Lately, Sir Henry James, the distinguished head of the Ordnance Survey Department, has shown that the length of one of the sides of the pyramid base, with the casing stones added, as measured by Colonel H. Vyse--viz. 9168 inches--is precisely 360 derahs, or land cubits of Egypt; the derah being an ancient land measure still in use, of the length of nearly 25-1/2 British inches, or, more correctly, of 25.488 inches; and he has pointed out that in the construction of the body of the Great Pyramid, the architect built 10 feet or 10 cubits of horizontal length for every 9 feet or 9 cubits of vertical height; while in the construction of the inclined passages the proportion was adhered to of 9 on the incline to 4 in vertical height, rules which would altogether simplify the building of such a structure.[254] The Egyptian derah of 25.48 inches is practically one-fourth more in length than the old cubit of the city of Memphis. Long ago Sir Isaac Newton showed, from Professor Greaves' measurements of the chambers, galleries, etc., that the Memphis cubit (or cubit of "ancient Egypt generally") of 1.719 English feet,[255] or 20.628 English inches, was apparently the _working_ cubit of the masons in constructing the Great Pyramid[256]--an opinion so far admitted more lately by both Messrs Taylor and Smyth; "the length" (says Professor Smyth) "of the cubit employed by the masons engaged in the Great Pyramid building, or that of the ancient city of Memphis," being, he thinks, on an average taken from various parts in the interior of the building, 20.73 British inches.[257] According to Mr. Inglis' late measurement of the four bases of the pyramid, after its four corner sockets were exposed, the length of each base line was possibly 442 Memphis cubits, or 9117 English inches; or, if the greater length of the French Academicians, Colonel Vyse, and Mahmoud Bey, be held nearer the truth, 444 Memphis cubits, or 9158 British inches. But Professor Smyth tries to show that (1.) if 9142 only be granted to him as the possible base line of the pyramid; and (2.) if 25 pyramidal inches be allowed to be the length of the "Sacred Cubit," as revealed to the Israelites (and as revealed in the pyramid), then the base line might be found very near a multiple of this cubit by the days of the year,[258] or by 365.25; for these two numbers multiplied together amount to 9131 "pyramidal" inches, or 9140 British inches--the British inch being held, as already stated, to be 1000th less than the pyramidal inch. Was, however, the "Sacred Cubit"--upon whose alleged length of 25 "pyramidal" inches this idea is entirely built--really a measure of this length? In this matter--the most important and vital of all for his whole linear hypothesis--Professor Smyth seems to have fallen into errors which entirely upset all the calculations and inferences founded by him upon it. * * * * *