n, and so many Objects cannot be view'd long enough
by them to be throughly examin'd; besides that, oftentimes the Weather
is so dark and cloudy, that for many dayes together nothing can be
view'd: And because also there are many Objects to be met with in the
night, which cannot so conveniently be kept perhaps till the day,
therefore to procure and cast a sufficient quantity of light on an
Object in the night, I thought of, and often used this, Expedient.

I procur'd me a small Pedestal, such as is describ'd in the fifth
Figure of the first _Scheme_ on the small Pillar AB, of which were two
movable Armes CD, which by means of the Screws EF, I could fix in any
part of the Pillar; on the undermost of these I plac'd a pretty large
Globe of Glass G, fill'd with exceeding clear Brine, stopt, inverted,
and fixt in the manner visible in the Figure; out of the side of which
Arm proceeded another Arm H, with many joynts; to the end of which was
fastned a deep plain _Convex glass_ I, which by means of this Arm could
be moved too and fro, and fixt in any posture. On the upper Arm was
placed a small Lamp K, which could be to mov'd upon the end of the Arm,
as to be set in a fit posture to give light through the Ball: By means
of this Instrument duly plac'd, as is exprest in the Figure, with the
small flame of a Lamp may be cast as great and convenient a light on
the Object as it will well indure; and being always constant, and to be
had at any time, I found most proper for drawing the representations of
those small Objects I had occasion to observe.

None of all which ways (though much beyond any other hitherto made use
of by any I know) do afford a sufficient help, but after a certain
degree of magnifying, they leave us again in the lurch. Hence it were
very desirable, that some way were thought of for making the
Object-glass of such a Figure as would conveniently bear a large
Aperture.

As for _Telescopes_, the only improvement they seem capable of, is the
increasing of their length; for the Object being remote, there is no
thought of giving it a greater light then it has; and therefore to augment
the. Aperture, the Glass must be ground of a very large sphere; for, by
that means, the longer the Glass be, the bigger aperture will it bear, if
the Glasses be of an equal goodness in their kind. Therefore a six will
indure a