In late 1947 work on the Educational and Musical Arts drawings was initiated under the direction of Louis P. Christman and carried through to completion by him. Christman has stated that Orville Wright was critical of the Science Museum drawings but just what he thought incorrect is not known. Whatever his reasons, he did encourage Christman to undertake the major task of duplication. Christman worked directly with Orville Wright for a period of six weeks and had access to all the records and parts the Wrights had preserved. The resultant drawings are also very complete and, regardless of the differences between these two primary sets, both give a sufficiently accurate picture of the first engine for all purposes except that of exact reproduction in every detail. There exists a still unsolved puzzle in connection with what seems to be yet another set of drawings of the first engine. In December 1943, in writing to the Science Museum telling of his decision to have the airplane and engine brought back to the United States, Orville Wright stated, "I have complete and accurate drawings of the engine. I shall be glad to furnish them if you decide to make a replica."[7] No trace of these particular drawings can be found in any of the museums, institutions, or other repositories that normally should have acquired them and the executors of Orville Wright's estate have no record or knowledge of them. The date of his letter is four years before the Dayton drawings were commenced; and when Christman was working on these with Orville Wright they had copies of the Science Museum drawings, with complete knowledge of their origin, yet Christman has no knowledge of the drawings referred to in Orville's letter to the Museum. Finally, the evidence is quite conclusive that there were no reproducible or permanent drawings made at the time the first engine was constructed, and, of course, the reconstructed engine itself was sent to England in 1928 and not returned to this country until 1948.[8] [Footnote 7: The Science Museum expressed a desire to have these but never received them. There is a reference to them in a letter to the Museum from the executors of his estate dated 20 February 1948, but is seems rather obvious from the text that by this time the drawings mentioned by Orville Wright in his 1943 letter had become confused with those being prepared by Christman for the Smithsonian Institution. The Science Museum did have constructed from its own drawings a very fine replica which is completely operable at this time.]