into Lenses for Microscopes. 149 



I shall not fatigue my readers by describing the difficulties 

 which were encountered in the prosecution of the design of 

 making diamond lenses. Nature does not seem to permit us 

 to produce any thing of surpassing excellence without propor- 

 tional effort, and I shall simply say, that in its infancy the pro- 

 ject of grinding and polishing the refractory substance of ada- 

 mant was far more hopeless than that of making achromatic 

 glass lenses of 0.2 of an inch focus. I conceive it just to state, 

 that Messrs Rundell and Bridge, of Ludgate Hill, had, at the 

 time of the commencement of my labours, many Dutch diamond 

 cutters at work, and that the foreman Mr Levi, with all his men, 

 assured me that it was impossible to work diamonds into spheri- 

 cal curves ; the same opinion was also expressed by several others 

 who were considered of standard authority in such matters. 



Notwithstanding this discouragement, in the summer of the 

 year 1824, I was instigated by Dr Goring (at his expence) to 

 undertake the task of working a diamond lens. For this pur- 

 pose Dr Goring forwarded to me a brilliant diamond, which, 

 contrary to the expectation of many, was at length ground into 

 a spherical figure, and examined by Mr Levi, who expressed 

 great astonishment at it, and added, that he was not acquainted 

 with any means by which that figure could have been effected. 

 Unfortunately this stone was irrecoverably lost. Mr Varley hav- 

 ing returned from the country, becoming now thoroughly heat- 

 ed with the project, permitted me to complete another diamond 

 which had been presented to me by Dr Goring. This is a plane 

 convex of about ^^^th of an inch focus. It was not thought adrt 

 visable to polish it, more than sufficed to enable us to see ob- 

 jects through it, because several flaws, before invisible, made 

 their appearance in the process of polishing. In spite of all 

 its imperfections, it plainly convinced us of the superiority which 

 a perfect diamond lens would possess by its style of perfor- 

 mance, both as a single magnifier, and as the object lens of a 

 compound microscope. After the lapse of a short interval of 

 a few months, I devoted some time to the formation of a per- 



have been executed ; but the testimony of lenses of diamond would cer- 

 tainly be far more respectable, and is at least worthy of trial and exami- 

 nation.— C. R. G. 



