II
Now, the first point to be noticed about the doubles is that bilateralism, or the quality of being double, is not a universal trait of the canals, either actually or potentially; it is not even a general one. Out of the four hundred canals seen at Flagstaff, only fifty-one have at any time displayed the quality; that is, one eighth roughly of the whole number observed. This point is most important; for the fact is of itself enough to disprove any optical origin for the phenomenon. The characteristic of doubling so confidently ascribed by those who have not seen it to general optical or ocular principles proves thus the exception, not the rule, with the canals, and by so doing disowns the applicability of any merely optical solution. We shall encounter many more equally prohibitive bars to illusory explanation before we have done with the doubles, but it is interesting to meet one in this manner at the very threshold of the subject.
On the other hand, the characteristic when possessed is persistent in the particular canal, in posse if not in esse. Once shown by a canal, that canal may confidently be looked to at a proper time to disclose it again. In short, bilateralism, or the state of being dual, is an inherent attribute of the individual canal, as idiosyncratic to it as position and size.
The catalogue of canals possessing this property, so far as they have been detected at Flagstaff to date, number fifty-one if we include in the list wide parallels like the Nilokeras I and II. Eight of these were observed in 1894; nineteen more were added in 1896, making twenty-seven; in 1901 the total was raised to thirty; in 1903 to forty-eight; and in 1905 to fifty-one. Arranged by years they are tabulated below, where the numeral to the left registers for each its first recording and the position held by it in the list. The starred canals much exceed the others in width, and possibly denote a different phenomenon.
In spite of possessing the property of pairing, a canal may not always exhibit it. To the production of the phenomenon the proper time is as essential as the property itself. So far as a primary scanning or first approximation is capable of revealing, a canal will be single at one Martian season and double at another. Thus these canals alternated in their state to Schiaparelli and for the earlier of his own observed oppositions to the writer. In consequence Schiaparelli deemed gemination a process which the canal periodically underwent. Three stages in the development were to him distinguishable: the single aspect, a short confused aspect, and the clearly dual one.
In the single state the canal remained most of the time. It then underwent a chrysalid stage of confusion to emerge of a sudden into a perfect pair. Furthermore, he noted the times at which the pairing took place, to the formulating of a law in the case—derived from the observations of more than one opposition. His law was that the gemination occurred, on the average, three months (ours) after the summer solstice of the northern hemisphere, lasted four to five months, then faded out to begin afresh one month after the vernal equinox of the same hemisphere and continue for four months more. Expressed in Martian seasonal chronology, the periods would be about half as long. At certain times then the most pronounced specimens of doubles showed obstinately single, while the periodic metamorphosis that transformed them into duplicates was timed to the changes of the planet’s year. Gemination, then, was a seasonal phenomenon.
Advance in our knowledge of the phenomenon since Schiaparelli’s time, while still showing the thing to be of seasonal habit, has changed our conception of it. It now appears that in some cases certainly, and possibly in all, the dual aspect is not a temporary condition, but the differing pronouncement of a permanent state, the fact of gemination so called being confined to a filling out of what is always skeletonly there. As the canals have come to be better seen, the three stages of existence have in some cases become recognizable as only different degrees in discernment of an essential double condition; the single appearance being due to the relative feebleness of one of the constituents and the confused showing to the weakness of both, which are then the more easily blurred by the air waves. In certain canals the last few oppositions, 1901, 1903, and 1905, have disclosed this unmistakably to be the case, as with the Phison and Euphrates, for example. With them the double character has been continuously visible, appearing not only when by Schiaparelli’s law it should, but at the times when it should not; only on these latter occasions it was harder to see, whence the reason it was previously missed. So that further scrutiny, while in no sense discrediting the earlier observations, has extended to them some modification, and disclosed the underlying truth to be the varying visibility, the thing itself, except for strength in part or whole, persisting the same. Improvement in definition has lowered the see-level to revelation of continuous presence of the dual state. It is only on occasion that the improvement is sufficient for the thing when at its feeblest to loom thus above the horizon of certainty; yet at such moments of a rise in the seeing it is enough to allow it to be glimpsed. Thus it fared with the Adamas at the opposition of 1903, with the Gigas, and with many another in years gone by. Separation has come with training and generally in the case of the wider doubles, which leads one to infer that ease of resolution is largely responsible for assurance of the permanency of the dual state. Perplexing exceptions, however, remain, so that it is possible at present only to predicate the principal of most of the double canals but not of all. Leaving the exceptions out of account for the moment, we pass to those general characteristics which are intimately linked with what has just been said.
