Of Monsieur Hevelius's promise of imparting to the world his invention of making optick glasses; and of the hopes given by Monsieur Hugens of Zulichem, to perform something of the like nature; as also of the expectations, conceived of some ingenious persons in England, to improve telescopes

Abstract

That eminent astronomer of Danzick, Monsieur Hevelius, writes to his correspondent in London, as followeth: What hath been done in the grinding of optick glasses in your parts, and how those beginnings, mention'd by you formerly, do continue and succeed, I very much covet to hear.