The advantage of using powder and dynamite combined is thus explained. If dynamite alone were used, the breakage would be carried

too far; the fragments could not be as conveniently loaded by cranes. The effect of powder would be to project the fragments too far, thus damaging, it might be, the neighboring works. As regards the use of

AMERICAN DREDGE (reduced from cut in "Scientific American").

dynamite, we might query whether, if a still stronger explosive were employed, the rock might not be reduced to pebbles or sand. In this state it might be handled by the buckets of excavators, and the slower operation of cranes be avoided. We might speculate further, whether the explosives said to have been recently invented in France and Germany, or like substances, might not be of service. If, as is understood, the governments which possess them desire to keep the process of manufacture secret, some difficulty might be experienced in procuring them. But civilization might be the gainer if such inventions were used to blast a thoroughfare at Panama instead of to enhance the rapidity with which human slaughter is carried on.*

Of all writers who have interested themselves in the Panama Canal no one has given the amount of attention to inventions bestowed by Mr. Bigelow in his report to the New York Chamber of Commerce. We can not do better than give his views upon this topic. These, again, may serve to introduce further particulars as to the machinery employed. After observing that the wages of unskilled labor when work was begun were ninety cents a day, and have since advanced to a minimum of $1.75, and that even at this price the company does not readily get the labor needed,† he says:

The question then arises, Must the work be prosecuted under the present conditions?

"When the Jews were required to make brick without straw, Moses came. May not the exigency, like child-bearing, work its own cure?

In all ages and nations, when manual labor has become too costly to do the work for which there was a universal or even a general need, a substitute for it has been promptly devised. It was to the need of economizing muscular labor that we owe the hoe, the wheelbarrow, and the plow. Had laborers' wages never risen above a shilling a day, we should never have heard of McCormick's reaper, or of Howe's and Singer's sewing-machines. It is equally certain that the portion of our planet which lies under the tropics will never play the part in human history to which its territorial extent and productive power entitle it, until our present assortment of mechanical substitutes for muscular power has been very largely increased. Machines do not mind malaria; they are not poisoned by marshy water; they thrive on the black-vomit; they have no fear of chills or sunstrokes; and, what is more, they are never tired, and will work all the days and nights of their natural lives without interruption, if properly fed and cared for.

That is the class of operatives for out of-door work in the tropics, and it is to them that M. de Lesseps must, and I presume does, look for an early completion of his canal; for it is in that direction his own remarkable experience

* No secret seems to attach to the composition of a new explosive, bellite, to which an article is devoted in the "Scientific American," May 14, 1887. This explosive, it is stated, has been found more effective in quarries than any nitro-glycerine compound.

One of the chief difficulties of the company at present is getting an adequate laborsupply. In the "Canal Bulletin," June 16, 1887, the fact is noticed that at several points part of the machinery provided was lying idle, owing to this lack. Several hundred Chinese had arrived but recently, and it was hoped that their labor would prove as effective as that of the Chinese employed upon the Panama Railroad forty years since. VOL. XXXII.-11

has certainly taught him to look with some confidence. When the work on the Suez Canal was begun, and under climatic conditions much the same as those at the Isthmus of Panama, the Suez Canal Company was entitled by its charter to as many native laborers as it required up to forty thousand, and at an almost nominal price. As these men were drafted into the company's service by corvée, England protested against a "revival of slavery" in Egypt. The Khedive was constrained to break his contract with the company, for which he had afterward to pay an indemnity of thirty-eight million francs, and M. de Lesseps had the mortification of seeing his little army of twenty thousand fellahs dispersed as suddenly and as irrevocably as an April fog.

The logic of the situation promptly suggested the replacing of the men with machines; the putting of slaves without souls or sensibilities in the place of slaves with both. The inventive genius of his countrymen was stimulated by the gravity of the crisis, and in due time from eighty to one hundred dredges, with an appropriate supply of barges, elevators, steam-tugs, locomotives, etc., had taken the place of a large portion of the men withdrawn; and this machinery, with only four thousand men, increased the monthly output from ten thousand cubic metres to two million, and executed more excavation in the last three years of the work than had been done in the previous seven. May not the scarcity and cost of manual labor on the Isthmus in like manner develop the means of dispensing with at least that portion which the labor market will not cheerfully supply?

The results already accomplished in that direction justify the expectation that, to a considerable extent, it may. There are already at work on the Isthmus machines for dredging and for excavation, far more powerful and efficient than any ever used on the Suez Canal or anywhere else.

It is the opinion of Mr. Bigelow that De Lesseps's "remarkable experience" at Suez has led him to anticipate the forwarding of the Panama work by similar means. This expectation is illustrated by an incident of the Paris Congress. Lavalley, the inventor of the dredges, was there was in fact a member; and to him De Lesseps referred at one of the sittings as an engineer "who had already invented so many machines, and who, under similar circumstances, would know how to invent more."

Mr. Bigelow observes, with regard more especially to excavators, "There is no reason to suppose that, in the creation of such machines, art and science have reached a limit in any direction." One might say with Arago:

"Croire tout inventé n'est qu'une erreur profonde;

C'est prendre l'horizon pour les bornes du monde."

