961 



CLAY. 



CLERGY. 



662 



which is the common method and an improvement on the old system 

 of two crops and a fallow, five might easily be obtained, especially if 

 tares and Trifolium incarnatum are considered as crops. For example : 

 1. Oats or barley ; 2. Clover; 3. Wheat; 4. Trifolium cut in May, and 

 succeeded by spring tares, cabbages, or potatoes. Mangold wurzel is 

 another green crop easily cultivated on clay soils. At all events the 

 trifolium or winter tares may always be had in the year in which the 

 land is to be cleaned by repeated ploughings ; as they may be cut early 

 in summer, and leave ample time for the operations. 



The great disadvantage of clay soils in a moist climate like that of 

 Great Britain, arises from an excess of water," and the obvious remedy 

 is perfect draining of the subsoil. This is effected by numerous hollow 

 drains judiciously arranged to convey the water to a proper outlet. 

 [DRAINING.] 



Clay is extensively used in many parts of England to improve light 

 land, by being carried on the surface in considerable quantities, but 

 this is chiefly where it approaches to the quality of marl, by having a 

 considerable portion of calcareous earth in its composition. 



The effect of burnt clay as a manure has been highly extolled, and 

 not without some reason in particular situations. Clay by burning 

 alters its nature ; it becomes insoluble in water, and loses its attraction 

 for it, becoming more sandy in its texture. The addition of it will 

 thus improve a very strong retentive clay, tempering it and rendering 

 it more porous. To burn clay, it is dug out in lumps and dried ; heaps 

 are made of these at regular distances in a field, with a small cavity in 

 the centre, in which dry furze and brushwood are introduced. This 

 being lighted, the fire is allowed to burn very slowly, and the smoke 

 kept in by adding a sod or clod wherever it bursts out. When the 

 heap is once burning, more clay may be added even without being 

 dry, and the combustion goes on without other fuel. It must be so 

 managed as to bake the clay without heating it too much ; and when 

 the heaps are cooled and opened the whole should appear pulverised, 

 and of a red colour if oxide of iron exists in the soil. A coat two or 

 three inches thick spread over a field and ploughed in will greatly 

 improve its texture ; but sufficient animal or vegetable manure nrast 

 be added to make it fertile. 



CLAY. Clays are more or less pure compounds of alumina and 

 sih'c acid. [ALUMINA.] 



CLEF (Fr. clef, a key), in Music, a character placed at the beginning 

 of the staff, to give names to the lines and spaces, and determine the 

 acuteness or gravity of each note. 



There are three clefs the treble, the mean (or c clef), and the base. 

 The Treble Clef is now only placed on the second line, which it 

 names o. 



The Mean Clef gives the name of c to any line on which it is placed : 

 it is called the soprano clef when placed on the 1st line, the mezzo- 

 soprano when on the 2nd, the alto, or contmtenor, or countertenor, when 

 on the 3rd, and the tenor when on the 4th. By this contrivance the 

 use of numerous ledger lines is avoided, and the music becomes more 



easy to read. 



C C C C 



The Base Clef is now placed only on the 4th line, giving it the 

 name of F. 



The treble clef is appropriated to female and boys' voices, and to 

 instruments the scales of which run high. Of the four kinds of mean 

 clef, the first is used for female and boys' voices ; the third and fourth 

 for 'men's voices, also for the viola, the two higher trombones, and 

 occasionally for the clarinet and violoncello. The base clef is appro- 

 priated to the lowest male voices, and to instruments the scales of 

 which run deep. 



In the 17th century the treble cleffwas used on both 1st and 2nd 

 lines, and the base on both 3rd and 4th. The correction of so great an 

 eVil was a step towards, simplification, and, in 1672, a distinguished 

 mathematician (Thomas Salmon, M.A., of Trinity College, Cambridge) 

 published his plan for a complete amelioration, by the abolition of all 

 clefs and substituting for them one universal character. The plan was 

 simple and feasible ; but it was at once violently, and successfully 

 opposed by the musicians of the day, at the head of whom was 

 Matthew Lock. Thus was strangled in its birth a rational attempt to 

 emovemuch of the difficulty attending the practice of music. The 

 c clef is now gradually falling into disuse, but we fear that its final 

 rciection is not near at hand, and that a long time will elapse before 

 other desirable reforms in music, calculated to remove many of the 

 mpediments to the practice of the art, will be accomplished. 



CLEMENTINES is the name given to a collection of decretals and 



constitutions of Pope Clement V., which was published in 1308 under 



lie title of ' Liber septimus Decretalium,' being the seventh book in 



order of time of the collection of the decisions and rescripts of the 



ABTS AND SCI. DIV. VOL. II. 



popes on matters of ecclesiastical discipline, and also on matters con- 

 cerning laymen which then came within the cognisance of the eccle- 

 siastical courts. [CANON LAW.] The first printed editions of the 

 Clementines are those of Mainz, 1460 and 1467, fol. 



