November 22, 1894J 



NA TURE 



89 



The Canals or Chanmels. 



All the vast extent of the continents is' furrowed upon every 

 side by a network of numerous lines or fine stripes of a more or 

 less pronounced dark colour, whose aspect is very variable. 

 These traverse the planet for long distances in regular lines, 

 that do not at all resemble the winding courses of our streams. 

 Some of the shorter ones do not reach 500 kilometres (300 

 miles), others on the other hand extend for many thousands, 

 occupying a quarter or sometimes even a third of a circum- 

 ference of the planet. Some of these are very easy to see, 

 especially that one which is near the extreme left-hand limit of 

 our map, and is designated by the name of Nilosyrtis. Others 

 in turn are extremely difficult, and resemble the finest thread of 

 spider's web drawn across the disc. They are subject also to 

 great variations in their breadth, which may reach 200 or even 

 300 kilometres (120 to 180 miles) forthe Nilosyrtis, whilst some 

 are scarcely 30 kilometres (18 miles) broad. 



These lines or stripes are the famous canals of Mars, of 

 which so much has been said. As far as we have been able to 

 observe them hitherto, they are certainly fixed configurations 

 upon the planet. The Nilosyrtis has been seen in that place 

 for nearly one hundred years, and some of the others for at 

 least thirty years. Their length and arrangement are constant, 

 or vary only between very narrow limits. Each of them always 

 begins and ends between the same regions. But their appear- 

 ance and their degree of visibility vary greatly, for all of them, 

 from one opposition to another, and even from ore week to 

 another, and these variations do not take place simultaneously 

 and according to the same laws for all, but in most cases 

 happen apparently capriciously, or at least according to laws 

 not sufficiently simple for us to be able to unravel. Often one 

 or more become indistinct, or even wholly invisible, whilst 

 others in their vicinity increase to the point of becoming con- 

 spicuous even in telescopes of moderate power. 



Every canal ' (for now we shall so call them) opens at its ends, 

 either into a sea, or into a lake, or into another canal, or else 

 into the intersection of several other canals. None of them 

 have yet been seen cut off in the middle of the continent, 

 remaining without beginning or without end. This fact is of 

 the highest importance. The canals may intersect among them- 

 selves at all possible angles, but by preference they converge 

 towards the small spots to which we have given the name of 

 lakes. For example, seven are seen to converge in Lacus 

 Phtenicis, eight in Trivium Charontis, six in Lunse Lacus, and 

 six in Ismenius Lacus. 



The normal appearance of a canal is that of a nearly uniform 

 stripe, black, or at least of a dark colour, similar to that of the 

 seas, in which the regularity of its general course does not ex- 

 -elude small variations in its breadth, and small sinuosities in its 

 two sides. Often it happens that such a dark line opening out 

 upon the sea is enlarged into the form of a trumpet, forming a 

 huge bay, similar to the estuaries of certain terrestrial streams. 

 The Margaritifer Sinus, the Aonius Sinus, the Auroras; Sinus, 

 and the two horns of the Sab.xus Sinus are thus formed, at the 

 mouths of one or more canals, opening into the Mare Ery- 

 thr.-eum or into the Mare Auslrale. The largest example of 

 such a gulf is the Syrtis Major, formed by the vast mouth of the 

 Nilosyrtis, so called. This gulf is not less than 1800 kilometres 

 {ivx> miles) in breadth, and attains nearly the same depth in 

 ■a longitudinal direction. Its surface is little less than that oi 

 the Bay of Bengal. In this case we see clearly the dark surface 

 of the sea continued without apparent interruption into that of 

 the canal. Inasmuch as the surfaces called seas are truly a 

 liquid expanse, we cannot doubt that the canals are a simple 

 prolongation of them, crossing the yellmv areas or continents. 



Of the remainder, that the lines called canals are truly great 

 furrows or depressions in the surface of the planet, destined for 

 the passage of the liquid mass, and constituting for it a true 

 hydrographic system, is demonstrated by the phenomena which 

 ■are observed during the melting of the northern snows. We 

 have already remarked that at the time of melting they appeared 

 surrounded by a dark zone, forming a species of temporary sea. 

 At that time the canals of the surrounding region become 

 blacker and wider, increasing to the point of converting, at a 

 certain time, all of the yellow region comprised between the 

 edge of the snow and the parallel of 60" north latitude, into 

 numerous islands of small extent. Such a slate of things does 

 not cease, until the snow, reduced to its minimum area, ceases 



1 The correct Iransl.ilion of the Italian word idHrt/f, used with reference 

 to the streaks on Mars, is channel or strait, and not canal. 



