William Shepherd.

Systematic education: or Elementary instruction in the various departments of literature and science; with practical rules for studying each branch of useful knowledge (Volume 1) online

. (page 29 of 44)
Online LibraryWilliam ShepherdSystematic education: or Elementary instruction in the various departments of literature and science; with practical rules for studying each branch of useful knowledge (Volume 1) → online text (page 29 of 44)
Font size
QR-code for this ebook

and in cases where the time, the place, and the quantity of an
eclipse are mentioned, though not with astronomical exact-
ness, it is not difficult, by certain rules of calculation, to fix
the very year, and often day, when the event happened. For,
considering the great variety which the three circumstances of
time, place, and quantity, occasion in the appearance of
eclipses, there is no room to suspect that any two, happening
within a moderate distance of one another, can be in the least
danger of being confounded.

Dr. Playfair, Ferguson, and others, have given long lists of
eclipses that occurred before the Christian aera, observed by
astronomers, or recorded by historians: likewise of all the
eclipses that have occurred, and that will happen between the
birth of Christ, and the end of the present century, and have
shewn how they may be applied to the verification of dates in
history. The following example will point out in what man-
ner this kind of knowledge is to be appreciated ; and how the
date of the events is ascertained by its help.

In Thucydides' history, an eclipse of the moon is thus re-
corded : " Upon the arrival of Gylippus to the assistance of
the Syracusans, the Athenians, finding that they were no
match for the united force of their enemies, repented that
they had not quitted their situation before, and immediately
came to the resolution to sail out of the harbour as secretly
as possible. But when every thing was ready for sailing, the
moon was eclipsed, for it was then full moou. Upon this,
most of the Athenians; alarmed at the omen, desiied their


coinmnndcrs to proceed no farther ; aud Nicias, being him-
self a superstitious observer of such prodigies, declared that
he would not come to any final resolution about quitting the
place till they had staid three days longer, according to the
advice of the soothsayers. This occasioned the Athenians to
remain in the place, which tliey had never after an opportunity
of leaving, and in which they almost to a man perished." This
event is placed by historians in the year 413, B.C. To ascertain
the truth of this fact, we refer to the astronomical tables,
from which it appears that the moon was full about midnight
at London, on the 27 th of August* in that year, when the
sun wais so near the nodes, as to be within the limits of Lunar
eclipses, and when of course there must have been a total
eclipse of the moon, which would be visible, from beginning
to end, to the Athenians, and may therefore reasonably be
supposed to have produced the effect ascribed to it by the

A history, which contains an account of a sufficient number
of these phenomena, furnishes the surest test of its authenticity.
It may be farther observed, that the truth of the Scripture
history being unquestionable, and relating to times prior to
the age, in which history began to be written by any other
people than the Jews, it is the best guide to the kno^^ledge
of prophane antiquity. It was in pursuing this plan, that
Sir Isaac Newton was led to correct the ancient chronology
of the Greeks, by itself. The principles on which he reduces
their accounts are, as we have seen, founded on nature, and
"independent of any arguments drawn from Scripture. But
it is probable that believing (see his Chronology, p. 66-79.)
Sesostris to have been the vame person witli Sesac, or
Shisak, of whom an account is given in the history of Reho-
boam, in the second book of Chronicles, he first fixed the
date of tliat expedition according to the Scriptures ; and after-

In Playfaifs tables, the date of the year is 423, which is evidently a
mistake of the printer, who inserted the 2 iustcad of 1.


wards from considering the subject in various points of light,
he was led to the other arguments that have been referred to,
by which he was able to confirm the Scriptural date of that
event, and also the dates of the principal facts in the history
of Greece connected with it, in a manner independent of the
authorities on which he originally founded his opinion. Then,
having by the joint assistance of Scripture and reason, recti-
fied the chronology of the Greeks, he made use of it to ad-
just the contemporary affairs of the Egyptians, Assyrians,
Babylonians, Medes and Persians, which are the subjects of.
the several chapters contained in his " Chronology of Ancient
Kingdoms amended," 8cc;

Having briefly shewn in what way the astronomy of
eclipses, and of the precession of the equinoxes; and the
use of observations on the intervals between the generations
of men, and succession of kings, are apphed to ascertain the
dates of past events, as recorded on the page of history, ' we
shall proceed to notice and explain the several artificial divi-
sions of time, which are of great importance to the student in

The divisions of time which are considered in chronology,
relate either to the different methods of computing days,
mouths and years, or the remarkable aeras or epochas from
which any year receives its name, and by means of which the
date of any event is fixed.

