Chapter X: Front Matter (10)

_Astronomical Chronographs._--The astronomical chronograph is an
instrument whereby an observer is enabled to register the time of
transit of a star on a sheet of paper attached to a revolving
cylinder. A metal cylinder covered with a sheet of paper is rotated by
clockwork controlled by a conical pendulum, or by a centrifugal clock
governor such as is used for driving a telescope. By means of a screw
longer than the cylinder, mounted parallel with the axis of the
cylinder and rotated by the clockwork, a carriage is made to traverse
close to the paper. In some instruments this carriage is furnished
with a metal point, and in others with a stylographic ink pen. The
point or pen is made to touch the paper by an electromagnet, the
electric current of which is closed by the observer at the transit
instrument, and a mark is recorded on the revolving cylinder. The
movement of the same point or pen is also controlled by a standard
clock, so that at the end of each second a mark is made. The cylinder
makes one revolution per minute, and the minute is indicated by the
omission of the mark. In E.J. Dent's form (_Nature_, 23, p. 59)
continuous observations can be recorded for 6-2/3 hours. The conical
pendulum used to govern the rotation of the cylinder was the invention
of Sir G.B. Airy. The lower end is geared to a metal plate which
sweeps through an annular trough filled with glycerin and water. When
the path of the pendulum exceeds a certain diameter it causes the
plate to enter the liquid more deeply, its motion being thereby
checked; also, when the pendulum moves in a smaller circle the plate
is lifted out of the liquid and the resistance is diminished in the
same proportion as the force. The compensatory action is considerable;
doubling the driving power produces no perceptible difference in the
time. To prevent the injury of the conical pendulum and the wheel work
by any sudden check of the cylinder, a ratch-wheel connexion is placed
between the cylinder and the train of wheel work; this enables the
pendulum to run on until it gradually comes to rest. The pendulum,
which weighs about 18 lb, is compensated, and makes one revolution in
two seconds; it is suspended from a bracket by means of two flexible
steel springs placed at right angles to one another.

The observatory of Washburn, University of Wisconsin, is furnished
with a chronograph of the same type as that of Dent (_Annals Harvard
Coll. Obs._ vol. i. pt. ii. p. 34), but in this instrument the
rotation of the cylinder is controlled by a double conical pendulum
governor of peculiar construction. When the balls fly out beyond a
certain point, one of them engages with a hook attached to a brass
cylinder which embraces the vertical axle loosely. When this mass is
pulled aside the work done on it diminishes the speed of the governor.
The pendulum ball usually strikes the hook from 60 to 70 times per
minute. Governors on this principle were adopted by Alvan Clark for
driving heliostats in the United States Transit of Venus Expedition,
1874.

Grubb.

In the astronomical chronograph designed by Sir Howard Grubb (_Proc.
Inst. Mech. Eng._, July 1888), the recording cylinders--two in
number--are driven by a weight acting on a train of wheel work
controlled by an astronomical telescope governor. The peculiar feature
of this instrument is that the axle is geared to a shaft which
communicates motion to the cylinders through a mechanism whereby the
speed of rotation is constantly corrected by a standard clock. Should
the rotation fall below the correct speed it is automatically
accelerated, and if its speed of rotation rises above the correct one
it is retarded. The accelerator and retarder are thrown into action by
electromagnets, controlled by a "detector" mounted on the same shaft.
The rather complicated mechanism employed to effect the correction is
described and fully illustrated in the reference given. The cylinders
are covered with paper, but all the markings are made with a
stylographic pen. The marks indicating seconds are dots, but those
made by the observer are short lines. When an observation is about to
be made the observer first notes the hour and minute, and, by pressing
a contact key attached to a flexible cord at the transit instrument,
marks the paper with a letter in Morse telegraph characters,
indicating the hour and minute; he then waits till a micrometer wire
cuts a star and at the instant closes the circuit, so that the second
and fraction of a second are registered on the chronograph paper. When
a set of observations have been taken, the paper is removed from the
cylinder, and the same results are obtained by applying a suitably
divided rule to the marked paper, fractions of a second being
estimated by applying a piece of glass ruled with eleven straight
lines converging to a point. The ends of these lines on the base of
the triangle so formed are equidistant on one edge of the glass, so
that when the first and last lines are so placed as to coincide with
the beginning and end of the markings of a second, that second is
divided into ten equal parts. The base of the triangle is always kept
parallel with the line of dots. The papers, after they have been
examined and the results registered, are kept for reference.

Hipp.

In the astronomical chronograph of Hipp, used in determining
longitudes, the movement of a recording cylinder is regulated by means
of a toothed wheel, the last of a clockwork train, controlled by a
vibrating metal tongue; this important feature is described in detail
in Favarger's work cited above.

Regnault.

