1012
THEORY AND PRACTICE OF ENGINEERING.
Book II,
Derrick Crane used at Granton Pier, Edinburgh , was of a very superior kind, and wasexecuted by Mr. Vightman: it consisted of a vertical post, supported by two timberback stays, and a long movable der-rick or gib, hinged at the bottom ofthe post; the top of this gib was heldby a chain, which passed from a barrelover a pulley at the top of the post,so that the gib could be raised orlowered. This crane commanded acircle of from ten feet to sixty radiuswithout being moved.
A similar machine was used by theancients, and is thus described byVitruvius :—“ Three pieces of timberare prepared, suitable to the weight tobe raised, connected at the top by apin, but spreading extensively at thefeet; these are raised by means ofropes made fast to the top, and whenraised are kept steady ; to the top isfixed a block, by some called rechamus,in which two pulleys turn on axles.”
— (Yit. cap. ii. lib. 10.)
Tackle used by the East LondonWaterworks Company in hoisting theirStand Pipe . — A piece of timber9 inches square was attached to theupper fianch of the pipe, and held inits place below by an iron hoop orgirdle. Guy ropes were fastened atthe top of this upright, which servedalso to suspend the snatch blocksthrough which the fall ropes passedto the crab winches: attached to theiron hoop were two pivots which tra-versed the lower ends of two timbergibs, connected at top by a cross timber, from thecentre of which were suspended the blocks and tackleconnected with the large crab. After each joint ofpipe had been elevated to its place, the gib framewas drawn up vertically by the tackle from thesmall crab, and the pipe was lowered to its place; thepins were then passed through its flanches. Thisoperation was continued for each successive length ofpipe, until the whole had reached a height of upwardsof 1:10 feet.
The architects and engineers of the middle ageswere celebrated for moving and lifting great weights,and probably the inscription at Pisa Cathedral , whichinforms us that Buschettum in the eleventh centuryraised the granite columns, each weighing upwards of16 tons, by a machine so simple that children couldwork it, refer to similar contrivances as those nowunder our consideration: the inscription is curious,as it exhibits the admiration which this engineer calledforth by his ingenuity.
QD VIX MILLE BOU rOSSENT JUGA JUNTA MOVE
ET QUOD VIX POTUIT P MARE FERRE RATIS
BUSKETI NISU QD ERAT MIRABILE VISU
DENA PVELLARE TVRBA LEVABIT ONUS.
AA/iAJL
Fig. 1530. EAST LONDON WATERWORKS.
Devonport Column is built of granite from Holman’s Hill quarry, and is in height 101 feet4 inches above the surface of the rock upon which it stands : the shaft is 11 feet in diameter,and its height to the top of the capital 65 feet 4 inches; the abacus is formed of fourstones, each weighing between three and four tons. Mr. John Fulston raised the stones