The divisions of time which probably first attracted the
notice of mankind, were those marked by the revolutions of
the heavenly bodies, as days, lunar months, and years ; and if
these had exactly corresponded with each other, so that every
lunation had consisted unifbrmly of the same number of days,
and each year of a regular number of lunations, the business
of chronology would have been comparatively easy. But as
this is not the case, the embarrassments and difficulties atten-
ding the subject, have been owing to the methods that have
been adopted to accommodate the three methods of com-


pitting time, viz. by days, months, and years, to one another,

so as to make use of tliem all at the same time.

Besides these three natural divisions of time, there is
another into weeks of seven days ; which division, however,
though used by Jews, Christians and Mahometans, and by
almost all the people of Asia and Africa, was not observed
by the ancient Greeks and Romans. We shall now proceed
to give an account of the above named divisions of time, and
point out the methods, as briefly as we can, of accommodating
them to one another.

Of^ the day. It must be observed that days have been very
differently begun, and divided by different people, in different
ages : thus the ancient Babylonians, Persians and other eastern
nations, began their day with the sun's rising. The ancient
Athenians, Jews, and many German nations, the modern
Italians, and Chinese, reckon from the sun's setting : the
Arabians, &c. with modern astronomers, reckon from noon ; and
the Egyptians and Romans, with the modern English, French,
Dutch, Germans, Spaniards, and Portuguese, from midnight.

The Jews, Romans, and most other ancient nations divided
their day into twelve hours, and the night into watches. But
the custom now generally prevails in the western part of the
world, to divide the day into 24 equal portions : with a few
of the nations, as the Italians, the Poles, and Bohemians,
the twenty-four hours are counted on without interruption,
but in general they are divided into twice twelve, to which
our time-pieces are accommodated.

Of the month. There is scarcely any doubt, but that the
division of time into months was originally suggested by the
phases, or periodical changes of the moon, and that in
ancient computations, the months were lunar. As a complete
lunation consists of about 29^ days, and the changes of the
moon are very visible, there was no great difficulty in accom-
modating them to each other, or in fixing what number of
days should be allowed to a month. In general the ancients


jnade them consist of 29 and 30 days alternately. When
months came to be reckoned not by lunations, but were con-
sidered as the twelfth, part of a year consisting of about 365^
days, it became necessary to allow sometimes SO and some-
times 31 days to a month, as in the Roman Calendar.*
Whenever months are mentioned as divided into days in the
Scriptures, they are supposed to consist of 30 days each, and
in these cases 12 months, or 360 days, are reckoned in the year.

Of the year. Different nations have made their years
begin at different times, and have used a variety of methods
to give names to them, and distinguish them from each other.
The Jews, for instance, began the year for civil purposes in
the month called Tizriy which answers to our September ; but,
for ecclesiastical purposes, they began with Nizafi, which
answers to our April, at which time they kept the passover.
The people of Athens began the year with the month which com-
menced with the first new moon after the summer solstice.
The early Romans had only ten months in their year, but
Numa Pompilius added two others, viz. January and February.

In modern Rome, there are two modes of reckoning : one
begins the year at Christmas, on account of the nativity of
our Saviour : this the notaries and public men make use of,
by prefixing to their deeds a nativitate: by the other, the
commencement is in March, which refers to the incarnation
of Christ, hence the pope's bulls are dated, anno incarnationis.

In England, we had, till the year 1752, two beginnings of
the year, one in January, and the other on the 25 th March ;
but by act of Parliament, at the period alluded to, the first
of January was appointed to be the beginning of the year for
all purposes.

