Notwithstanding this discouragement, in the summer of the year 1824, I was instigated by Dr. Goring (at his expense) to undertake the task of working a diamond lens: (being then under the tuition of Mr. C. Varley, who was however at that time absent.) For this purpose, Dr. G. forwarded to me a brilliant diamond, which, contrary to the expectation of many, was at length ground into a spherical [p017] 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 having returned from the country, becoming now thoroughly heated with the project, permitted me to complete another diamond, which had been presented to me by Dr. G.: this is a plano-convex of about the 1/20th of an inch focus: it was not thought advisable to polish it more than sufficed to enable us to see objects 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 performance, both as a single magnifier and as the object lens of a compound microscope. After the completion of my articles with Mr. V., being entirely under my own command, I devoted some time to the formation of a perfect diamond lens, and have at length succeeded in completing a double convex of equal radii of about 1/25th of an inch focus, bearing an aperture of 1/30th of an inch with distinctness on opaque objects, and its entire diameter on transparent ones; it was finished at the conclusion of last year. The date of its final completion has by many been considered a remarkable epoch in the history of the microscope, being the first perfect one ever _made_ or thought of in any part of the world[4]. I think it sufficient to say of this adamantine lens that it gives vision with a trifling chromatic aberration, but in other respects exceedingly like that of Dr. G.’s Amician reflector, but without its darkness: for it is quite evident that its light must be superior to that of any compound microscope whatever, acting with the same power and the same angle of aperture. The advantage of seeing an object _without aberration_ by [p018] the interposition of but a single magnifier, instead of looking at a picture of it (however perfect) with an eye-glass, must surely be duly appreciated by every person endowed with ordinary reason. It requires little knowledge of optics to be convinced that the simple unadulterated view of an object must enable us to look farther into its real texture, than we can see by any artificial arrangement whatever; it is like seeing an action performed instead of a scenic representation of it, or being informed of its occurrence by the most indisputable and accurate testimony.