hide Matching Documents

The documents where this entity occurs most often are shown below. Click on a document to open it.

Document Max. Freq Min. Freq
Knight's Mechanical Encyclopedia (ed. Knight) 18 0 Browse Search
View all matching documents...

Browsing named entities in Knight's Mechanical Encyclopedia (ed. Knight). You can also browse the collection for Richard Varley or search for Richard Varley in all documents.

Your search returned 9 results in 6 document sections:

Knight's Mechanical Encyclopedia (ed. Knight), E. (search)
e-ter. An instrument to measure the amount of an electrical force. In Coulomb's torsion electrometer (a) the force opposed to that of electricity is the resistance to twisting offered by an elastic thread. In Henly's quadrant electrometer (b) the electric force is measured by the amount of repulsion which it produces upon a pith-ball attached to a silk fiber suspended from the center of a graduated are. c is the gold-leaf electroscope. See electroscope. Sir William Thomson's and Varley's electrometers are the most delicate of all, and are used in reading the insulating power of telegraph-cables. See galvanometer. Electrometers. The strength of the electric force excited by the rubbing of glass, sulphur, amber, wax, resin, etc., was measured by Gilbert by means of an iron needle (not very small) moving freely on a point, versorium electricum; very similar to the apparatus employed by Hauy and Brewster, in trying the electricity excited in different minerals by warmth
Knight's Mechanical Encyclopedia (ed. Knight), I. (search)
cup is an annular non-conducting disk. c has a shank to enter the telegraph-post, and a two-pronged stem covered with vitreous enamel. d has a flanged disk to prevent the accumulation of a film of moisture around the stem. e, the metallic hook is socketed in a hard rubberplug which enters the telegraph-post. A flaring cap is rooted to the insulator-plug, and its rim approaches the hook. Insulators. f has a bell around the disk on the rubber socket of the hook-shank. g is Varley's insulator, which obtained the prize at the Paris Exposition. It has a paraffine cup and a conducting shield which conducts off atmospheric electricity. h i j are three views of Cooke's insulator (English). e e are earthenware thimbles for the wires. b b are insulating earthenware struts. r r are winding ratchets for the reels t t on which the wires are strained. Posts at intervals of 400 yards. All bodies are conductors of electricity; but while in some the degree of conductivity
Knight's Mechanical Encyclopedia (ed. Knight), P. (search)
down an inclined vibrating plane whose motion is automatically reversed each time the ball reaches either end. Pneumatic devices are a prominent subject. Among these is the occasionally recurring hollow cylinder, in which a weight or pressure of some kind is applied on one side of a chamber, fixed on an arm or spoke, while the air is exhausted from the other side. We believe it is the correct thing to inclose concerns of this kind in a water-chamber; at all events, this was done by Richard Varley, according to the specification of his English patent (1790), because water has no spring. A drum journaled in a cylinder axially divided by a vertical air and water tight partition, one side containing liquid and the other air, has also been claimed as a perpetual motor; the periphery of the wheel is provided with reservoirs containing a substance lighter than the liquid; these necessarily rise therethrough, but being heavier than air have a downward tendency on reaching that part of
Knight's Mechanical Encyclopedia (ed. Knight), S. (search)
cessing the door and providing an interior flange, behind which the bolts shoot to prevent the introduction of wedges. Varley's, 1865, is the first patent for an electro-magnetic alarm for safes. The signal is given by means of a bell caused to r Other forms, as the ellipsoid and cylinder, may be substituted for the sphere. Besides the electro-magnetic alarms of Varley and others, signals have been devised to indicate by the sudden extinguishment of a light if an attempt has been made to a watchmaker's and bench instrument for many years before it had any place in the machine-shop. Fig. 4721 illustrates Varley's screw-cutting apparatus, applicable to the hand-lathe. The mandrel a is surrounded by a tube on which four threads of ing between each course of the plows. The first steam-plow patented in England was the invention of Clarke, Freeman, & Varley, 1846. This system used a track for a locomotive on each side of the piece to be cultivated, and the plows were drawn ba
Knight's Mechanical Encyclopedia (ed. Knight), T. (search)
nd the ball falls. By galvanometers placed in the circuits of the time wire to Liverpool, and the return wire, it was ascertained that the time elapsing between the receipt of the current in London and the discharge of the ball in Liverpool was 1 1/20 of a second; of this 2/20 were occupied by the automatic circuit-closer, 4/20 by the ball-trigger mechanism, leaving 5/20 of a second for the passage of the current by the underground wire. By means of an improved arrangement devised by Mr. Varley for connecting the observatory at the Cape of Good Hope with time-balls at Simonstown and Port Elizabeth, the time elapsing between the passage of the current at Capetown and that announcing the falling of the ball at Port Elizabeth, 500 miles distant, is found to be but 1/15 of a second. Time-ta′ble. 1. A table giving the times of starting and arrival at each station of the daily trains on a given road. 2. A record of time of employes. 3. A board divided by vertical and horizo
Knight's Mechanical Encyclopedia (ed. Knight), U. (search)
perm candle burning 120 grains per hour. The standard for gas is that the flame, burning at the rate of five cubic feet per hour, shall give a light equal to the light of 14 sperm candles, each consuming at the rate of 120 grains per hour. The units of electricity. The unit of resistance of the British Association (B. A. unit) is called an ohm, from the German savant Ohm, who reduced the measurement of electric forces to a system. Siemen's unit of resistance = .9564 of an ohm. Varley's unit = about 25 ohms. The unit of tension, or electro-motive force, is called a volt, from the illustrious name Volta. It does not differ greatly from a Daniel's cell, which is = 1.079 volt. The unit of quantity is called a farad, from the philosopher Faraday; it is that quantity of electricity which, with an electro-motive force of one volt, will flow through a resistance of one megohm (1,000,000 ohms) in one second. The unit of current is a current of one farad per second. T