NO. 1308, VOL. S'] 



to melt. Then the breadth of the canals diminishes, the tem- 

 porary sea disappears, and the yellow region again returns to its 

 former area. The different phases of these vast phenomena are 

 renewed at each return of the seasons, and we have been able 

 to observe them in all their particulars very easily during the 

 oppositions of 1882, 1884, and 18S6, when the planet presented 

 its northern pole to terrestrial spectators. The most natural 

 and the most simple interpretation is that to which we have 

 referred, of a great inundation produced by the melting of the 

 snows — it is entirely logical, and is sustained by evident analogy 

 with terrestrial phenomena. We conclude, therefore, that the 

 canals are such in fact, and not only in name. The network 

 formed by these was probably determined in its origin in the 

 geological state of the planet, and has come to be slowly 

 elaborated in the course of centuries. It is not necessary to 

 suppose them the work of intelligent beings, and notwithstand- 

 ing the almost geometrical appearance of all of their system, 

 we are now inclined to believe them to be produced by the 

 evolution of the planet, just as on the Earth we have the 

 English Channel and the Channel of Mozambique. 

 The Gemination of the Canals. 



The most surprising phenomenon pertaining to the canals of 

 Mars is their gemination, which seems to be produced princi- 

 pally in the months which precede, and in those which follow 

 the great northern inundation, at about the times of the equi- 

 noxes. In consequence of a rapid process, which certainly 

 lasts at most a few days, or even perhaps only a few hours, and 

 of which it has not yet been possible to determine the par- 

 ticulars with certainty, a given canal changes its appearance, 

 and is found transformed through all its length, into two lines 

 or uniform stripes, more or less parallel to one another, and 

 which run straight and equal with the exact geometrical pre- 

 cision of the two rails of a railroad But this exact course is 

 the only point of resemblance with the rails, because in dimen- 

 sions there is no comparison possible, as it is easy to imagine. 

 The two lines follow very nearly the direction of the original 

 canal, and end in the place where it ended. One of these is 

 often superposed as exactly as possible upon the former line, 

 the other being drawn anew, but in this case the original line 

 loses all the small irregularities and curvature that it may have 

 originally possessed. But it also happens that both the lines 

 may occupy opposite sides of the former canal, and be located 

 upon entirely new ground. The distance between the two lines 

 differs in different geminations, and varies from 600 kilometres 

 (360 miles) and more, down to the smallest limit at which two 

 lines may appear separated in large visual telescopes — less than 

 an interval of 50 kilometres (30 miles). The breadth of the 

 stripes themselves may range from the limit of visibility , which 

 we may suppose to be 30 kilometres (iS miles), up to more than 

 100 kilometres (60 miles). The colour of the two lines varies 

 from black to a light red, which can hardly be distinguished 

 from the general yellow background of the continental sur- 

 face. The space between is for the most part yellow, 

 but in many cases appears whitish. The gemination 

 is not necessarily confined only to the canals, but tends 

 to be produced also in the lakes. Often one of these is 

 seen transformed into two short, broad, ilark lines parallel to 

 one another, and traversed by a yellow line. In these cases 

 the gemination is naturally short, and does not exceed the limits 

 of the original lake. 



The gemination is not shown by all at the same time, but 

 when the season is at hand, it begins to be produced here and 

 there, in an isolated, irregular manner, or at least without any 

 easily recognisable order. In many canals (such as the Nilo- 

 syrtis for example) the gemination is lacking entirely, or is 

 scarcely visible. After having lasted for some months, the 

 markings fade out gradually and disappear until another season 

 equally favourable for their formation. Thus it happens that in 

 certain other seasons (especially near the southern solstice of 

 the planet) that few are seen, or even none .it all. In different 

 oppositions the gemination of the .same canal m.iy present dif- 

 ferent appearances as to width, intensity and arrangement of the 

 two stripes, also in some cases the direction of the lines may 

 vary, although by the smallest quantity, but still deviating by a 

 small amount from the canal with which they are directly asso- 

 ciated. From this important fact it is immediately understood 

 that the gemination cannot be a fixed formation upon the 

 surface of Mars, and of a geographical character like the canals. 



The observation of the geminations is one of the. greatest 

 difficulty, and can only be made by an eye well practised in 



