CHAP. VIII.
CHAP. VIII. Of the Kinds of Platforms, their Forms and
Figures, and which are the most serviceable and lasting
Of the Skrew and its Circles or Worm, and in what Manner great Weights are either drawn, carried or pushed along.We have already treated of Wheels, Pullies and Leavers; we are now to proceed to the Skrew. A Skrew consists of a Number of Circles like Rings, which take up on themselves the Burthen of the Weight. If these Rings were entire, and not broken in such a Manner, that the End of one of them is the Beginning of the other; it is certain the Weight which they support, though it might be moved about, would neither go upwards nor downwards, but evenly round upon an equal Plain according to the Direction of the Rings:The Weight therefore is forced to slide either upwards or downwards along the Slope of the
Rings, which act herein after the Manner of the Leaver. Again, if these Rings or this Worm be of a small Circumference, or be cut in too near to the Center of the Skrew, the Weight will then be moved by shorter Leavers and with a smaller Force. I will not here omit one Thing which I did not think to have mentioned in this Place: Namely, that if you could so order it that the Bottom or Keel of any Weight which you would move might (as far as could be done by the Art and Skill of the Workman) be made no broader than a Point, and be moved in such a Manner upon a firm and solid Plain as not in the least to cut into it, I would engage you should move Archimedes' s Ship, or effect anything else of this Nature whatsoever. But of these Matters we shall treat in another Place. Each of these Forces in particular, of which we have alreadyspoken, are of great Power for the moving of any Weight; but when they are all joined together, they are vastly stronger. In Germany you everywhere see the Youth sporting upon the Ice with a sort of wooden Pattens with a very fine thin Bottom of Steel, in which with a very small Strain they slip over the Ice with so much Swiftness, that the quickest flying Bird can hardly out go them. But as all Weights are either drawn, or pushed along, or carried, we may distinguish them thus: That they are drawn by Ropes; pushed along by Leavers; and carried by Wheels, Rollers and the like: And how all these Powers may be made use ofat the same Time, is manifest. But in all these Methods, there must of Necessity be some one Thing, which standing firm and immoveable itself, may serve to move the Weight in Question. If this Weight is to be drawn, there must be some greater Weight, to which you may fasten the Instruments you are to employ; and if no such Weight can be had, fix a strong iron
Stake of the Length of three Cubits, deep into the Ground which must be rammed down tight all about it, or well strengthened with Piles laid cross ways: And then fasten the Ropes of your Pullies or Cranes to the Head of the Stake which stands up out of the Ground. If the Ground be sandy, lay long Poles all the
Way for the Weight to slide upon, and at the Head of these Poles fasten your Instruments to a good strong Stake. I will take Notice of one Thing which the Unexperienced will never allow, till they understand the Matter thoroughly; which is, that along a Plain it is more convenient to draw two Weights than one; and this is done in the following Manner: Having moved the first Weight to the End of the
Timbers laid for it to slide upon, fix it there with Wedges in such a Manner that nothing can stir it, and then fasten or tie to it the Engines, or Instruments with which you are to draw your other Weight; and thus the moveable Weight will be overcome and drawn along the same Plain by the other Weight, which is no more than equal to it, but only that it is fixed. If the Weight is to be drawn up on high,we may very conveniently make use of one single Pole, or rather of the Mast of a Ship;but it must be very stout and strong. This Mast we must set upright, fastening the Foot of it to a Stake, or fixing it strong in any other Manner that you please. To the upper End of it we must fasten no less than three Ropes, one on the right Side, another on the lest, and the other running down directly even with the Mast. Then at some Distance from the Foot of the Mast fix your Capstern and Pullies in the Ground, and putting this last Rope through the Pullies, let it run through them so as to draw the Head of the Mast a little downwards, and we may guide it which way we think proper by means of the two side Ropes, as with two Reins, making it either stand upright whenever we find it necessary, or stoop whichever way we Please to set down the Weight in the proper place. As to these two side