We can not suppose that an horizon of inventive impossibilities has settled down about Panama.

With regard to Mr. Bigelow's statement that there are at work machines for dredging and excavation "far more powerful" than any ever used elsewhere, it has been already stated that the greater power of these mechanisms is chiefly due to their increased dimensions and the higher steam-power employed. Let us take the "City of New

York," the greatest dredge probably ever constructed; built by the American Contracting and Dredging Company, and by them used at Panama. The engines of the largest Suez dredges had a force of seventy-five horse-power. Those of the "City of New York" have a force of three hundred. To run all parts of the complicated machinery, no fewer than eight are employed. The huge ladder which carries the buckets is one hundred and ten feet long; the chain to which the buckets are immediately attached, if ruptured, would reach from the top to the bottom of Bunker Hill Monument. Two discharge-pipes, each three feet in diameter and one hundred and eighty feet long, carry the earth to the banks. By means of steam-pumps, as in the case of the Suez dredges, water is forced into the bell or hopper, and the discharge facilitated. The effectiveness of this mechanism is not due solely to its construction on an enlarged scale; contrivance comes in for part of the credit, and has effected part of the result. One of the peculiarities of the American dredges may be referred to. To steady the vessel and hold the buckets against the bank, two spuds or pile-anchors are employed. In the case of the "City of New York" these spuds are sixty feet high and two feet in diameter. They pass through the hull, one on each side, and the iron chiselpoint at the termination of each weighs eighteen hundred pounds. This is planted in the bottom. When spud No. 1 descends, it serves as a pivot around which the dredge, carrying the bucket-ladder in operation, slowly revolves, thus traversing the arc of a circle. When No. 1 is raised, No. 2 is lowered, and serves in like manner as a center. After this fashion, planting a foot at a time, this huge digging, spouting creature, as one might term it, advances. The movement through an arc is regulated by two distance-lines, so called. These are attached to windlasses, one on each side of the forward deck, the other end being attached to the shore. As one line is drawn in, the other is paid out, and by this simultaneous process the motion in curves is maintained.* A high degree of interest attaches to a structure combining power, ingenuity, and complexity as these are not united in any other mechanism of the sort. Such among contrivances of the kind is the "City of New York."

With regard to the amount of excavation effected by the dredgers of the American Company, Mr. Bigelow sets it down as about double the largest output of any machine at Suez. Lieutenant Kimball, comparing the output of the later American dredges with the best at Suez, sets it down as more than double, twelve hundred cubic metres per hour, as compared with four hundred and eighty.

While in the matter of dredges Americans have contributed of late more than others by fresh devices and an increase of dimensions, the French seem to have effected like results with regard to excavators.

* For these particulars as to the working of the spuds, etc., the writer is indebted to Lieutenant W. W. Kimball, U. S. Navy.

Those first employed at Panama had a force of twenty-four horsepower, while the powerful machines more recently sent out have a force of ninety. The French have lately employed in connection with their excavators a mechanism similar to the élévateur, already described. It is called the transporteur, and consists of an elevated structure which performs the same service for an excavator that the élévateur does for a dredge. The earth is deposited from the buckets upon an endless belt. This passes round two drums about two hundred feet apart, and in the interval rests upon friction-rollers. The earth is thus carried outward from the excavation, and at the same time upward.

While, owing to the power and size of her digging mechanisms, the Panama undertaking has quite an advantage over Suez, it is not to be assumed that this advantage may not be further increased. Upon this contingency the decision of important questions may depend. Whether the canal be finished, at least provisionally, as a lock-canal or cut immediately to the sea-level, is possibly one of these. But the decision as to locks will have to be expeditiously arrived at; and if inventors are to step in and affect in any sort of way the result, they have not much time for contrivance and experiment. At all events, we may hope much from the fact that the undertaking is probably in the best hands to which it could have been intrusted. Owing to the completion of former contracts, or the substitution of later for earlier ones, the greater part of the work devolves at present upon French or American contractors. The portion undertaken by the American company consists, it is true, wholly of dredging-the easiest part of the work. There can be no doubt as to the satisfactory, and, should it prove necessary, rapid completion of this part of the undertaking; the chief difficulty lies in the excavation of dry earth and rock, and this is chiefly in the hands of the French.* But American inventions and skill may be as serviceable here as in any other section of the work. It is a pledge of earnest effort that the two republics which have the work in charge have also a greater stake than others in the completion of the undertaking-France, because French capital has furnished the funds; America, because of our need of a

* According to the plans of the company, as described recently by Charles de Lesseps, Vice-President of the Suez and Panama Companies, part of the work which it was thought must be done by excavators may be effected by dredging. With this end in view, he tells us, the company is making preparations. It is proposed to introduce into the works, between Gamboa and Paraiso, the waters of the upper Chagres. An analogous plan served the same purpose at Suez: fresh water was introduced from the Nile; nine dredges were carried up by a lock and floated upon it. These operated upon a temporary lake, whose level was seventeen feet above the Mediterranean. Whether such a plan, by some thought impracticable, may be successfully applied at Panama, remains to be seen.

For a description of the manner in which the Nile water was employed, see Fitzgerald, vol. i, pp. 190-194.