(sof) 
mention'd from him : in 'Numb, 4 fag.tr, of fh dcTrmfiib^ 
@?l Prepare (faith fa) two GlafTes, the one exactly Hat on both 
£des the other fiat on the one fide, and convex on the otheiy 
©f what Sphere you pleafe. Let the fiat Glafs be a little broa~. 
der than the other. Then let there be made a Ceil or Rsng. 
of Brafs very exa&ly turn'd, into which thefe two Glafles 
may be Vo faftned with Cement, that the plain furfaces of 
them may lye exa&ly paralelh and that the Convex- fide of the 
Plano-convex- Glafs may lye inward ; but io, as not to touch 
the flat of the other Glafs. h hefe being cemented into ^the 
Rino- very clofely about the edges, by a imaii hole in the fide 
of the Brafs- ring or Cell, fill the interpofed fpace between- 
thefe two with Water, Qyl of Turpentine , Spirit of Wine, Salim 
Liquors , f£e ; then flop the hole with a fcrew : and accord- 
ing to the differing reira&ion of the interpofed Liquors, 
fo fhall the Focus of this compound Glafs be longer or flior^ 
tcr» * 
But this ( adds the Fropofer ) I would only have look £ upon, 
as- one in fiance of many ( for there may be others; of the. 
Feflibilky of making, a Glafs, ground in a fmaller Sphere, to 
Conftitute a Iddcopeof a. much greater length: Though, 
f not to raife too great exfpedtation ) I mu ft add * That or 
Stberical objed glaffes, thofeare the beft, which are made, of , 
the grdateft Sphere, and. whole fubftance hath the greatest; 
refra&dom • ■ / 
Ohfervations 
About SHning Worms in Oyfters, 
Tliefe Obfervations occur in the French journal or April 1 2^, 
1666. in two letters, written- by M. Atqont to M. Dela : - 
Voye 5 whereof the, fubftance may be reduced to the follo wing: 
particular 
4 That M. Dela Voye having obferved , as be thought 
feme,: 
