 3. Fig. i; 

 where A B reprefenteth the Object Me fl, C D 

 the Eye-glafs, F their common Focus, and O 

 the other Focus of the Metal, in which the N Ob- 

 ject is placed. 



But to return from this digreftion, I told 

 you, that Light is not fimilar, or homogeneal, 

 but confifts of diffcrm Rays, fbme of which are 

 more refrangible than others : So that of thofe, 

 which are alike incident on the feme Medium, 

 f ome mall be more refracted than others, and 

 that not by any virtue of the Glafs, or other 



externa] 