Inasmuch as the act of getting into a state antedates the fact of being there, it is logical to let the description of the first precede. An account of the process of gemination may thus suitably come before that of its result.
Flux, affecting the double canals in whole or part, is the cause of the apparent gemination. According as the flux is partitive or total is a single or a dual state produced. At the depth of its inconspicuousness the canal may cease to be visible at all; this occurs when both lines fade out. On the other hand, the one line may outfade the other, and we are presented with a seemingly single canal, at this its minimum showing. In such seasons of debility the one line may appear and the other not, or occasionally the other show and the one not, according to the air waves of the moment. It is at these times that the double simulates a single canal, and unless well seen and carefully watched might easily masquerade successfully as such. The Hiddekel in the depth of its dead season is peculiarly given to this alternately partitive presentation. As the flux comes on, one or both lines feel it. If one only we are likely to have a confused canal; if both, a difficult double. The strength of the lines increases until at last both attain their maximum, and the canal stands revealed an unmistakable pair, the two lines paralleling one another in appearance as in position.
At the canal’s maximum and minimum the equality of its two constituents is chiefly to be remarked, though it occurs on other occasions as well. But, what is significant, when the two differ it is always the same one that outdoes its fellow. It may be the right-hand twin in one pair, the left-hand one in another; but whichever it be, for the particular canal its preëminence is invariable. It is this canal which, except for adventitious help or hindrance from the air-waves, alone shows when the double assumes the seemingly single state. We may therefore call it the original canal, the other being dubbed the duplicate. In some cases it has been possible to decide which is which. It might seem at first sight as if this point should always be ascertainable. But the determination is more dilemmic than appears, not from any difficulty in seeing the canal, but from the absence of distinguishing earmark at its end. In a long stretch of commonplace coast, the precise point of embouchure of a solitary canal cannot be so certainly fixed as to be decisive later between two which show close together in the same locality. It is only where some landmark points the canal’s terminal that the problem admits of definite solution. This telltale tag may be a bay like the Margaritifer Sinus, or double gulfs like the Sabaeus Sinus, or portions of a marking not too large to permit of partitive location like the Mare Acidalium, or a canal connection like the Tacazze which prolongs the one line and not the other. In these and similar instances the two lines become capable of identification, and in such manner have been found those comprised in the following list:—
| Double Canal | Original Line | Date of Ascertainment |
| Phison | The Eastern | 1894 |
| Euphrates | The Western | 1894 |
| Titan | The Western | 1896 |
| Hiddekel | The Eastern | 1896 |
| Gihon | The Western | 1896 |
| Gigas | The Northwestern | 1896 |
| Djihoun | The Western | 1901 |
| Laestrygon | The Eastern | 1903 |
| Nilokeras I and II | The Northern | 1903 |
| Astaboras | The Southern | 1903 |
| Jamuna | The Eastern | 1905 |
| Ganges | The Western | 1905 |
In this list of originals the canals stand chronologically marshaled according to date of detection. The Phison and Euphrates were the first to permit of intertwin identification in 1894, while the Jamuna and Ganges were the last to be added to the column in 1905. The list is not long, though the time taken to compile it was. In the case of the Ganges and the Jamuna, for example, although suspected for some time on theoretic grounds, it was only at the opposition just passed that the fact was observationally established. In his Memoria V, Schiaparelli has a list of similar detection, and if the present list be compared with his, the two having been independently made, the concordance of the result will prove striking, corroborative as it is of both. For the necessary observations are very difficult.
