CHRONOLOGY. 
357 
insertion, viz. after the sixth of the calends 
March) was called bissextile, or leap-year. 
61 is form of the year is still called the Julian 
fear. But the true length of the year being 
bt quite six hours more than the 365 days, 
[is allowance was too much ; and pope 
[regory XIII. introduced another amend- 
[ent, i'11 the year 1582, by ordering that 
pee in 133 years a day should be taken out 
f the calendar, in the following manner, viz. 
tom the year 1600 every hundredth year 
which, according to the Julian form, is al- 
lays bissextile or leap-year) was to be com- 
lon ; but every four-hundredth year was to 
bntinue bissextile, as in the Julian account. 
[The Mahometans make their year to con- 
ist of lunar months only, without endeavour- 
|g lo adapt it to the course of the sun ; so 
hat with them the beginning of the year 
;oes through all the seasons at the rate of 
bout eleven days every year. But since 
he exact time of twelve moons, besides the 
S54 whole days, is about eight hours and 48 
ninutes, which make 1 1 days in 36 years, 
(lev are forced to add 1 1 days in 30 years, 
/Inch they do by means of a cycle, invented 
>y the Arabians, in which there are 19 years 
z'ith 354 days only, and 1 1 intercalary of 355 
lays, and they are those in which the number 
if hours and minutes more than the whole 
(ays in the vear is found to be more than half 
I day, such' as 2, 5, 7, 10, 13, 16, 18, 21, 24, 
6, and 29, by which means they till up all 
he inequalities that can happen. 
I It has been of some consequence to Clrris- 
jans to adjust the days of the week to the 
lays of the month, and of the year, in order 
0 get a rule for finding Sunday. Had there 
|een no bissextile, it is evident that, since the 
lear consists of 52 weeks and one day, all 
he varieties would have been comprized in 
even years. But the bissextile returning 
(very fourth year, the series of dominical 
fitters succeeding each other is interrupted, 
lincl does not return in order ; but after four 
[nner, 7 years, or 28 years, which is there- 
fore commonly called the solar cycle, serve 
is a rule to lind Sunday, and consequent- 
ly all the days of the week of every month 
md year. 
1 Besides the above-mentioned periods of 
(ears, called cycles, there are some other 
jombinations or systems of years that are of 
ise in chronology ; as that called the indic- 
uon, w hich is a period of 15 years, at the 
[ml of which a certain tribute was paid by 
lie provinces of the Roman empire, and by 
vhich the emperors ordered public acts to 
»e dated. 
i But the most remarkable of all the periods 
n chronology, is that called the Julian period, 
invented by Joseph Scaliger ; and called Ju- 
lian, from the years of which it consists be- 
ing Julian years. His object was to reduce 
jo a certainty the different methods of com- 
1 uting time, and fixing the dates of events 
y different chronologers. For this purpose 
nothing was necessary but a series of years, 
some term of which was fixed (that, for in- 
fctance, by which the present year should be 
denominated), comprehending the whole ex- 
tent of time ; since, if each chronologer 
would apply that common measure to his 
particular scheme, they would all perfectly 
understand one another. To accomplish 
this, he combined the three periods of the 
Bun, the moon, and the indiction, together ; 
that is, multiplying the numbers 28, 19, and 
15, into one another, which produces 7980; 
after which period, and not before, all the 
three cycles will return in the same order 
every y ear, being distinguished by tjie same 
number of each. In order to fix the begin- 
ning of this period, he took the cycles as he 
then found them settled in the Latin church; 
and tracing them backwards through their 
several combinations, he found that the year 
in which they would all begin together was 
the year before the creation 71 4, according 
to Usher; and that the first year of the Chris- 
tian ara would be 4714 of this period. There 
is a farther convenience in this period, viz. 
that if any year is divided by the number 
composing the cycles, viz. 28, 19, or 15, the 
quotient will shew the number of the cycles 
that have elapsed since the commencement, 
of it, and the remainder will give the year 
of the cycle, corresponding to the year given. 
We cannot help observing that this boast- 
ed period seems to have been unnecessary 
for the chief purpose for which it was in- 
vented, viz. to serve as a common language 
for chronologers ; and that now little use is 
made of it, notwithstanding all writers still 
speak, of it in the same magnificent terms, 
'lire vulgar Christian rera answers the same 
purpose as effectually. 
