of the Knives measured from the point of their concourse to
the distance of the edges of the Knives at the end of that Length, and
so is the fifth Part of an Inch to the 160th Part. So then the dark
Lines above-mention'd meet in the middle of the Light which passes
between the Knives where they are distant the 160th Part of an Inch, and
the one half of that Light passes by the edge of one Knife at a distance
not greater than the 320th Part of an Inch, and falling upon the Paper
makes the Fringes of the Shadow of that Knife, and the other half passes
by the edge of the other Knife, at a distance not greater than the 320th
Part of an Inch, and falling upon the Paper makes the Fringes of the
Shadow of the other Knife. But if the Paper be held at a distance from
the Knives greater than the third Part of an Inch, the dark Lines
above-mention'd meet at a greater distance than the fifth Part of an
Inch from the end of the Light which passed between the Knives at the
concourse of their edges; and therefore the Light which falls upon the
Paper where those dark Lines meet passes between the Knives where the
edges are distant above the 160th part of an Inch.

For at another time, when the two Knives were distant eight Feet and
five Inches from the little hole in the Window, made with a small Pin as
above, the Light which fell upon the Paper where the aforesaid dark
lines met, passed between the Knives, where the distance between their
edges was as in the following Table, when the distance of the Paper from
the Knives was also as follows.

-----------------------------+------------------------------
| Distances between the edges
Distances of the Paper | of the Knives in millesimal
from the Knives in Inches. | parts of an Inch.
-----------------------------+------------------------------
1-1/2. | 0'012
3-1/3. | 0'020
8-3/5. | 0'034
32. | 0'057
96. | 0'081
131. | 0'087
_____________________________|______________________________

And hence I gather, that the Light which makes the Fringes upon the
Paper is not the same Light at all distances of the Paper from the
Knives, but when the Paper is held near the Knives, the Fringes are made
by Light which passes by the edges of the Kniv