Having thus realized the original by means of its superior showing, and then identified it by its position, it is suggestive to discover that the duplicate betrays its subordinate character, not only by its relative insignificance, but by its secondary position as well. The original always takes its departure from some well-marked bay, seemingly designated by nature as a departure-point, or from a caret belonging clearly to itself; the adjunct, on the other hand, leaves from some neighboring undistinguished spot, as in the case of the additional Djihoun, or makes use of a neighbor’s caret, as in the case of the second Phison and the supplementary Euphrates. In either case it plays something of the part of an afterthought; and yet the postscript when finished reads as an integral part of the letter. An example will serve to make the connection evident while leaving the character of the connection as cryptic as ever.
In the long stretch of Aerial coastline bounding the Mare Icarium, which sweeps with the curve of a foretime beach from the Hammonis Cornu to the tip of the Edom Promontory, there stand halfway down its far-away seeming sea-front two little nicks or indentations. Even in poor seeing they serve to darken this part of the coast while in good definition they come out as miniature caret-like bays. They are the Portus Sigaei, and mark the spots where the Phison and the Euphrates respectively leave the coast. About four degrees apart, the eastern makes embouchure to the original Phison, the western to the original Euphrates, and each in some mysterious manner is associated not only in position but in action with the canal itself. In the single state each canal leaves the Mare from this its own caret, the Phison proceeding thence northeast down the disk, the Euphrates nearly due north, so that starting four degrees apart at the south they are forty degrees asunder at their northern termini. Clearly at these latter points they are not even neighbors, and except for the accident of close approach at their other ends have nothing in common anywhere. And yet when gemination takes place a curious thing occurs: each borrows its neighbor’s terminal as departure-point for its own duplicate canal. Having thus got its base the replica proceeds to parallel its own original canal without the least reference to the other canal whose own caret it has so cuckoo-wise appropriated. What the Phison thus does to the Euphrates, the Euphrates returns the compliment by doing to the Phison. In this manner is produced an interrelation which suggests, without necessarily being, an original community of interest; suggests it on its face and yet appears to be rather of the nature of an adaptation to subsequent purposes of a something aboriginally there.
Mouths of Euphrates and Phison.
June. 1903.
That such latter-day appropriation is the fact is clearly hinted by the behavior of another understudy of an original canal, in this case the duplicate of the Djihoun, which in consequence of the position of its original finds no neighboring embouchure already convenient to its use. The single or original Djihoun leaves the tip of the needle-pointed Margaritifer Sinus, which serves a like end to the Oxus and the Indus, both single canals. The Sinus is itself a single bay, and so large that for many degrees its shores on both sides converge smoothly to their sharp apex. Because of this probably, the coast in the immediate neighborhood is without canal connection, no canal being known along either side till one reaches the Hydraotes at the Aromaticum Promontorium, which marks the western limit of the gulf. The consequence is that when the Djihoun doubles, the duplicate canal, not having any terminus ready to its hand, has to make one for itself by simply running into the Margaritifer Sinus, some distance up its eastern side. It thus advertises its adjunctival character, and at the same time the general fact that a neighbor’s terminus, though used from preference, when convenient, is not an essential in the process. Gemination occurs of its own initiative, but is conditioned by convenience.
Whether one canal shows thus to the exclusion of the other, or whether both stand so confused as not to be told apart, the fact remains that the double is not always recognizable as such. If we turn to the list of the doubles on page [222], we shall note that the same canals were not always seen in the dual condition at successive oppositions. Some, indeed, are so emphatically of the habit as to appear year after year in a paired state, but others are not so constant to their possibilities. Now, when it is remembered that at different oppositions we view Mars at diverse seasons of its tropical year, we see that this means that the phenomenon is seasonal; and furthermore that its exhibition depends upon the canal’s position. Gemination, like the showing or non-showing of the single canal, is conditioned by the place of the canal upon the planet.