MUGFORD'S TEMPORARY RUDDER.

A, (Plate V. Fig. 7.) Is the main stern-post from which the original rudder has been torn.

B. Is the false stern-post made of a spare top-mast sided so as to fit the main stern-post, with mortices to receive the braces h h h, or the fragments thereof which remain upon the post.

C, Is the temporary rudder made of the (residue of the) topmast and the sprit sail yard, studding sail booms, or any spars that can be spared with the least inconvenience-They are cut to the proper length and partially sided and firmly bolted or treenailed together. The sides are then flatted a little with the adze and boards nailed across and wooldings of rope bind the whole together as represented in the figure.

DDDD, Represent the spars of which the rudder is constructed.

E, Is a small spar or piece of plank fitted on each side of the false post to lead the guys clear and prevent their chafing; they are also bolted through from side to side and rivetted to secure the false post from splitting, or if bolts are not to be had lashings are substituted as represented in the figure.

F F, Are stout flat cleats well nailed or bolted on each side of the false post under the spars E, and embrace the main post. Their use is to sustain the false post against a lateral shock.

G, Is a yoke made of an iron tiller, or other sufficient substitute, firmly fitted through the after part of the rudder near the surface of the water.

HHH, Are the temporary braces and pintles-They are formed of eye bolts drawn out of the gun carriages or from the various parts of the hull, masts, or caps, and driven into the false post and rudder alternately so that the eyes just meet each other; some of those in the post, below those in the rudder, and others above, in order to confine the rudder from rising-The pintles are made of crowbars, a kedge anchor-stock, or the long stout bolts out of the windlass bits.

hhh, Are the old rudder braces or the fragments thereof remaining on the post.

I, Is the profile of the stern of the ship.

K K, Are guys, the bites of which are well served and lashed to the after part of the false post, and lead separately (or combined as represented in the figure) to the fore and after parts of the main chains.

LL, Are knots worked on the guys to preserve them from chafing against the bottom and quarters.

M, Is a rope the bite of which is lashed to the after part of the rudder below the yoke, and also to the extremities of the yoke, and from thence led through blocks attached to the end of a spar projecting over each quarter to the wheel by which the ship is steered.

N, Is a slip rope rove through a hole in the heel of the rudder and both ends passed up through the rudder case to the head of the false post and made fast.

O, Is a grommet (travelling on the slip rope) to which a gun or kedge anchor or any sufficient weight is attached, in order to sink the rudder until it is hung and secured.

P, Is a hauling line attached to the grommet, and by which the weight is lowered down and hauled up. When the rudder is secured in its place, the weight is removed, and the slip rope unrove.

Q, are the rudder pendents to save the rudder in case of accident.

R, Is the lower deck.

S, Is the quarter deck.
T, Is the quarter rail.

V, The arch board of the Stern.

REMARKS.

The merit of this invention is to be tested by a just comparison with the best substitute hitherto known, which is undoubtedly that of Capt. Pakenham's excellent invention, an account and description of which may be found in the 7th volume of the Transactions of the London Society for the encouragement of arts, manufactures and commerce.

The difference consists in Captain Mugford's new and ingenious contrivance of a false stern post, to which his rudder is

secured by eye bolts serving as braces, and crow-bars or other substitutes as pintles, on which it works with as much ease and effect as the original rudder. The false post is also firmly secured to the main post by the guys, and the old rudder braces which are tenoned into it.

Captain Pakenham's rudder depends entirely upon the very slight hold which the cap has on the post, and does not appear to be sufficiently secured to resist a sudden lateral shock; it is however very simple in its construction, and requires, perhaps, less labor and fewer materials (particularly of iron) than Capt. Mugford's, and has the advantage of steering upon deck with a common tiller in the usual way.

Capt. Mugford's rudder must work with much less friction, and consequently will require less power, as the axis on which it moves is only an inch and a half in diameter, whereas that of Capt. Pakenham's is the diameter of the top-mast; say 10 or 12 inches.