_Acoustic Chronographs._--In the chronograph devised by H.V. Regnault
(_Acad. des Sc._, 1868) to determine the velocity of sound propagated
through a great length of pipe, a band of paper 27 mm. wide was
continuously unrolled from a bobbin by means of an electromagnetic
engine. In its passage over a pulley it passed over a smoky lamp
flame, which covered it with a thin deposit of carbon. It next passed
over a cylinder in contact with the style of a tuning-fork kept in
vibration by electromagnets placed on either side of its prongs, the
current being interrupted by the fork; it was also in contact with an
electric signal controlled by a standard clock. Also an
electromagnetic signal marked the beginning and end of a time period.
Thus three markings were registered on the band, viz. the time of the
pendulum, the vibrations of the fork, and the marking of the signal
due to the opening and closing of the current by electrical contacts
attached to diaphragms on which the sound wave acted. The contacts
consisted of minute hammers resting on metal points fixed to the
centre of diaphragms which closed the end of the experimental pipes.
The signal marked the instant at which a sound wave impinged on a
diaphragm. The markings on the paper band gave the period of time
between two events, and the number of vibrations of the tuning-fork
per second was estimated by means of markings due to the clock. The
sound wave was usually originated by firing a pistol into the pipe
furnished with diaphragms and contact pieces.

Ayrton and Perry.

In the chronographic use of the Morse telegraph instrument (Stewart
and Gee, _Elementary Practical Phys._ p. 234) a circuit is arranged
which includes a seconds' pendulum furnished with a fine platinum wire
below the bob, which sweeps through a small mass of mercury forming a
part of the circuit. There is a Morse key for closing the circuit. A
fast-running Morse instrument and a battery are placed across this
circuit as a shunt. A succession of dots is made on the paper ribbon
by the circuit being closed by the pendulum, and the space between
each adjacent dot indicates a period of one second's duration. Also,
when the key is depressed, a mark is made on the paper. To measure a
period of time, the key is depressed at the beginning and end of the
period, causing two dots to be made on the ribbon; the interval
between these, when measured by the intervals due to the pendulum,
gives the length of the period in seconds, and also in fractions of a
second, when the seconds' interval is subdivided into convenient equal
parts. This apparatus has been used in determination of the velocity
of sound. In the break circuit arrangement of pendulum key and Morse
instrument the markings appear as breaks in a line which would
otherwise be continuous. This combination was employed by Professors
W.E. Ayrton and J. Perry in their determination of the acceleration of
gravity at Tokio, 1877-1878 (_Proc. Phys. Soc. Lond._ 3, p. 268).

Hipp.

Mayer.

In the tuning-fork electro-chronograph attributed to Hipp a metal
cylinder covered with smoked glazed paper is rotated uniformly by
clockwork, a tuning-fork armed with a metallic style being so adjusted
that it makes a clear fine line on the smoked paper. The tuning-fork
is placed in the secondary circuit of an induction coil, so that when
the primary circuit is broken an induced spark removes a speck of
black from the paper and leaves a mark. The time period is deduced by
counting the number of vibrations and fractions of vibration of the
tuning-fork as recorded by a sinuous line on the cylinder. In later
forms of this instrument the cylinder advances as it rotates, and a
spiral line is traced. To obtain good results the spark must be very
small, for when large it often leaps laterally from the end of the
style, and does not give the true position of the style when the
circuit is broken. The same arrangement of tuning-fork and revolving
cylinder, with the addition of a standard clock, has been used by A.M.
Mayer (_Trans. Nat. Acad. Sci. U.S.A._ vol. iii.) and others for
calibrating tuning-forks, and comparing their vibrations directly with
the beats of the pendulum of a standard clock the rate of which is
known. The pendulum marks and breaks the primary circuit by carrying a
small platinum wire through a small mercury meniscus. Better and
apparently certain contacts can be obtained from platinum
contact-pieces, brought together above the pendulum by means of a
toothed wheel on the scape-wheel arbor. Sparking at the contact points
is greatly reduced by placing a couple of lead plates in dilute
sulphuric acid as a shunt across the battery circuit.

Fick.

_For Physiological Purposes._--A. Fick's pendulum myograph or
muscle-trace recorder is described in _Vierteljahrsschr. der
naturforsch. Ges. in Zürich_, 1862, S. 307, and in _Text-book of
Physiology_, M. Foster, pp. 42, 45. It was used to obtain a record of
the contraction of a muscle when stimulated. In many respects the
instrument is similar to the electro-ballistic chronograph of Navez. A
long pendulum, consisting of a braced metal frame, carries at its
lower end a sheet of smoked glass. The pendulum swings about an axis
supported by a wall bracket. Previous to an experiment, the pendulum
is held on one side of its lowest position by a spring catch; when
this is depressed it is free to swing. At the end of its swing it
engages with another spring catch. In front of the moving glass plate
a tuning-fork is fixed, also a lever actuated by the muscle to be
electrically stimulated. When the pendulum swings through its arc, it
knocks over the contact key in the primary circuit of an induction
coil, the secondary of which is in connexion with the muscle. The
smoked plate receives the traces of the style of the tuning-fork and
of the lever attached to the muscle, and also the trace of an
electromagnetic signal which marks the instant at which the primary
circuit is broken. After the traces are made, they are ruled through
with radial lines, cutting the three traces, and the time intervals
between different parts of the muscle curve are measured in terms of
the period of vibration of the tuning-fork, as in other chronographs
in which the tuning-fork is employed.

Du Bois Reymond.

In the spring myograph of E. Du Bois Reymond (Munk's _Physiologie des
Menschen_, p. 398) a smoked glass plate attached to a metal rod is
shot by a spiral spring along two guides with a velocity which is not
uniform. The traces of a style moved by the muscle under examination,
and of a tuning-fork, are recorded on the glass plate, the shooter
during its traverse knocking over one or more electric keys, which
break the primary circuit of an induction coil, the induced current
stimulating the muscle.

