Among the earlier workers in the first decade of this century will be found the name of Bernardo Marzoni, who was curator of the Physical Laboratory of the Lyceum of Brescia. He, an amateur optician, it has come to light, in 1808 constructed an achromatic objective, and exhibited it at Milan in 1811, when he obtained the award of a silver medal for its merits, under the authority of the “Institute Reale delli Scienzo.” Through the good offices of the late Mr. John Mayall one of Marzoni’s objectives, which had been carefully preserved, was presented to the Royal Microscopical Society of London in 1890.[20] This objective is a cemented combination, with the plane side of the flint-lens presented to the object. This was an improvement of a practical kind, and of which Chevalier subsequently availed himself. In 1823 Selligue, a French optician, is credited with having first suggested the plan of combining two, three, or four plano-convex achromatic doublets of similar foci, one above the other, to increase the power and the aperture of the microscope. Fresnel, who reported upon this invention, preferred on the whole Adam’s arrangement, because it gave a larger field. Selligue subsequently improved his objective by placing a small diaphragm between the mirror and the object. In this country, Tully was induced by Dr. Goring to work at the achromatic objective, and his first efforts were attended with a success quite equal to that of Chevalier’s. Lister on examining these lenses said:--“The French optician knows nothing of the value of aperture, but he has shown us that fine performance is not confined to triple objectives.” Amici, the amateur optician of Modena, visited this country in 1827 and brought his achromatic microscope and objectives, which were seen to give increase of aperture by combining doublets with triplets. The most lasting improvement in the achromatic objective was that of Joseph Jackson Lister, F.R.S., the father of Lord Lister, and one of the founders of the Royal Microscopical Society of London. Lister’s discoveries at this period (1829) in the history of the optics of the microscope were of greater importance than they have been represented to be. That he was an enthusiast is manifest, for, being unable to find an optician to carry out his formula for grinding lenses, he at once set to work to grind his own, and in a short time was able to make a lens which was said to be the best of the day.