Peter Ewart

Peter EwartIn existographies, Peter Ewart (1767-1842) (CR:2) was British engineer, noted for []

Dalton | Atoms
In 1810, John Dalton had Ewart make him a set of wooden balls, shown below, of different sizes, that could be connected via metal pins and holes in each ball, so to demonstrate his newly "atomic theory": [1]

Dalton’s wooden ball atomic model

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Education
Ewart was trained by James Watt and Matthew Boulton, and was said to have been an adherent of the caloric theory of heat. [3]

Quotes | On
The following are quotes on Ewart:

“The question has long been agitated, whether mechanical force is to be measured by the mass multiplied into the velocity, or into the square of the velocity. The last of these opinions was adopted by Hooke and Huygens, in consequence of their observations on the motions of pendulums. It was also adopted by Smeaton, in consequence of his experiments on the mechanical action of water. Ewart supports the opinion of Smeaton with great force of reasoning. The essay is remarkable for the extensive knowledge of the subject which the author displays, and for the great perspicuity of his reasoning, which is the consequence of this extensive knowledge. He gives a number of examples, which he considers as inconsistent with the common notion, discusses these examples, and gives us a very full history of the opinions of mechanical writers on the subject.”
— Washington Irving (1814), The Analectic Magazine, Volume Three (pg. 352)

“My friend Ewart, at my suggestion, suggestion, made me a number of equal balls about an inch in diameter about thirty years ago; they have been in use ever since, I occasionally showing them to my pupils. One ball had 12 holes in it equidistant, and twelve pins were stuck in the other balls so as to arrange the 12 around the one and be in contact with it; they (the 12) were about 1/10th of an inch asunder. Another ball, with 8 equidistant holes in it; and they (the 8) were about 3/10th of an inch asunder, a regular series of equidistant atoms. I had no idea at the time that the atoms were all of a bulk, but for the sake of illustration I had them made alike.”
John Dalton (1842), “On the Analysis of Sugar” [2]

References
1. Imagining Atoms – Science and Industry Museum.
2. (a) Dalton, John. (1848). “On the Analysis of Sugar”. Publisher.
(b) Henry, William. (1854) Memoirs of the Life and Scientific Researches of John Dalton (equal balls, pg. 124). London: The Cavendish Society.
(c) Imagining Atoms – Science and Industry Museum.
3. Cardwell, Donald S.L. (1971). From Watt to Clausius: the Rise of Thermodynamics in the Early Industrial Age (Ewart, 16+ pgs; trained, pg. 162). Cornell University Press.

Further reading
● Ewart, Peter. (1813). “On the Measure of Moving Force” (abs), Memoirs of the Literary and Philosophical Society of Manchester, 2(2):105-258.

External links
Peter Ewart – Wikipedia.

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