Let the line 3, 3, in the diagram, fig. I., represent that of the sea's mean level; the line 3 C, or 3 B, the sea's mean depth; the triangle B A C, a rising continent; and the internal triangles, whose apices reach the lines 3, 3, and 5, 5, respectively, its comparative bulk or volume during its various intermediate stages of elevation. When the rising triangle (i. e. continent) reaches the line 3, 3 (that of the sea-line ere the land began to rise), its mass, equal to that of the parallelogramic band 1 B C 1, shall have displaced water to that amount, and sent it to the surface, which shall have risen, in consequence, from the line 3, 3, to the line 5, 5. When the continent reaches the line 5, 5, there will be another band, equal to half the mass of the first, displaced and sent to the surface, which shall now have risen to the line 6, 6; and not until the point of the triangle (i. e. continent) has reached the line 7, 7, will it have overtaken the rising surface. Such, in proportion to its bulk, would be the effect, on the oceanlevel, of a rising continent, were there to be no equivalent sinking of the surface elsewhere, just as, when the mercury of the thermometer is rising in the tube, there is no corresponding sinking of metal contained in the instru ment elsewhere, or, even if there were an equivalent sinking, were that sinking to take place in the interior of some immense tract of table-land. Let us now, however, turn to the diagram fig. II., and consider whether the full realization of the fiction of sinking hollows within the sea, exactly correspondent in their cubic contents to the rising continents, would be at all adequate to preserve the hypothetical fixity of ocean surface. Let the line B, C, fig. II. represent the bottom of the ocean, and the triangle B, A, C, a depression of the earth's crust, exactly equal in cubic amount to the rising land in fig. I., and taking place exactly at the same time. It will be at once seen, in running over the details, that even the hypothesis of balancing hollows formed in the sea as a set-off against the elevations, is wholly insufficient to establish the theory of a fixed line of sea-level. The hollow might be formed, and yet the level affected notwithstanding. Until the elevation had risen above the line 3, 3, in the diagram fig. I., and the corresponding hollow sunk to the line 3, 3, in the diagram fig. II., the surface-line would remain unaffected, -the water displaced by the rising eminence would be contained in the sinking hollow; but immediately as the land rose over the surface, there would be a portion of it - the sub-aërial portion — which would displace no water. The hollow, if it took place in the exact ratio of the elevation, and such is the stipulated condition of the theory, — would receive, after this point, exactly double the quantity of water that the land displaced, and the line of the sea-level would fall. When the elevation would have risen to the point A of the one diagram, and the hollowing depression sunk to the point A of the other, the amount of water received over water displaced would be equal in quantity to one of the parallelogramic bands, 1 2, 2 1, or 2 3, 3 2, fig. I.; and the sea-level would in consequence sink to the line 2, 2. The exactly balanced hollow would fail to preserve the balance. And so I cannot continue to hold as a first principle, that the line of the sea-level is a fixed and stable line; seeing that ere I could do so I would have to believe, first, that the earth's radius has undergone no diminution since the earliest geologic periods in which an ocean existed; second, that for every elevation which takes place on the surface of the globe there takes place a corresponding depression upon it elsewhere; third, that if the elevation takes place within the bed of the sea, the depression also takes place within the bed of the sea; and, fourth, that the elevations and depressions bear always a nicely-adjusted proportion to each other in their contents, different at two different stages of their formation, being up to a certain point exactly as one to one; and after that point has been reached, exactly as one to two. And I can find no adequate grounds for believing all this. But though it be thus far from self-evident that the mean level of the ocean is a fixed line, its rises and falls must have been slight indeed compared with those of the land. There are some of the Alps more than fifteen thousand feet in height; but, if spread equally over Europe, they would raise the general surface, says Humboldt, little more than twenty-one feet. And the displaced masses of the ocean, whether occasioned by the rising or the sinking of continents, have always to be spread over a surface thrice. greater than that of all the land. A displacement, however, effected by the sinking of a continent which bore as large a proportion to the ocean as that borne by the Alps to Europe, would lower the general sea-line from the mean level of by far the best-marked of our ancient coast lines to the mean level of the existing one. THE CHAIN OF CAUSES. "It is no recent discovery," says an ingenious French writer of the last century, "that there is no effect without a cause, and that often the smallest causes produce the greatest effects. Examine the situations of every people upon earth; they are founded on a train of occurrences seemingly without connection, but all connected. In this immense machine all is wheel, pully, cord, or spring. It is the same in physical nature. A wind blowing from the southern seas and the remotest parts of Africa brings with it a portion of the African atmosphere, which, falling in showers in the valleys of the Alps, fertilizes our lands. On the other hand, our north wind carries our vapors among the negroes: we do good to Guinea, and Guinea The chain extends from one end of the universe to the other." Waiving, however, for the present, the moral view of the question, I may be permitted to present my readers with an illustration of the physical one, -i. e. the dependence of the conditions of one country on the conditions on which some other and mayhap very distant country exists, which may be new to some of them, and which the Frenchman just quoted could have little anticipated. to us. When in the island of Bute, to which I had gone on two several occasions in the course of a few weeks, in -- order to examine what are known to geologists as the Pleistocene deposits of the Kyles, my attention was directed to a deep excavation which had just been opened for the construction of a gas tank in the middle of the town of Rothesay. It was rather more than twenty feet in depth, and passed through five different layers of soil. First, passing downwards, there occurred about eighteen inches of vegetable mould, and then about seven feet of a partially consolidated ferruginous gravel, which rested on about eighteen inches more of peat moss,-once evidently a surface soil, like the overlying one, though of a different character, abounding in what seemed to be the fragments of a rank underwood, and containing many hazelnuts. Beneath this second soil there lay fully nine feet of finely stratified sea-sand; and under all, a bed of arenaceous clay, which the workmen penetrated to the depth of about two feet, but, as they had attained to the required depth of their excavation, did not pass through. And this bed of clay, at the depth of fully twenty feet from the surface, abounded in sea-shells, not existing in the petrified condition, but, save that they had become somewhat porous and absorbent, in their original state. Not a few of them retained the thin brown epidermis, unchanged in color; and the gaping and boring shells, whose nature it is to burrow in clay and sand, and which were present among them in two well-marked species, occupied, as shown by their position, the place in which they had lived and died. Now, of these ancient deep-lying shells, though a certain portion of them could be recognized as still British, there were proportionally not a few that no longer live within the British area;—in vain might the conchologist cast dredge for them in any sea that girdles the three kingdoms; and the whole, regarded as a group, |