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XIII. Results of the Comparisons of the Standards of Length of England , Austria , 
Spain, United States, Cape of Good Hope, and of a second Russian Standard, made 
at the Ordnance Survey Office, Southampton. By Lieutenant-Colonel A. II. Clarke, 
C.B., R.E., F.R.S., &c., under the direction of Major-General Sir Henry James, 
R.E., F.R.S., Ac., Director-General of the Ordnance Survey. With a Preface and 
Notes on the Greek and Egyptian Measures of Length by Sir Henry James. 
Received May 21, — Read June 19, 1873. 
The following account of the results of the Comparisons of the Standards of Length of 
England, Austria, Spain, United States, Cape of Good Hope, and of a second Russian 
Standard at the Ordnance Survey Office has been drawn up by Lieutenant-Colonel 
Clarke, and is a sequel to the abstract of the results of the Comparisons of the Standards 
of Length of England, France, Belgium, Prussia, Russia, India, and Australia which the 
Royal Society has done us the honour to publish in the Philosophical Transactions for 
1867, vol. clvii. p. 161. 
The accurate determination of the lengths of the various standards employed by so 
many nations in the measure of the bases of their triangulations, which are now being 
united into one vast network of triangles, covering the whole of Europe, can scarcely 
fail to be of great importance for the advancement of physical science. To the compa- 
rison of these lengths I have added the result of our endeavours to recover the correct 
lengths of the most ancient measures of length with which we are acquainted, viz. those 
of Ancient Egypt, not only because our own measures are obviously derived from them, 
but also because we thus obtain the accurate relative value of the measures and distances 
given in the most ancient works on Astronomy and Geodesy which have come down to us. 
The Ancient Egyptians employed two measures of length, viz. the common and the 
royal cubits. 
1st. As regards the common cubit, we have the statement of Herodotus that the 
Egyptian cubit was equal to the Greek cubit, “ that of Samos and we learn from the 
measurements of the Hecatompedon at Athens, by Mr. Penrose, that the Greek foot 
was equal to 1-013 foot, or 12-156 inches, and consequently the Greek cubit was equal 
to 1-520 foot, or 18-240 inches. 
2nd. The most recent measures of the base of the First or Great Pyramid, that of 
King Ci-ieops, viz. those made by the Royal Engineers and Mr. Inglis, a civil engineer, 
give a mean length of 9120 inches, or 500 cubits of 18*240 inches for the side of the 
square base, or 750 Egyptian feet, each Egyptian foot being equal to 1"013 English foot. 
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