20.628 " = 1 cubit of Memphis;

and Newton himself says, at p. 360, vol. ii. _Life at the Pyramids_,--

"The cubit of Memphis of 1.719 English feet,"
12
------
or 20.628 inches,

and, therefore, there can be no possible doubt but that this is Newton's
determination of the length of the cubit of Memphis.

But Newton goes on to say in the same page, the cubit "double the length
of 12-3/8 English inches (=24.75 inches) will be to the cubit of Memphis
as 6 to 5."

Therefore, if we add 1/5 to 20.628 inches,
4.126
------
we have 24.754

as Newton's determination of the length of the Sacred Cubit.

Newton's determinations are therefore--

Length of Sacred Cubit 24.754 inches.
" Cubit of Memphis 20.628 "

The cubit measured by Mersennus (_see_ p. 362, vol. ii. _Life at the
Pyramids_) was 23-1/4 Paris inches, and Mr. Greaves estimated the Paris
foot as equal to 1.068 of the English foot; therefore 23.25 +
1.068=24.831 was the length of this cubit, if we take Greaves'
proportion of the Paris to the English foot; but by the more exact
determination of the proportion of the Paris to the English foot made at
the Ordnance Survey Office, Southampton, it is found to be as 1 to
1.06576 and 23.25 + 1.06576=24.780 English inches, which differs only in
excess .026 from the length of the Sacred Cubit determined by Newton.

The double Royal Cubit of Karnak, which is in the British Museum, was
found by Sir Henry James to measure 41.398 inches; the length of the
single cubit was therefore 20.699 inches, and differs only in excess
.071 inches from the length of the cubit of Memphis, as determined by
Newton.

It will be observed that the lengths of the cubits derived by Newton
from the length of the King's chamber are shorter than the measured
lengths of the cubits which have come down to us. But if

we add 1/5 or = 4.140 to the length of the
Karnak cubit = 20.699,
------
we have 24.839 for the Sacred Cubit.

The one measured by Mersennus = 24.780 and the
------
mean of the two = 24.810, whilst the
length derived by Newton was = 24.754, showing