Cellular Respiration Mammals Heat

Engineer Bridges and causeways

Purchased earlier in this book in a bookseller promising title: Viaduct Erdre. Treaty practice for construction of steel bridges arched by Mr. Ch. Dupuy, Chief Engineer of Roads and Bridges in charge of the Company's service of Orleans, with the assistance of Mr. Stephen Lauras, civil engineer, alumnus of Central School, assistant engineer at the Orleans Company, Paris, Dunod Publisher, 1879.

Save the date: 1879, three years before the commencement of construction of the viaduct Garabit by Gustave Eiffel. We caught the monumental work of someone who represents the engineer-hero of the late nineteenth century rather than the obscure MM calculations. Dupuy and Lauras. It is true that the viaduct Erdre is much more modest - the main span arch measuring 95m, 165m to Garabit cons (of 564m in all) and is about twenty feet above the water, what is there so much less dramatic than the mountains cantaloupes. The viaduct Erdre is also certainly not the first of its kind - after all, we built a viaduct arch over the Severn, beams cast iron and not exactly a century earlier. The authors did not, moreover, that claim, only to publish the calculations they had employed so that their successors can enjoy this experience.

From calculations: it is what it is. I admit I vaguely hoped, by buying this little book on the Seine, find some implementation plan, perhaps even prints of the work. But the content is this: formulas, tables of values to be used in such formulas; few diagrams to explain these calculations (see page among others, shown more than average and it is taken into account the constraints of expansion). The lover of beautiful drawings (I am) is disappointed, but not the historian of technology, here is a magnificent example of what became the science of engineering in the aftermath of the Second Empire.

This science, he had been born with a view to Belidor Bernard Forest in the 1720s (see Langin, Conserving the Enlightenment , Chapter 9), which sought to establish rules for calculating the construction of fortifications. "The structures, he said, must draw their strength of workmanlike rather that the abundance of materials. She is now in full possession of his means, to the point of feeling able to accurately predict the behavior of a structure of a new type. The material is indeed suitable for calculation, with beams that work only in the direction of the length - to the point that one wonders if the success of the structures "eiffelliennes" does not come primarily from their adaptation for engineering calculations.

Science Engineering is a science of calculation and prediction. But it is also an experimental science: this project is a bench trial, where the measures taken have confirmed the a priori calculations . And, of course,

Whatever this respect the views of manufacturers, we believe that the discussion in which we delivered demonstrates the confidence that should inspire the arch span. Certainly study projects is not difficult, and the results which lead calculations are maximums which, in practice, will never be achieved.

and Laura Dupuy, op. cit. , p.78.

Bridge Erdre may well be a bit forgotten, if indeed it still exists (and there Nantais in the room? This must be the bridge Jonelière, just left of the highway bridge Beaujeoire going to Chapelle-sur-Erdre) - but it represents an example of the engineering triumph of the late nineteenth century. It is not nothing anyway!

[NES, January 30: A nice reader Nantes confirms that it is the bridge Jonelière but was destroyed by the Germans in 1944 and rebuilt in concrete in 1948 . His comment see below.]