388 PROFESSOR C. PIAZZI SMYTH'S ACCOUNT OF 



to measure the angle contained between two adjacent base-sides of the Pyramid, 

 as defined by their sockets ; and found such angle to be equal to 90°, all but the small 

 quantity of 44" ; so small a quantity, that if produced by an error in the length 

 of the opposite side, such error could be only the 3-eWth part of the whole side. 



Proposition II. 



The next assumption has usually been, that the four sides or slopes of the 

 Great Pyramid incline towards the central vertical axis at equal angles. But 

 against such a belief, Dr Perry has recorded in his Travels, that every one can 

 see that each of the sides of the Pyramid inclines at a different angle, one 3°, 

 another 4°, and another even 8°, from its fellow. There was a memorandum 

 also handed to me before going out to the Pyramid, by a member of the Egyptian 

 Institute in Cairo, making, from recent observations, differences of as much as 4°. 



These differences, no doubt, arise to some extent from the present dilapidated 

 and worn state of the surface of the monument, all the ancient exterior of which 

 has been long since stripped off, and only the ruined courses of the mere internal 

 bulk of masonry remain. Yet, nevertheless, when I tried, after a familiarity of 

 some months with features and accidents of the Pyramid, to choose out stones 

 above and below, very little weathered, and measure between them, with better 

 instruments too than my predecessors had used, the difference of any two sides 

 was reduced to 18'. 



In the second place, the angles of elevation at the corners of the Pyramid 

 being measured from the exact stand-points given by the sockets cut in the rock, 

 the greatest difference of any one angle from another was found to be, on reducing 

 them all to one level, only 3'. 



And, in the third place, by looking about among the heaps of broken stones 

 on every side of the foot of the Pyramid, innumerable fragments of the ancient 

 casing stones were picked up ; and all which admitted of measure, proved to have 

 practically the same angle on whatever side of the Pyramid they were found. 



The nature of the casing stones of the Pyramid may be easily gathered from 

 the accompanying model. The great bulk of the Pyramid is constructed of coarse 

 masonry in rectangular steps, like these which form its present exterior ; but out- 

 side them a casing for the whole Pyramid was anciently laid on, thus, — first, one 

 or two layers of smooth, and comparatively small-sized, but well-cut rectangular 

 white stones ; and, finally, a layer, rectangular within, but beveled off outside, 

 at the general angle of the whole Pyramid. 



These stones were always laid in accurately horizontal courses ; and having 

 had a number of their veritable fragments recently inserted into a horizontal 

 section of this carefully constructed model of the theoretical Pyramid (App. II.), 

 no difference in the outer slope of each of the stones can be detected, as dependent 

 on the side of the original Pyramid, from which the specimen came. 



