cm . 
and that of Septaiius muffc. fcatter them in the cotnpafs of 
three Inches. Some here do intend to make of them, yea 
and bigger ones 5 but we muft ftay till they be done s &c. 
• ;i -■ ■ - . '■ ■ ; " j • ■ 
Of Monfienr HeveliusY Fromife of imparting to 
the World his Invention of making Optick 
GlaiTes j and of the hopes given by Monjieur 
Hagens of Z^alicbem, to perform fame thing of 
the lih^e nature 5 as alf 0 of the Expectations 5 
conceived of f owe Ingenious Ferfonsin England^ 
to improve Telefcopes, 
That eminent Aftronome’r o £ D;mtz?ck 0 Monfieur Heve- 
litiS) writes to his Correspondent in London 3 as followeth : 
What hath been done in the grinding of .Optick glades 
in your parts, and how thofe beginnings, mention’d by 
you formerly, do continue and fucceed, I very much covet 
to hear. Tis now above ten Years, fince I mydelf invent- 
ed a peculiar nay of grinding fuch Glades, and reduced it 
alfointo pra&ife , by which ’tiseafie, without any consider- 
able danger of failing, to make and : pollifh Optick glades of 
any Conick, Se&ion, and that (which is moft notable) in any 
dim of any Se&ion of a sphere : which invention t have as 
yet difeovered to none, my purpofe being, for the Improve- 
ment of Natural Knowledge, to deferibe the whole me- 
thod thereof in my Celeflial Machine^ and to propole it to 
the Examination and Judgement of the Royd Society ^ not 
doubting at all, but they will finds the way true and pra- 
cticable, my felf having already made feveral Glades by it,, 
which many Learned Men have feen and tryed, 
Monfieur Bugem^ inquiring alfo in a Letter, newly writ- 
ten by him to a Friend of his in E ngUnd 9 of the fuccefs of 
the attempts made by an Ingenious EngliJIo Man for perfect- 
ing inch ffiaffe, gad urging the profession of the fame, 
fo 
