(203)
mention'd from him in Numb. 4 pag. 67, of these Transactions.
Prepare (saith he) two Glasses, the one exactly flat on both sides, the other flat on the one side, and convex on the other, of what Sphere you please. Let the flat Glass be a little broader than the other. Then let there be made a Cell or Ring of Brass, very exactly turn'd, into which these two Glasses may be so fastned with Cement, that the plain surfaces of them may lye exactly paralell, and that the Convex-side of the Plano-convex-Glass may lye inward; but so, as not to touch the flat of the other Glass. These being cemented into the Ring very closely about the edges, by a small hole in the side of the Brass-ring or Cell, fill the interposed space between these two with Water, Oyl of Turpentine, Spirit of Wine, Salme Liquors, &c; then stop the hole with a screw; and according to the differing refraction of the interposed Liquors, so shall the Focus of this compound Glass be longer or shorter.
But this (adds the Proposer) I would only have look't upon, as one instance of many (for there may be others) of the Possibility of making a Glass, ground in a smaller Sphere, to constitute a Telescope of a much greater length: Though (not to raise too great exspectation) I must add, That of Spherical object glasses, those are the best, which are made of the greatest Sphere, and whose substance hath the greatest refraction.
Observations
About Shining Worms in Oysters.
.
These Observations occur in the French journal of April 12. 1666. in two letters, written by M. Auzout to M. Dela Voye; whereof the substance may be reduced to the following particulars.
1.That M. Dela Voye having observed, as he thought,
