CHAPTER XIX
CANALS IN THE DARK REGIONS
Seventeen years after the recognition of the canals in the light regions occurred another important event, the discovery of a similar set in the dark ones. The detection of these markings in the dark areas was a more difficult feat than the perceiving of those in the light, and in consequence was later accomplished. Also was it one where recognition came by degrees.
I have previously pointed out what this discovery did for the seas—nothing less than the taking away of their character in a generally convincing manner. To one who had carefully considered the matter, the seas had indeed already lost it, as was shown in Chapter X, but to those who had not these canals presented a very instant proof of the fact.
From such not wholly supererogatory service they went on to furnish unlooked-for help in other directions. Their discovery showed in the first place that no part of the planet’s surface was free from canal triangulation.
But it did more than this. For these canals in the dark regions left the edge of the ‘continents’ at the very points where the canals of the light regions entered them, which fact proved for them a community of interest with the latter. Such continuation was highly significant, since it linked the two together into a single system, compassing the whole surface of the planet. Starting from the places where the light-region canals come out upon the great girdle of seas that stretches all round the planet, most of the new canals headed toward the passes between the islands south, as nearly polewards as circumstances of local topography would permit. In the broader expanses of the Syrtis Major and the Mare Erythraeum, besides main arteries others went to spots in their midst after the same fashion as those of the light regions. These spots differed in no way apparently from their fellow oases elsewhere. From a spot in the centre of the Syrtis three great lines thus traveled south: the Dosaron, heading straight up the Syrtis on the meridian till it struck the northernmost point of Hellas; the Orosines, inclined more to the right, passing through the dark channel to the west of that land and so proceeding south; and lastly the Erymanthus turning eastward till it brought up finally at the Hesperidum Lucus. Where, on the other hand, the long chain of lighter land, called by Schiaparelli islands, and stretching from the Solis Lacus region westward to Hellas, offered only here and there an exit, the canals made for these exits. The canals in the Mare Sirenum, the Mare Cimmerium, and the Mare Tyrrhenum struck more or less diagonally across those seas from their northern termini to the entrances of the straits between the islands, thus lacing the seas in the way a sail is rolled to its spar. From the exact manner in which they connected with the light-region canals they proved the two to be part and parcel of one system, which in its extension was planet-wide and therefore proportionately important. Whatever of strange interest the curious characteristics of the canals themselves suggested was now greatly increased by this addition; for the solidarity of the phenomenon affected the cogency of any argument derived from it.
In 1894 only the dark areas of the southern hemisphere were found to be thus laced with lines. For then so great was the tilt of the planet’s south pole toward the earth, that while those zones were well displayed the dark patches of the northern hemisphere were more or less hull-down over the disk’s northern horizon.
Contrast was the open sesame to their detection. When the maria show dark, the lines are lost in the sombreness of the background. As the maria lighten the lines come out. Such was amply witnessed by the effect in 1894 and 1896. In 1894 I found it impossible to perceive them, except where the Padargus crossed Atlantis, for the hue of the maria themselves was then very dark. In 1896, on the other hand, I saw them without difficulty. What is also of interest: so soon as seen they appeared small, without haziness or distention.
As the oppositions succeeded one another the northern regions rose into view, and with their appearance came the detection in them of the same phenomena. No large dark areas like the diaphragm exist there, but the smaller patches of blue-green which bestrew them proved to be similarly meshed. At first canals were evident upon their peripheries, contouring them about; then the bodies themselves of the patches showed grid-ironed by lines.
The Mare Acidalium with its adjuncts, the Lucus Niliacus on the south and the Lacus Hyperboreus on the north, thus stood out in 1901. On a particularly good evening of definition at the end of May, the Mare suddenly made background for a sunburst of dark rays, six of them in all radiating from a point between it and the Lacus Hyperboreus. Considering how sombre the Mare was at the time, this was as remarkable a vision as it was striking to see. Although at the moment the sight was of the nature of a revelation, these lines have been amply verified since, as the Martian season has proved more propitious.