Water-immersion was introduced by Amici in 1840, and was improved by E.
C. par Theodore Parrhase (Amsterdam, 1699); and Vita et opera ad annum Mdccxi., amici ejus opusculum, philosophicis Clerici operibus subjiciendum, also attributed to himself.
He used chiefly a highly curved piano-convex front lens, which has since always been employed in strong systems. Even if the object-point on the axis cannot be reproduced quite free from aberration through such a lens, because aberrations of the type of an under-correction have been produced by the first plane outer limiting surface, yet the defects with the strong refraction are relatively small and can be well compensated by other systems. Amici chiefly employed cemented pairs of lenses consisting of a plano-convex flint lens and a biconvex crown lens(fig.
For this reason Amici constructed objectives of a similar aperture and focus for different thicknesses of glass covers.
The reversion to the Roman communion of his old friend Crotus led to his mordant Responsio amici (1532, anon.) to the Apologia (1531) of Crotus.
GIOVANNI BATTISTA AMICI (1786-1863), Italian astronomer and microscopist, was born on the 25th of March 1786 at Modena.
The Tractatus consolatorius pro morte amici and the Liber de eruditione filiorurn regalium (dedicated to Queen Margaret) were printed at Basel in December 1480.