Ropes, if you have no greater Weight to fasten them to, you may fix them in the following
Manner: Dig a square Pit in the Ground, and in it lay the Trunk of a Tree, to which fasten one or more Loops that may stand up out of the Ground; then lay some cross Timbers over
the Trunk, and fill up the Pit with Earth, ramming it down very close, and if you wet it, it will be the heavier. In all the other Particulars, you may observe the Rules we have laid down as to the Plain on which the Weight is to slide: For you must fasten Pullies both to the Head of the Mast and to the Weight which is to be raised, and near the Foot of the Mast you must fix your Capstern, or whatever other Instrument you use that acts with the Power of the Leaver. In all Engines of this Nature designed for the moving of great Weights, we should take Care that none of the Parts of the Machine which are to have any Stress upon them, be too small, and that none of our Ropes, Spokes, or any other Medium which we use in the Movement be weak by means of their Length; for indeed long and thin are in a Manner synonimous Terms, and so, on the
Contrary, are short and thick. If the Ropes are small let them run double in the Pullies; if they are very thick, you must get larger Pullies, that the Rope may not be cut by the
Edges of the Pull wheel. The Axis of the Pully should be Iron, and not less in Thickness than the sixth Part of the Semidiameter of the Pully itself, nor more than the eighth Part of the whole Diameter. If the Rope be wetted, it will be the more secure from taking Fire,which sometimes happens by means of its Motion and Friction in the Pully; it will also turn the Pully round the better, and keep better within the Wheel. It is better to wet the Rope with Vinegar than with Water; but if you do it with Water, Seawater is best. If you wet with fresh Water, and it is exposed to the Heat of the Sun, it will rot presently. Twisting the Ropes together is much safer than tying them; and especially you must take Care that one Rope does not cut the other. The Ancients used a Bar or Rule of Iron, to which they fastened the first Knots of their Ropes,and their Pullies, and for taking up any Weight,and especially of Stone, they had a Kind of
Pincers or Forceps of Iron. The Shape of these Pincers or Forceps was taken from theLetter X, the lower Limbs of it being turned inwards like a Crab' s Claw, by which means it fastened itself to the Weight. The two upper Limbs had Holes at the Top, through which they put a Rope, which being tied, and strained tight by the moving Force, made the Teethof the Pincers keep closer to the Weight .In very large Stones, and especially in the Middle of Columns, though perfectly smooth in all other Parts, I have seen little Knobs left jutting out, like Handles, against which the
Ropes were hitched, to prevent their slipping. It is also common, especially in Cornices, to make a Hole in the Stone like a Mortise, after this Manner; you make a Hole in the Stone like an empty Purse, of a Bigness answerable to the Size of the Stone, narrower at the Mouth than at the Bottom. I have seen some of these Holes a Foot deep. You then fill it with iron
Wedges, −B−the two side Wedges being shaped like the letter D, which are put in first to
fill up the Sides of the Hole, and the middle Wedge is put in last between these two. All these three Wedges have their Ears which project out beyond the Mortise, and these Ears have a whole drilled in them, through which you put an iron Pin, which fastens on a strong Handle or Ring; and to this Ring you fasten the Rope which runs through the Pully that is to draw up the Weight. My way of fastening my Ropes about Columns, Jambs of Doors, and other such Stones which are to be set up right, is as follows. I make a Cincture or Hoop of Wood or Iron of a due Strength for bearing the Weight which I am to move, and with this Hoop I surround the Column or other Stone in some convenient Part, making it tight to the Stone with long thin Wedges drove in gently with a Hammer, then I fasten my Ligatures to this Hoop, and by this Means
I neither spoil the Beauty of the Stone by making Mortises in it, nor break the Edges of the
