Thursday, May 11, 2017

Silk




Glossaries

Here are some glossaries taken from the book The Encyclopedia of the History of Technology, by Ian McNeil.


POWER GLOSSARY
1.       Bell crank a means of turning a pulling motion at right angles. Two arms at right angles are mounted to pivot about a point between their tips. 
2.       Cog and rung gears a gear system in which plain, unshaped teeth engage with a set of staves held between two flanged rings. 
3.       Cycloidal gears gears formed to a precise profile so that when they engage they roll along the face of the teeth to give a smooth motion and not the striking effect of the cog and rung gear. 
4.       Fantail a means of turning a windmill into the wind automatically. This consists of a set of blades mounted at the back of the mill at right angles to the sails, which rotate the cap by means of a gear train. 
5.       Grain elevator a series of small rectangular buckets mounted on a continuous belt inside a double wooden shaft. Grain is poured in at the bottom of the rising shaft so that it falls into the buckets which empty themselves into a hopper at the top when the belt goes over the top pulley. 
6.       Great spur wheel mounted on the upright shaft in a mill, drives the millstones by means of the stone nuts and stone spindles. 
7.       Greek mill a mill in which a horizontal waterwheel is mounted on the same shaft as the runner millstone. As the horizontal waterwheel turns so the runner millstone is turned at the same speed. This type of watermill is in common use from Portugal across the Mediterranean area. 
8.       Hemlath the longitudinal member at the outer edge of a sail frame. 
9.       Horizontal feed screw a means of carrying meal horizontally in a watermill. A rotating shaft in a long square box or sheet metal tube carries a continuous screw of sheet metal or a series of small paddles set in a screw form. The meal is pushed along to the appropriate opening by the motion of the screw.  
10.    Horizontal waterwheel a waterwheel mounted to rotate in a horizontal plane so that its rotation is transmitted into the mill by means of a vertical shaft. 
11.    Hurst frame the frame of stout timbers which carry the millstones. Often this frame is independent of the structural timbers of the mill. 
12.    Impulse wheel waterwheels, or more particularly turbines, which are driven by the pressure of the water being forced on them through a nozzle, rather than by the weight of water flowing on to them directly. 
13.    Lantern gears and pinions gears (resembling a lantern) having staves between two flanges, turned by pegs on the rim of another wheel. 
14.    Mortice wheel a cast-iron wheel in which sockets in the rim are set to receive wooden gear teeth. 
15.    Moulin pendant a form of watermill still to be found in France in which an undershot waterwheel is suspended in a frame so that the whole can be raised or lowered to meet variations in the water level caused by flood water. 
16.    Norse mill another name given to the drive system found in the Greek mill (q.v.). This form of mill still exists in Scandinavia and was common in the north of Scotland and the Faroes. 
17.    Overshot waterwheel a waterwheel in which the water is delivered to the top of the wheel so that it turns in the direction of flow. 
18.    Panster Muhle the German equivalent of the French moulin pendant (q.v.) which can still be found in the German Democratic Republic. In some instances the frame carrying the waterwheel is hinged and raised by chains and large man-operated lifting wheels. 
19.    Pit wheel name given to the first gear wheel in a watermill mounted on the waterwheel shaft. Because of its large size it usually runs in a pit on the inside of the wall which separates the waterwheel from the mill machinery. 
20.    Querns name given to primitive hand-operated millstones. These can be stones between which the grain is ground by rubbing or in which an upper flat-faced circular stone is rotated over a fixed flat-faced stone. 
21.    Stream waterwheel waterwheel in which there is no head of water but in which the floats are driven round by the flow of water striking them. 
22.    Tail water the water emerging from the bottom of a waterwheel while it is turning. 
23.    Undershot waterwheel a waterwheel in which there is a small head of water driving the wheel around. The water hits the wheel at about 60° below the horizontal line through the centre of the wheel. 
24.    Vertical waterwheel waterwheel mounted on a horizontal axis and rotating in a vertical plane. 
25.    Vitruvian mill the simplest form of watermill with a vertical waterwheel. The waterwheel is coupled by a pit wheel to a single runner millstone by means of a gear on the stone spindle. It is so called because it is described by Vitruvius in the tenth book of De Architectura which was published in about 20 BC. 
26.    Wallower a gear wheel which transmits the drive from the pit wheel to the upright shaft in a watermill or from the brake wheel on the windshaft to the upright shaft in a windmill.

