The flying surfaces of an airplane are made by stretching cloth over the frames. When we came into war it was supposed that linen was the only common fabric with sufficient strength for this use, and linen was almost exclusively used by the airplane builders, although Italian manufacturers were trying to develop a cotton fabric. Of the three principal sources of flax, Belgium had been cut off from the allies, Russia was isolated entirely after the revolution there, and Ireland was left as the sole available land from which flax for airplane linen could be obtained. As late as August, 1917, England assured us that she could supply all of the linen that would be needed. It rapidly became evident that England had underestimated our requirements. An average airplane requires 250 yards of fabric, while some of the large machines need more than 500 yards. And these requirements do not take into consideration the spare wings which must be supplied with each airplane. This meant a demand for millions of yards put upon the Irish supply, which had no such surplus above allied needs. For some time prior to April 6, 1917, the Bureau of Standards at Washington had been experimenting with cotton airplane cloths. Out of the large variety of fabrics tested several promising experimental cloths were produced. The chief objection to cotton was that the dope which gave satisfactory results on linen failed to work with uniformity on cotton. Therefore, it became apparent that if we were to use cotton fabric, we should have to invent a new dope. Two grades of cotton airplane cloth were finally evolved--A, which had a minimum strength of 80 pounds per inch, and B, with a minimum strength of 75 pounds per inch. Grade A was later universally adopted. This cloth weighed four and one-half ounces per square yard. We placed our first orders for cotton airplane fabric in September, 1917--orders for 20,000 yards--and from that time on the use of linen decreased. By March of 1918 the production of cotton airplane cloth had reached 400,000 yards per month. In May the production was about 900,000 yards; and when the war ended this material was being turned out at the rate of 1,200,000 yards per month. Starting with a few machines, our cotton mills had gradually brought 2,600 looms into the enterprise, each loom turning out about 120 yards of cloth in a week. A total of 10,248,355 yards of cotton fabric was woven and delivered to the Government--over 5,800 miles of it, nearly enough to reach from California to France. The use of cotton fabric so expanded that in August, 1918, we discontinued the importations of linen altogether.