Good health on the Canal Zone seems a very simple matter now, and such it is; but when the doctors and sanitary engineers began work it was an exceedingly serious situation that they undertook to cure, and without their work there could be no Canal to-day. The complete elimination of the last case of yellow fever has made entirely harmless the mosquito carriers where they occasionally appear on the Isthmus. The best test of the work of the Sanitary Department is the fact that the Zone and terminal cities have remained clean and that there is no indication of relapse. Before work could begin, a whole system of transportation had to be organized, a steamer line put into operation, and an immense purchasing department gotten into working order. Before men could be brought to the Isthmus to do the work some provision had to be made for housing and feeding, and the question of materials, supplies, food, fuel, recreation, and education was no small matter. To dig the Canal required not only engineers and officials, but an army of common laborers, and the labor question was not easy. The Panamanian might have dug the Canal, but he did not do it; he did not want to do it, and the probability is that he never could have done it. Employers on the Zone refused to hire Panamanians for Canal work. Chinese coolies might have been imported from Canton or Amoy, but Panama is a long way from southern China and still further from India, and no intelligent man ever seriously proposed importing Hindus. If enough Panamanian Indians could have been found, they might have done the work, but the native Indian is a very uncertain and fragmentary factor of life on the Isthmus. At this juncture the West Indian filled the breach and supplied the labor for the job. Up to forty-five thousand of them were employed at one time, and with the ebb and flow of the human tide between the Isthmus and the Caribbean Islands several times that number came to the Isthmus. Somebody else _might_ have supplied the labor, but the fact is West Indian _did_ do the work, and at least deserves proper recognition therefor. The problems of suitable construction machinery were in a way simple. Given a definite task, it remained to devise mechanical means to meet the conditions. In practice, however, the case was not so simple as this sounds, and some very difficult knots were untangled before the work was well under way. Some of the old French machinery was used clear through the construction period, but the jungle was sown with scrap iron of the old French equipment that has only recently been removed. The electrical and mechanical equipment for the operation of the locks is a marvel of adaptation and invention and nothing short of a technical description can do the subject justice. To see the locks in operation is to wonder at the mechanical contrivances which seem almost intelligent, and some of the design work is the result of real genius.