be ten times less,
and so of other Proportions. That is, the Mixture of the Rays in the
greater Figure PT will be to their Mixture in the less _pt_, as the
Latitude of the greater Figure is to the Latitude of the less. For the
Latitudes of these Figures are equal to the Diameters of their Circles.
And hence it easily follows, that the Mixture of the Rays in the
refracted Spectrum _pt_ is to the Mixture of the Rays in the direct and
immediate Light of the Sun, as the breadth of that Spectrum is to the
difference between the length and breadth of the same Spectrum.

So then, if we would diminish the Mixture of the Rays, we are to
diminish the Diameters of the Circles. Now these would be diminished if
the Sun's Diameter to which they answer could be made less than it is,
or (which comes to the same Purpose) if without Doors, at a great
distance from the Prism towards the Sun, some opake Body were placed,
with a round hole in the middle of it, to intercept all the Sun's Light,
excepting so much as coming from the middle of his Body could pass
through that Hole to the Prism. For so the Circles AG, BH, and the rest,
would not any longer answer to the whole Disque of the Sun, but only to
that Part of it which could be seen from the Prism through that Hole,
that it is to the apparent Magnitude of that Hole view'd from the Prism.
But that these Circles may answer more distinctly to that Hole, a Lens
is to be placed by the Prism to cast the Image of the Hole, (that is,
every one of the Circles AG, BH, &c.) distinctly upon the Paper at PT,
after such a manner, as by a Lens placed at a Window, the Species of
Objects abroad are cast distinctly upon a Paper within the Room, and the
rectilinear Sides of the oblong Solar Image in the fifth Experiment
became distinct without any Penumbra. If this be done, it will not be
necessary to place that Hole very far off, no not beyond the Window. And
therefore instead of that Hole, I used the Hole in the Window-shut, as
follows.

_Exper._ 11. In the Sun's Light let into my darken'd Chamber through a
small round Hole in my Window-shut, at about ten or twelve Feet from the
Window, I placed a Lens, by which the Image of the Hole might be
distinctly cast upon a Sheet of white Paper, placed at the distance of
six, eight, ten, or twelve Feet from the Lens. For, according to the
difference of the Lenses I used various distances, which I think not
worth the while to describe. Then immediately after the