By kind permission of Baron de Bradsky's widow, I am enabled to give an authentic account of his ideas concerning the “ de Bradsky ” balloon, of its construction, and of the causes that produced the lamentable accident on October 13lh, 1902, in which Baron de Bradsky (Fig. 1) [to the left] and his engineer, Morin [to the right], lost their lives. Baroness de Bradsky thought it due to her husband's memory to have this account published, particularly as the details in the papers at the time of the accident were more or less incorrect, and none of their authors had grasped the fundamental idea which actuated Baron de Bradsky in the construction of his airship ; Baroness de Bradsky was also of the opinion that a reliable account would be of interest to aëronauts in general, and might be of use in solving the numerous and difficult problems which assail them.

The central plain of Mexico is at a considerable elevation, ranging from 3,000 ft. at the frontier to 7,300 in the immediate neighbourhood of the City of Mexico. The air is, consequently, considerably rarefied, and one would suppose that birds would find it difficult to practise sailing and circling flight; but that does not seem to be the case, as, at any time during the day, numbers of turkey-buzzards can be seen sailing or floating and circling with only a rare flap of wing; and, as a proof that rarety of atmosphere does not seem to diminish their sailing powers, I have seen at Tres Marias, a station on the Cuemavaca line, as it crosses the hills bounding the southern limit of the plain, at an elevation of over 10,000, these birds sailing equally gracefully and without any appearance of labour. There can be little doubt that the air at this elevation has less supporting power, and, therefore, it must be compensated for by the greater speed if the upward current, and shows how wonderfully adapted the wing of the turkey-buzzard is for sailing flight, and that at a lower elevation the wing could support more than the weight of the bird.

Recent experiments have led me in two directions—both a good deal governed by considerations of construction, which, in any case, is always poor.

In one direction I improved the steadiness of flight, but was very dissatisfied with the angle of fall; in the other direction I improved, by diminishing, the angle of fall, but was extremely dissatisfied with the steadiness of flight.

In trying different wing profiles—such as could be easily made by bending a piece of thin cardboard, I found the steadiest forms were those that required the centre of gravity to be furthest, forward, but they did not give good angles, while the best angles were given by shapes which, wherever the centre of gravity was, would always pitch forward unless controlled by a large and well turned up tail.

It appeared probable that in the steady form with the bad angle all the lift came from a limited part of the wing near the forward edge, while the bulk of the after part of the surface acted more or less as a steadying rudder or tail.