OF THE GREAT PYRAMID. 



705 



The ell fits its bed tightly. The yard was not tried. 



Each bed is marked at both ends with the crown and letter E, the former device as close as 

 possible to the terminal edge of the I'ecess, in order, apparently, to denote that it is a standard at 

 that point. But the rudeness of the workmanship renders the beds quite valueless for such purposes. 



On the edge of the yard I'ecess there are very coarse divisions (filed probably), intended to 

 represent 12 inches (2 of which ai-e halved); the total 12 inches being 0-12 inch too long. 



Experiment 4. 



Queen Elizabeth's ell vvas laid on the horizontal comparator. One of its extremities was brought 

 into the same vertical plane with O of the comparator scale by means of two T squares, one placed 

 vertically against the ell, the other horizontally on division 0. The two adjacent edges of the 

 squares were then cautiously brought into contact by means of the longitudinal screw of the com- 

 parator. 



A T square was now laid horizontally to coincide with the 36 inch division of the comparator, 

 and a fine line drawn on the ell with a steel point. [I have used the word " horizontal," in 

 speaking of the position of the T squares, for simplicity's sake. The divisions of the comparator 

 are in truth cut on a plane inclined about 20° to the horizon. One surface of the ell was brought 

 into the same plane by means of the two wooden angular supports on which it rested.] 



There now remained to be determined the value of the nominal 9 inches contained between the 

 line drawn (as above) on the eil and its extremity. 



A piece of brass, prepared for the purpose, had a fine line di'awn across it near one end. This 



piece of brass was tied edgeways along the marked side of the ell ; in section, thus 



Ell 



The 



line on the piece of brass was brought, with a magnifier, into as exact coincidence as possible with 

 the line on the ell. A T square was now applied to the end of the ell, and a fine line drawn across 

 the piece of brass with a steel point. The following diagram will perhaps help to explain the 

 arrangement : 



Ell 



•3 S 



<r 



The two lines on the piece of brass may now be taken to represent the nominal 9 inches bv 

 which the ell exceeds the yard of the compai*ator. The value of this space is a matter of future 

 determination. There are longitudinal lines on the brass, and the measure is to be taken between 

 those marked with crosses, thus 











X 



> 



X 













The T squares used were obtained from Messrs Hotzapffel, expressly for the purpose, and were 

 of excellent workmanship, appreciably correct. 



