train of reasoning; and such, from his “Narrative,” we are led to believe, must have been the case with Smeaton in his own conception of the form most suitable for his great work. In that “Narrative” (§ 81), he seems to imply, that the trunk of an oak was the counterpart or antitype of that form which his (§ 246) “feelings, rather than _calculations_,” led him to prefer. Now, there is no analogy between the case of the tree and that of the Lighthouse, the tree being assaulted at the top, and the Lighthouse at the base; and although Smeaton goes on, in the course of the paragraph above alluded to, to suppose the branches to be cut off, and water to wash round the base of the oak, it is to be feared the analogy is not thereby strengthened; as the _materials_ composing the tree and the tower are so different, that it is impossible to imagine that the same opposing forces can be resisted by similar properties in both. It is obvious, indeed, that Smeaton has unconsciously contrived to obscure his own clear conceptions in his attempt to connect them with a fancied natural analogy between a tree which is shaken by the _wind_ acting on its _bushy top_, and which resists its enemy by the _strength_ of its fibrous texture and wide-spreading ligamentous roots, and a tower of masonry, whose _weight_ and _friction_ alone enable it to meet the assault of the _waves_ which wash round its _base_; and it is very singular, that, throughout his reasonings on this subject, he does not appear to have regarded those properties of the tree which he has most fitly characterized as “its elasticity,” and the “coherence of its parts.” One is tempted to conclude that Smeaton had, in the first place, reasoned quite soundly, and arrived by a perfectly legitimate process at his true conclusion; and that it was only in the vain attempt to justify these conclusions to others, and convey to them conceptions which a large class of minds can never receive, that he has misrepresented his own mode of reasoning. In the paragraph preceding that which refers to the tree (§ 80), he has, in point of fact, clearly developed the true views of the subject; and, with the single exception of the allusion to the oak, he has discussed the question throughout in a masterly style. * * * * * In a word, then, the sum of our knowledge appears to be contained in this proposition--_That, as the stability of a sea-tower depends_, cæteris paribus, _on the lowness of its centre of gravity, the general notion of its form is that of a cone; but that, as the forces to which its several horizontal sections are opposed decrease towards its top in a rapid ratio, the solid should be generated by the revolution of some curve line convex to the axis of the tower, and gradually approaching to parallelism with it_. And this is, in fact, a general description of the Eddystone Tower devised by Smeaton. * * * * * [Illustration: No. 1.]