Few accounts have survived detailing the techniques employed for the p
roduction of optical glass for astronomical and microscopical instrume
nts during the seventeenth century in Italy; the period during which t
he art was being developed in the shops of Eustachio Divini and Giusep
pe Campani, and other optical instrument-makers. Indeed, few of the to
ols of the lens-makers have been described in any detail, and few if a
ny have survived. Consequently, the discovery of a hitherto apparently
unknown Italian treatise, or what appears to have been notes for a sh
op manual of the period, is a contribution to present knowledge of len
s-making technology even though the identity and region of the author
remain unknown.