Burch.

In the photo-electric chronograph devised by G.J. Burch, F.R.S.
(_Journ. of Physiology_, 18, p. 125; _Electrician_, 37, p.436), the
rapid movements of the column of mercury in a capillary electrometer
used in physiological research are recorded on a sensitive plate
moving at a uniform angular velocity. The trace of the vibrating
prongs of a tuning-fork of known period is also recorded on the plate,
the light used being that of the electric arc. The images of the
meniscus of the mercury column and of the moving fork are focused on
the plate by a lens. Excellent results have been obtained with this
instrument.

Marey.

An important development of a branch of chronography is due to E.J.
Marey (_Comptes rendus_, 7. août 1882, and _Le Mouvement_, par E.J.
Marey, Paris, 1894), who employed a photographic plate for receiving
successive pictures of moving objects, at definite times, when
investigating the movements of animals, birds, fishes, insects, and
also microscopic objects such as vorticellae. The instrument in one of
its forms consisted of a camera and lens. In front of the sensitive
plate and close to it a disk, pierced with radial slits, revolved at a
given angular velocity, and each time a slit passed by the plate was
exposed. But since, in the time of passage of the space between the
slits, the object had moved by a certain amount across the field of
view, a fresh impression was produced at each exposure. The object,
well illuminated by sunlight, moved in front of a black background.
Since the angular velocity of the disk was known, and the number of
slits, the time between the successive positions of the object was
also known.

Marey (_La Méthode graphique_, pp. 133, 142, 456), by means of
pneumatic signals and a rotating cylinder covered with smoked glazed
paper, measured the time of the movements of the limbs of animals. The
instrument consists of a recording cylinder rotated at a uniform
angular velocity by clockwork controlled by a fan governor, and
pneumatic signal, constructed thus. One end of a closed shallow
cylinder, about 4 cm. dia., is furnished with a stretched rubber
membrane. A light lever, moving about an axis near the edge of the
cylinder, is attached to the centre of the membrane by a short rod,
its free end moving as the membrane is distended. The cylinder is
connected by a flexible tube with a similar cylinder and membrane, but
without a lever, which is attached to that part of the body of the
animal the movement of which is under investigation. The system is
full of air, so that when the membrane attached to the animal is
compressed, the membrane which moves the lever is distended and the
lever moved. Its end, which carries a scribing point, marks the smoked
paper on the rotating cylinder. The pneumatic signal is called by
Marey "tambour à levier."

_References to Chronographic Methods:_--(1) Chronographs used in
Physiology: Helmholtz, "On Methods of measuring very small Portions of
Time," _Phil. Mag._ (1853), 6; Id., _Verhandlungen der
physikalisch-medicinischen Gesellschaft in Würzburg_ (1872); Harless,
"Das Attwood'sche Myographion," _Abhandlungen der k. bayerischen
Akademie der Wissenschaften_ (1862); Id., _Fall-Myographion
aufgestellt in der Wiener Weltausstellung in der Abteilung für das
Unterrichtswesen von Ungarn_ (Budapest, 1873); Hensen, "Myographion
mit vibratorischer Bewegung," _Arbeiten aus dem Kieler physiol.
Instit._ (1868); Brücke, _Sitzungsber. d Wien. Acad._ (1877); Pflüger,
"Myographion ohne Bewegung," _Untersuchungen über die Physiologie des
Electrotonus_ (1859); Pouillet, _Compt. rend._ (1844); I. Munk,
_Physiologie des Menschen_ (for Pflüger's cylinder governed by conical
pendulum); J.G. M'Kendrick, _Life in Motion_ (1892) (for early form of
cylinder chronograph by Thomas Young); Stirling, _Outlines of
Practical Physiology_ (for reaction-time chronographs of F. Galton and
Exner). (2) Chronographs used in gun work and for other purposes:
Sabine, _Phil. Mag._ (1876); Moisson, _Notice sur la chronographie
système Schultz_ (Paris, 1875); Paul la Cour, _La Roue phonique_
(Copenhagen, 1878); Mach, "Collected Papers on Chronographs,"
_Nature_, 42, p. 250; C.V. Boys, "Bullets photographed in Flight,"
_Nature_, 47, p. 415; Pneumatic Tube Co., Paris, "Chronograph,"
_Nature_, 9, p. 105; G.C. Foster, "Laboratory Chronograph," _Nature_,
13, p. 139; E.S. Holden, "Astronomical Chronograph," _Nature_, 26, p.
368; D'Arsonval, _La Lumière électrique_ (1887); Dunn, "The
Photo-retardograph," _Journal United States Artillery_, 8, p. 29; E.J.
Marey, _La Méthode graphique_ (for Deprez accélérographe); Werner
Siemens, "Electric Spark Chronograph," _Wied. Ann._ (1845), 66.
(F. J. J. -S.)

