Page:Popular Science Monthly Volume 32.djvu/171

Rh demonstrated this superiority, engaged in a little controversy in which patriotism was mixed up. Finally, I wrote to the American contractors that I had never come to any prejudiced decision, that I was wholly disposed to make use of their skill, which I acknowledged to be incontestable, and of their great experience in public works.

The essential difference between the French and American excavator is as follows: The French, as has been said, carries a series of buckets attached to an endless chain. The American—with which Americans are comparatively familiar—has a single bucket; it is larger than the French buckets, and is worked at the end of a lever. The French buckets, though smaller, revolve rapidly; their number and constant motion compensate perhaps for their size. Cuts of each system are annexed. It may be remarked as to French excavators, that sometimes the buckets ascend filled with earth below the bucket-ladder, as in the cut, and sometimes, the motion of the chain and position of the buckets being reversed, above it. The cut of the French excavator is a reduced cut of an illustration in Lieutenant Kimball's government report. That of the American excavator, also that of the American dredge, found farther on, are reduced from illustrations which appeared in "The Scientific American" in 1884 and 1886. The principle of the French excavator is applied with differences of detail in several ways. There are, or have been recently, at work at Panama the following French or Belgian excavators—named respectively after the manufacturer or designer, Ville-Châtel, Evrard, Weyer et Richemond, Gabert, Boulot, Demange, and Andriessen. There were of the American excavator two types, the Osgood and Otis.

The director-general, after this reference to excavators, observed that in rocky parts excavators could not be used.

In rock excavation a method has recently been tried of breaking up masses of rock by powder and dynamite combined. An explosion of this kind was witnessed by De Lesseps and the party which accompanied him in February, 1886. In a subsequent communication to the French Academy of Sciences, he gave an account of the wreck of a mass of porphyry amounting to thirty thousand cubic metres, on this occasion. The charge consisted of two parts dynamite to one of powder. Some idea of the force of the explosion may be derived from the pains taken to block the passage which led to the charged chamber. For the space of thirty feet it was packed with masonry. Upon a public occasion soon after, De Lesseps held up a fragment of the rock dislocated, observing that here was one-billionth part of it!