A year’s flying in the mail service, with all types and temperaments of aviators, has established the fact that 200 feet visibility from the ground is the limit of practical flying, although a number of runs have been made with the mail between New York and Washington during which a part of the trip was flown at an altitude as low as 50 feet. The objection of aviators to flying above a ground-fog, rain, snow, or heavy clouds with single motor-planes is the possibility of the motor stopping over a village, city, or other bad landing-place, with the radius of visibility so little as to afford no opportunity to pick out a place for landing. It is generally accepted that with two or more motors, forced landings under such conditions can be avoided. FLYING IN ROUGHEST WEATHER A number of severe gales have been encountered during the flights between New York and Washington. Gales of from 40 to 68 miles an hour have been encountered and overcome. Pilot J. M. Miller, who was formerly a naval flier, made the flight from Philadelphia to New York in a Curtiss R4 with a 400 horse-power Liberty motor, rising from the field against a 43-mile gale and arriving in New York through a blinding snow-storm with a wind velocity reported by the Weather Bureau to be 68 miles an hour and which was 15 per cent greater at the altitude at which he flew. Mr. Praeger says in his report that from experience it is learned to be useless to send against a 40-mile gale a plane having a top speed of no more than 75 or 80 miles. “The two types of planes in the air mail service of this speed,” he said, “are the Standard JR 1 mail plane, having a wing spread of 31 feet 4 inches, and the Curtiss JN 4, having a wing spread of 43 feet 7⅜ inches. Each plane of this type is equipped with a (Hispano-Suiza) 150 horse-power motor, which does not provide enough reserve power to combat the disturbed air conditions at the surface in a wind of more than 40 miles an hour, especially if the wind comes in descending columns or gusts. Under these conditions it is possible to make headway only with a Liberty engine, which has plenty of reserve power. A plane equipped with a 150 horse-power motor, if it succeeds in breaking through the surface winds, can make only slow and laborious headway against a full or a quartered head wind of about 40 miles. There have been many instances where the planes equipped with 150 horse-power motors have been held down to a speed of between 30 and 37 miles an hour; and also many instances where a hundred-mile-an-hour plane equipped with a Liberty motor has been held to between 55 and 60 miles. A few wind-storm conditions were encountered where the planes at the height of the gust were actually carried backward.”