Jambs by the Rubbing of the Ropes against them: Besides that it is the most expeditious, convenient and safest Way of fastening the Ropes that has been thought of. In another Place I shall enlarge more particularly upon many Things relating to this Subject. All I shall observe further here is, that all Engines may be looked upon to be a Sort of Animals, with prodigious strong Hands; and that they move Weights just in the same Manner as we
CHAP. VIIICHAP. VIII ของชนิดของแพลตฟอร์ม ฟอร์มของพวกเขา และตัวเลข และรายการที่กล้ามากที่สุด และยั่งยืนSkrew และวงกลม หรือหนอน และ ในลักษณะใดน้ำหนักดีมีวาด ดำเนิน หรือผลักไป เราได้รับล้อ Pullies และ Leavers เรามีตอนนี้ไป Skrew Skrew ประกอบด้วยตัวเลขของวงเช่นแหวน ที่มีค่าในตัวเอง Burthen ของน้ำหนัก แหวนเหล่านี้ได้ทั้งหมด และไม่เสียเช่นอย่าง สิ้นสุดอันหนึ่งของอื่น ๆ แน่นอนน้ำหนักที่พวกเขาสนับสนุน แม้ว่าอาจจะย้ายเกี่ยวกับ จะไม่ไปขึ้น หรือลง แต่เท่า ๆ กันรอบตามธรรมดาเป็นเท่าโดยแหวน: น้ำหนักจึงถูกบังคับให้เลื่อนขึ้น หรือลงตามความชันของการแหวน ที่ดำเนินการซึ่งหลังจากของที่ Leaver อีกครั้ง ถ้าแหวนเหล่านี้หรือหนอนนี้ไซส์เล็ก หรือจะตัดเกินไปใกล้กับศูนย์ Skrew จะน้ำหนัก แล้วย้าย Leavers สั้น และ มีกองกำลังขนาดเล็ก ฉันจะไม่นี่ข้ามสิ่งหนึ่งที่ผมไม่ได้คิดว่า จะมีกล่าวถึงในนี้: ได้แก่ ว่าถ้าคุณสามารถให้สั่งซื้อที่ด้านล่างหรือ Keel ของน้ำหนักที่คุณจะย้าย (เท่าที่สามารถทำงานศิลปะและทักษะของการรำ) อาจทำให้ไม่กว้างกว่าจุด และย้ายในลักษณะดังกล่าวตามราบที่มั่นคง และแข็งแกร่งเป็นไม่ในน้อยที่สุดในการตัด มา ฉันจะจ้างคุณควรย้ายของเอสเอสเรือ หรือสิ่งอื่นใดของธรรมชาตินี้เลยผลการ แต่ของเรื่องเหล่านี้ เราจะรักษาที่อื่น แต่ละกองกำลังเหล่านี้โดยเฉพาะ ที่เราได้ alreadyspoken มีอำนาจในการย้ายมีน้ำหนัก แต่เมื่อทั้งหมดรวมกัน พวกเขาจะแข็งแกร่งเสมือน ในเยอรมนี คุณทุกเห็นเยาวชนกีฬาเมื่อน้ำแข็งกับการเรียงลำดับของไม้ Pattens ด้วยดีบางล่างของเหล็ก ที่มีขนาดเล็กมากต้องใช้พวกใบเหนือน้ำแข็งกับ Swiftness มาก ว่า นกที่บินเร็วที่สุดสามารถแทบไม่ออกไปนั้น แต่เป็นน้ำหนักทั้งหมดจะ ออก หรือการผลักดันตาม หรือดำเนินการ เราอาจแตกต่างดังนั้น: ว่า จะวาด โดยเชือก การผลักดันตาม ด้วย Leavers และดำเนินการ โดยล้อ ลูกกลิ้งเช่น: วิธีการทั้งหมดอาจทำอำนาจเหล่านี้ใช้ ofat กัน เป็นรายการ แต่ในวิธีเหล่านี้ทั้งหมด จำเป็นต้องมีบางสิ่งหนึ่ง ที่ยืนของบริษัท และ immoveable ตัวเอง อาจเป็นการย้ายน้ำหนักสอบถาม ถ้าน้ำหนักนี้จะวาด ต้องมีน้ำหนักมากกว่าบาง ซึ่งคุณอาจติดเครื่องมือที่จะใช้ และถ้าสามารถ มีน้ำหนักเช่นไม่ แก้ไขเหล็กแข็งแรงStake of the Length of three Cubits, deep into the Ground which must be rammed down tight all about it, or well strengthened with Piles laid cross ways: And then fasten the Ropes of your Pullies or Cranes to the Head of the Stake which stands up out of the Ground. If the Ground be sandy, lay long Poles all theWay for the Weight to slide upon, and at the Head of these Poles fasten your Instruments to a good strong Stake. I will take Notice of one Thing which the Unexperienced will never allow, till they understand the Matter thoroughly; which is, that along a Plain it is more convenient to draw two Weights than one; and this is done in the following Manner: Having moved the first Weight to the End of theTimbers laid for it to slide upon, fix it there with Wedges in such a Manner that nothing can stir it, and then fasten or tie to it the Engines, or Instruments with which you are to draw your other Weight; and thus the moveable Weight will be overcome and drawn along the same Plain by the other Weight, which is no more than equal to it, but only that it is fixed. If the Weight is to be drawn up on high,we may very conveniently make use of one single Pole, or rather of the Mast of a Ship;but it must be very stout and strong. This Mast we must set upright, fastening the Foot of it to a Stake, or fixing it strong in any other Manner that you please. To the upper End of it we must fasten no less than three Ropes, one on the right Side, another on the lest, and the other running down directly even with the Mast. Then at some Distance from the Foot of the Mast fix your Capstern and Pullies in the Ground, and putting this last Rope through the Pullies, let it run through them so as to draw the Head of the Mast a little downwards, and we may guide it which way we think proper by means of the two side Ropes, as with two Reins, making it either stand upright whenever we find it necessary, or stoop whichever way we Please to set down the Weight in the proper place. As to these two sideRopes, if you have no greater Weight to fasten them to, you may fix them in the followingManner: Dig a square Pit in the Ground, and in it lay the Trunk of a Tree, to which fasten one or more Loops that may stand