Page:Proceedings of the Royal Society of London Vol 1.djvu/516

Rh Since the luminous appearance of the Milky Way is caused by stars that are invisible to the naked eye, this part of the heavens pre- sents a vast ﬁeld for observation on the existence of a clustering power. To the naked eye it is visibly divided into large patches ; and a telescope shows it to be still further subdivided into unequal groups, which, though now not completely detached, it is presumed Will hereafter become insulated ; so that the Milky Way will ﬁnally be broken up, and cease to be a stratum of clustered stars.

The same mode of reasoning that leads the imagination to con- ceive the progressive changes of its future existence, involves also ‘ the supposition of its origin at some period certainly very remote, but which it may possibly be in the power of future astronomers to estimate, by means of accurate observations on the rate of those changes that may be discovered to have taken place in the course of ages yet to come.

With respect, however, to the extent in space of that portion of inﬁnity through which any objects are discernible, and the arrange- ment and relative distances of all celestial bodies yet observed, the author is of opinion, that some present judgement may be formed; and he is now engaged in a. series of observations, with a view to investigate the visible extent of the universe.

After remarking upon the length of time that has elapsed since any considerable improvement has taken place in the art of shipbuilding, and the causes that appear to have prevented amendments being introduced, the author give a general outline of the structure of ships, as hitherto built, which he represents as consisting generally of pieces of timber or plank, all placed nearly at right angles to each other. For, ﬁrst, the ribs rise at right angles to the keel. The ribs are crossed, on their inner as well as outer side, with planks at right angles to them, and parallel to the keel. And within the inner linings are also a secondary series of ribs, called riders, at some distance from each other, parallel to the former set, and at right angles to the keel. Across this fabric are placed beams, connecting the opposite sides of the vessel; and these also are at right angles to all the parts before mentioned. From beam to beam, at right angles, are the carlings, which support joists parallel to the beams, on which are laid the planks of the deck, in a right line from head to stern, and accordingly preserving uniform adherence to the parallehand rectangular structure, which in every other instance of carpentry is known to every common mechanic to be the weakest form in which any number of lines can be framed together, as it affords no check to that bending of the materials to which they are liable in the direction of their greatest length. To this cause is to be ascribed the well-known