of this corporation which had just been completed at Garden City, L. I. It is interesting to note in connection with this removal that all those engaged upon this design work completed their work in Buffalo at the usual time in the afternoon, were carried to Garden City on a special train at night, and reported for work at the Garden City plant on the following morning, without any loss of time on the design work.

The design, because of the immense amount of detail involved, seemed to progress very slowly and it was not until January 19, 1918, that it was finished sufficiently to begin the building work of the machines. For this construction work a contract was made

VECTORS SHOWING LONGITUDINAL STABILITY FROM WIND TUNNEL DATA + CENTER OF GRAVITY. ANGLES ARE MEASURED BETWEEN THE THRUST LINE AND THE HORIZONTAL.

with the Curtiss Engineering Corporation for four complete seaplanes. For these craft, the Navy Department was to supply three of the hulls, and all the engines. The fourth hull was to be built by the Curtiss Engineering Corporation. A contract was let on the basis of actual cost plus 10 per cent for profit.

To facilitate construction, various parts were made under subcontracts from the Curtiss Company. The principal ones which may be noted are as follows. Wing panels, control surfaces, and wing struts, were built by Locke & Company of New York City, expert manufacturers of high-class motor car bodies. Metal parts were made by Unger Brothers, Newark, N. J., manufacturers of silverware, jewelry and all kinds of metal articles ordinarily

handled by jewelers. Later, to expedite the production of metal parts, some of these were manufactured by the Beaver Machine Works of Newark, and some by Brewster and Company of New York City. Wing tip floats were built by the Albany Boat Company, builders of high-class steam launches and motor boats. These, later were replaced by larger floats built by the Naval Aircraft factory of Philadelphia. The outriggers supporting the tail were built by the Pigeon-Fraser Hollow Spar Company of Boston, makers of masts and spars for racing yachts. The gasoline tanks were built by the Aluminum Company of America of Pittsburgh. The construction of these tanks was the largest and most difficult job of this nature ever undertaken by any aluminum manufacturer. Two of the hulls to be supplied by the navy were built by Lawley & Sons of Neponsit, Mass., and one by the Herreshoff Manufacturing Company of Bristol, R. I. These hulls were built on the basis of cost, plus 10 per cent profit on an estimated cost, with the understanding, if the cost could be reduced below the estimated cost, the contractor would be paid 10 per cent on the estimated cost, and, in addition, 25 per cent of the difference between the actual and the estimated costs.

To assist the Curtiss Company in expediting the production of these parts, and to aid in every way in the construction and assembly of the machine, four officers attached to the office of the writer, were detailed to work with Mr. Gilmore of the Curtiss Engineering Corporation, who had been placed in full charge of the construction work on these four machines. Only because of the faithful work of these officers was it possible to complete the first of these flying boats in September, 1918.

This boat, known as the NC-1, had a power plant which consisted of three low compression direct drive liberty engines, arranged to drive tractor propellers. This arrangement was chosen because of the necessity of keeping the weights of the motors forward to bring the center of gravity in the required position with respect to the center of lift. After actual tests of the machine it was found that slight variations in the position of the center of gravity had practically no effect upon its operating characteristics, and it was decided to change the arrangement on the third and fourth boats to two tractor motors and one pusher motor. This installation was later decided on for the second boat as well.

The NC-1 was completed and assembled for tests at the Rockaway Beach Naval Air Station in September, 1918. The engines were tried out for the first time on October 1, and the boat was weighed, to determine the total bare weight, on October 2. In weighing this machine, four platform scales of 8000 lbs. capacity each were used. These scales were so placed that jacks resting upon the scale platforms could be placed directly under the engine section wing beams, at the outer strut stations. By jacking up, the entire weight of the machine was transferred to these four points. The summation of the four scale readings

gave the weight of the plane. By carefully adjusting the position of the machine, leveling it fore and aft and transversely, the weights as indicated on the scales made possible the calculation of the fore and aft position of the center of gravity. The total weight was 12,740 lbs. This weight did not include any supplies or equipment. It was the net bare weight of the machine itself. The estimated weight for the complete machine as worked out by the Curtiss Engineering Corporation was 11,900 lbs., 840 lbs. or 6.6 per cent less than the actual weight. The center of gravity was 65 inches aft of the leading edge of the lower engine section wing panel, or 28 inches aft of the mean center of lift of the wing panels. This condition indicated very decided tail heaviness, and, in the first