FOOTNOTE:

[1] The velocity of the projectile is found thus. Let V be the
velocity of the bob, due to the impact of the projectile, _v_ the
velocity of the projectile, _h_ the height through which the bob is
raised vertically, then

V² ___
h = --, and V = \/2gh.
2g

If W be the weight of the bob, and _w_ the weight of the projectile,
then

/ W \ ___
wv = (W + w)V, and v = ( --- + 1 ) \/2gh.
\ w /

If _l_ be the true length of suspension, and C the length of the
chord of the arc of displacement of the bob after being struck, then

___
/ W \ / g
C² = 2hl, and v = ( --- + 1 ) / --- . C.
\ w / \/ l

Also if T be the time of a complete small oscillation of the
pendulum,

___
2[pi] / g
----- = / ---,
T \/ l

/ W \ 2[pi]C
so that v = ( --- + 1 ) ------.
\ w / T

CHRONOLOGY (Gr. [Greek: chronologia], computation of time, [Greek: chronos]), the science which treats of time, its object being to arrange and exhibit the various events which have occurred in the history of the world in the order of their succession, and to ascertain the intervals of time between them. The term "chronology" is also used of the order in time itself, as adopted, and of the system by which the order is fixed.

The preservation of any record, however rude, of the lapse of time implies some knowledge of the celestial motions, by which alone time can be accurately measured, and some advancement in the arts of civilized life, which could be attained only by the accumulated experience of many generations (see TIME). Before the invention of letters the memory of past transactions could not be preserved beyond a few years with any tolerable degree of accuracy. Events which greatly affected the physical condition of the human race, or were of a nature to make a deep impression on the minds of the rude inhabitants of the earth, might be vaguely transmitted through several ages by traditional narrative; but intervals of time, expressed by abstract numbers, and these constantly varying besides, would soon escape the memory. The invention of the art of writing afforded the means of substituting precise and permanent records for vague and evanescent tradition; but in the infancy of the world, mankind had learned neither to estimate accurately the duration of time, nor to refer passing events to any fixed epoch.

For these reasons the attempt at an accurate chronology of the early ages of the world is only of recent origin. After political relations began to be established, the necessity of preserving a register of passing seasons and years would soon be felt, and the practice of recording important transactions must have grown up as a necessary consequence of social life. But of these deliberate early records a very small portion only has escaped the ravages of time and barbarism.

The earliest written annals of the Greeks, Etruscans and Romans are irretrievably lost. The traditions of the Druids perished with them. A Chinese emperor has the credit of burning "the books" extant in his day (about 220 B.C.), and of burying alive the scholars who were acquainted with them. And a Spanish adventurer destroyed the picture records which were found in the _pueblo_ of Montezuma.

Of the more formal historical writings in which the first ineffectual attempts were made in the direction of systematic chronology we have no knowledge at first-hand. Of Hellanicus, the Greek logographer, who appears to have lived through the greater part of the 5th century B.C., and who drew up a chronological list of the priestesses of Here at Argos; of Ephorus, who lived in the 4th century B.C., and is distinguished as the first Greek who attempted the composition of a universal history; and of Timaeus, who in the following century wrote an elaborate history of Sicily, in which he set the example of using the Olympiads as the basis of chronology, the works have perished and our meagre knowledge of their contents is derived only from fragmentary citations in later writers. The same fate has befallen the works of Berossus and Manetho, Eratosthenes and Apollodorus. Berossus, a priest of Belus living at Babylon in the 3rd century B.C., added to his historical account of Babylonia a chronological list of its kings, which he claimed to have compiled from genuine archives preserved in the temple. Manetho, likewise a priest, living at Sebennytus in Lower Egypt in the 3rd century B.C., wrote in Greek a history of Egypt, with an account of its thirty dynasties of sovereigns, which he professed to have drawn from genuine archives in the keeping of the priests. Of these works fragments only, more or less copious and accurate, have been preserved. Eratosthenes, who in the latter half of the 2nd century B.C. was keeper of the famous Alexandrian library, not only made himself a great name by his important work on geography, but by his treatise entitled _Chronographia_, one of the first attempts to establish an exact scheme of general chronology, earned for himself the title of "father of chronology." His method of procedure, however, was usually conjectural; and guess-work, however careful, acute and plausible, is still guess-work and not testimony. Apollodorus, an Athenian who flourished in the middle of the 2nd century B.C., wrote a metrical chronicle of events, ranging from the supposed period of the fall of Troy to his own day. These writers were followed by other investigators and systematizers in the same field, but their works are lost. Of the principal later writers whose works are extant, and to whom we owe what little knowledge we possess of the labours of their predecessors, mention will be made hereafter.

The absence or incompleteness of authentic records, however, is not the only source of obscurity and confusion in the chronology of remote ages. There can be no exact computation of time or placing of events without a fixed point or epoch from which the reckoning takes its start. It was long before this was apprehended. When it began to be seen, various epochs were selected by various writers; and at first each small separate community had its own epoch and method of time-reckoning. Thus in one city the reckoning was by succession of kings, in another by archons or annual magistrates, in a third by succession of priests. It seems now surprising that vague counting by generations should so long have prevailed and satisfied the wants of inquiring men, and that so simple, precise and seemingly obvious a plan as counting by years, the largest natural division of time, did not occur to any investigator before Eratosthenes.

Precision, which was at first unattainable for want of an epoch, was afterwards no less unattainable from the multiplicity, and sometimes the variation, of epochs. But by a natural process the mischief was gradually and partially remedied. The extension of intercourse between the various small groups or societies of men, and still more their union in larger groups, made a common epoch necessary, and led to the adoption of such a starting point by each larger group. These leading epochs continued in use for many centuries. The task of the chronologer was thus simplified and reduced to a study and comparison of dates in a few leading systems.

