§ 2. THE ORIGINAL CUBIT MEASURE OF THE GIZEH GROUP.
Mr. J. J. Wild, in his letter to Lord Brougham written in 1850, called the base of Cephren seven seconds. I estimate the base of Cephren to be just seven thirtieths of the line DA. The line DA is therefore thirty seconds of the Earth's Polar circumference. The line DA is therefore 3033·118625 British feet, and the base of Cephren 707·727 British feet.
I applied a variety of Cubits but found none to work in without fractions on the beautiful set of natural dimensions which I had worked out for my plan. (See table of connected natural numbers.)
I ultimately arrived at a cubit as the ancient measure which I have called the R.B. cubit, because it closely resembles the Royal Babylonian Cubit of ·5131 metre, or 1·683399 British feet. The difference is 1/600 of a foot.
I arrived at the R.B. cubit in the following manner.
Taking the polar axis of the earth at five hundred million geometric inches, thirty seconds of the circumference will be 36361·02608—geometric inches, or 36397·4235 British inches, at nine hundred and ninety-nine to the thousand—and 3030·0855 geometric feet, or 3033·118625 British feet. Now dividing a second into sixty parts, there are 1800 R.B. cubits in the line DA; and the line DA being thirty seconds, measures 36397·4235 British inches, which divided by 1800 makes one of my cubits 20·2207908 British inches, or 1·685066 British feet. Similarly, 36361·02608 geometric inches divided by 1800 makes my cubit 20·20057 geometric inches in length. I have therefore defined this cubit as follows:—One R.B. cubit is equal to 20.2006 geo. inches, 20·2208 Brit. inches, and 1·685 Brit. feet.
I now construct the following table of measures.
| R. B. CUBITS. | PLETHRA OR SECONDS. | STADIA. | MINUTES. | DEGREES. |
| 60 | 1 | |||
| 360 | 6 | 1 | ||
| 3600 | 60 | 10 | 1 | |
| 216000 | 3600 | 600 | 60 | 1 |
| 77760000 | 1296000 | 216000 | 21600 | 360 |
Thus there are seventy-seven million, seven hundred and sixty thousand R.B. cubits, or two hundred and sixteen thousand stadia, to the Polar circumference of the earth.