be made to
refract the Rayes of light to a _Focus_ of a far greater distance, than is
usual._

This is proposed by Mr. _Hook_, in consequence of what was {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 fastened 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_, _Saline Liquors_, _&c;_ then stop the hole with a screw:
and according to the differing refraction of the interposed Liquors, so
shall the _Focus_ of the 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, {204} some shining
Worms in Oysters; M. _Auzout_, being made acquainted with it, did first
conceive, they were not Worms (unless they were crushed ones) that shin'd,
as having not been able then to discern any parts of a Worm; but only some
shining clammy moysture; which appeared indeed like a little Star of a
blewish colour, and stuck to the Oyster-shell; being drawn out, shone in
the Air its whole length (which was about four or five lines,) and when put
upon the _Observers_ hand, continued to shine there for some ti