The most important of these systems in what we call ancient times were the Babylonian, the Greek and the Roman. The Jews had no general era, properly so called. In the history of Babylonia, the fixed point from which time was reckoned was the era of Nabonassar, 747 B.C. Among the Greeks the reckoning was by Olympiads, the point of departure being the year in which Coroebus was victor in the Olympic Games, 776 B.C. The Roman chronology started from the foundation of the city, the year of which, however, was variously given by different authors. The most generally adopted was that assigned by Varro, 753 B.C. It is noteworthy how nearly these three great epochs approach each other,--all lying near the middle of the 8th century B.C. But it is to be remembered that the beginning of an era and its adoption and use as such are not the same thing, nor are they necessarily synchronous. Of the three ancient eras above spoken of, the earliest is that of the Olympiads, next that of the foundation of Rome, and the latest the era of Nabonassar. But in order of adoption and actual usage the last is first. It is believed to have been in use from the year of its origin. It is not known when the Romans began to use their era. The Olympiads were not in current use till about the middle of the 3rd century B.C., when Timaeus, as already mentioned, set the example of reckoning by them.

Even after the adoption in Europe of the Christian era, a great variety of methods of dating--national, provincial and ecclesiastical--grew up and prevailed for a long time in different countries, thus renewing in modern times the difficulties experienced in ancient times from diversities of reckoning. An acquaintance with these various methods is indispensable to the student of the charters, chronicles and legal instruments of the middle ages.

In reckoning years from any fixed epoch in constant succession, the number denoting the years is necessarily always on the increase. But rude nations and illiterate people seldom attach any definite idea to large numbers. Hence it has been a practice, very extensively followed, to employ cycles or periods, consisting of a moderate number of years, and to distinguish and reckon the years by their number in the cycle. The Chinese and other nations of Asia reckon, not only the years, but also the months and days, by cycles of sixty. The Saros of the Chaldaeans, the Olympiad of the Greeks, and the Roman Indiction are instances of this mode of reckoning time. Several cycles were formerly known in Europe; but most of them were invented for the purpose of adjusting the solar and lunar divisions of time, and were rather employed in the regulation of the calendar than as chronological eras. They are frequently, however, of very great use in fixing dates that have been otherwise imperfectly expressed, and consequently form important elements of chronology. (W. L. R. C.)

_Modern Results of Archaeological Research_.

When Queen Victoria came to the English throne, 4004 B.C. was still accepted, in all sobriety, as the date of the creation of the world. Perhaps no single statement could more vividly emphasize the change in the point of view from which scholars regard the chronology of ancient history than the citation of this indisputable fact. To-day, though Bibles are still printed with the year 4004 B.C. in the margin of the first chapter of Genesis, no scholar would pretend to regard this reference seriously. On the contrary, the scholarship of to-day regards the fifth millennium B.C. as well within the historical period for such nations as the Egyptians and the Babylonians. It has come to be fully accepted that when we use such a phrase as "the age of the world" we are dealing with a period that must be measured not in thousands but in millions of years; and that to the age of man must be allotted a period some hundreds of times as great as the five thousand and odd years allowed by the old chronologists. This changed point of view, needless to say, has not been reached without ardent and even bitter controversy. Yet the transformation is unequivocal; and the revised conception no longer seems to connote the theological implications that were at first ascribed to it. It has now become obvious that the data afforded by the Hebrew writings should never have been regarded as sufficiently accurate for the purpose of exact historical computations: that, in short, no historian working along modern scientific lines could well have made the mistake of supposing that the genealogical lists of the Pentateuch afforded an adequate chronology of world-history. But it should not be forgotten that to many generations of close scholarship these genealogical lists seemed to convey such knowledge in the most precise terms, and that at so recent a date as, for example, the year in which Queen Victoria came to the throne, it was nothing less than a rank heresy to question the historical accuracy and finality of chronologies which had no other source or foundation.

This changed point of view regarding the chronology of history may without hesitation be ascribed to the influence of evidence obtained in a single field of inquiry, the field, namely, of archaeology. No doubt the evidence as to the age of the earth and as to the antiquity of man was gathered by a class of workers not formally included in the ranks of the archaeologist: workers commonly spoken of as palaeontologists, anthropologists, ethnologists and the like. But the distinction scarcely covers a real difference. The scope of the archaeologist's studies must include every department of the ancient history of man as preserved in antiquities of whatever character, be they tumuli along the Baltic, fossil skulls and graven bones from the caves of France, the flint implements, pottery, and mummies of Egypt, tablets and bas-reliefs from Mesopotamia, coins and sculptures of Greece and Rome, or inscriptions, waxen tablets, parchment rolls, and papyri of a relatively late period of classical antiquity. If at one time the monuments of Greece and Rome claimed the almost undisputed attention of the archaeologist, that time has long since passed. For the most important historical records that have come to us in recent decades we have to thank the Orientalist, though the classical explorer has been by no means idle. It will be sufficient here to point out in general terms the import of the message of archaeological discovery in the Victorian Era in its bearings upon the great problems of world-history.

Chronology of ancient history.

