SIXTH. 



SKEW-BRIDGE. 



684 



aggressors, and had schemed to increase their income by admitting 

 other persons, as well as the sworn or under-clerks, to practise in thei: 

 names. This was a bone of contention for many years. Before 169', 

 the under-clerks had obtained the privilege of filling up all the vacancies 

 in the office by taking articled clerks themselves. From this time til 

 their abolition, the office of Six-Clerk became a complete sinecure, anc 

 the Six Clerks were only mentioned in the court's annals with respec 

 to the fees that they are entitled to demand from suitors. The offici 

 was abolished by Lord Brougham's Act, which enacted that vacancies 

 should not be filled up till the number of Six Clerks was reduced to 

 two. Nearly the same story has to be told over again with reference 

 to the sworn clerks. For a long time these under-clerks were the prin 

 cipal solicitors of the court ; and until the middle of the last century 

 the chief business of the court was transacted by them without the 

 intervention of a solicitor. The same principle of monopoly led with 

 them to nearly the results that it did with their titular superiors. A 

 vesttd right to fees in the various stages of equity proceedings brought 

 about an inattention to business, which has led to the transfer of the 

 prosecution of suits to the solicitors. 



An effort was made in 1825 to get the offices of Six-Clerk and clerk 

 in court abolished. It was broadly stated at this time by a solicitor ol 

 celebrity, that Mr. S. (a gentleman whose mind had failed him) was 

 " quite as good a clerk in court after he was a lunatic ; " and the expense 

 of the office to the suitor was insisted on. Lord Eldon, however, saw 

 no reason to interfere with these offices, and they remained condemned 

 by the unanimous voice of the whole profession for many years longer. 

 Ultimately they were abolished, the then holders of the offices receiving 

 compensations so extravagant, that frequent attempts have been made, 

 though unsuccessfully, to reopen the question. 



Fur further information as to this office, the reader is referred to the 

 case "Exparte the Six Clerks," 3 Vesey's 'Reports,' 519; to the 

 ' Reports of the Commissioners on the Offices of Courts of Justice ' of 

 1816 ; to the ' Report of 1825 of the Chancery Commission ; ' to Beames's 

 ' Orders of the Court of Chancery ' ; to pamphlets by Mr. Spence, 

 Mr. Field, Mr. Merivale, and Mr. Wainewright; and to a powerful 

 speech on Equity Reform, made in the end ef the session of 1840, by 

 Mr. Pemberton (now Lord Kingsdown), which was afterwards published 

 in a separate form. 



SIXTH, a musical interval, a concord, the ratio of which is 5 : 3. 



[COKCOHD ; H.UIMu.NV.] 



Of the Sixth there are three kinds : the Minor Sixth, the Major 



:ind the Extreme Mm-/. AW.'A. The first (K, c). is composed of 



three tones and two semitones ; the second (c, A), of four tones and 



one semitone; the third (c, AS), of four tones and two semitones. 



Ex. :- 



1st. 



. 



2nd. 



3rd. 



SIZAR, a term used in the University of Cambridge for a class of 

 students who are admitted on easier terms as to pecuniary matters 

 than others. These pecuniary advantages arise from diilerent sources 

 in different college, and are of different value. Originally certain 

 duties were required of the students so admitted approaching to the 

 character of menial, but these have been long discontinued. A similar 

 class of students at Oxford are called Servitors. The word Sizar is 

 supposed to be derived from rizt, which is used in the University to 

 denote an allowance of provisions at the college buttery; and that 

 from the verb to attize, which in much the same as the modern cuaea, 

 which means api>wtivn. 



SIXK. [GIJ-K MAKOFACTCBE.] 



SKEW-BACK, in civil engineering, the course of masonry forming 

 the abutment for the voussoirs of a segmental arch, or, in iron bridges, 

 for the ribs. In the latter case a plate of cast-iron is usually laid upon 

 the stone skew-backs, extending the whole width of the bridge, and 

 forming a tie to the masonry. On account of the expansion and con- 

 traction of iron under changes of temperature, the ribs should not, 

 especially in large arches, be fixed to their abutments. The ribs of 

 Southwark Bridge, over the Thames, were originally bolted to the 

 masonry of the piers ; but it was found necessary, on this account, to 

 detach them, during the progress of the works. 



