Pagina:Scientia - Vol. VII.djvu/262

254 scientia

IV. — In the opposition of 1864-5, the Rev. W. R. Dawes, observing with a telescope of 8 inches aperture, noted that in addition to the two bright white caps round the poles, there were white spots at other points of the surface. He also noted that the «seas», or dark regions of the planet, were not uniform in tone, and that the «lands» or bright regions were crossed by several long narrow lines.

V. — During the opposition of 1877, Mars was observed by a great number of astronomers, but by far the most important work was that accomplished by Schiaparelli, who continued his observations much longer after the planet had passed opposition than any other observer. It was partly in consequence of this perseverance that he detected that the bright equatorial regions of the planet were crossed by a number of narrow lines, similar to those which Dawes had shown, and mostly lying along meridians. To these lines he gave the name «canali» in conformity with the type of nomenclature adopted by previous areographers, who had divided Mars into seas, continents, islands, isthmuses, straits, and the like. But as Schiaparelli was himself careful to point out, these designations «were not intended to prejudge the nature of the spots, and were nothing but an artifice for helping the memory and shortening descriptions». And he added «we speak in the same way of the lunar seas although we well know that there are no true seas on the Moon».

The discovery of the «canals» in 1877, was the achievement of Schiaparelli that ranks the highest in popular esteem. But in the regard of astronomers, an even greater work was his micrometric triangulation of the surface of the planet; the determination of the areographic coordinates of 62 fundamental points. This work, by one who was a master in the use of the micrometer, was continued in the following oppositions, and is by far the most valuable basis that we have, for the exact delineation of the Martian surface.

VI. — In 1894, Mr Percival Lowell commenced at Flagstaff, Arizona, that persevering study of Mars which he has continued to the present time. The chief results, obtained by him, have been the detection of many new «canals», the discovery of a number of round dots, termed by him «oases» at the junctions of the «canals», and the demonstration that the «canals» and certain of the dusky regions are subject to