CLE'PSYDRA (\f if iiSpa, from /t\eWeii/, SSap). Before the invention 

 of pendulum clocks, it was not unusual in astronomical observations to 

 measure time by the flowing of water, upon a principle which, in its 

 most simple application, resembled that of the hour-glass, but which 

 was varied by contrivances for accuracy or ornament. Such an instru- 

 ment was used, up to the time of Galileo, by Tycho Brand for instance ; 

 but as he does not describe it among his instruments, we may suppose 

 that he hardly considered it to rank among the primary aids of an 

 observer. 



The Chaldtcans, it is said, divided the zodiac into twelve equal parts, 

 as they supposed, by allowing water to run out of a small orifice during 

 the whole revolution of a star, and dividing the fluid into twelve equal 

 parts, the time answering to each part being taken for that of the pas- 

 sage of a sign over the horizon. The authority for this story is Sextus 

 Empiricus (' Adv. Math.' cap. 21), who adds, that they regularly used 

 the instrument in finding their astrological data, and remarks that the 

 unequal flowing of the water, and the variations of temperature of the 

 atmosphere, would affect the accuracy of their results. Pliny men- 

 tions Scipio Nasica as the first who introduced clepsydras into Rome. 



We might perhaps object to Sextus Empiricus as an authority on 

 Chaldee usages ; but a good presumption of the early use of clepsydras 

 in India is afforded by the arithmetical treatise of Bhascara, written in 

 the 12th century. The prediction at the birth of his daughter, Lili- 

 wati, was that she should die unmarried. The father determined to 

 have at least one struggle against the prophecy, and accordingly pro- 

 cured a bridegroom and an astrological determination of a lucky hour. 

 The girl remained in her ornaments near the clepsydra, watching for 

 the moment when she and her parent might set fate at defiance. But 

 at length it was ascertained that the hour was past ; and on examining 

 the clock, which should have prevented such a catastrophe, it was 

 found that a pearl had escaped from the daughter's dress and closed 

 the orifice through which the water should have flowed. The father, 

 thus disappointed, said to his unfortunate daughter, " I will write a 

 book of your name, which shall remain to the latest times." The 

 Liliwati accordingly remains, and bids fair to realise the prediction. 

 (Taylor's ' Liliwati,' Bombay, 1816.) 



In the account given by Vitruvius (' De Architectural lib. ix.), he 

 attributes the invention to Ctesibius ; but the instrument described is 

 so complicated that we by no means suppose he intends to assert that 

 this was the first application of the principle even at Alexandria. Some 

 mode of measuring time by the efflux of water, however rude it might 

 be, was used at Athens before the time of Ctesibius, as we see by 

 various passages in Demosthenes. The instrument described by Vi- 

 truvius is an elaborate contrivance, which shows the hour, day, month, 

 and sign of the sun. The astronomical clepsydra was rejected by 

 Ptolemy on account of its imperfections, and it is not necessary to 

 follow the moderns through the various modifications under which 

 they have attempted to apply the principle. Such instruments con- 

 tinued to be common, as toys at least, until the middle of the last 

 century. 



If we suppose a clepsydra made of a glass cylinder, with a very small 

 orifice at the bottom, and the apparatus being filled with water, the 

 orifice to be opened, the upper surface of the fluid will not descend 

 equally in equal times, according to the notion which Sextus Empiricus 

 attributes to the Chaldrcans. If the water be pure, and the orifice 

 very small and unclogged, the following will be the law of descent. 

 Ascertain first the whole time of emptying the cylinder : then in the 

 fraction m of the whole time, the fraction m (2 m) of the fluid will 

 have discharged itself ; or that same fraction of the whole height will 

 have been fallen through. Thus in one-half the whole time of empty- 

 ing, 4 (2 4) or f of the whole fluid will have been discharged, while 

 in If of the whole time ^ of the whole will have been discharged. It 

 is totally out of the question to suppose that the ecliptic was so nearly 

 divided into twelve equal parts as actually was done, by any such 

 imperfect process; though it is not impossible that by keeping the 

 clepsydra constantly full, or very nearly so, equal times may have been 

 estimated by the discharge of equal bulks of fluid. Supposing the 

 cylinder to be kept constantly full, it would discharge its own bulk 

 of fluid in exactly one-half the time in which it would empty itself 

 undisturbed. 



CLERGY, a collective term, under which that portion of the popu- 

 lation of a country is comprehended who are in holy orders. It is used 

 in contradistinction to laity, which comprehends all other persons. 

 Like most ecclesiastical terms, it is of Greek origin, the word K\TIPIKOS 

 (cl(5ricus) having been used in the sense of " appertaining to spiritual 

 persons " by the Greek ecclesiastical writers. From dericus comus the 

 word clerk, which is still a law term used to designate clergymen, but 

 which appears anciently not to have been confined to persons actually 

 in holy orders, but to have been applied to persons possessed of a certain 

 amount of learning. 



The distinction of clergy and laity in the Christian Church may bo 

 considered as coeval with the existence of the Church itself ; for in the 

 apostolic period there were officers in the Church specially appointed to 

 discharge the duties of pastors or deacons, and even, as many suppose, 



3Q 



