A five-day conference between Mr. Hall and Mr. Vincent, called by Mr. Deeds and Mr. Waldon of the Aircraft Production Board to consider aeroplane-engine design and production, was held. The two engineers got together in designing a standardized, directly driven, five-bearing crank-shaft engine of 8 cylinders, and one of 12 cylinders, with a seven-bearing crank-shaft. After a session of twenty hours’ work in a room at the New Willard Hotel, in Washington, during which meals were served the two men, and both lived, worked, and slept in the apartments of Mr. Deeds, a new 8-cylinder 230 horse-power aeroplane engine was laid out, described, and drawings of transverse and longitudinal sections were made by Vincent and Hall themselves. This was the first Liberty motor designed. On the morning of May 30, 1917, near the close of the designing session, Mr. Vincent dictated a joint report to the Aircraft Production Board. The salient points and a rough draft had been agreed upon the night before. It was dated May 31, 1917, and signed jointly by E. J. Hall and Jesse G. Vincent. WASHINGTON, D. C., May 31, 1917. AIRCRAFT PRODUCTION BOARD, WASHINGTON, D. C. _Gentlemen_: At your request we have made a careful study of the aircraft motor situation and hasten to submit our report as follows: In order to get this report in your hands promptly we have condensed it as much as possible and have covered the essentials only. In view of the fact that there are a number of good motors for training-machines available, we have disregarded this type of motor and have confined our attention strictly to the high-efficiency, low-weight per horse-power type, such as is necessary at the front. In order that any motors that are built by this country may be of any value when received at the front, it is, of course, absolutely necessary that their efficiency be brought up to or a little beyond the best now available in Europe. This, of course, made it necessary for us to know just what has been accomplished in Europe. The French and English Commission has enabled us to obtain this information by answering our questions very clearly and completely. From information obtained from these gentlemen and from other sources, we believe that the Loraine Dietrich is the coming motor in Europe. This motor has not been built in large quantities as yet, but some thirty had been constructed and carefully tested out at sea-level and also at about 6,000 feet elevation. The important facts about this motor are as follows: Eight cylinders: 120 mm. bore by 170 mm. stroke.