Page:The National Geographic Magazine Vol 16 1905.djvu/522
white man can work without expense of physical energy, where he can work seated, so to speak, protected from the sun, protected from the rain; second, because it is the only instrument where the colored man remains under immediate supervision, where he is attached to tasks always the same and under the eye of the overseer; third, because it is the instrument least liable to suffer from an error or an accident. If a little slide comes it withdraws and is not buried, as an excavator or a steam shovel. If the attack of the ground is too hard, it simply stops instead of risking to lose its equilibrium ; it does not derail," &c.
DREDGING WAS PREFERRED TO OPEN AIR ROCK EXCAVATION DURING THE OLD PANAMA COMPANY WORK, WITH MUCH LESS POWERFUL DREDGES THAN ARE NOW USED
"Anybody who has worked on the Isthmus with the two systems cannot but be struck with the enormous superiority of the dredge. It is so apparent, so obvious, that I did not hesitate at Culebra, as soon as the conditions became compatible with a dredging plant, to endeavor to substitute the work of the dredge to that of dry digging, and this in a hard clay that necessitated the employment of explosives for the work of excavating machines.
"Unfortunately, the plant was just in action when the collapse of the old company came; but however small has been its period of activity, perhaps a couple of months, the result completely confirmed my expectations and filled my hopes. Unfortunately for the canal, the inevitable and blind reaction which followed such a disaster as that of the Panama enterprise put into suspicion the clearest results obtained. I consider that it has been, among others, one of the most fatal mistakes of the New Panama Canal Company not to continue in the same line of effort.
"What they have done in the Culebra Cut would have been infinitely cheaper and quicker done if they had followed my last plans and not simply continued dry excavations, which I had put in action for a much longer period than the wet process.
"Since that time no more dredging has been done on the Isthmus, and therefore the truth has not been able to be again found and recognized.
"It can be stated with certainty from practical experience, such as the records of the Suez Canal may show, that under the very propitious conditions in which the excavation will be made on the Isthmus, without currents or without variation of water level, it can be made at a cost less than $1 per cubic yard, including repairs and depreciation of machinery. It can be equally stated from the same Suez Canal records that m their rock may be extracted and dumped, including repairs and amortization of machinery, at a cost not reaching 75 cents a cubic yard. As for the hard clay, even with the light blasting it requires, the price ought to be kept below 30 cents a cubic yard with ordinary dredging and much reduced with electrical appliances, even including 12 cents for the amortization of the locks ascending to Lake Gamboa. The excavation of hard clay may be brought still lower with the new dredging apparatus resulting from the combination, of cutters and suction pumps, but this is an eventuality of the future, and, though already resting on large experiments in Canada, it is not sufficiently proved adaptable to the isthmian ground to base reasonable and conservative estimates on, such as I give today.
"I have prepared the way for the employment of electricity in the working; of the dredges, and I had built in Holland by Smulders an electric-driven dredge in 1895, according to special plans which I drew, and which was, so far as I know, the first electric dredge ever employed in public works. The results I obtained on the River Elsa, in