All that can be necessary for chronologers 
to speak the same language, and be perfect- 
ly understood by one another, and by all 
mankind, is to give every year the same 
name or designation ; which is most conve- 
niently" done by expressing them in a series 
of numbers in arithmetical progression, any 
one term of which they shall agree to affix to 
the same year, a year in which any well- 
known event happened. Let it, for example, 
be that in which the peace of Amiens was 
made, and let it be called 1801. If, besides 
this, it is only agreed in what part of the re- 
volution of the sun, or in what month and 
day, the year begins, there can be no diffi- 
culty" in giving a name to every other year 
preceding or following it, and thereby ascer- 
taining the interval between all transactions. 
For all the events that took place the year 
before that peace, will be referred to the 
year 1800, and all in the year after it to 1802. 
This period having had a commencement 
since the date of history, is no inconvenience; 
for whenever we have gone back to number 
T of this period, the year preceding it may- 
be called one before its commencement , the 
year preceding that two before it, &c. and 
thus proceeding ad infinitum both ways. 
That Christ might not have been born in 
the first of that system of years to which it 
serves to give a name, is no inconvenience 
whatever ; since, whatever differences of opi- 
nion there may be among chronologers about 
the time when Christ was born, they r all agree 
in calling the present year, and consequently 
every other year, by the same name ; and 
therefore they have the same idea of the in- 
terval between the present year and any other 
vear in the system. The real time of Christ’s 
birth can no mop: affect the- proper use of 
this system than that of any other indifferent 
event; since, using the same system of dates, 
they may say Christ was born in the third, 
fourth, fifth, or sixth year before the Christian 
ana. 
Whenever, therefore, chronologers ceased 
to date events from the Creation, which was 
very absurd (since they did not agree in fix- 
ing the intervals between the present year 
and the date of that event, and therefore gave 
all the years different names), they had no 
occasion to have recourse to any such period 
as the Julian; since another, capable Ol an- 
swering the same purposes, was already in 
common use, supplying, them with a language 
which they all equally understood. 
/Eras or epochas are memorable events, 
from which time is reckoned, and from winch 
any subsequent year receives its denomina- 
tion. The Greeks for a long time had na- 
fixed ana; afterwards they reckoned by Olym- 
piads, which were games celebrated in honour 
of Jupiter once in four years, and began in 
midsummer, 776 years before Christ. 4 he- 
Athenians gave names to their years from 
their archons. The Romans called tlv-ir 
years from the names of the consuls who 
presided in them: and afterwards they dated' 
events from the building of their city, sup- 
posing it to have been built 753 years before 
Christv- 
Some histories are regulated by the era 
of Nabonassar, who began his reign in the 
year 747 before Christ, of the Julian period' 
3867. It is supposed to have commehced on 
the 26th of February" in the afternoon. 
The Jews before Christ reckoned by the 
year of the Seleucida, sometimes called the 
year of the Contracts ;■ which began hr the- 
year 342 before Christ, of the Julian period 
4402, some time in the spring. 
The Christians, about 360 years after the 
birth of Christ, began to make use of that 
ara,. which, is now used in all Christian coun- 
tries.. 
The Mahometans reckon their years from- 
the flight of Mahommed from M ecca. This 
ara is called the Ilegyra. It began in the- 
year 622 after Christ, of the Julian period . 
5335, on the 16th of July. 
The old Spanish sera is dated from the years* 
38 before Christ, about the time when they 
were subdued by the Romans. It was used 
till the year 1333, under John J. of Castile. 
The Egyptians long reckoned from the 
battle of Aetium, which happened in the year 
31 before Christ, of the Julian period 4683, 
on the 3d of September. 
Before the Christian ara. was used, the 
Christians for some time made use of the 
Dioclesian ara, which took its rise from the 
persecution by Dioclesian, in the year 284 
after Christ. 
The ara of Y erdigerd is dated from the 
last king of Persia; who was conquered by 
the Saracens under Abubecher, in the battle 
of Merga, in the year 632 afler Christ, of the 
Julian period 534.5, on the 16th of June. 
With regard to all these methods of deno- 
minating time,- care must be taken that the 
year be reckoned according to the method of 
computation followed by- the people who use 
it. Thus, in reckoning from the Ilegyra, 
a person would be led into a mistake who 
should make those years correspond to Julian 
years. He must deduct eleven days from 
every year which has elapsed since the com- 
mencement of it. Thus, though the first 
year of this ara corresponded to the year 
622 after Christ, and began 011 the 16th of 
July, the year 326 of the Hegyra corre- 
sponded to the year 937 of Christ, and began 
Novembers: and the year of the Hegyra 
655 commenced on the 19th of. Jail. 1257." 
