RECENT numbers of the Sailplane and Glider, the official organ of the British Gliding Association, give evidence not only of the advances that have been made in the technique of motorless flight, but also of the scientific knowledge that it is producing. The development of aeroplanes has been so spectacular that development of sailplanes may be overlooked. But these have attained an airspeed of 87 m.p.h., a straight line distance of 313 miles and a height of more than 19,000 feet ; records all beyond those of power planes in 1911. It has long been a reproach that sailplanes were dependent on hills and winds ; but an effort was made last June to meet this by the organization of a cross-country circular tour. A definite route of 415 miles, beginning and ending at Darmstadt, was laid out, the time allowed being ten days and each separate flight was to start with an aeroplane tow to not more than 500 metres. Of the eight pilots who got away, four completed the course in the time, the first taking only seven days. The use of 'thermals'—ascending currents apart from clouds—has become more widespread. Of late, at four or five English gliding centres, pilots have been pulled up to a few hundred feet by a winch and have got away without any help from the wind or from a hill.