The following remarks are frankly speculative, and their subject one on which certainty is unlikely to be attained. It seems worth offering them because, though the conclusions are only tentative, they were reached by way of some observations which have a certain interest of their own. Anaximenes, we are told, said that the sun is flat like a leaf, and that it and the other heavenly bodies ‘ride upon’ the air owing to their flat shape, as does the earth also.