RECENT MEASURES AT THE GREAT PYRAMID. 389 



Proposition III. 



Our third proposition is to the effect that the angle of elevation of any one of 

 the sides of the Great Pyramid is 51° 51' 14" 3. This quantity was affirmed by 

 the late venerable John Taylor of London, founding on Colonel Howard Vyse's 

 measures of his two colossal casing stones in situ. Most important too is John 

 Taylor's statement, if proved to be real; for on possessing that precise angle, 

 and that only amongst any number of possible angles, depends the power of the 

 Pyramid to symbolize by its height and length of perimeter of base, one of the 

 most radical and important truths in both pure and applied science, viz., the 

 proportion of radius to circumference in a circle. 



But that angle for the Pyramid, though derived from good measures, has by 

 no means been allowed to stand unchallenged either by observers, or theorists ; 

 one of the very greatest of whom, the late eminent Baron Bunsen, insists on 

 51° 20' 25" being the true quantity, because it results from a favourite hypothesis 

 about the employment of the profane Egyptian cubit. 



I beg therefore to report from my practical proceedings, — 



First, That the mean of many measures on all the present sides of the Pyra- 

 mid, dilapidated though they be, amounts to 51° 49' nearly. 



Second, The mean of the angles of nineteen fragments of casing stones, many 

 of which you see before you, gave, on being carefully measured, 51° 54'. 



Third, The angles of the corner lines of the Pyramid being measured from the 

 sockets, and reduced to the equivalent angle of the sides, give, with an assumed 

 probable thickness of the ancient casing near the top of the Pyramid, — the measures 

 too having been taken with the large Playfair altitude azimuth instrument, — 

 give 51° 51'. 



And, fourth, There is a completely different and a new testimony to be referred 

 to, the azimuth trenches. (See Plate XXVII.) 



These are long and deep pits cut in the solid limestone of the hill, with 

 hammer and chisel, on the eastern side of the Great Pyramid ; and there is 

 nothing analogous to them about any other of its sides, or indeed any side of any 

 other Pyramid. 



Speculation has been various on these trenches ; men of architectural turn of 

 mind have pronounced them the pits in which the mortar was mixed at the 

 building of the Pyramid, and others of Egyptological pursuits have declared them 

 tombs. To myself, however, they gave so eminently the impression of a laying 

 out of angles before the erection of the Pyramid, that I set to work with the 

 powerful discrimination of the large altitude azimuth circle to ascertain what 

 the angles were. 



Placing the instrument therefore at the very remarkable general converging 

 point, it was first ascertained, and through agency of the Pole star again, that 



VOL. XXIV. PART II. 5 N 



