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Fig. '1 represent* one of various form* of the ingenious contrivance 

 known u llooke'd universal joint, an apparatus by Inch shafts which 



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do not lie in a straight lino with each other, or which are liable to 

 change their relative positions in thin respect, may be made to turn 

 each other. While it may be used as a substitute cither for an ordi- 

 nary coupling or for bevil gear, this joint or connection will accomplish 

 what neither of those contrivances can do. As an illustration of the 

 circumstance* under which such a coupling may be employed, we may 

 allude to a scheme patented in 1825, by Hr. James, for propelling 

 railway carriages on steep inclinations by communicating the rotatory 

 motion generated in a locomotive engine to all the wheels of every 

 carriage in the train, through the medium of a system of rods thus 

 connected, and consequently capable of receiving and imparting motion, 

 whether the train were in a straight line or on a curve so great as (p 

 cause the aide of one carriage to form an angle of 30 with that of the 

 adjoining one. The details of this specimen of ingenuity, which is 

 here referred to simply as affording a striking illustration of the powers 

 of the universal joint as a coupling, arc given in Hebert's ' Engineer's 

 and Mechanic's Encyclopedia," vuL ii., pp. 465, 466. 



When power is conveyed to a considerable distance by means of a 

 series of revolving shafts, the motion often becomes irregular and 

 uncertain ; but this evil may be in a great measure rectified by placing 

 a fly-wheel to equalise the motion at or near the extremity of the 



In all contrivances for disengaging and re-engaging machinery while 

 in motion, it is necessary to consider the effect of inertia, which renders 

 it both difficult and hazardous to bring a machine suddenly from a 

 state of rest to one of rapid motion. When the connection is formed 

 by toothed or cogged wheels this difficulty is especially felt, and, con- 

 sequently, while it is very easy to disconnect such wheels, or, as it is 

 commonly termed, to throw them out of year, either by removing the 

 axis of one of the wheels, or by gliding one wheel along its axis until 

 its teeth are disengaged from the other, they cannot be re-engaged 

 without great risk of breaking the teeth. In this respect, as shown 

 under WHEELS, a connection by means of straps or cords is for prefer- 

 ble. Such a connection always has some degree of elasticity and 

 power of yielding under the effect of sudden strains, and when employed 

 in connection with the fast and loose pulley (a contrivance illustrated 

 under SAW-HILL), it affords perhaps the safest method known of starting 

 and stopping machinery. Sometimes a similar effect is produced by 

 the use of an endless cord or band passing round two pulleys, one of 

 which is on a moveable axle, by the shifting of which the tension of 

 the band may be destroyed. Where neither the axle of the driving 

 pulley, nor that of the driven one, can be made moveable, the same 

 effect may be produced by the urn of a third pulley, or drum, so 

 mounted that by pressing it against the band the tension may be 

 increased to any desired amount, or by removing it out of the way, it 

 may be destroyed. The small wheels (t, e) in the cut of part of 

 Brunei's block machinery, given under SAW-MILL, though merely 

 employed for increasing the tension, and not for taking it off to stop 

 the revolving saw, will illustrate such a contrivance. Bands are some- 

 times applied to a sliding pulley, which may be locked to the machinery 

 at pleasure by engaging it with revolving glamU. r with a bayonet 

 roupling ; but in such a case the shock of starting is not avoided, 

 tli. .n^li the elasticity of the band, and its power of slipping on the 

 pulley under the effect of sudden resistance, render it less hazardous 

 than with cog-wheels. 



Clutches or bayonet connections are sometimes employed to start 

 a train of wbcelwork in which the teeth themselves arc never actually 

 thrown nut of gear. The disadvantages of such a mode of coupling 

 may be in a great measure avoided by the use of a friction dulrh, in 

 which the driving-arms or projections are attached to an elastic open, 

 hoop or band i.f metal, sprung on to a smooth wheel or drum, and 

 fitted with tightening screws. Lv whieh it may lw pressed to any 

 degree of tightness; so that while it will slip round until the inertia of 

 the machinery is overcome in starting, or under the effect of accidental 

 resistance, its friction will be sufficient, under ordinary circumstances, 

 to cause it and the drum to turn together, as if they were one piece. 



In another contrivance of the same character the connection is 

 effected by pushing a solid conical wheel or drum, mounted upon one 

 shaft, into a hollow cone attached Ui an adjoining shaft, in doing which 

 the friction, and consequent power of transmitting motion, increases 

 in proportion to the advance of the solid into the hollow cone. Friction 

 wheels, with their peripheries formed of the end of the grain of wood, 

 which may be compared to a collection of indefinitely small teeth, 

 pressed together by levers, or friction wheels or discs placed side by 



aide so u to be either a little separated or pressed together at pleasure, 

 are also occasionally used. A coupling which starts the machinery 

 gradually by friction may be connected with a fixed clutch or I. 

 coupling in such a way that, when once started, the connection .'.t il..- 

 machinery shall be rigid, and no longer dependent upon mere fri. 