A start was made through the efforts of the palaeontologists and geologists, with only indirect or incidental aid from the archaeologists. The new movement began actively with James Hutton in the later years of the 18th century, and was forwarded by the studies of William Smith in England and of Cuvier in France; but the really efficient champion of the conception that the earth is very old was Sir Charles Lyell, who published the first edition of his epoch-making _Principles of Geology_ only a few years before Queen Victoria came to the throne. Lyell demonstrated to the satisfaction, or--perhaps it should rather be said--to the dissatisfaction, of his contemporaries that the story of the geological ages as recorded in the strata of the earth becomes intelligible only when vast stretches of time are presupposed. Of course the demonstration was not accepted at once. On the contrary, the champions of the tradition that the earth was less than six thousand years old held their ground most tenaciously, and the earlier years of the Victorian era were years of bitter controversy. The result of the contest was never in doubt, however, for the geological evidence, once it had been gathered, was unequivocal; and by about the middle of the century it was pretty generally admitted that the age of the earth must be measured by an utterly different standard from that hitherto in vogue. This concession, however, by no means implied a like change of view regarding the age of man. A fresh volume of evidence required to be gathered, and a new controversy to be waged, before the old data for the creation of man could be abandoned. Lyell again was in the forefront of the progressive movement, and his work on _The Antiquity of Man_, published in 1863, gave currency for the first time to the new opinions. The evidence upon which these opinions were based had been gathered by such anthropologists as Schmerling, Boucher de Perthes and others, and it had to do chiefly with the finding of implements of human construction associated with the remains of extinct animals in the beds of caves, and with the recovery of similar antiquities from alluvial deposits the great age of which was demonstrated by their depth. Every item of the evidence was naturally subjected to the closest scrutiny, but at last the conservatives were forced reluctantly to confess themselves beaten. Their traditional arguments were powerless before the array of data marshalled by the new science of prehistoric archaeology. Looking back even at the short remove of a single generation, it is difficult to appreciate how revolutionary was the conception of the antiquity of man thus inculcated. It rudely shocked the traditional attitude of scholarship towards the history of our race. It disturbed the most cherished traditions and the most sacred themes. It seemed to threaten the very foundations of religion itself. Yet the present generation accepts the antiquity of man as a mere matter of fact. Here, as so often elsewhere, the heresy of an elder day has come to seem almost an axiomatic truth.

If we go back in imagination to the beginning of the Victorian era and ask what was then known of the history of Ancient Egypt, Mesopotamia and Asia Minor, we find ourselves confronted with a startling paucity of knowledge. The key to the mysteries of Egyptian history had indeed been found, thanks to the recent efforts of Thomas Young and Champollion, but the deciphering of inscriptions had not yet progressed far enough to give more than a vague inkling of what was to follow. It remained, then, virtually true, as it had been for two thousand years, that for all that we could learn of the history of the Old Orient in pre-classical days, we must go solely to the pages of the Bible and to a few classical authors, notably Herodotus and Diodorus. A comparatively few pages summed up, in language often vague and mystical, all that the modern world had been permitted to remember of the history of the greatest nations of antiquity. To these nations the classical writers had ascribed a traditional importance, the glamour of which still lighted their names, albeit revealing them in the vague twilight of tradition rather than in the clear light of history. It would have been a bold, not to say a reckless, dreamer who dared predict that any future researches could restore to us the lost knowledge that had been forgotten for more than two millenniums. Yet the Victorian era was scarcely ushered in before the work of rehabilitation began, which was to lead to the most astounding discoveries and to an altogether unprecedented extension of historical knowledge. Early in the 'forties the Frenchman Botta, quickly followed by Sir Henry Layard, began making excavations on the site of ancient Nineveh, the name and fame of which were a tradition having scarcely more than mythical status. The spade of the discoverer soon showed that all the fabled glories of the ancient Assyrian capital were founded on realities, and evidence was afforded of a state of civilization and culture such as few men supposed to have existed on the earth before the Golden Age of Greece. Not merely were artistic sculptures and bas-reliefs found that demonstrated a high development of artistic genius, but great libraries were soon revealed,--books consisting of bricks of various sizes, or of cylinders of the same material, inscribed while in the state of clay with curious characters which became indelible when baking transformed the clay into brick. No one was able to guess, even in the vaguest way, the exact interpretation of these odd characters; but, on the other hand, no one could doubt that they constituted a system of writing, and that the piles of inscribed tablets were veritable books. There were numerous sceptics, however, who did not hesitate to assert that the import of the message so obviously locked in these curious inscriptions must for ever remain an absolute mystery. Here, it was said, were inscriptions written in an unknown character and in a language that for at least two thousand years had been absolutely forgotten. In such circumstances nothing less than a miracle could enable human ingenuity to fathom the secret. Yet the feat pronounced impossible by mid-century scepticism was accomplished by contemporary scholarship, amidst the clamour of opposition and incredulity. Its success contains at once a warning to those doubters who are always crying out that we have reached the limitations of knowledge, and an encouragement and stimulus to would-be explorers of new intellectual realms.

