Mars and Its Canals

At the opposite end of the series stands the Djihoun. As the Ganges is the widest of the instantly impressive doubles, so the Djihoun is the narrowest the eye has so far been able to make out. Only two fifths of the width of the Ganges pair, this slender double is very nearly at the limit of resolvability. So well proportioned are its lines to the space between them, however, that in ease of recognition it surpasses many wider pairs. In form, too, it is distinctive, turning by a graceful curve the trend of the Margaritifer Sinus into the Lucus Ismenius. With its fundamental branch—the northern of the two—it joins what is evidently the main line of the Protonilus—also the northern one—to the Margaritifer Sinus’s tip.

It differs from the Ganges in some other important particulars besides width. In its case no band of shading distinguishes it at any time. It has always been two lines whenever it has been seen other than as a single penciling; the only confusion about it being evidently our own atmosphere’s affair. These two lines, furthermore, have showed, within the errors of observation, always the same distance apart. So that not only no change of intercommunication between the lines but no change in their places apparently occurs.

Between these extremes in width, two hundred miles more or less for the Ganges and seventy-five miles for the Djihoun, the distance parting the pairs of most of the double canals lies. From 3° to 3°.2 on the planet may be taken as that of the average; the degrees denoting latitudinal ones on the surface of Mars, the length of which is equal to thirty-seven of our English statute miles.

Most of the canals conform apparently to the type of the Djihoun rather than to that of the Ganges. Careful consideration of them fails to find any increase or decrease of distance, between the pairs of the same canal at different times, which cannot be referred to errors inevitable to observation of such minute detail. In short, the double is made by the addition of a second line in a particular position and not by a growth out to it of a line coincident to begin with with the first.

I have said that the average width between the two lines of the doubles was about 3°. It must not be supposed that this average width denotes anything more than an average; or, in other words, that it denotes anything in the nature of a norm. The remark is important in view of a suggestion which I have heard made that we have here a system based on fundamental Martian units, in which, or in multiples of which, the dimensions of the canals are implicitly expressed. Such, however, does not seem to be the case. In some instances, indeed, we have certain evidence to the contrary and that the width of the double is conditioned solely by antecedent place. The Phison and Euphrates offer a case in point. These two important arteries in duplicate leave, as we saw, from two carets in the Mare Icarium, the Portus Sigaei, held in common tenancy by both. Each pair then proceeds down the disk inclined at its own particular angle to the meridian in order to reach by a great circle course a certain spot; the Pseboas Lucus in one case, the Luci Ismenii in the other. As one of these angles is thirty-five degrees while the other is only three, they must, from the circumstances of their setting out, have not only different widths, but widths determinately different in advance, since each is, roughly speaking, foreshortened by the degree of divergence from the meridian. The one, therefore, must be about four degrees to the other’s something less than three and a half. This is what they actually are as determined by measurement from observation. That the calculated value agrees with that found from observation helps certify to a community of starting-points, but it completely does away with comprehensive design in the question of their widths. For if the one were so settled, the other could not be.

Indeed, the next example seems to deny it to both. This example occurs, too, not far away from the scene of the first, in the twin bays of the Sabaeus Sinus, from which depart, mutatis mutandis, the double Hiddekel and the two Gihon. These twin gulfs bear so little imprint of being other than natural formations, that they have been universally and very likely quite rightly taken for such ever since Dawes discovered them in 1859, long before things like canals were dreamed of. It is strange that when the Hiddekel and the Gihon were found by me to be double in 1897, with a branch of both leading from each bay, the connection between the sceptically scouted doubles and the thoroughly believed-in bays should have been apparent. For to link a ghost to materiality, if it does not discredit the materiality, serves to substantialize the ghost. Furthermore, it shows that in this case neither the one double nor the other can have had its width engineered on any preconceived scale, unless the twin bays be themselves so accounted for. So that it seems useless to seek for cryptic standards in the canals or to think to find them a measure of value from the fact of their being a medium of exchange.

A third instance of the same thing in the case of the Ganges and the Jamuna was proved at the last opposition after having long been suspected without my being able to make sure of it. These instances, taken in connection with the wide range of values in the widths presented by different canals, serve to show that the distance between the twin lines is an individual characteristic of the particular canal, and further to point to its cause, in some cases certainly and possibly in all, as topographical. The duplicate line makes a convenience of a neighbor, and suits its distance from its fellow to friendly feasibility. To cut a ‘canal’ to conform to the country seems logical if not obligatory, and quite in keeping with the nomenclature of the subject; but here the starting-point appears to be the only thing considered—the canal once safely launched being left to shift, or rather not shift, for itself.

IV

Topography thus introduced to our notice for its effect on the breadth of the doubles proves upon inspection to be of extended application to the whole subject. Examined for position these canals turn out to have something to say for themselves bearing on the question of their origin and office.

With regard to position, probably the first query to suggest itself to an investigator to ask is of the direction in which they run. Is there a preponderance manifest in them for one direction over another? Do they show an inclination to the vertical, to the horizontal, or to some tilt between? To answer this we may box the compass, and taking the four cardinal points with the twelve next most important points between for sectional division segregate the doubles according to their individual trend. As we have no means of determining in which sense any direction is to be taken,—if indeed it is not to be taken alternately in each,—we get eight compartments into one or the other of which all the doubles must fall. This they do in the following manner:—

* Wide canals.

† Northern hemisphere exclusively.