The eastern nations generally distinguish the year by the
reigns of their princes. The Greeks named their years from
the magistrates who presided over them, as in Athens^

This Calendar, as it existed in the days of Julius Caesar, may b*
fbund in Danet's Classical Dictionary 4to. 1700: it was copied into a
very entertaining periodical work, entitled " Time's Telescope, for 1814."


from the Archons. The Romans likewise named the year by
the consuls, and it was a long time before names were assigned
to years, from any particular a^ra or lemarkable event. At
length the Greeks reckoned from the institution of tlie Olympic
games, and the Romans from the building of their city. It
was not till about the year 360, that Christians began to
reckon from the birth of Christ, and hence the difficulty of
ascertaining with precision, the true time of that important

Cycles. The chief difficulty in chronology, has been to
accommodate the two methods of computing time, viz. by the
course of the moon, and that of the sun, to each other; the nearest
division of the year by months, being twelve, but twelve lunar
months falling eleven days short of a complete year. This
gave birth to many cycles in use among the ancients.

Cycles are fixed intervals of times, composed of the suc-
cessive revolutions of a certain number of years. The Greeks
for instance reckoned by Olympiads, or periods of Jour years :
and the Romans by hustra, or periods of five years. These,
strictly speaking, may be denominated cycles, though the
term is usually appropriated to larger intervals, connected with
the periodical return of certain appearances.

As the twelve Lunar months did not agree with the number
of days in a year, the Greeks were accustomed to add, or as
it is technically called, intercalate, a month every other year,
this was eight days too much, and was lio doubt rectified by
omitting the addition, when it was observed, by comparing the
seasons with their annual festivals, that they ought so to do.
This method would therefore never have deviated far from the
truth, had not other circumstances occurred of a political
nature, which baffled all regular computation. When, for
instance, it was the interest of the chief magistrate to lengthen
or shorten a year, for purposes of ambition, all other con-
siderations were often sacrificed to it, and the greatest con-
fusion was introduced. Hence they found themselves under
the necessity of having some certain rule to compute by, and


at first they added, or intercalated one mouth in every four
years, but as four times 1 1 is 44, the error would be still 14
days in that cycle or period of time. They then intercalated
three months or 90 days in 8 years, in this, there was an ex-
cess of about 2 days, which error being but trifling, the cycle
continued in use a considerable time.

Lunar cycle. Melon, an Athenian Astronomer, invented
the cycle of 19 years, in which 7 months were intercalated.
This, which was called from the inventor, the Metonic cycle,
brought the two methods to so near an agreement, that after
the expiration of the period, the new and full moons return on
the same days of the year, on which they were nineteen years be-
fore, hence it is called the Lunar cycle. This cycle, somewhat
improved, was adopted by the Christians, A. D, 325, at the
council of Nice, for the purpose of settling the time for
Easter, and the other feasts, which depend upon it. This
period, however, falling short of 19 years, almost an hour
and half, the new and full moons in the heavens have
anticipated the new and full moons in the calendar of the
Common-Prayer book, at this time, 1815, by 117 hours, or
nearly 5 days.* These last are called Calendar new moons,
to distinguish them from the real new moons.

From the great utility of this cycle to the purposes above-
mentioned, the council of Nice caused the numbers df it to
be written in golden characters, whence it obtained the name
of the golden number. If the lunar cycle had been made,
or supposed to commence with the Christian aera, the golden
number for any year would have been the remainder found by
dividing the given year by 19. But this consideration was ne-
glected, and in reckoning back, it was found that the first year
of our aera corresponded to the second year of the cycle of
19 years. Therefore the golden number is found for any
year by adding 1 to the given year, and dividing by 19; and
the remainder left after division is the number sought : thus

* 1815325=1490 and this multiplied by l| and divided by 19, gives
117 hours.


for the year 1815, we say 1^=95 and 11 over, therefore
the Golden number for the year is 1 1 ; if there be no remain-
der, then the Golden number is IQ.

Julian year. Before we come to the Solar cycle, we must
give some account of the method of adjusting the number of
days to a year, in which there was considerable difficulty,
inasmuch as the period that the earth takes in going round the
sun, which is the length of the year, does not consist of any
even number of days, but of 365 days 5 hours and 49 minutes.

The Egyptians, Chaldeans and Assyrians, reckoned at tirst
360 days to the year, and aftenvards 365. The consequence
of this was, that the beginning of their year, would go back
through all the seasons, though slowly, viz. at the rate of 5
hours and 49 minutes every year. Of this form were the
years which took their date from the reign of Nabonassar of
Babylon, Yesdigerd of Persia, and the Seleucidae of Syria,
of which we shall soon have occasion to speak.

