686 PROF. C. p. SMYTH ON THE REPUTED METROLOGICAL SYSTEM 



construction above the coffer room, of the fraction representing the earth's mean 

 density,"^ I tried applying that to 50\ and got the contents of the coffer at once, 

 though in the form of being multiplied by 10. Striking off, however, one figure,— 

 so as to have the number of places of figures as given by the pure capacity 

 reduction, — then the precise value of the coffer's cubic contents in inches was 

 obtained, to at least this very close degree of approach, viz. : 



^' X 5-672 = 70,900 ; 



but 70,900 being Pyramid inches, must be increased to 



70,970-2 



in order to represent the same in English inches. The measured quantity, in the 

 same terms, it will be remembered, gave 70,982*4 ; but we shall now use the 

 theoretical determination of 70,9702 in preference. 



This then forms a definite raetrological quantity, derived thus simply from the 

 one ten-millionth of the earth's axis of rotation, influenced only by the combined 

 qualities of the earth's capacity power, and mean density, or weight-power ; and 

 has therefore eminent scientific recommendations for the grand standard of ca- 

 pacity and weight measures. 



(8.) Of what Weight "? 



The capacity of the coffer is already given at 70,9702 English cubic inches; 

 but what weight shall be assigned to it ? 



The best plan is, to fill the vessel of that given size, with pure water, and 

 weigh the contents. Now the Great Pyramid seems to have had in its normal 

 state a deep well penetrating down to lower strata, soaked with and filtering 

 the Nile water : while the so-called Queen's Chamber, with its peculiar depressed 

 floor and air-tight masonry, served as a reservoir at once large and conveniently 

 placed : water therefore could be had. But then, of what temperature would it 

 be ? for water alters its density rapidly on heating or cooling. 



The mere mention of this scientific requirement of modern times, seemed at 

 first to threaten ruin to the sufficiency of any arrangement descended from primeval 

 days of the world, to meet the exacting demands of present physical science ; but 



* The history of the experimental determination of the earth's mean density, is a very interesting^ 

 one, and its honours fall almost entirely to Great Bi'itain. It has been tried by the attraction of the 

 plumb line on mountains : by the effect on a pendulum at the top and bottom of a mine, and by the 

 '• Cavendish experiment," between the parts of a philosophical apparatus ; and has varied in the first 

 case from 4*5 to 5-4 ; in the second from 6 to 6-5 ; and in the last from 54 to 58 ; or in the latest, 

 and most perfect trial of it, by Francis Baily, from 568 to 5-66. His own published mean is 

 5-675, but uncorrected for some circumstances which he himself thinks should be corrected, and 

 which we have estimated, in accordance with his numerical indications, at — -003. — See further 

 at p. 699. 



