Alberti, Leone Battista
,
Architecture
,
1755
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and we may guide it which way we think
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proper by means of the two ſide Ropes, as with
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two Reins, making it either ſtand upright
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whenever we find it neceſſary, or ſtoop which
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ſoever way we Pleaſe to ſet down the Weight
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in the proper place. </
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<
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>As to theſe two ſide
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Ropes, if you have no greater Weight to faſten
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them to, you may fix them in the following
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Manner: Dig a ſquare Pit in the Ground, and
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in it lay the Trunk of a Tree, to which faſten
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one or more Loops that may ſtand up out of
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the Ground; then lay ſome croſs Timbers over
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the Trunk, and fill up the Pit with Earth, ram
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ming it down very cloſe, and if you wet it, it
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will be the heavier. </
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<
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>In all the other Particu
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lars, you may obſerve the Rules we have laid
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down as to the Plain on which the Weight is
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to ſlide: For you muſt faſten Pullies both to
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the Head of the Maſt and to the Weight which
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is to be raiſed, and near the Foot of the Maſt
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you muſt fix your Capſtern, or whatever other
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Inſtrument you uſe that acts with the Power of
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the Leaver. </
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<
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>In all Engines of this Nature de
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ſigned for the moving of great Weights, we
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ſhould take Care that none of the Parts of the
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Machine which are to have any Streſs upon
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them, be too ſmall, and that none of our
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Ropes, Spokes, or any other Medium which
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we uſe in the Movement be weak by means of
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their Length; for indeed long and thin are in
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a Manner ſynonimous Terms, and ſo, on the
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Contrary, are ſhort and thick. </
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<
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>If the Ropes
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are ſmall let them run double in the Pullies;
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if they are very thick, you muſt get larger
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Pullies, that the Rope may not be cut by the
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Edges of the Pully-wheel. </
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<
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>The Axis of the
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Pully ſhould be Iron, and not leſs in Thickneſs
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than the ſixth Part of the Semidiameter of the
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Pully itſelf, nor more than the eighth Part of
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the whole Diameter. </
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<
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>If the Rope be wetted,
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it will be the more ſecure from taking Fire,
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which ſometimes happens by means of its Mo
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tion and Friction in the Pully; it will alſo turn
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the Pully round the better, and keep better
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within the Wheel. </
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<
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>It is better to wet the
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Rope with Vinegar than with Water; but if
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you do it with Water, Sea-water is beſt. </
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<
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>If
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you wet with freſh Water, and it is expoſed to
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the Heat of the Sun, it will rot preſently.
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<
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>Twiſting the Ropes together is much ſafer than
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tying them; and eſpecially you muſt take Care
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that one Rope does not cut the other. </
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<
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>The
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Ancients uſed a Bar or Rule of Iron, to which
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they faſtened the firſt Knots of their Ropes,
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and their Pullies, and for taking up any Weight,
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and eſpecially of Stone, they had a Kind of
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Pincers or Forceps of Iron. </
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<
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>The Shape of
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theſe Pincers or Forceps was taken from the
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Letter X, the lower Limbs of it being turned
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inwards like a Crab's Claw, by which means it
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faſtened itſelf to the Weight. </
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<
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>The two upper
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Limbs had Holes at the Top, through which
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they put a Rope, which being tied, and ſtrain
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ed tight by the moving Force, made the Teeth
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of the Pincers keep cloſer to the Weight -A-.
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In very large Stones, and eſpecially in the
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Middle of Columns, though perfectly ſmooth
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in all other Parts, I have ſeen little Knobs left
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jutting out, like Handles, againſt which the
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Ropes were hitched, to prevent their ſlipping.
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<
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>It is alſo common, eſpecially in Cornices, to
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make a Hole in the Stone like a Mortiſe, after
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this Manner; you make a Hole in the Stone
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like an empty Purſe, of a Bigneſs anſwerable
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to the Size of the Stone, narrower at the Mouth
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than at the Bottom. </
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<
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>I have ſeen ſome of theſe
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Holes a Foot deep. </
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<
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>You then fill it with iron
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Wedges, -B-the two ſide Wedges being ſhap
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ed like the letter D, which are put in firſt to
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fill up the Sides of the Hole, and the middle
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Wedge is put in laſt between theſe two. </
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<
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>All
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theſe three Wedges have their Ears which pro
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ject out beyond the Mortiſe, and theſe Ears
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have a Hole drilled in them, through which
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you put an iron Pin, which faſtens on a ſtrong
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Handle or Ring; and to this Ring you faſten
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the Rope which runs through the Pully that
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is to draw up the Weight. </
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<
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>My way of faſten
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ing my Ropes about Columns, Jambs of Doors,
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and other ſuch Stones which are to be ſet up
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right, is as follows. </
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<
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>I make a Cincture or
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Hoop of Wood or Iron of a due Strength for
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bearing the Weight which I am to move, and
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with this Hoop I ſurround the Column or
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other Stone in ſome convenient Part, making
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it tight to the Stone with long thin Wedges
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drove in gently with a Hammer, then I faſten
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my Ligatures to this Hoop, and by this Means
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I neither ſpoil the Beauty of the Stone by ma
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king Mortiſes in it, nor break the Edges of the
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Jambs by the Rubbing of the Ropes againſt
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them: Beſides that it is the moſt expeditious,
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convenient and ſafeſt Way of faſtening the
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Ropes that has been thought of. </
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<
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>In another
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Place I ſhall enlarge more particularly upon
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many Things relating to this Subject. </
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<
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>All I
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ſhall obſervc further here is, that all Engines
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may be looked upon to be a Sort of Animals,
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with prodigious ſtrong Hands; and that they
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move Weights juſt in the ſame Manner as we
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