[The production of optical glass in France and the experiences of Ruggiero Boscovich for the production of lead glass (Part One)].

The experiences that in 1758 led John Dollond to create the first achromatic telescope highlighted the serious difficulties related to the production of lenses with a correction for chromatic aberration. These difficulties were due to the lack of suitable tools for measuring the refraction index and for verifying the curvatures of the lenses of such optical instruments. To this was added what was perhaps the greatest difficulty: i.e., that of acquiring the kinds of glass, the so-called "common" (crown) glass and "lead" (flint) glass, of which the lenses had to be made. If the theoretical works of Alexis Clairaut, of Samuel Klingenstierna, and of Ruggiero Boscovich furnished the theoretical basis for producing such lenses, and subsequently--after Boscovich's discovery of the role of the eyepieces--for creating also achromatic eyepieces, the greatest challenge from the practical point of view was that of the availability of the flint glass. In this first part of the article there is then a study of the numerous attempts and directions pursued by Clairaut and his valid collaborators--Anthéaulme, George father and son, Charles François de l'Etang, and Claude Siméon Passemant--in order to find common glass and lead glass, and to produce the first achromatic lenses and binoculars in France. An analysis follows of the experiences conducted by Boscovich, first in Vienna, and then in Milan and Venice-Murano, addressed to the production of flint glass.