Extremely rare association copy (1898)

BAZIN, Henri-Émile

Étude d'une nouvelle formule pour calculer le débit des canaux découverts.

Published: Paris, P. Vicq-Dunod et Cie

Date: 1898

8vo (252 × 165 mm), pp. 55, [1, blank]; one folding engraved plate printed in black and red; pp. 46-55 containing an appendix with 9 printed tables; text crisp, slightly toned; ink inscription to half-title; bound in three-quarter morocco over pebble grained blue cloth boards, corners slightly bumped, else near fine.

William Cawthorne Unwin (1838-1933) 'After receiving a bachelor degree, Unwin became professor of engineering at the Central Technical College, London (1884-1904). In 1868 he became an instructor at the Royal School of Naval Architecture and Marine Engineering, Kensington (1872), later professor of hydraulic engineering at the Royal Indian Engineering College.' (Bibliotheca Mechanica, p. 332)

See Rouse & Ince, History of hydraulics, pp. 172-179. Not in Bibliotheca Mechanica; the European Library shows one copy in the BN Paris; OCLC adds Iowa University.

Extremly rare original offprint from the Annales des Ponts et Chaussées, 4, 1897, inscribed by the author to William Cawthorne Unwin (1838-1933), then professor of civil and mechanical engineering at the City and Guilds College. ‘The son of a professor at Nancy, Bazin [1829-1917] attended the Polytechnique and entered the Corps des Ponts et Chausées in 1848. He was sent to Dijon in 1854, where he met Darcy, who assigned him to hydraulic experiments until 1863. He was engineer-in-chief from 1875, when he took overall responsibility for the canal de Bourgogne, becoming inspector general of the corps in 1886 and sitting on its general council. He was also a corresponding member of the Académie from 1900 and a non-resident member from 1913. 'An innovator and experimenter of the first order in his field, for half a century no course in applied mathematics was taught either in France or abroad, which did not contain his formulas. He discovered and explained the fact that in open channels the maximum speed of the current often occurs below the surface of the water. He also explained the action of tide in a river and explained the phenomenon known as mascaret (tidal wave in an estuary).' (Bibliotheca Mechanica, p. 26) The work offered here presents the results of Bazin's long studies in open-channel flow begun in 1865. His '1865 treatise on open-channel flow contained a wealth of new information, presented in a lucid style completely at variance with his notoriously timid manner of speaking. The tests had been conducted in canals of cement, wood, brick, gravel, and rock, with rectangular, trapezoidal, and semi-circular cross sections. For conditions of uniform flow it was known that – as in Darcy's pipe tests – the resistance depended not only upon the type of boundary but also upon the relative size of cross-section. In fact, whereas the Prony formula indicated that RS = (a + b/V) V2 according to the Darcy-Bazin data this had to have the form RS = (a + b/R) V2 which, with variation in the two coefficiants according to boundary material, gave results ranging from half to twice those of Prony's accepted formula.' (Rouse & Ince, History of hydraulics, pp. 173-174)

Near fine

Half morocco