‡ Southern hemisphere exclusively.

No conclusively marked preponderance for one direction over another manifests itself by this partitionment. Nevertheless, a certain trend to the east of north, as against the west of north, is discernible. More than twice as many doubles run northeast and southwest or within forty-five degrees of this as do similarly northwest and southeast, there being twelve of the latter and twenty-six of the former. That this seems to mean something the nearly equal pairing of quadrantal points goes to show. Thus:—

a fairly equable division in direction. A trend to the westward would be given a particle descending from the north to the equator by the planet’s rotation, thus turning it southwesterly; and one to the west to a particle travelling equatorwards from the south, turning it northwesterly. As the doubles lie in the northern hemisphere, either in whole or part, to the extent of 93%, this might account for the preponderating tilt to the east of north and west of south exhibited by them. It would correspond with the lines of flow.

To see whether this be so we will take only those double canals that lie exclusively in the northern and southern hemispheres respectively, and note those in the former that trend to the west of south as against those that run to the east of it, and vice versa in the southern. In the northern the proportion of the westerly to the easterly ones is 17 to 4; in the southern, 1 to 0 the other way.

Of those whose course is common to both hemispheres we find for the ratio of the southwesterly to the southeasterly 8 to 7. But the proportion of the course of these canals in the two hemispheres is on the side of this same ratio.

From their direction we now pass to consideration of their distribution in longitude. It appears that some meridians are more favored than others. The hemisphere which has the Syrtis Major for centre is more prolific in them than its antipodes. From longitude 80° to 200° there are ten doubles, from 200° to 320° twenty-four, and from 320° to 80° seventeen; or, roughly, in the proportion of 2, 5, and 3. That this distribution means anything by itself is doubtful; it is much more likely to be a general topographical consequence of their distribution in another direction, which proves to be highly significant and which we shall now expose—that of latitude.

If we separate the surface into zones, each ten degrees wide, and count the doubles found traversing in whole or part the several zones, we find the following arrangement:—

From this tabulating of them it is apparent that the doubles are practically confined to the zones within forty degrees of the equator. Only 7% of them straggle farther north than this, while above 63° north latitude and 35° south latitude there are none. Such a distribution is not in proportion to the areas of the zones, which though diminishing toward the poles do so at no such rate. The surface included between the equator and 40° of latitude is 65% of the hemisphere, whereas the fraction of the number of doubles found there is 93%. The doubles are, then, an equatorial feature of the planet, confined to the tropic and temperate belts.

To perceive the tropical character of the doubles in another way we have but to consider the zonal distribution of the single canals. Unlike the former the latter do not thin out as one advances toward the poles; since in the arctic regions single canals bemesh the surface as meticulously as elsewhere. It is only that they there replace the doubles; or, not to put the cart before the horse, it is the doubles that in part replace the singles in the tropics. And that this arrangement has something physical behind it by way of cause is curiously shown by two canals, the Arnon and the Kison, which are neither of the one kind nor yet the other, but a cross between the two. For the Arnon and the Kison are convergent doubles; the two lines of the Kison leaving a common point at the edge of the polar cap and separating as they travel south, while the two Arnon take up and continue the divergence, connecting at last with the parallel pair of the Euphrates. These canals thus make transition between the true doubles and the true singles, and may be looked upon as endowed with the potentialities of both. From their association with the double Euphrates, it is clear that the transition between the two forms is not only formal but physical, and that the stopping of the dual condition at the fortieth parallel is not the outcome of chance.

It may occur to the thoughtful that the doubles appear confined to the more tropical portions of the planet because of a better presentation of those zones, the reader supposing the planet to be seen axised perpendicularly to the plane of sight, as geographies represent the earth’s globe. The supposition, however, is erroneous. We sometimes see the planet so, but more often not. Such is the tilt of the Martian axis to the plane of the Martian ecliptic that the different zones are rarely seen on an even keel, so to speak, their aspects shifting totally from one opposition to another. What shows in mid-disk on one occasion may be forty-eight degrees removed from it at another, a distance amounting to three-quarters of the way from apparent equator to apparent pole.

Thus the double canals are for some intrinsic reason equatorial features of the planet as opposed to polar ones. And this not simply because of greater space there. Duality is a result of conditions intrinsic to the several localities. What the cause may be is related to the character of the things themselves, which we shall later consider. For the moment we may note that the fact disposes quietly of the diplopic theory of their manufacture. For, for diplopic doubles to show such respect for the equator would betoken a courtesy in them to be commended of Sydney Smith.

But this is not their only geographic bias. In addition to not being partial to the poles, the double canals show a certain exclusiveness toward the dark areas generally. Not only do they avoid the arctic and antarctic zones entirely, but they largely shun the blue-green regions. In these but two suspicions of doubles occur, in the Aonium Sinus, although single canals there are as numerous as anywhere else on the planet.

Nevertheless, although they avoid running through them, they run from them in a manner that is marked. Proceeding from the great diaphragm are no less than 28 out of the 53 doubles. Connecting directly with these are 17 more; while the remaining 8 are also associated through the intermediarism of dark areas, the Solis Lacus and the Trivium.

In like relation to dark regions, they are limited on the north by the Mare Acidalium, the Propontis, the Wedge of Casius and their interconnecting bands, the Pierius, Callirrhoe, Helicon. In this manner do they form a broad girdle round the planet’s waist, leaving the polar extremities bare.