BRIDGE GLOSSARY

1.       Abutment a construction that takes the thrust of an arch or vault or supports the end of a bridge 
2.       Arch a curved structure, usually in the vertical plane, that spans an opening or gap 
3.       Beam a long, straight piece of wood, metal or concrete used as a horizontal structural member Caisson a watertight compartment or chamber, open at the bottom and containing air under pressure, used for carrying out work under water 
4.       Caisson disease Divers working at higher than normal atmospheric pressure breathe in increased nitrogen, which is dissolved in the bloodstream. When they return to normal pressure, the nitrogen forms bubbles which, if collected in the capillary vessels, causes cramps (‘the bends’). If it collects in the joints, damage to nerve endings can cause paralysis, temporary or permanent 
5.       Cantilever a beam or girder fixed at one end only; a part of a beam or structure which projects beyond its support 
6.       Centring a temporary structure, usually of timber, which serves to support an arch under construction 
7.       Coffer dam a watertight structure enclosing an area below water level, pumped dry so that construction work can take place 
8.       Corbel a projection of timber or stone etc., jutting out from a wall to support a weight
9.       Falsework a temporary framework used during building 
10.    Girder a substantial beam, usually made of iron or steel 
11.    Keystone the central stone forming the top of an arch or a dome or vault (also called a quoin or headstone) 
12.    Lintel a horizontal beam as used over a door or a window 
13.    Pier a vertical member or pillar that bears a load 
14.    Pile a column of timber, iron, steel or concrete, driven into the ground or river-bed to provide a foundation for a structure 
15.    Soffit the underside of a structure such as an arch, beam or stair 
16.    Spandrel the space between the shoulder of an arch and the surrounding rectangular moulding or framework, or between the shoulders of adjoining arches and the moulding above 
17.    Springer part of an arch where the curve begins; the lowest stone of this 
18.    Starling an arrangement, usually of piles, that surrounds a bridge pier to protect it from erosion caused by scouring, debris etc. 
19.    Truss a structural framework of wood or metal, usually arranged in a formation of triangles, forming a load-bearing structure 
20.    Voussoir a wedge-shaped stone or brick used in the construction of an arch or vault.

WATERWAYS GLOSSARY

1.       Balance beam the heavy beam projecting landwards from a lock gate which, in providing the leverage for opening the gate, balances the weight of the gate. Found especially on British lock gates 
2.       Cylindrical sector rotating gate a modern type of lock gate which rotates horizontally through 90° from the vertical position where it closes the lock to a horizontal position in the bed of the canal to allow boats to pass over it 
3.       Flash a body of water suddently released to provide greater depth to allow navigation over shoals and shallows in a river 
4.       Flash lock an arrangement on rivers whereby the water could be held or penned back by a removable barrier across the flow. When a boat travelling downstream wished to pass the barrier was removed and a flash of water rapidly flowed through the opening earning the boat over shallows below the barrier. For vessels travelling upstream a wait was necessary until the flow had diminished and then the boats would be manually hauled or winched to the upper level. Also known as staunches 
5.       Inclined plane a device by which boats can be carried from one level to another either on cradles or in tanks travelling up and down a slope 
6.       Lift a device on the same principles as an inclined plane but with the tanks rising and falling vertically Lock a means by which boats can move from one level of a navigation to a different level 
7.       Paddle door a gate either pivoted or capable of rising and falling for opening and closing the orifice through which water enters or leaves a lock 
8.       Péniche the standard 300 tonne French canal barge. A law passed in 1879, under the direction of Charles de Freycinet, included minimum dimensions for the French waterways: depth 2m (7ft), locks 38.5m by 5.2m (127ft by 7ft), bridge clearance 3.7m (12ft). Barges which conformed to these constraints were said to be of Freycinet type 
9.       Pound lock a chamber, generally in brick or masonry, with gates at each end in which the water is impounded and through which boats pass from one level to another. The change is effected by the opening of paddles, paddle doors or sluices to allow water to enter or leave the chamber when the gates are closed. The gates are opened when the water level in the lock is the same as that either below or above the lock. The gates can be single, as on some narrow canals, or double so that the gates meet at an angle to withstand the water pressure. In this case they are called mitre gates. Also used are guillotine gates, which are raised and lowered vertically; radial gates, which turn on a horizontal axis to lie under the water below the draught of the vessel; or sliding horizontal gates which retract into recesses constructed in the side of the lock 
10.    Shaft lock a modern type of very deep lock with a fixed structure across the lock at the lower end. This structure houses a guillotine gate which rises from the canal into the structure and thus exposes a tunnel through which the boats pass to the lower level of the canal. Normal gates are provided at the upper level but gates would be impracticable at the lower level owing to the height of water impounded in the chamber 
11.    Staunch, see Flash lock 
12.    Summit level where a canal passes across a ridge from one valley to another the highest part of the canal is called the summit level. Into this generally run the feeders which supply the principal water for the locks on both sides of the ridge 
13.    Tide lock a lock provided where a canal enters the sea or a tidal estuary to allow vessels to pass at different states of the tide 
14.    Transporter bridge a type of bridge, generally in flat country, a number of which were built at the end of the nineteenth and beginning of the twentieth century, sufficiently high to allow tall-masted vessels to pass under the structure. A frame ran on rails at the upper level of the bridge and from this was suspended a cradle on which road traffic crossing the canal could be carried. The cradle passed to and fro between piers on the banks and thus shipping was not impeded by the passage of road traffic. Examples can be seen in England at Middlesbrough across the Tees and at Rendsburg in Germany across the Kiel or Nord-Ostsee Canal