The inconvenience attending the form of the year above
noticed was remedied by Julius Czesar, who added one day
to every foiu-th year, which, from its place of insertion, viz.
the sixth of the calends of March, was called bissextile, or
the sixth repeated, answers to our leap year. This form is,
from its inventor, called the Julian year.

Gregorian year. The true length of the year being 11
minutes short of 365 days 6 hours. Pope Gregory XIII. in-
troduced another amendment in the year 1582, by ordering a
day to be taken out of the calendar once in 133 years, or
what amounted to the same thing, that three days should be
taken out of 400 years, in the following manner: vizv from and
after the"year 1600, every hundredth year, which according to
the Julian form, should be bissextile, or leap year, was to be
reckoned common, but every four hundredth year was to con-
tinue bissextile, as in the Julian account. When this pope
undertook to rectify the calendar, the error which had crept
in by the former method amounted to ten days ; he, therefore,
commanded the ten days between tlie 4th and 15th of Octo-


her, in thtit year, to be suppressed, so that the 3th was called
the 1 3th. Tins alteration took place, at the same time, through
the greater part of Europe, and the year was afterwards called
the Gregorian year, or New Style, which was not admitted
into our calendar till 1752, when the error amounted to eleven
days, which were taken from the month of September, by
calling the 3d of that month the 14th. By act of parliament
at the same time. New Year's day was changed from the 25th
of March to the 1st of January. Of course the following
months of January, February, and March, up to the 24th,
inclusive, which would, by the old method, have been reck-
oned part of the year 1752, were accounted as die first three
months of the year 1753. Hence in many books printed after
that period, we read of such dates as 20th February, 1774,5,
that is, by old style it would be 1 774, but by the new it was

Solar Cycle. It has been of consequence to Christians to
adjust the days of the week to the days of the month, and of
the year, in order to get a rule for finding Sunday. Had there
been no bissextile, as the year consists of fifty-two weeks and one
day, all the varieties that could have happened, would have been
comprised in seven years. But the bissextile returning every
fourth year, the series is interrupted, and does not return in
order, until after four times seven, or twenty-eight years,
which is, therefore, called the solar cycle, serving as a rule to
find Sunday, and of course the other days of the week. At the
expiration of this period of twenty-eight years, the sun returns
to the sign and degree of the ecliptic, which he had occupied
at the conclusion of the preceding period, and the days of the
week correspond to the same days of the month as at that time.

In finding what year of the solar cycle corresponds to any
given year of the Christian aera, it must be remembered, that
the first year of the Christian aera is supposed to correspond
to the tenth of the solar cycle, and the rule is as follows :

To any given year add nine, and divide the sum by 28,
the quotient gives the number of the revolutions of the cycle

VOL. I. 2 a


since its commencement, and the remainder will be the year of

the cycle. If there be no remainder, the year of the cycle is

called 28. ITie year of the solar cycle for the present year, 1815,

1815+9 1824 J , . , . ,

* ^ =-^ =65 and the remainder, 4, is the number of the

solar cycle.

In our calendars the days of the week are distinguished by
the first seven letters in the alphabet. A, B, C, D, E, F, G.
The letter A is always put for the first day of the year, B, for
the second, and so on in succession to the seventh. If, for
example, the first of January fall on a Sunday, the dominical,
or Sunday letter, will be A, Monday, B, 8cc. ; and as the
number of letters is the same as that of the days of the week,
A, will fall on every Sunday, B, on every Monday, C, on
every Tuesday, &,c., throughout the year. Had the year
consisted of 364 days, making an exact number of weeks. A,
would have been a perpetual Sunday letter, but as it contains
one more, the dominical letter for the following year will be
G, because, Sunday, being the first day of the preceding year,
will also be the last, the first Sunday will fall on the seventh
day, and will be marked by the seventh letter, or G. This
retrocession of the letters will, from the same cause, con-
tinue every year, sp as to make F, the dominical letter of the
third year, E, of the fourth, and so on. In leap-years, for
obvious reasons, the Sunday letter will, after the 28th of Fe-
bruary, be thrown back two letters. Thus, in the year 1814,
the dominical letter was B, in the present year it is thrown
back a letter, and is A, and in January and February, 18 IG,
it will be G, but in the other ten months, as a day is added
to Februajy, the Sunday letter will be F. If a table be con-
structed for the years of one of these solar cycles, it will
answer for the corresponding years in every successive cycle.

