268 Joty—On the Origin of the Canals of Mars. 
its orbit to some extent, and also in drawing it down nearer to the surface of the 
planet. The latter effect will result in the orbit departing further from the sur- 
face at other points. These may indeed be but very gradual and very slight effects. 
But very gradual and slight effects favouring one direction more than another, 
that is, favouring continuance of the satellite, or its approximation to the surface, 
along this direction, will be effective if they suffice to distinguish this direction 
from among, probably, innumerable directions in which satellites have left a record 
of their presence. ‘‘ What their number may be hes quite beyond the possibility 
of count at present; for the better our own air, the more of them are visible.” 
So writes Mr. Lowell of the actual number of lines visible on the Martian disk. 
(‘‘ Mars,” p. 135.) What we see then are the incomplete fragments of curves 
and the survival of the fittest. Any cause favouring one direction, serving to 
intensify the physical effects of a satellite rotating in or near this direction, 
may be held conducive to this survival. If we suppose, now, that such a line as 
the Eumenides-Orcus is formed as a line of disturbance in the first imstance, and 
the oases formed by the crossing of secondary lines, such a manifold radiant as 
the Sinus Titanum would arise as the result of directions which favoured the 
approach or retention of a satellite or satellites; directions taking in the raised 
masses of the oases, and the coast-line elevations. An appearance resembling the 
tying of triangles in survey triangulation would thereby be produced. Future 
observations as to the actual nature of the oases and the coast features will 
throw light on this matter. Consideration of the dynamical questions involved 
will be not less important. 
It only remains for me to express the hope that others able to enter more fully 
on the many difficult matters touched upon in the course of this Paper will not 
deem the question unworthy of attention. The prize is great. Should these 
suggestions prove to have a foundation in fact, the face of Mars will have proved 
a very Principia; an open book on which is written not only confirmation of views 
on the physics of a planet’s crust which as yet must rank as speculative geology 
only, but also experimental illustration of far reaching deductions from lunar 
theory. 