SKEW BRIDGE, a bridge in which the passages over and under the 

 arch intersect each other obliquely. In conducting a road or railway 

 through a district in which there are many natural or artificial water- 

 courses, or in making a canal through a country in which roads are 

 frequent, such intersections very often occur. As, however, the con- 

 struction of an oblique or skew arch is more difficult than that of one 

 built at right angles, skew-bridges were seldom erected before the 

 general introduction of railways; it being more usual to build the 

 bridge at right angles, and to divert the course of the road or of the 

 stream to accommodate it, as represented in f<j, 1 , in which a A is a 

 stream crossed by the road, the general direction of which is indicated 

 by the dotted line c d. In a railway, and sometimes in a common 

 road or a canal, such a deviation from the straight line of direction is 

 inadmissible, and it therefore becomes necessary to build the bridge 

 oMi'juely, as represented in the plan fi /?y. 2. Where space aud neatness 

 do not require to be con.-<i<terefl,aii oblique arch may be avoided, either 

 l.y tmilding the bridgn wju.ii i- ;tli the upper passage, and making the 



ARTS A!CD SCI. DIV. VOL. VII. 



span so wide as to allow the stream to pass under it without being 

 diverted; or by building the arch square with the stream, and of 



sufficient length to allow the upper passage to take an oblique course 

 over it ; but either of these is a clumsy expedient, although well 

 adapted for some situations. The arches or tunnels by which the 

 North- Western railway is conducted under the Hampstead Road and 

 Park Street, near the London terminus, are instances of the latter kind 

 of construction ; the length of the arches being such that they present 

 faces square with the line of railway, notwithstanding the oblique 

 direction of the roads over them. A similar case occurs at Denbigh 

 Hall, on the same line, where the railway crosses over the London and 

 Holyhead road at such an angle that the difference of direction is only 

 25. In this case a long gallery is constructed under the railway, con- 

 sisting of iron ribs or girders, resting upon walls built parallel with the 

 turnpike road ; the ribs, and consequently the faces of the bridge, 

 being at right angles with it. This gallery is about two hundred feet 

 long and thirty-four feet wide ; and by its adoption, the necessity of 

 building an oblique arch of eighty feet span was avoided. The 

 necessity of increasing the span of an arch according to its degree of 

 obliquity, by which the expense and difficulty are materially increased, 

 is illustrated by fig. 3, the ground-plan of an oblique arch across a 



Hs- 3. 



stream a. b. Here it is evident that c y is the actual span of the arch ; 

 although c rf, the breadth of the stream, would be the span of a straight 

 arch, leaving the same width of passage underneath. 



Very little is known respecting the origin of skew-bridges. It has 

 been repeatedly asserted that those built by George Stephenson on the 

 Liverpool and Manchester railway were the first erections of the kind ; 

 but this is certainly incorrect, there being some of earlier date even in 

 Lancashire. A paper m the ' Transactions of the Institution of Civil 

 Engineers,' vol i., p. 185, alludes to an oblique arch erected about the 

 year 1530 by Nicolo, called " 11 Tribolo," over the river Mugnone, 

 near Porta Sangallo, at Florence. It appears however that the 

 principle upon which such bridges should be constructed was too little 

 understood to render an attempt at constructing them on a large scale 

 advisable. The next information the writer has met with on the 

 subject is contained in the article ' Oblique Arches,' in Rees's ' Cyclo- 

 paedia ; ' an article which appears to have escaped the notice of modern 

 writers on this branch of engineering science. It is written by an 

 engineer named Chapman, who mentions oblique bridges as being in 

 use prior to 1787, when he introduced a great improvement in their 

 construction. Down to that time, as far as he was informed, such 

 Bridges had always been built in the same way as common square 

 arches, the voussoirs being laid in courses parallel with the abutments. 

 Sow very defective such an arch would be may be seen by reference 

 to fig. 3, in which lines are drawn to indicate the direction of the 

 courses. It is evident that here the portion cilfe is the only part of 

 .he arch supported by the abutments ; the triangular portions cdg and 

 efh being sustained merely by the mortar, aided by being bonded 

 with the rest of the masonry. This plan could therefore only be 

 adopted for bridges of very slight obliquity, and even then with con- 

 siderable risk. About the time mentioned above, Mr. Chapman was 

 employed as engineer to the Kildare canal, a branch from the Grand 

 ..'anal of Iix-laml to the town of Naas. on which it was desired to avoid 

 livertiug certain roaJs which had to be crossed. He was therefore 

 ed to look for some method of constructing oblique arches upon a 

 sound principle, of which he considered that the leading feature must 



QQ 



