352 
Proceedings of the Royal Society 
principal head of the Ordnance Survey, may think that there is a 
new and very authoritative determination of the length of the 
base side of the Great Pyramid. But a little examination will soon 
show,— first, a slight inaccuracy; for 360 times 25 - 488, or 9175*68, 
is not th e precise equivalent of 9163 inches ; second , that it (9175 68) 
does not lie within the limits of any of the known socket measures 
of the Great Pyramid ; and third, that the derail of 25*488 British 
inches long, is not known to be an ancient Egyptian land measure. 
For on what does the alleged statement that it is such a measure 
depend? So far as I can ascertain, merely this: that Sir Henry 
James saw the length and name mentioned — in one of Weales’ 
rudimentary treatises giving the weights and measures of all 
nations for Is and 6d — as a modern Egyptian measure. But more im- 
portant works on modern Egypt, as Lane’s and "Wilkinson’s, do not 
acknowledge, so far as I can find, such a modern land measure, 
neither do they mention it as belonging to past history. While all 
of the works together, or Weales’ also as well as these last, agree 
that the standard national cubit of ancient Egypt was very near to 
20 7 British inches in length, or totally different from 25*488 of 
the same inches. 
Hence I am inclined to fall back after all on my former con- 
clusions from the Pyramid socket observers above stated ; or to 
believe that the true length of a mean side of the Great Pyramid, 
when properly measured under guidance of the 1, 2, and 3 of p. 340, 
will be found to lie within the limits of 9142 rfc 25 British 
inches : i.e. the present uncertainty is within of the whole. A 
large proportional error — compared to what it might be reduced to 
any day, if the Government were consenting to spend on the 
measures the merest fraction of what the surveying of this country 
costs them every year; but only a small proportional error — as con- 
trasted with what affected our knowledge of the Great Pyramid 100 
years ago ; and sufficiently limited to enable us to test, with con- 
siderable approach to sufficiency, several theories already before the 
world. 
SIZE OF THE EARTH. 
In the- course of my investigations into the nature and objects 
of the Great Pyramid, I have had — beginning with 1864— to com- 