Ci/cle of' Roman Indiction. Besides the above mentioned
periods of years, there is one called the cycle of Roman In-
diction, a period of fifteen years, at the end of which, a cer-
tain tribute was paid by the provinces of the Roman empire,
and by which the Roman Emperors ordered their public acts


to be dated. The current year of thetiRoman Indiction is
found by adding 3, and dividing by 15, the remainder, 3, is

- , , , 1815 + 3 1818

the number of the year sought, thus j^ -jr-:=:\Q,i and 3

Julian period. Tliis, which has been called the most re-
markable of all tlie periods in chronology, was invented by
Joseph Scaliger, it takes its name from the yeai*s of which it
consists being Julian years. The object of the inventor was
to reduce to a certainty, the different methods of computing
time, and fixing the dates of events by different chronologers.
For this purpose, nothing wSs necessary but a series of years,
some term of which was tixed, comprehending the whole ex-
tent of time. Since if al^ chronologers would apply that com-
mon measure to their several schemes, they would understand
one another.

?To attain this object, the author combined the three periods
of the sun, the moon, and indiction, together, that is, multi-
plying the numbers 28, 19, and 15, into one another, which
produces 7980; after which, all the three cycles will return in
the same order, every year, being distinguished by the same
number of each. To fix the beginning of this period, he
took tBe cycles as he then foimd them settled in the Latin
church, and tracing them back through their several combina-
tions, he found that the year in which they would all begin
together was the year before the Creation, 714, and that Uie
first year of the Christian aera would be 47 1 4 of this period.
The year of the Julian period corresponding with any given year,
before or since the commencement of the Christian aera, may be
found by the following rule. If the year required be since the
commencement of I he Christian aera, add to it 4713, and the
sum will be the year required. If it be before the Christian sera,
then subtract the year B. C. from 4714, and the difference
will be the result.

Christian &ra. The period just mentioned is now seldom
used, notwithstanding the high estimation in which it wag for-
merly held, because, in truth, the very general adoption of

2 A 2


tlie Ciiristian asra, supersedes the want of any otlier standard
of time tliaii that. It is true there may be a difference of
opiuion respecting the time when Christ was born, but this is
no inconvenience, since all chronologers agree in calling the
present, and of course every other year, by the same name,
and, therefore, they have the same idea of the interval be-
tween the present year, and any other year in the system.
The real time of the birth of Christ cannot affect the use of
this system, since, using the same system of dates, they may
say Christ was born in tlie third, fourth, fifth, sixth, or seventh,
or any other year before the Christian aera. Whenever, there-
fore, chronologers ceased to date events from the Creation,
tbey had no occasion to have recourse to any such period as
the Julian, since another, capable of answering the same pur-
poses, was already in common use, supplying them with a
lai^uage which they all equally understood.



' ' ...^ /i/ ^




nw Continued.

Epochas and ^ras Creation of the World Deluge Argonautic expe -
dition Destruction of Troy Olympic Games Rbman yEra; yEra of
Nabonassar ^ra of the* Selencidae Spanish ^ra Christian ^ra
Mohammedan vEra Memoria Technica.

W E shall now give some account of the Epochas and ffiras
which are most known in history, and which are of frequent
recurrence, as well in chronology as in history. An Epocha
or Epoch, relates to a certain point of time, which is generally
determined by some remarkable event, from which subsequent
events are reckoned, and the years reckoned from that period
are denominated an JBra : thus the birth of Christ is consi-
dered as an epocha ; but the series of years flowing from and
after that event, are called the years of the Christian aera :
bence we date the present year. Anno Domini, 1815.

Online LibraryWilliam ShepherdSystematic education: or Elementary instruction in the various departments of literature and science; with practical rules for studying each branch of useful knowledge (Volume 1) → online text (page 29 of 44)