up out of the Ground; then lay some cross Timbers overthe Trunk, and fill up the Pit with Earth, ramming it down very close, and if you wet it, it will be the heavier. In all the other Particulars, you may observe the Rules we have laid down as to the Plain on which the Weight is to slide: For you must fasten Pullies both to the Head of the Mast and to the Weight which is to be raised, and near the Foot of the Mast you must fix your Capstern, or whatever other Instrument you use that acts with the Power of the Leaver. In all Engines of this Nature designed for the moving of great Weights, we should take Care that none of the Parts of the Machine which are to have any Stress upon them, be too small, and that none of our Ropes, Spokes, or any other Medium which we use in the Movement be weak by means of their Length; for indeed long and thin are in a Manner synonimous Terms, and so, on theContrary, are short and thick. If the Ropes are small let them run double in the Pullies; if they are very thick, you must get larger Pullies, that the Rope may not be cut by theEdges of the Pull wheel. The Axis of the Pully should be Iron, and not less in Thickness than the sixth Part of the Semidiameter of the Pully itself, nor more than the eighth Part of the whole Diameter. If the Rope be wetted, it will be the more secure from taking Fire,which sometimes happens by means of its Motion and Friction in the Pully; it will also turn the Pully round the better, and keep better within the Wheel. It is better to wet the Rope with Vinegar than with Water; but if you do it with Water, Seawater is best. If you wet with fresh Water, and it is exposed to the Heat of the Sun, it will rot presently. Twisting the Ropes together is much safer than tying them; and especially you must take Care that one Rope does not cut the other. The Ancients used a Bar or Rule of Iron, to which they fastened the first Knots of their Ropes,and their Pullies, and for taking up any Weight,and especially of Stone, they had a Kind ofPincers or Forceps of Iron. The Shape of these Pincers or Forceps was taken from theLetter X, the lower Limbs of it being turned inwards like a Crab' s Claw, by which means it fastened itself to the Weight. The two upper Limbs had Holes at the Top, through which they put a Rope, which being tied, and strained tight by the moving Force, made the Teethof the Pincers keep closer to the Weight .In very large Stones, and especially in the Middle of Columns, though perfectly smooth in all other Parts, I have seen little Knobs left jutting out, like Handles, against which theRopes were hitched, to prevent their slipping. It is also common, especially in Cornices, to make a Hole in the Stone like a Mortise, after this Manner; you make a Hole in the Stone like an empty Purse, of a Bigness answerable to the Size of the Stone, narrower at the Mouth than at the Bottom. I have seen some of these Holes a Foot deep. You then fill it with iron
Wedges, −B−the two side Wedges being shaped like the letter D, which are put in first to
fill up the Sides of the Hole, and the middle Wedge is put in last between these two. All these three Wedges have their Ears which project out beyond the Mortise, and these Ears have a whole drilled in them, through which you put an iron Pin, which fastens on a strong Handle or Ring; and to this Ring you fasten the Rope which runs through the Pully that is to draw up the Weight. My way of fastening my Ropes about Columns, Jambs of Doors, and other such Stones which are to be set up right, is as follows. I make a Cincture or Hoop of Wood or Iron of a due Strength for bearing the Weight which I am to move, and with this Hoop I surround the Column or other Stone in some convenient Part, making it tight to the Stone with long thin Wedges drove in gently with a Hammer, then I fasten my Ligatures to this Hoop, and by this Means
I neither spoil the Beauty of the Stone by making Mortises in it, nor break the Edges of the
Jambs by the Rubbing of the Ropes against them: Besides that it is the most expeditious, convenient and safest Way of fastening the Ropes that has been thought of. In another Place I shall enlarge more particularly upon many Things relating to this Subject. All I shall observe further here is, that all Engines may be looked upon to be a Sort of Animals, with prodigious strong Hands; and that they move Weights just in the same Manner as we
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