The air flows past unseen as one flies. As it flows the invisible meridians and parallels pass with it, sharp but arbitrary demarcations imposed mathematically by man upon a sphere which he learned to measure long after he began to move intelligently about its surface; geographically non-existent hair lines which stubble the ends of certain radii projecting to the surface from the centre of our globe. But these same lines are cartographically displayed upon our maps, where we designate them graticules. And so the air navigator, resolving his position in the air above the surface of the earth as a mathematically unique point, knows both cartographically and geographically exactly where he is.

The views expressed are my own at the time of writing the paper and may or may not be shared by others. As any living thing such as aviation must beconstantly growing and changing slightly, I expect to have to modify my opinions in the future.

Civil primary training should endeavour to train the whole able bodied civil population to use the air as their lawful occasions demand.

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 purpose of this note is to point out that in certain simple cases an immediate solution of the problem of finding- an initial stress is provided by an inverse application of the functions tabulated by A. Berry in his work on the generalised theorem of three moments.