The mean of the only four series of such socket or casing stone measures as have been recorded hitherto by the French Academicians (9163), Vyse (9168), Mahmoud Bey (9162), and Inglis (9110), amounts to nearly 9150. The first three of these observers were only able to measure the north side of the pyramid. Mr. Inglis measured all the four sides, and found them respectively 9120, 9114, 9102, and 9102, making a difference of 18 inches between the shortest and longest. Professor Smyth thinks the measures of Mr. Inglis as on the whole probably too _small_, and he takes two of them, 9114 and 9102--(but, strangely, not the largest, 9120)--as data, and strikes a new number out of these two, and out of the three previous measures of the French Academicians, Vyse, and Mahmoud Bey; from these five quantities making a calculation of "means," and electing 9142 as the proper measure of the basis line of the pyramid--(which exact measure certainly none of its many measurers ever yet found it to be); and upon this _foundation_, "derived" (to use his own words) "from the best modern measures yet made," he proceeds to reason, "as the happy, useful, and perfect representation of 9142," and the great standard for linear measure revealed to man in the Great Pyramid. Surely it is a remarkably strange _standard_ of linear measure that can only be thus elicited and developed--not by direct measurement but by indirect logic; and regarding the exact and precise length of which there is as yet no kind of reliable and accurate certainty.