Accession No


Brief Description

Piazzi-Smyth’s great pyramid measure, by Charles Piazzi-Smyth, Egyptian, 1865: piece of basalt marked with 5-inch standard; and wooden standard rule, by Bryson, Scottish, 1881, made from the original template


Egypt; Giza; and Scotland; Edinburgh


Piazzi-Smyth, Charles [basalt standard] Adie and Son [thermometers] Bryson [wooden standard]


weights & measures; metrology

Earliest Date

Jan. 1, 1865

Latest Date

Dec. 31, 1881

Inscription Date


metal (brass, white metal, mercury); wood (mahogany, boxwood); stone (basalt); glass


box for original: length 342mm; breadth 174mm; height 85mm wooden standard length 126mm; breadth 25mm; thickness 7mm

Special Collection


Donation in 1952.


‘5-inch standard at Great
Pyramid 1865, C.P.S’ (scratched on stone)
‘ADIE & SON EDINBURGH’ (thermometers)
‘BRYSON EDINBURGH 1881’ (back of wooden standard)

Description Notes

Charles Piazzi-Smyth’s great pyramid measure, 1865: piece of basalt marked with 5-inch standard; and wooden standard rule, by Bryson, 1881, made from the original template.

Mahogany(?) box containing two mercury-in-glass thermometers (by Adie & Son) and a piece of basalt set in the centre (on wooden stand) on which is engraved the original Five-Inch standard which Piazzi Smyth marked down on his visit to the Pyramids of Giza. Basalt is engraved with “5-inch standard at Great Pyramid 1865, C.P.S”. Box has brass hinges and handles; the lid is missing.

Separate wooden standard rule, marked 1155.1, inscribed “Bryson Edinburgh 1881”. One edge of rule has 5 inch scale divided [0] - 5, numbered by 1; 1st, 3rd and 5th inches divided to 0.1; 2nd and 4th divied to 0.05. Other edge has single inch marked and divided to 0.1 inches. Inscription on centre of standard: ‘5 Great Pyramid Inches = one fifth of the Sacred Cubit of Ancient Israel = 5.005 mod British Inches = one 50 millionth of the Earth’s semi-axis of rotation or distance from Center to either Pole’ and ‘1 G.P. inch = one 500 millionth of Earth’s Axis of Rotation or dist. from Pole to Pole’.

Condition good; incomplete (lid missing from box).


Joshua Nall; ‘Charles Piazzi Smyth and His Imperial Measures’; Explore Whipple Collections online article; Whipple Museum of the History of Science; University of Cambridge; 2020:


When Charles Piazzi-Smyth (1819–1900) travelled to the Great Pyramid of Giza in 1864–65, he intended to measure the Pyramid according to a system of linear measurement that would settle the debate regarding the structure’s true size. When Piazzi-Smith’s intended measuring system failed, he improvised with the construction of this object now held in the Whipple Museum. Based on a piece of basalt found in Egypt, Piazzi-Smyth created a 5-inch standard that enabled him to accurately measure the Great Pyramid. A measurement standard, such as Piazzi-Smyth’s, provides a common benchmark of length for conducting measures. It was Piazzi-Smyth’s hope that his measurements would demonstrate the use of divine units in the construction of these ancient monuments, and that these divine units would prove to be the origins of British (’imperial’) units of length and volume.
Created by: Allison Ksiazkiewicz on 05/11/2013


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