In a few words the manner of the discovery was this. It appears at a glance that the Assyrian written character consists of groups of horizontal, vertical or oblique strokes. The characters thus composed, though so simple as to their basal unit, are appallingly complex in their elaboration. The Assyrians with all their culture, never attained the stage of analysis which demonstrates that only a few fundamental sounds are involved in human speech, and hence that it is possible to express all the niceties of utterance with an alphabet of little more than a score of letters. Halting just short of this analysis, the Assyrian ascribed syllabic values to the characters of his script, and hence, instead of finding twenty odd characters sufficient, he required about five hundred. There was a further complication in that each one of these characters had at least two different phonetic values; and there were other intricacies of usage which, had they been foreknown by inquirers in the middle of the 19th century, might well have made the problem of decipherment seem an utterly hopeless one. Fortunately it chanced that another people, the Persians, had adopted the Assyrian wedge-shaped stroke as the foundation of a written character, but making that analysis of which the Assyrians had fallen short, had borrowed only so many characters as were necessary to represent the alphabetical sounds. This made the problem of deciphering Persian inscriptions a relatively easy one. In point of fact this problem had been partially solved in the early days of the 19th century, thanks to the sagacious guesses of the German philologist Grotefend. Working with some inscriptions from Persepolis which were found to contain references to Darius and Xerxes, Grotefend had established the phonetic values of certain of the Persian characters, and his successors were perfecting the discovery just about the time when the new Assyrian finds were made. It chanced that there existed on the polished surface of a cliff at Behistun in western Persia a tri-lingual inscription which, according to Diodorus, had been made by Queen Semiramis of Nineveh, but which, as is now known, was really the work of King Darius. One of the languages of this inscription was Persian; another, as it now appeared, was Assyrian, the language of the newly discovered books from the libraries of Nineveh. There was reason to suppose that the inscriptions were identical in meaning; and fortunately it proved, when the inscriptions were made accessible to investigation through the efforts of Sir Henry Rawlinson, that the Persian inscription contained a large number of proper names. It was well known that proper names are usually transcribed from one language into another with a tolerably close retention of their original sounds. For example, the Greek names _Ptolemaios_ and _Kleopatra_ became a part of the Egyptian language and appeared regularly in Egyptian inscriptions after Alexander's general became king of Egypt. Similarly, the Greek names _Kyros_, _Dareios_ and _Xerxes_ were as close an imitation as practicable of the native names of these Persian monarchs. Assuming, then, that the proper names found in the Persian portion of the Behistun inscription occurred also in the Assyrian portion, retaining virtually the same sound in each, a clue to the phonetic values of a large number of the Assyrian characters was obviously at hand. Phonetic values known, Assyrian was found to be a Semitic language cognate to Hebrew.

These clues were followed up by a considerable number of investigators, with Sir Henry Rawlinson in the van. Thanks to their efforts, the new science of Assyriology came into being, and before long the message of the Assyrian books had ceased to be an enigma. Of course this work was not accomplished in a day or in a year, but, considering the difficulties to be overcome, it was carried forward with marvellous expedition. In 1857 the new scholarship was put to a famous test, in which the challenge thrown down by Sir George Cornewall Lewis and Ernest Renan was met by Rawlinson, Hincks, Oppert and Fox Talbot in a conclusive manner. The sceptics had declared that the new science of Assyriology was itself a myth: that the investigators, self-deceived, had in reality only invented a language and read into the Assyrian inscriptions something utterly alien to the minds of the Assyrians themselves. But when a committee of the Royal Asiatic Society, with George Grote at its head, decided that the translations of an Assyrian text made independently by the scholars just named were at once perfectly intelligible and closely in accord with one another, scepticism was silenced, and the new science was admitted to have made good its claims.

Naturally the early investigators did not fathom all the niceties of the language, and the work of grammatical investigation has gone on continuously under the auspices of a constantly growing band of workers. Doubtless much still remains to be done; but the essential thing, from the present standpoint, is that a sufficient knowledge of the Assyrian language has been acquired to ensure trustworthy translations of the cuneiform texts. Meanwhile, the material found by Botta and Layard, and other successors, in the ruins of Nineveh, has been constantly augmented through the efforts of companies of other investigators, and not merely Assyrian, but much earlier Babylonian and Chaldaean texts in the greatest profusion have been brought to the various museums of Europe and America. The study of these different inscriptions has utterly revolutionized our knowledge of Oriental history. Many of the documents are strictly historical in their character, giving full and accurate contemporary accounts of events that occurred some thousands of years ago. Exact dates are fixed for long series of events that previously were quite unknown. Monarchs whose very names had been forgotten are restored to history, and the records of their deeds inscribed under their very eyes are before us,--contemporary documents such as neither Greece nor Rome could boast, nor any other nation, with the single exception of Egypt, until strictly modern times. There are, no doubt, gaps in the record; there are long periods for which the chronology is still uncertain. Naturally there is an increasing vagueness as one recedes farther into the past, and for the earlier history of Chaldaea there is great uncertainty. Nevertheless, the Assyriologist speaks with a good deal of confidence of dates as remote as 3800 B.C., the time ascribed to King Sargon, who was once regarded as a mythical person, but is now known to have been an actual monarch. Indeed, there are tablets in the British Museum labelled 4500 B.C.; and later researches, particularly those of the expedition of the University of Pennsylvania at Nippur, have brought us evidence which, interpreted with the aid of estimates as to the average rate of accumulation of dust deposits, leads to the inference that a high state of civilization had been attained in Mesopotamia at least 9000 years ago.