Very full details upon the subject of this article are given in the 

 excellent ' Practical Essays on Mill- Work and other Machinery,' by 

 Robertson Buchanan, with additions by Tredgold and Qeorge Reunie, 

 8vo, Loud., 1841, pp. 262-304, where allusion is made to couplings 

 which disengage themselves under the influence of any undue strain 

 upon the machinery, and a plan is proposed fur diminishing the risk of 

 engaging cogged wheels, by introducing spring spokes in the larger 

 wheel of the pair, the teeth of which are more likely to break than 

 those of the pinion. The subject is also treated at some length in 

 Barlow's ' Treatise on Manufactures and Machinery,' in tl. 



paxlia Metropolitana,' sect, 46-51. 

 COURANTE, or CORA 



CORANTO, a quick dance in triple time. In 



Handel's, Mattheson's, and other lessons for the harpsichord, composed 

 towards the end of the 17th and beginning of the 18th centuries, a 

 Coumntr \ generally introduced as one of the movements. 



COURIER, from the French courir, to run; a messenger sent in 

 haste, or express ; a bearer of despatches. The advantage of receiving 

 the earliest intelligence, and of conveying orders with celerity, must 

 have given rise to the employment of couriers at a very early period. 

 Herodotus (viii. 98) gives a particular description of the speed of the 

 Persian royal messengers who proceeded by relays. He says this mode 

 of conveying intelligence was called by the Persians ayyafd)iov ( Anga- 

 reion); and the couriers themselves liyyapoi (augaroi). Another 

 description of couriers among the Greeks were called 7)Mpo5p<W', wno 

 appear to have been armed with a light spear or dart, &c. (Suidas I'M 

 rin-r.) Herodotus (vi. 105) says that a little before the battle of Mara- 

 thon, Pheidippides (an fifupoSpdftot, a ninner by profession) being sent 

 by the Athenian generals, arrived at Sparta on the second day after 

 leaving Athens, a distance not less than 140 or 150 miles. (See also 

 Suidas, r. 'In-fat.) The mode of employing couriers by Cyrus, as 

 described by Xenophon (' Cyropiedia,' viii., 6), appears to be nothing 

 more than the system already referred to as described by Herodotus. 

 He ascertained the journey which a horse could fairly perform within 

 a day, and placed stables at regular distances, so that messengers eould 

 receive or deliver letters from hand to hand. Gibbon, in his ' Decline 

 and Fall of the Roman Empire ' (chap, ii.), speaks of the swiftness and 

 regularity of the Roman posts. The Romans called such messengers 

 eunont : they were sometimes sent on foot and sometimes on hone- 

 back. The earliest couriers of the European nations were probably 

 what have since been called running-footmen. In manuscripts of the 

 13th century such messengers are occasionally styled trottarii or 

 trotters. The running-footmen or couriers, who accompanied John 

 Duke of Marlborough in his wars, are several times represented in the 

 tapestries at Blenheim-house. The word has also been used in modern 

 times for a travelling attendant on persons or families journeying in a 

 foreign country. 



COURSE OF EXCHANGE. [EXCHANGE.] 



COURT BARON. [MANOR.] 



COURT-MARTIAL, a tribunal occasionally instituted for the pur- 

 pose of trying military and naval men for the commission of offences 

 affecting discipline in either of those branches of the public service. 



Courts for the trial of rebels by martial law appear to have early 

 existed in this country ; and in the time of Henry VIII., the Marshal 

 of England held one regularly for the trial of causes connected with 

 military discipline. In the reigns of Elizabeth and her successor, 

 those courts of war, as they were called, were superintended not by the 

 marshal, but by a president chosen for the purpose. This president 

 was probably a general or field-officer, but captains of companies were 

 allowed to sit as members. The colonel of each regiment was charged 

 with the duty of preparing the evidence relating to offences whi* 

 under his cognisance, and of bringing it before the court. 



But courts-martial in their present form were instituted in the reign 

 of James II. in the year 1080, when ordinances of war were issued for 

 rcgulating^the discipline of the army. Since the revolution ,.f 1088, their 

 existence and jurisdiction depend on the will of Parliament, expressed 

 year by year in statutes known as the Mutiny Act, and the M 

 Mutiny Act, which are expressly limited to the ilurntion of one year. 

 Nav.il courts-martial differ in this from courts-martial in the army or 

 the marines, that the former derive their constitution and authority 

 u ' in .1 prriii.-iiii-nt statute, the 22 Geo. II., c. 33. The East ln.li 

 pony's European troop* in India continued to lie subject to the Mutiny 

 Act and Articles of War, in force with regard to the troops of t!>. 

 United Kingdom, until the year 1754, when an Act was passed, ami 

 Articles of War, very similar to those in force for the royal army 

 were promulgated expressly for that division of the Company's t 

 A new code was afterwards framed in the year 1823, and alterations 

 have been made in successive years up to the latest Act, jxu- 

 July, 184U, and the Articles of War, issued the same year. Tin 

 pany's native troops continued to serve, subject to the discipUni :md 

 rules of the British Mutiny Act and Articles of War, till k se|.. 

 codes were framed for the three presidencies in the end of the last 

 century. These separate codes for the native troops were revised and 

 consolidated in the year 1845, and again altered and framed anew, an a 



