422 
Proceedings of the Royal Society 
Monday , 17 th April 1871. 
The Hon. LORD NEAVES, Vice-President, in the Chair. 
The following Communications were read : — 
1. Notes on the Antechamber of the Great Pyramid. Based 
on the Measures contained in vol. ii. “ Life and Work 
at the Great Pyramid,’’ by C. Piazzi Smyth. By Captain 
Tracey, R.A. Communicated by St John Vincent Day, 
Esq., C.E., F.R.S.E. 
In considering the authority for the division of the sacred cubit 
into 25 inches, we have, first, the architectural fact that the, 
Queen’s chamber, containing the visible expression of that cubit, 
stands in or upon the 25th course of masonry, comprising the whole 
Pyramid. And here, though not strictly bearing on the case, may 
be mentioned a connection between the lengths of the two pas- 
sages (the first ascending, and the horizontal passages) leading to 
that chamber, remarkable when expressed in inches, of which 25 
make a cubit. 
Thus, the length of the first ascending passage from the axis of 
descending passage to north wall of Grand Gallery (see p. 54, 
v. ii., L. and W.)* = 15444 B. I., or 1542-9 inches, of which 25 
make a sacred or Pyramid cubit, and which for the future we will 
term “Pyramid inches.” 
Now, this length of 1542-9 P. I. — 25 = 1517*9 P. I. — is the 
exact length of the horizontal passage from north wall of the 
Grand Gallery to the north wall of the Queen’s Chamber — 
E.g ., length of horizontal gallery (see ) ^ ^ ^ 
p. 57, v. ii., L. and W., last line), J 
1-5 
1517*9 P. I. 
* In this paper the following abbreviations are used: “ L. and W.,” for 
‘ Life and Work at the Great Pyramid ; ” B. I. = “ British Inches ; ” P. I. 
— “ Pyramid Inches ” Pyramid Inch= British Inch x 1001. 
