Description of the series of microscopic lenses developed by Giovanni Battista Amici, by Achille Brachet Paper signed and in Brachet's hand. Description accompanying a series of missing illutrations of the achromatic lenses, series 3 and 6, as well as description of Amici's immersion technique which used droplets of distilled water as additional magnification. Brachet, a collector, commissioned a microscope and series of objectives from Amici in 1852 and received the instrument in 1853, this description of the optical apparatus uses the water immersion rather than oil, which would indicate that the paper was written before 1856. 1850s