Pagina:Scientia - Vol. VII.djvu/263

the “canals„ of mars 255

strictly seasonal change, as really as the polar caps themselves. Mr Lowell observed with a refractor of 18 inches aperture.

VII. — In the opposition of 1909, M. Antoniadi observed Mars with the 33 inch refractor of the Mendon Observatory. The results of his observations will be referred to later.

The progress of the telescopic scrutiny of the planet Mars has therefore shown us a certain analogy to our own Earth. Each of its two poles is covered during its winter by a bright white substance stretching for a great distance, which may naturally be conceived to be snow. The rest of the planet is diversified with brighter and darker markings; the brighter being as a rule of a reddish ochre colour, and usually assumed to be land; whilst the darker spots, which are of a bluish-green or bluish-grey tint, were at one time supposed to represent water. But in addition to these a feature has been recognised which has no complete analogue in our terrestrial experience. «The surface of the planet is very curiously meshed by a fine network of lines and spots»; the lines being those to which Schiaparelli has given the name of «canali», the spots those that Lowell has termed «oases». It is with this network of lines and spots, i. e. of «canals» and «oases», that the present paper is concerned.

In the last number of «Scientia», Vol. VII, pages 4 and 5, Mr Lowell thus describes the appearance of these lines and spots:

«29. The lines of the network are each wonderfully straight, as if they had been laid down with the utmost regularity.
«30. They run into one another at definite points, sometimes as many as fourteen converge into one of these junctions.
«31. Each is of the same width throughout, so far as we may observe.
«32. They differ however as between themselves some being much larger and more prominent than others.
«33. Their average width is apparently from ten to fifteen miles, certainly not more, and of the finer sort running down to a mile or two.
«34. At the places where they meet are small, round, dark spots, which have been called oases by the writer.