In an interesting paper on the meteorology of India read before the Society in 1925, Sir Gilbert Walker gave a comprehensive account of the main elements of climate which affect the industrial and social well-being of the country, and dealt with the great question of seasonal weather forecasting, on which he has become the chief authority. I propose to-day to take up some of the newer means of dealing with Indian problems, and to add the consideration of a fresh item, the safeguarding of international aviation.

Last year I was fortunate enough to visit Germany and America at the kind invitations of Dr. Eckener and Admiral Moffett, and I hope that a short description of the development abroad will be of interest.

I propose to devote the short time at my disposal to these two countries, as, although France is still building non-rigid and semi-rigid airships for naval work and Russia has embarked on a most extensive airship programme, I think that the recent developments and improvements of the rigid type airship will be of more interest.

The temperature distribution and thermal stresses are calculated in a configuration consisting of a cylindrical fuselage shell with bulkheads or frames. It is shown that at supersonic speeds thermal stresses are set up in a conventional fuselage structure as a result of the bulkhead restraint against circumferential expansion of the fuselage skin. The thermal stresses due to restraint by fuselage frames are usually less severe. The relative merits of various combinations of materials for the skin and the bulkhead diaphragm are discussed. Furthermore, the possibility of the use of light alloy bulkheads to alleviate thermal stresses is investigated. Diagrams are given for calculating maximum thermal stresses and stress-time variation for various rates of heat input in the fuselage skin due to aerodynamic heating.

Snow falls in a great variety of forms, depending on a large number of conditions affecting the crystallisation of the moisture in the atmosphere. The forms may even vary from place to place or from time to time in one storm.

The character of snow as a medium for transportation depends not only on the form of its constituent crystals, but on the nature of the ground on which they fall, the depth of the total covering, the previous history of the underlying layers, and of course on the history of the last fall and the atmospheric temperature of the moment. Considering the characteristics for the purpose of aircraft operation, it is sufficient to make the broad classifications shown in Table I (page 504).

Accidental dispersals of medically and agriculturally undesirable insects by sea and air transport are discussed, with attention to the relative importance of the roles of ships and aircraft. World-wide records of insects found on board aircraft and discovered to have been introduced at airfields are briefly reviewed, and consideration is given to ways of meeting the problem by insecticidal treatment and airport insect control. It is felt that the insecticidal treatment of aircraft, even when provided for by comprehensive international regulations and conscientiously undertaken, does not alone provide sufficient protection against insect introductions, and that greater attention should be paid to the preventive aspects of the problem, with particular regard to the control of insects of both medical and economic significance at international airports.