CHROMO-UTHOG11APH 



. nous, ..win-,' In their corrosive and Ojddicing 

 a.-tion on organic tissues. Chronic Stn-1 containing 

 u small percentage <>f chromium is valued fi its 

 toughness an. I strength; ami chromium is now 

 rally used with iron for projectiles. 



Chromo-lltliograph. See LITHOGHAPHY. 



<'liroiuos|>li>rr. s. Srx. 



Chronicle (<!r. i-lmmoa, 'time') denotes a 

 hisiory in which event* are treated in the order of 

 tinif. A chronicle is understood to differ from 

 annals in Ix-in- more connecte<l and full, the latter 

 merely recording individual occurrences under the 

 successive years or other dates. Most of our older 

 histories wen- callc.l chronicles, such as the Saxon 

 Chronicle, Holinshed's Chronicle, Baker's Chronicle. 

 The minif is also given to two historical books of 

 the Old Testament, and is not infrequently in 

 modern days adopted by a newspaper, as the Morn- 

 ing Clt run it'll 1 . 



Chronicles* THE FIRST AND SECOND BOOKS 

 OF THE, an historical work standing in the third 

 part of the Hebrew canon, and recapitulating the 

 history of 2d Samuel and the Books of Kings, with 

 many'omissions, and many additions, genealogical 

 and 'other. The Hebrew name means 'events of 

 the days ; ' the Septuagint entitles it Paraleipomena 

 ( 'things passed over' ) ; Eusebius called it a ' Chroni- 

 con of the whole divine history ' whence its present 

 name. First and Second Chronicles are one book, 

 of which Ezra and Nehemiah are continuations. 

 'The last three verses of 2d Chronicles are the first 

 three of Ezra, only the last verse of Chronicles 

 ends in the middle of a sentence, which is com- 

 pleted in Ezra, i. 3. In contrast to the older 

 Histories, which were written from the prophetic 

 standpoint, Chronicles shows a strongly Levitical 

 tendency. Most modern scholars hold its date to 

 be about 330 B.C. or later, at the beginning of 

 the Greek supremacy in Asia. The most useful 

 commentaries are by Bertheau (2d ed. 1873) and 

 Keil(1870). See BIBLE. 



Chronogram, or CHRONOGRAPH (Gr. chronos, 

 'time,' gramma, ' a letter,' or grapho, ' I write'), a 

 whimsical device of the later Romans, resuscitated 

 during the Renaissance period, by which a date is 

 .given by selecting certain letters amongst those 

 which form an inscription, and printing them 

 larger than the others. The principle will be 

 understood from the following example, made from 

 the name of George Villiers, first Duke of Bucking- 

 lian i : 



GEORGlVS DVX BVCKlNGAML. 



The date MDCXVVVIII ( 1628) is that of the year 

 in which the Duke was murdered by Felton at 

 Portsmouth. Another well-known example con- 

 veys the date in the inscription upon a medal struck 

 by Gustavus Adolphus in 1632 : 



CHRlSTVS DVX ; ERGO TRlVMPHVs. 



See collections by Hilton (1882, 1885, and 1896). 



Chronograph ('time-marker' or 'recorder'), 

 an instrument to note, within a certain fraction of a 

 second, the instant when a particular event occurs. 

 The most recent are electrical, now indispensable 

 to astronomers, since the transit of a star can, by 

 touching a stud, be noted to within rj^th of a 

 second of time. The typical form of the chrono- 

 .graph is a cylinder which revolves once a minute, 

 and carries on its surface a sheet of paper divided 

 all round into equal parts, indicating fractions of a 

 second. If, for example, the cylinder is 30 inches 

 round, it is evident that very minute subdivisions 

 of time are attainable. 



A valuable application of the chronograph is for 



determining the longitude e.g. in trigonometrical 



-surveys. Thus two observers note simultaneously 



the transit of a star, say at Vienna and Paris ( and 



119 



CllliONOI.OrJY 



that without any reference to right ascension or 

 declination), anil having telegraph OH well aft 

 chronograph, determine very easily the difference 

 of time with an accuracy never dreamt of formerly. 



/;. IIMIII'.I chronograph, by a lever movement, 

 measures intervals of time down to tenths of a 

 second for use at horse-races, &c. By a special con- 

 trivance the seconds hand on a horizontal dial carries 

 ink, and marks the plate l>eneath at the instant 

 when a string is pulled. Another mode of recording 

 the exact instant of start or finish is by having a 

 paper travel under a pencil, so that when the latter 

 is pressed a mark is made on or near one of the 

 cross lines showing tenths or twelfths of a second. 



Other forms of the chronograph are used for 

 determining the velocity of projectiles. The most 

 general arrangement consists in causing the bullet 

 to pass through a series of screens ; the rupture of 

 each screen breaks for a moment the continuity of an 

 electric current, sets in action an electro- magnetic 

 apparatus, and makes a permanent mark or record. 



Chronology ( Gr. , ' time-reckoning'), the science 

 of time, especially in regard to ( 1 ) the occurrence, 

 recurrence, and succession of events, or (2) the 

 duration of periods and cycles. The immense array 

 of facts with which chronology is occupied may be 

 distributed under two great lieads Mathematical 

 or Astronomical Chronology, and Technical or Polit- 

 ical Chronology. The former deals with celestial 

 phenomena, their order and the laws of their occur- 

 rence and duration, events outside of man's sphere 

 or influence. The latter branch deals with the 

 whole history of our race upon this planet ; and by 

 the selection of certain fixed points in time called 

 Epochs, refers to each of them the succession 

 of social and political events occurring in the 

 period immediately following it, and reckoned 

 from it, which we term its Era. As soon as the 

 elements of mathematical chronology were under- 

 stood, political chronology had solid ground to 

 build upon, and assume a systematic form : then 

 a science of history became possible. A 'year,' 

 for example, seems now an easy and natural unit 

 of time-measurement ; but for long ages the only 

 ! idea suggested by the word was that of a vague, 

 intangible period. So late even as 450 B.C. we find 

 Herodotus expressing duration of time by the 

 phrase ' three generations ' ( = a century ) or ' five 

 generations ; ' and in all languages we find ' six 

 summers' or 'sixty winters' instead of so many 



years. 



In the rudimentary stage of chronology, a nation 

 referred its history to the lifetime of some central 

 figure, such as the king, the tribal chieftain, &c.; 

 of which custom we actually find a survival in our 

 ' system of dating acts of parliament. The priestess 

 of Juno at Argos was another instance ; and in the 

 Roman and Athenian republics, where the chief- 

 magistrates were chosen annually, an event was 

 conveniently said to have occurred ' when Plancus 

 was consul, or ' in the archonship of Kallixenos.' 

 Similar to the Roman consul and the Athenian 

 i o-i'Iinn was the Assyrian limit or 'eponym,' from 

 whose name Babylonian and Assyrian documents 

 were dated far more frequently than from that of 

 the reigning king. Such a chronology, however, 

 could only oe of use within narrow limits l>oth 

 of time and place; and at all the great centres 

 of civilisation we find that as men's historical 

 \i.-\\s widened with the national growth, they 

 began to invent eras, some from national or 

 political motives, others ecclesiastical, and a few 

 scientific. Progress in astronomy, such as we 

 find in China and Babylonia at the dawn of 

 history, was of notable service at this stage. To 

 the Accadians of the latter country indeed both 

 astronomical and political chronology owe a lasting 

 debt of gratitude. The Chinese, no doubt, show a 