Upon the whole, as the construction of Capt. Mugford's rudder requires only the skill and materials which are usually to be found on ship board, and as it appears to be better secured, and works with more ease than Capt. Pakenham's, it may (without derogating from the merit of the latter) be justly considered as a valuable and useful invention.

Capt. Mugford's rudder is susceptible of a very simple and important improvement, viz. If the archboard of the stern V was cut off, and the after part of the rudder case taken down, the stock of the rudder might be continued to the upper deck, and steer with the tiller in the usual way. Capt. Mugford's mode of steering is exceptionable, as the yoke is at the surface of the water, and the wheel ropes leading from the yoke to the spar, broad upon the quarter; the angle which the rope makes with the yoke when the rudder is hard over, is so obtuse as greatly to diminish the effort of the power; and moreover the rudder is necessarily so broad at the surface of the water, as to expose a dangerous resistance to the action of the sea.

It is also to be observed, that few merchant ships under 350 ton's burthen have either wheel or iron tiller. If the rudder was continued to the deck, the breadth might be diminished

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at the surface of the water and enlarged at the heel, which would increase its effect and render it less liable to injury.

In the drawing, the cleats F F, are added to the side of the false post, and overlapping the main post, which will give it great additional security. Some minor alterations are also made, viz. In the drawing the four guys 1111, (which are separate in the model) are combined into two K K, leading through a thimble or clinch; the reason is, that a more equal tension can be obtained of two ropes than of four, and that when combined they lead in a fairer direction under the buttock of the ship.

Indeed the number of guys are superfluous, the lower one would be amply sufficient, as the upper end of the post can be made very secure. Captain Pakenham has but a single guy leading from the cap on each side.

The drawing represents a mode of applying and removing the weight to sink the rudder, by which the whole can be removed with more ease when the rudder is secured.

When the rudder is fixed, the only apprehension is, the guys chafing off. There is however on board every ship a complete remedy viz. Take two of the topmast back stay chain plates and one of the bolts, and bolt them to the heel of the false stern post, one on each side; to these hook the top-blocks and mouse the hooks well; then reeve the guys through the blocks, and take both parts to the fore part of the main chains: by this means the guys may be overhauled through the blocks and examined at pleasure, keeping them always well taught and veering away one part as you haul in upon the other. These remarks are the more diffuse as the subject is considered impor-tant, and is still susceptible of great improvement.

Captain Mugford was some days before he could hang his rudder, owing to bad weather.

The man will deserve well who shall invent a simple substitute for a rudder that can be made and applied immediately inany weather; and it need not be despaired of, if men of ingenuity, without waiting for the calamity, would only try expe riments while their ships are in a sound state.

No. XXXV.

Facts and Observations relative to THE BEAVER of North-America. Collected by Mr. John Heckewelder, in answer to Queries proposed by Professor Barton.-Communicated to the Society by Professor Barton.

Read November 16th, 1804.

I. PEMAHOLEND, a famous Beaver-Trapper, an aged and much respected Delaware-Indian, and a friend of mine, gives the following account.

The Beavers build their dams for the safety of themselves and their young; and in order to convey food to their houses. They are very particular in chusing the ground or situation upon which they intend to build. They always, in the first place, carefully examine, whether there be near them a sufficiency of trees and shrubs, especially Aspin, Sassafras, and Shellbark-Hickery near at hand, so that they need not venture too far out, to cut them: for the barks of these trees are their principal foods.

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They carefully examine the run or brook; whether it be manent, or does not dry up in the summer season, and whether there be a sufficient quantity of water to extend or enlarge the dam, if occasion should require it.

Having surveyed the ground well, and chosen the time when the waters are neither too high nor too low, they cut down bushes, and drag and lay them in a line for the foundation, which, at this time, has the appearance of a brush-fence. They sometimes make one or more offsets, altering their course as they think best, both for the security of the dam, and to give them advantages.

The foundation being finished, they cut down small trees, from six to twelve, and even fifteen inches, in diameter; and these they cut up into blocks, of three, four, five, and sometimes six feet in length. These blocks they draw by their teeth, walking backwards, to the brush foundation, and place, in a sloping direction, every block, with one end on the brush,