This is not the only life boat that has been propo sed, nor can we affirm that it is not susceptible of es sential improvements ; yet, having met with more ge neral approbation, and having been more frequently put to practical use, we shall treat of it in preference to others.
The inventor's attention was originally attracted to the principle on which the life boat is constructed, by observing, as he Hmself expresses it, " that each part of a spheroid divided into quarters, nearly re sembles a wooden bowl having projecting ends. If this be thrown into the sea, or broken waters, it can not be upset, or lie with the bottom upwards." With these remarks in view, Mr Greathead formed his life boat, the keel being a curved beam, and both the stem and stern raking towards each other.
The size of the life boat is arbitrary, depending on the different service it has to perform ; and if certain definite dimensions, such as we are about to describe, be adopted, it is from conceiving them sufficient for the intended purpose, and not by a comparison of the advantages attending life boats of various sizes. The life boat is thirty feet in length, ten in breadth, and in depth, from the top of the gunwale to the lower part of the keel in midships, three feet four inches, from the gunwale to the piatforhi within two feet four inches, from the top of the sterns to the bottom of the keel five feet nine inches. Both ends of the boat are alike, the sterns being segments of a circle, with a considerable rake towards each other. The keel consists of a beam three inches thick, of a proportionate breadth in midships, nar rowing gradually towards the ends to the breadth of the sterns at the bottom, and bending with a great convexity downward. The bottom section to the floor heads is a curve fore and aft with the sweep of the keel ; the floor timber has a small rise, curving from the keel to the floor heads ; a bilge plank is wrought in on. each side next the floor heads, with a double rabbit or groove of the same thickness as the keel ; on the outside of this are fixed two bilge trees, nearly corresponding with the level of the keel. The ends of the bottom section resemble the lower part of a kind of fishing boat which in Scot land is called a coble ; from whence to the top of the stern it becomes more elliptical, and forms a considerable projection. The sides, from the floor heads to the top of the.gunwale, Haunch off on each side, in proportion to about half the breadth of the .floor. The breadth continues far forward towards the ends, leaving a sufficient length of straight side at the top. The sheer is regular along the straight side, and more elevated towards the ends ; the gun wale, fixed on the outside, is three •inches thick. From the under part of the gunwale, extending 21 feet 6 inches along the whole length of the regu lar sheer, the sides are cased with layers of cork, sixteen inches downward, and four inches thick ; whence the casing projects a little without the gun .wale at the top. The boat is fastened with copper nails, and the cork on the outside secured with thin plates or slips of copper. There are five seats, or thwarts, double banked, therefore the boat may be rowed with ten oars, and these thwarts are firmly stanchioned. The oars are short, and made of fir of
the best quality, which is preferable to any other wood ; for experience has proved, that an ash oar, dressed clean and light, is too flexible among break ers, and if strong and heavy the rower becomes soon exhausted. The oars are slung over an iron thole, provided with a grommet, which enables the rowers, merely by facing about, to row either way without turning the boat ; a circumstance of infinite import ance in broken water. The boat is steered by an oar at 'each end, one-third longer than the rowing oars ; and, for the convenience of the steersman, a platform within, at the bottom of the boat, is hori zontal the length of the midships, and elevated at the ends. From the under part of the thwarts down to the platform, the inside of the boat is cased with cork ; on the quantity of which, indeed, the chief pro perties of the life boat, in our opinion, depend. No less than 7 cwt. of cork being used in the construction of the life boat now described, the great specific levi • ty, if we may so express ourselves, will sustain an ? amazing weight, while the parts of the boat itself hold together. It is rot only of great service in keeping the boat in her due position on the sea, but also in crea ting a tendency immediately to recover from any sud den cant, or lurch, from a heavy wavd; and it is, be sides, beneficial in diminishing the violence of beating against the sides of the vessel which she may go to re lieve. Other important properties have been sought for in the figure and construction of the boat itself ; points assuredly meriting the deepest consideration, as they may demonstrate the causes of an unsuccessful attempt, or lead to the formation of life boats on an improved principle. Exclusive of the utility of the cork, it is maintained, that the similarity of the ends of the boat, which admits of her being rowed either way, facilitates her rising over the waves ; the curva ture of the keel aids her motion in turning, and con tributes to the ease of steerage, because a single stroke of the steering oar produces an immediate ef fect, the boat moving as it were on a centre. When rowing against the waves, the fine entrance below is of use in dividing them ; and, combined with the convexity of the bottom, and elliptical form of the stern, enables the boat to rise with wonderful buoy ancy in a high sea, as also rapidly to launch forward without shipping water, when a common boat would be in danger of filling. It is said to be proved by experience, that boats of the construction of the life boat, in spreading from the floor heads to the gun wale, are best adapted for rowing against turbulent waves ; and that the continuation of the breadth for ward, is a great support to her in the sea. When full of water, the life boat is in no danger either of sinking or upsetting, as her internal shallowness, her peculiar figure, and bulk of the cork within, admit but a small quantity of it. These are some of the qua. lities which are conceived to result from the figure and structure of the life boat, compared with those of the ordinary construction.