152 THE POPULAR SCIENCE MONTHLY. 



These inventions show the admirable fertility of resource that regulates the- 

 work of forei^-n engineers, who devise machinery to suit the difficulties of each 

 stupendous work ; whereas in this country (England) the objection is often 

 made to such undertakings, that engineering does not furnish means to accom- 

 plish them. However this may be, the Mont Oenis Tunnel and Suez Canal are 

 excellent instances in point, the difficulties themselves prompting the discovery 

 of means to overcome them. 



For a detailed description of the Suez dredges and their appurte- 

 nances, Mr. Fitzgerald's work may be consulted, vol. i, pages 203- 

 212. Here we shall only give an account of the principles involved 

 and certain particulars, in which these mechanisms were in advance 

 of preceding ones. The great dredges and excavators employed at 

 Panama go back for their origin to this period. In 1860 an invention 

 was brought out by two engineers, Cave and Clapar^de, to facilitate 

 the excavation of canals and cuttings upon railroads. They proposed 

 to use a series of scoops or buckets attached to a revolving, endless 

 chain, and to apply this device both to the ordinary dredge, and to a 

 machine, constructed for the purpose, to be used in dry excavation. 

 This was the origin of the present chain-of-buckets dredge and chain- 

 of-buckcts excavator.* The latter machine was first used in France 

 in 18G0 upon the Ardennes Railroad, between Sedan and Thionville. 

 In an article in " Le Genie Industriel " for December, 1860, contain- 

 ing cuts of the chain-dredge and chain-excavator, it is said : " Such 

 machines may, above all, be applied to the work on the Suez Canal. 

 They will allow of the reduction in a notable manner of hand-labor, 

 and, in consequence, economize a considerable part of the expense." 



'J'his statement was written about eighteen months after work on 

 the Suez Canal was begun ; just what the writer anticipated oc- 

 curred. By one of the contractors, Lavalley, the principle of Clapa- 

 r^de was successfully applied to dredges ; and the Claparede excava- 

 tor was in like manner improved by another of the contractors, Cou- 

 vreux, who built Avhat is called the eo'cavateur Couvreux. lie took a 

 contract for excavating the souil d'El Guisr, a ridge which crosses the 

 line of the canal for a space of ten miles, its highest points being sixty- 

 five feet above the sea. This work was finished six months inside the 

 contract time, a result to be ascribed in part to the Couvreux excavator. 



One of the improvements introduced by Couvreux consisted in in- 

 serting movable bottoms in the buckets. In clayey and adhesive soils 

 the buckets sometimes clogged, so that much time was required to 

 clear them. By the new arrangement the bottom was forced for- 

 ward, and the clearance thus effected. The bucket having descended^ 

 a fresh load of earth drove the bottom into its original place. An 

 article in "La Propagation Iiidustrielle " for September 1, 1868, illus 



* This principle, it is true (the use of the endless chain), was applied to a certain ex- 

 tent in the case of dredfrin^i, both in France and Encland, early in the century, (l^ce 

 Knight's "American Mechanical Dictionary," vol. i, pp. 747, 748.) 



