Various modes of working Ship Pumps.
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Chap. 6.
it would hardly be just to omit it. In the course of Dampier’s voyageround the World, while sailing (in 1687) along the west side of Minda-nao , one of the Philippine Islands, he concluded to send the carpentersashore to cut down some trees for a bowsprit and topmast. “And ourpumps being faulty and not serviceable, they did cut a tree to make apump. They first squared it, then sawed it in the middle, and then hol-lowed each side exactly. The two hollow sides were made big enoughto contain a pump-box in the midst of them both, when they were joinedtogether; and it required their utmost skill to close them exactly to themaking a tight cylinder for the pump-box, being unaccustomed to suchwork. We learned this way of pump-making from the Spaniards, whomake their pumps that they use in their ships in the South Seas after thismanner; and I am confident that there are no better hand-pumps in theworld than they have.” (Dampier’s Voyages, vol. i, 443.) In the ab-sence of tools to bore logs the device is an excellent one, and in someparticulars such a pump would be Superior to the common one. It isnot so readily made as one of planks, but it is more durable.
Various ingenious modes of working their pumps have been devisedby seamen and otbers ; the power of the men has been applied as in theact of rowing—this plan by far the most efficient is adopted in the Frenchnavy. A rope crossed over a pulley and continued in opposite directionson a ship’s deck, so that any number of mer. may be employed at thesame time, has been extensively used in pumps with double suckers, asshown at No. 92. Dopes passed through blocks and connected to thebrake of the common pump have also been worked in a similar way.Captain Leslie, in a voyage from Stockholm to this country, adopted thefollowing plan, which in a heavy gale, may be very efficient: ‘ He fixeda spar aloft, one end of w'hich was ten or twelve feet above the top of hispumps, and the other projected over the Stern: to each end he fixed ablock or pulley. He then fastened a rope to the pump rods, and afterpassing it through both pulleys along the spar, dropped it into the seaastern. To the rope he fastened a cask of 110 gallons measurement andcontaining about 60 gallons of water. This cask answered as a balanceweigbt, and every motion of the ship from the roll of the sea made themachinery work. When the stern descended, or when a sea or any agi-tation of the water raised the cask, the pump rods descended ; and thecontrary motion of the ship raised the rods, when the water flowed out.The ship was cleared out in four hours, and the exhausted crew wereof course greatly relieved.’
A ship pump made of such boards or plank, as are commonly found onboard of large vessels, was devised by Mr. Perkins, for which he receiveda gold medal from the London Society of Arts. It is figured and describedin che 38th volume of the Society’s Transactions.
The facility with which wooden pumps are made and repaired, thecheapness of their material, the little amount of friction from pistonsworking in them, and their general durability, have always rendered themmore populär than others. Like many of our ordinary machines, theyseem to have been silently borne down the stream of past ages to the15th and 16th centuries, when, by means of the printing press, thev firstemerge into notice in modern times. The earliest representation of onewe have met with in print is in the German translation of Vegetius , on thesame page with No. 82, the bellows pump: No. 87, on next page, is a copy.It is square, made of plank and apparently designed to drain a pond ormarsh. The piston or sucker, which is separately represented, is cylin-drical and was perhaps intended to show a Variation in the construction
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