IN addition to the specially fitted Short flying boats, and the Mayo composite aircraft mentioned in NATURE of March 7, p. 390, an order has now been placed for two four-engined De Havilland monoplanes for experimental Atlantic flights. It is understood that a regular North Atlantic air mail service is first visualised, which will be thoroughly tried out before passenger services are attempted. The new De Havilland machines are based, in design, on the ‘Comet’ type, that won the recent England to Melbourne air race, and bear a strong resemblance to them in general appearance. They are monoplanes, with the four ‘Gipsy’ engines partially buried in the wings, and are fitted with retractable undercarriages. The bodies of the machines are constructed so as to float in the event of a forced landing on the water, and additional buoyancy is given by a watertight construction of the wings. Messrs. De Havilland's method of fabrication, as used on the ‘Comet’, lends itself very well to this requirement. It is estimated that the cruising speed of the machines will be more than two hundred miles an hour, with an air endurance of three thousand miles. This same type should also be suitable for long-range high-speed naval reconnaissance. It is anticipated that these machines will be ready for delivery by November or December next.