Besides the splendid photographs of Mars, many views of Jupiter and Saturn were shown, exhibiting clearly numerous fine details, markings, and wisps as to which much doubt had been expressed when some observers had shown them on their drawings. These beautiful and convincing results of the clever and original methods of planetary photography adopted at Flagstaff appeared to come as a complete revelation to the majority of those present, notwithstanding their scientific experience. Probably never before had anything so wonderful as these results of skill, patience, and prolonged research been exhibited, even in that great and historic home of science. As Professor Lowell remarked in a fine peroration: "They exhibited something of the advance recently achieved in our knowledge of solar science; on the other hand, they constituted in themselves the beginning of a set of records in which the future of the planet might be confronted with its achieved past, and which should endure after those who first conceived such registry had long passed away.... They were histories of the planets written by themselves--their autobiographies penned by light; and in their grand historical portrait-gallery astronomers yet to come might see the earlier stages of the great cosmic drama which was slowly but surely working itself out!" At the conclusion of this most interesting lecture M'Allister turned to me and said, "How I wish our old friend the Professor could have been here to-night; he would have keenly appreciated what we have heard." "Yes, he would indeed," I answered; "but remember, he knows more now than any one we see here could tell him about Martian matters!" Before concluding, it may be of interest to state that Professor Lowell still maintains the accuracy of the discovery made at Flagstaff that the existence of water vapour on Mars is demonstrated by the photographic spectrum of the Martian atmosphere; and he asserts that the attempt to disprove it has failed. A further discovery has since been made at the same observatory, viz. that oxygen also is present in the atmosphere of Mars! During the observations in 1909 several observers noted that, at times, very large areas on the surface of Mars had been so obscured by a yellowish veiling that all details were entirely blotted out. The announcement of this fact gave rise to sensational statements that a terrible catastrophe had occurred on the planet. The explanation is, however, very simple--seasonal mists arising from the canals, with the addition of clouds of sand particles in the upper air, as the result of desert sandstorms, caused a temporary obscuration of certain parts of the planet as viewed from the earth. Only this, and nothing more!