I welcome this opportunity of following in the footsteps of the eminent and erudite speakers who have given the Barnwell Memorial Lecture on previous occasions. A number of my predecessors in this role were closely associated with Captain Barnwell. Indeed, some were included among his personal friends. I cannot make any such claim, but I did have the privilege of working in association with him for brief periods during 1936 and 1937. At that time I was, in modern parlance, the Project Officer at the Royal Aircraft Establishment on the successful altitude record flights made by Sqn. Ldr. Swain in 1936 and Fit. Lt. Adam in 1937, in Barnwell's Bristol 138A mono-plane. We met on relatively few occasions but I well remember the kindly and tolerant attitude of this eminent aeronautical pioneer towards a very junior officer.

I would like to express my thanks to the Council of the Royal Aeronautical Society for inviting me to deliver this lecture. I am very happy that this honour has been extended to me: I am happy for myself, and also for my country, Barbados, one of the newest sovereign states, but one which has evolved with the British Commonwealth. Our relationship has existed since 1625 and apart from what I believe to be the first case of UDI in the British Colonial Empire in the Cromwell era, we have been stalwart members of the club.

In November 1966 Barbados became a sovereign state, the colonial days were over. From here on we have been a full member of the British Commonwealth of Nations.

It is a big honour to be invited to give this lecture in memory of that great engineer, Sir Henry Royce, but particularly so for anyone who happens to work in the Company of which he was co-founder and which of course represents the best memorial for which he could have wished.

I am very conscious of all this tonight but also, and with a distinct unease, that the Grand Old Man might be something less than sympathetic to my theme. The traditions of quality, craftsmanship and meticulous attention to detail design for which Royce is rightly famous, find, of course, their extreme justification in the construction of complex space vehicles, with their critical dependence on reliability. (There were about 15 million parts which had to work in the whole Apollo system, nearly half in the vehicle itself.) There is no doubt that he could have made immense contributions to space propulsion, as he did for land and air.

Strictly many materials such as ceramics, cement and even metals should be classed as polymers since the atoms within them are bound by strong chemical bonds into large groups usually of indefinite size. This article will deal only with the synthetic organic polymers and, in fact, will consider mainly the plastics, little attention being given to rubbers and fibres.

The industrial production of synthetic plastics has expanded greatly in the post-war years largely using petroleum as the starting material. The plastics produced do not have good mechanical properties compared, say, to metals and have other limitations such as poor resistance to heat and inflammability.

We have grown used to the idea that in the Middle Ages inventors produced several forerunners, either real or imaginary, of modern aerodynamic devices. The helicopter was designed, in principle, before Leonardo, while the rigid aerofoil, in the form of the plane-surface kite, achieved a remarkable degree of sophistication before the end of the sixteenth century. It has commonly been assumed that among these mediaeval inventions we should include some sort of three-dimensional kite, a precursor of Hargrave's box-kite, either in the form of a windsock equipped with wings, or in that of a primitive hot-air balloon, with or without additional lifting force provided by wings. I wish to examine the evidence for the existence of these objects, and to make a fresh assessment of the likelihood of their ever having flown.