CHAPTER VII.
_Construction and Destruction_.
The "Black Maria" is a vessel so unique in every respect, that the most detailed description of her cannot but be most interesting to all yachting men; and, so far from apologizing for the length of my observations, I would rather crave indulgence for the scanty information which this chapter will afford; but as it must prove pre-eminently dull to those who are ignorant of such matters, I would entreat them to pass it over, lest, getting through the first page, their ideas become bewildered, and, voting me a bore, they throw down the book, subjoining a malediction upon my poor innocent head.
The following notes were furnished me by Commodore Stevens and his brother, who were the designers and builders of this extraordinary yacht, and I therefore can vouch for their accuracy.
In case the term "centre-board" should be unknown to my reader, it may be as well to explain that it means a board passing longitudinally through the keel, above which a strong water-tight case is fixed for its reception; it is raised and lowered by hand or by machinery, according to its weight.

The advantages proposed by the centre-board are--the stability it gives to the vessel on a wind when let down; the resistance it removes if, when running before the wind, it be raised; the small draught of water which the vessel requires, thereby enabling her to keep close in-shore out of the influence of strong tides, &c.; and, lastly, the facility for getting afloat again, by merely raising the centre-board, should she take the ground.

To proceed with the notes:-- THE CUTTER YACHT "BLACK MARIA." Displacement, 145 tons.
Draught of water on straight keel, 5 feet 2 inches.
Length of straight keel, 60 feet, then running away in a curving line upwards, till at the bow it draws 10 inches.
Length of centre-board, 24 feet.
Total depth of ditto, 15 feet; weight, 7 tons.
Foremost end of ditto, about 8 feet abaft the foremost end of straight keel.
When let down, it descends 10 feet at the further end, and 8 feet at the foremost.

It is made of oak, with sufficient lead let in to make it sink.

By an ingenious mechanical contrivance one man is enabled to raise and lower it with perfect facility.
There is another centre-board abaft, about 10 feet from the stern, which is 8 feet long, with a total depth of 9 feet, and, when down, extending 5 feet below the keel.
Length over all, 113 feet.
The extreme beam is 26-1/2 feet at 40 feet from the rudder-post running aft to about 19 feet at taffrail; forward, it decreases about 20 inches when abreast of mast, thence runs away sharp to about four feet at the bow.
The mainmast is placed about 5 feet abaft the end of straight keel; it is 92 feet long, housing 8 feet: the diameter in the partners is 32 inches, tapering off to 23 inches at the hounds.