The production of some of the artillery sights proved to be almost beyond the mechanical ability of American workmen. It took three skilled organizations to produce the panoramic sights. Warner & Swasey, of Cleveland, built these sights, but had to turn to the J. A. Brashear Company, of Pittsburg, for the optical-glass prisms to go into them. That company, in turn, did not have a skilled force large enough to correct the roof angles of all the prisms required. The Ordnance Department found a man who understood the correction of optical plane surfaces in the person of Dr. G. W. Ritchey of the Mt. Wilson Observatory, Pasadena, California. He trained a number of men in this recondite craft, and they staffed an important department of the extensive optical shop which the Carnegie Institution built at government expense at Pasadena. An extensive production of military optical instruments was permitted after the armistice and before the contracts were terminated. The work of producing some of these instruments was long and difficult, the instruments themselves would not deteriorate in storage, and the evolution and improvement of such instruments is slow. Moreover, the labor cost is by far the greatest cost in making optical instruments. The value of the unfinished components as scrap, even from an industry as large as that created in 1917–1918, with its eighty-three factories at work on contracts of a value of $50,000,000, was almost negligible. As a result of this permission to proceed, the industry reached its peak of production late in January, 1919. The only contracts terminated were those under which no production had begun before the armistice, those the holders of which asked for termination, and those which had already produced undue excesses of easily made articles.