With this knowledge in their possession the Americans were able to do what the French were not--to control the chief enemy of mankind in torrid climes. In the first years of the work the public, and Congress, reflecting its views, were not sufficiently convinced of the efficacy of the new scientific discoveries to afford the means for putting them into effect. The Isthmian Canal Commission refused to honor requisitions for wire screens, believing that they were demanded to add to the comfort and luxury of quarters on the Zone, rather than for protection against disease. But the outbreak of yellow fever in 1905 was the occasion for furnishing the Sanitary Department, under Col. W. C. Gorgas, with the necessary funds, and thus provided, he speedily and completely stamped out the epidemic. From that time on, no one questioned the part that sanitation played in the success of the project. The cities of Panama and Colon were cleaned up as never were tropical cities cleaned before. All the time, every day, men fought mosquitoes that the workers in the ditch might not be struck down at their labors. The Americans, too, made mistakes. In the beginning they attempted to build the canal under the direction of a commission with headquarters in Washington. This commission, at long distance and by methods hopelessly involved in red tape, sought to direct the activities of the engineer in charge on the Isthmus. The public also was impatient with the long time required for preparation and insistently demanded that "the dirt begin to fly." The work was begun in 1904. It proceeded so slowly that two years later the chairman of the Isthmian Canal Commission asserted that it must be let out to a private contractor, this being, in his opinion, the only way possible to escape the toils of governmental red tape. The then chief engineer, the second man who had held that position while fretting under these methods, was opposed to the contract system. Bids were asked for, however, but all of them were rejected. Fortunately, Congress from the beginning had left the President a practically free hand in directing the course of the project. Mr. Roosevelt reorganized the commission, made Col. George W. Goethals, an Army engineer, chairman of the commission and chief engineer of the canal. The constitution of the commission was so changed as to leave all the power in the hands of the chairman and to lay all of the responsibility upon his shoulders. It was a master stroke of policy, and the event proved the choice of the man to be admirable in every way. From the day the Army engineers took charge there was never any more delay, never any halt in progress, and the only difficulties encountered were those of resistant Nature (such as the slides in Culebra Cut) and those of misinformed public opinion (such as the absurd criticism of the Gatun Dam).