While the Assyriologists have been making these astonishing revelations, the Egyptologists have not been behindhand. Such scholars as Lepsius, Brugsch, de Rougé, Lenormant, Birch, Mariette, Maspero and Erman have perfected the studies of Young and Champollion; while at the same time these and a considerable company of other explorers, most notable of whom are Gardner Wilkinson and Professor Flinders Petrie, have brought to light a vast accumulation of new material, much of which has the highest importance from the standpoint of the historian. Lists of kings found on the temple wall at Abydos, in the fragments of the Turin papyrus and elsewhere, have cleared up many doubtful points in the lists of Manetho, and at the same time, as Professor Petrie has pointed out, have proved to us how true a historian that much-discussed writer was. Manetho, it will be recalled, was the Egyptian who wrote the history of Egypt in Greek in the time of the Ptolemies. His work in the original unfortunately perished, and all that we know of it we learn through excerpts made by a few later classical writers. These fragments have until recently, however, given us our only clue to the earlier periods of Egyptian history. Until corroboration was found in the Egyptian inscriptions themselves, not only were Manetho's lists in doubt, but scepticism had been carried to the point of denying that Manetho himself had ever existed. This is only one of many cases where the investigations of the archaeologist have proved not iconoclastic but reconstructive, tending to restore confidence in classical traditions which the scientific historians of the age of Niebuhr and George Cornewall Lewis regarded with scepticism.

As to the exact dates of early Egyptian history there is rather more of vagueness than for the corresponding periods of Mesopotamia. Indeed, approximate accuracy is not attained until we are within sixteen hundred years of our own era; but the sequence of events of a period preceding this by two thousand years is well established, and the recent discoveries of Professor Petrie carry back the record to a period which cannot well be less than five thousand, perhaps not less than six thousand years B.C. Both from Egypt and Mesopotamia, then, the records of the archaeologist have brought us evidence of the existence of a highly developed civilization for a period exceeding by hundreds, perhaps by thousands, of years the term which had hitherto been considered the full period of man's existence.

We may note at once how these new figures disturb the historical balance. If our forerunners of eight or nine thousand years ago were in a noonday glare of civilization, where shall we look for the much-talked-of "dawnings of history"? By this new standard the Romans seem our contemporaries in latter-day civilization; the "Golden Age" of Greece is but of yesterday; the pyramid-builders are only relatively remote. The men who built the temple of Bel at Nippur, in the year (say) 5000 B.C., must have felt themselves at a pinnacle of civilization and culture. As Professor Mahaffy has suggested, the era of the Pyramids may have been the veritable autumn of civilization. Where, then, must we look for its springtime? The answer to that question must come, if it come at all, from what we now speak of as prehistoric archaeology; the monuments from Memphis and Nippur and Nineveh, covering a mere ten thousand years or so, are the records of recent history.

Archaeology and Bible history.

The efforts of the students of Oriental archaeology have been constantly stimulated by the fact that their studies brought them more or less within the field of Bible history. A fair proportion of the workers who have delved so enthusiastically in the fields of Egyptian and Assyrian exploration would never have taken up the work at all but for the hope that their investigations might substantiate the Hebrew records. For a long time this hope proved illusory, and in the case of Egyptian archaeology the results have proved disappointing even up to the very present. Considering the important part played by the Egyptian sojourn of the Hebrews, as narrated in the Scriptures, it was certainly not an over-enthusiastic prediction that the Egyptian monuments when fully investigated would divulge important references to Joseph, to Moses, and to the all-important incidents of the Exodus; but half a century of expectant attention in this direction has led only to disappointment. It would be rash, considering the buried treasures that may yet await the future explorer, to assert that such records as those in question can never come to light. But, considering the fulness of the contemporary Egyptian records of the XIXth dynasty that are already known, it becomes increasingly doubtful whether the Hebrews in Egypt played so important a part in history, when viewed from the Egyptian standpoint, as their own records had seemed to imply. As the forgotten history of Oriental antiquity has been restored to us, it has come to be understood that, politically speaking, the Hebrews were a relatively insignificant people, whose chief importance from the standpoint of material history was derived from the geographical accident that made them a sort of buffer between the greater nations about them. Only once, and for a brief period, in the reigns of David and Solomon did the Hebrews rise to anything like an equal plane of political importance with their immediate neighbours. What gave them a seeming importance in the eyes of posterity was the fact that the true history of the Egyptians, Mesopotamians, Arabians and Hittites had been well-nigh forgotten. The various literatures of these nations were locked from view for more than two thousand years, while the literature of Israel had not merely been preserved, but had come to be regarded as inspired and sacred among all the cultured nations of the Western world. Now that the lost literatures have been restored to us, the status of the Hebrew writings could not fail to be disturbed. Their very isolation had in some measure accounted for their seeming importance.

All true historical perspective is based upon comparison, and where only a single account has been preserved of any event or of any period of history, it is extremely difficult to judge that account with historical accuracy. An illustration of this truth is furnished in profane history by the account which Thucydides has given us of the Peloponnesian War. For most of the period in question Thucydides is the only source; and despite the inherent merits of a great writer, it can hardly be doubted that the tribute of almost unqualified praise that successive generations of scholars have paid to Thucydides must have been in some measure qualified if, for example, a Spartan account of the Peloponnesian War had been preserved to us. Professor Mahaffy has pointed out that many other events in Greek history are viewed by us in somewhat perverted perspective because the great writers of Greece were Athenians rather than Spartans or Thebans. Even in so important a matter as the great conflict between Persia and Greece it has been suggested more than once that we should be able to gain a much truer view were Persian as well as Greek accounts accessible.