When the aeroplane came into being ten years ago the parachute had no place in the practical politics of aeronautics.

The extensive use of observation balloons, throughout the war, brought the life-saving capabilities of the parachute to the front.

In pre-war days the parachute was regarded almost exclusively as a medium for daring displays.

Public interest has been aroused by the fact that the lives of over 800 men were saved from balloons by parachute and many more might have been saved from aeroplanes by the provision of this simple appliance.

For the last six months of the war the Germans were using a comparatively crude type of parachute in nearly all their aeroplanes. This equipment was entirely optional. Nine out of ten pilots elected to carry them. According to the best information I can get, of the pilots who had occasion to use them, nine out of ten saved their lives.

A proper treatment of the construction and properties of airship fabrics would require a book rather than an essay. In what follows, it is possible therefore to deal briefly only with the principal types of fabrics, classified according to the main functions of each, describing their structure and behaviour and the chief factors affecting their permanence when in service. There are, then three main classes :—

I. Fabrics for the envelopes of non-rigid airships.

II. Fabrics for the gasbags of rigid airships.

III. Fabrics for the outer covers of rigid airships.

In all cases low specific weight (expressed here in grammes per square metre) is clearly of the greatest importance.

I. Fabrics of this class must possess gas-holding properties, mechanical strength and pliability. The internal pressure (equal to about 30111ms. of water) which maintains the shape of the envelope sets up in its fabric considerable tension, and this is increased by the distributed weight of the whole ship.

In this lecture it is proposed to deal with the general aerostatical principles governing the flight of lighter-than-air craft, and also to describe briefly the various types of airships, with special reference to the rigid airship.

The future of lighter-than-air craft is undoubtedly dependent upon the development of the rigid airship, in which type of ship efficiency and performance increase at a greater rate than the gross lifting capacity.

To understand the working of a large airship it is essential to have a thorough grasp of the elementary aerostatic principles governing the flight of an ordinary free balloon, so it is proposed, first, to outline these principles and then to pass on to the non-rigid, semi-rigid and rigid types of airships, all of which are virtually balloons of varying type, rendered dirigible by the fitting of means of propulsion, and navigable by the introduction of controlling surfaces.