590 
MR. G. H. DARWIN ON PROBLEMS CONNECTED 
The great line of coast running from North Africa by Spain to Norway has a 
decidedly north-easterly bearing, and the long Chinese coast exhibits a similar ten¬ 
dency. The same may be observed in the line from Greenland down to the Gulf of 
Mexico, but here we meet with a very unfavourable case in Panama, Mexico, and the 
long Californian coast line. 
From the paucity of land in the southern hemisphere the indications are not so 
good, nor are they very favourable to these views. The great line of elevation which 
runs from Borneo through Queensland to New Zealand might perhaps be taken as an 
example of north-westerly trend. The Cordilleras run very nearly north and south, 
but exhibit a clear north-westerly twist in Tierra del Fuego, and there is another 
slight bend of the same character in Bolivia. 
But if this cause was that which principally determined the direction of terrestrial 
inequalities, then the view must be held that the general position of the continents 
has always been somewhat as at present, and that, after the wrinkles were formed, the 
surface attained a considerable rigidity, so that the inequalities could not entirely 
subside during the continuous adjustment to the form of equilibrium of the earth, 
adapted at each period to the lengthening day. With respect to this point, it is 
worthy of remark that many geologists are of opinion that the great continents have 
always been more or less in their present positions. 
An inspection of Professor Schiapparelli’s map of Mars,* I think, will prove that 
the north and south trend of continents is not something peculiar to the earth. In 
the equatorial regions we there observe a great many very large islands, separated by 
about twenty narrow channels running approximately north and south. The northern 
hemisphere is not given beyond lat. 40°, but the coast lines of the southern hemisphere 
exhibit a strongly marked north-westerly tendency. It must be confessed, however, 
that the case of Mars is almost too favourable, because we have to suppose, according 
to the theory, that its distortion is due to the sun, from which the planet must always 
have been distant. The very short period of the inner satellite shows, however, that 
the Martian rotation must have been (according to the theory) largely retarded; and 
where there has been retardation, there must have been internal distortion. 
The second problem which is considered in the first part of the present paper is 
concerned with certain secondary tides. My attention was called to these tides by 
some remarks of Dr. Jules Garret, t who says 
“ Les actions perturbatrices du soleil et de la lune, qui produisent les mouvements 
coniques de la precession des equinoxes et de la nutation, n’agissent que sur cette 
portion de l’ellipsoide terrestre qui excede la sphere tangente aux deux poles, 
c’est-a-dire, en admettant l’etat pateux de l’interieur, a peu pres uniquement sur ce 
* ‘ Appendice alle Memorie della Societa deg’li Spettroscopisti Italiani,’ 1878, vol. vii., for a copy of 
which I have to thank M. Schiapparelli. 
t Societe Savoisienne d'Histoire et d’Archeologie, May 23, 1878. He is also author of a work, ‘ Le 
Deplacement Polaire.’ I think Dr. Carret has misunderstood Mr. Evans. 
