John Robinson

John RobinsonIn existographies, John Robinson (1739-1805) (CR:3) was a British physicist, mathematician, and natural philosopher, noted for []

Overview
In 1797, Robinson, in his “Steam-Engine” article of Encyclopedia Britannica, supposedly gave the following illustration, in some form or another, of the Watt-Southern indicator diagram:

Robinson diagram

about which he commented the following:

“The accumulated pressure during the motion of the piston from EF to DC will be expressed by the area EFcDE and the pressure during the whole motion by the area ABFcDA. Now it is well known that the area EFcDE is equal to ABFE multiplied by the hyperbolic logarithm:

AD/AE = L AD/AE

and the whole area:

ABFcDA = ABFE (1 + L AD/AE)

It having been granted that FLc is a rectangular hyperbola.”

In commentary on this, Donald Cardwell (1971) points out that although this “remarkable analysis” soon came to be much-admired by contemporary writers on the steam engine, Robinson, as he commented in a letter to Watt, knew of Davies Gilbert’s earlier 1792 analysis of a similar nature.

Coulomb’s law
In 1769, Robinson announced that the balls of like electrical charges repel each other with a force that varies as the inverse-square of the distance between them; thus anticipating Coulomb's law (see: scale of things).

Watt
Robinson was a friend and associate of James Watt and published a number of summary articles on the specifics of Watt engine.

References
1. (a) Robinson, John. (1797). “Steam-Engine”, Encyclopedia of Britannica. Publisher.
(b) Rees, Abraham. (1819). The Cyclopedia, Volume 34 (§:“Steam-Engine”; quote, pg. #). Publisher.
2. (a) Robinson, John. (1797). “Letter to Watt”, Jul 22.
(b) Cardwell, Donald S.L. (1971). From Watt to Clausius: the Rise of Thermodynamics in the Early Industrial Age (pgs. 79-80). Cornell University Press.

Further reading
● Robinson, John. (1797). “Steam-Engine”, Encyclopedia of Britannica. Publisher.
● Robinson, John. (1818). The Articles Steam and Steam-Engines: Written for the Encyclopedia Britannica, by the Late John Robinson, with Notes and Additions by James Watt (§: Letter from Mr Watt to Dr Brewster on the History of the Steam Engine, pgs. iii; §: On Steam, pgs. 1-45; §: On the Steam Engine, pgs. 46-151; §: Appendix by Mr Watt, pgs. 152-80). Edinburgh: Murray.
● Robinson, John. (1822). A System of Mechanical Philosophy, Volume Two (notes: David Brewster) (quote, pg. 17). Edinburgh, 1822.

External links
John Robinson (physicist) – Wikipedia.

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