Chap. XXIX. ON THE CONSTRUCTION OF MACHINERY.
1565
and air-tight to prove very effective. In pumpingwater out of foundations or trenches, the bottom ofthe pipe should be pierced with holes, to prevent themud and soil from entering : the buckets and plungersmay be formed out of elm or beech, and the handleconnected by a wooden rod, the strength of which isconsiderable, particularly when made of deal.
The Construction of a Vessel belongs to the ship-builder rather than the civil engineer, although it is ofthe utmost importance that the latter should be ac-quainted with the principles upon which it is setout: plans, elevations, and sections through every partare required, before any of the timbers can be rightlyproportioned. The safety of a ship requires that thetimbers should uniformly cross the keel, and that theframe be filled up so as to form one compact bodyof timber; to trace the changes which have beenmade in the sections of ships by different nations,and at different periods, is of the highest value, andstill occupies great attention.
The Displacement of a Vessel , or the cubical contentsof that part which is below the water’s surface, maybe calculated from the principle that a body speci-fically lighter than waterwill sink until it has dis-placed a portion of the fluidequal in weight to theentire body itself: in de-signing a boat or vessel,the frst object is to formas accurate an estimateof this weight as possi-ble.
The universal joint maybe formed out of any hardwood, and the action ofthe concave upon the con-vex ball guided in anydirection required; thestrength of the globe issufficient in itself to resistfracture; but the casingwhich works upon it re-quires to be braced orstrengthened by a metalrim, into which the mov-able arm may be let.
Fig. 2925. pumps.
Fig. 2926. section of a vessel.
Fig. 2929,
Fig. 2929. ROPE LADDER.
Rope ladders are frequently in request by the mechanic, and are easily made by passingthe staves through a slip-knot, and fastening them in their position.