Professor Todd, Director of the Astronomical Observatory at Amherst College, in his book on Stars and Telescopes, in referring to drawings of a region in the southern portion of Mars, known as the Solis Lacus, and a complicated drawing of another region, says: "Whether one views this marvellous and intricate system as a whole, or in some portion of high detail, it is difficult to escape the conviction that the _canali_ have, at least in part, been designed and executed with a definite end in view." There are many who do not deny the existence of some forms of life on the planet, but are not prepared to admit the existence of intelligent creatures. Sir Robert Ball expresses himself as follows: "That there may be types of life of some kind on Mars is, I should think, quite likely." The number of astronomers above quoted, who have seen and drawn the canals, might be augmented, but a sufficient number have been cited to show that the evidence of the presence of these markings does not rest with a few, furthermore, some of these observers can only interpret the markings as the result of intelligent action. It may be urged that among those quoted are some whose opinion may not have great weight since they are not professional astronomers. One must insist that the study of planetary markings as well as the interpretation of their meanings comes not only within the province of planetary astronomers, but that any broad-minded man, with an acute eye and familiar with the sciences connected with the surface features of the Earth, is quite competent to make observations of his own and to judge of the merits of the question. VI THE STUDY OF PLANETARY MARKINGS _Their singular aspect, and the fact that they are drawn with absolute geometric precision as if they were the product of rule and compass, have induced some people to see in them the work of intelligent beings, inhabitants of the planet. I should be careful not to combat this supposition which involves no impossibility._ SCHIAPARELLI.