RAIL GLOSSARY
1.       Adhesion frictional grip of driving wheel upon rail 
2.       Bogie short-wheelbase four- or six-wheeled pivoted truck supporting end of locomotive, carriage or wagon 
3.       Rail, double-headed rail in which, in cross-section, a vertical web links bulbous upper and lower heads of equal size 
4.       Rail, bullhead rail similar to double-headed (q.v.) but with the upper head larger than the lower 
5.       Rail, flat-bottom rail of inverted ‘T’ cross-section with a bulbous upper head 
6.       Rail, fish-bellied rail of cast or malleable iron with lower edge convex for strength, between points of support; so-called from its appearance 
7.       Skew bridge bridge with line of arch not at right-angle to abutment 
8.       Tank locomotive steam locomotive in which supplies of water and, usually, fuel are carried upon the locomotive itself instead of in a separate tender 
9.       Torque converter transmission comprising centrifugal pump in circuit with turbine, or similar device to give infinitely variable gear ratios 
10.    Valve gear, gab Steam engine valve gear in which each eccentric rod terminates in a ‘V’-shaped gab, set at right angles to it to engage a pin on the valve rod, The appropriate rods are engaged and disengaged for forwards or reverse running Valve gear, link motion steam engine valve gear in which the ends of the eccentric rods for each cylinder are attached to a link, sliding about a die block connected to the valve rod. As well as selection of forward or reverse running, this enables the point in the piston stroke at which steam is cut off from entering the cylinder to be varied, so that economies can be made in steam consumption

Materials for the history of technology

New documents are available in the Politecnico "portale della Didattica":

- pictures of the instruments taken from "Nature" (year 1953)
- some chapters from the book La Nuova Scienza - 2. L'uomo e le macchine.

History of printing

L'innovazione di Gutenberg nasce su tre saperi:

La metallurgia della lega Pb-As
La meccanica fine per la preperazione degli stampi dei caratteri
La chimica degli inchiostri


Movable type (Caratteri mobili)


Wednesday, May 3, 2017

Flywheel, the mechanics and energy storage

The paper Flywheel machines in the pre industrial age: a historical overview by Vittorio Marchis is now available on the "Portale della Didattica".



Tuesday, May 2, 2017

The water mill


Il mulino ad acqua

Marc Bloch, storico francese della prima metà del XX secolo. Afferma che il mulino "invenzione antica, trovò la sua vera diffusione soltanto nel Medioevo". Lo storico Luigi Russo presenta una tesi differente in un suo saggio.



Thursday, April 27, 2017

Building paradigms

Since the Middle Age
Charpenterie: art of building with wood and plaster

Maçonnerie: art of building with stone

Some centuries later

Construction: art of building ships