Benjamin Robins

Benjamin Robins (1707-1751)

From Wikipedia: See Wikipedia entry for additional information: Benjamin Robins (1707-1751) was born in Bath of poor Quaker parents. He moved to London and taught mathematics, but soon devoted himself to engineering and the study of fortification. He carried out an extensive series of experiments in gunnery, embodying his results in his famous treatise on 'New Principles of Gunnery' (1742). He also conducted important experiments on the air resistance of projectiles, and on the force of gunpowder. He compared the results of his theory with experimental determinations of the ranges of mortars and cannon, and gave practical maxims for the management of artillery. He also made observations on the flight of rockets, and wrote on the advantages of rifled gun barrels. His work on gunnery was translated into German by Leonhard Euler, who added a critical commentary of his own. In 1749, he was appointed Engineer General to the East India Company, and went out to superintend the reconstruction of their forts. However, his health soon failed, and he died at Fort St David in India.

A more detailed biography is available online. We learn that his parents were John Robins (1666-1758) and Sarah Broughton, who married in 1700. John Robins was a tailor. After Benjamin gave up teaching and became an engineer, he constructed bridges, mills and harbours, made rivers navigable and drained fen land. He began to study gunnery and fortifications, and travelled through Flanders to study fortification work there. In addition to his 'New Principles of Gunnery' being translated into German by Euler, it was also translated into French by Le Roy at the request of the Académie des Sciences.

Robins is credited with inventing the 'whirling arm', used for experiments on aerofoils. In his ballistics studies, he predicted the velocity of sound in air, and established a method of measuring the velocity of projectiles on impact (ballistic pendulum). He also discovered what was to become known as the sound barrier.

In 1761 James Wilson MD published Robins's 'Mathematical Tracts of the Late Benjamin Robins' in two volumes, Vol 1 'Containing his NEW PRINCIPLES OF GUNNERY with several subsequent DISCOURSES on the same subject'. Robins clearly described his theories and experiments in great detail. For example, he discussed the 'nature and advantage of rifled barrel pieces' in Volume 1, observing that despite rifled barrels having long been used in Germany and Switzerland, he was unaware of any valid explanation having previously been offered to correctly account for the superior accuracy obtainable with rifled barrels.

Paul Gille notes that Robins observed the drift of projectiles and ascribed it to friction in the gun's barrel imparting spin to the projectile, from which he inferred that improved shooting accuracy would require the use of rifled barrels and elongated projectiles instead of balls. Gille also notes that the physicist Leonhard Euler dismissed Robins's theory about drift. Euler's prestige was such that Robins's ideas were neglected, and a century passed before experiments confirmed that Robins's findings were correct.

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