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Astrolabes. The two discs or tablets<br />
are engraved with azimuth circles,<br />
hour circles for various latitudes,<br />
etc. Jaipur, Rajasthan, c. 18th<br />
century. Brass.<br />
116<br />
'extreme atoms', are generally measured as being between<br />
1/1,000,000 to 1/349525 inch.<br />
Mathematical units of time were considered an integrated<br />
category for recording observations of a constellation correct to<br />
one second. There were three ranks of time. The first, cosmic or<br />
epochal time, is referred to the eternally recurring cosmic ages.<br />
The four ages, or yugas, are calculated to be in the order of ratio of<br />
4:3:2:1, each of which precedes the other until the universal<br />
cataclysm. The first cosmic age, called Krita or Satya-yuga, is<br />
1,728,000 solar years, the second, Treta-yuga, is 1,296,000 solar<br />
years long, the third, Dvapara-yuga, is 864,000 years long, and the<br />
last, Kali-yuga, the present age of mankind, is 432,000 solar years<br />
long. We are passing through the sixth millennium of the Kaliyuga,<br />
and so there are still about 427,000 years for it to run, after<br />
which the cycle will be renewed and the four ages will commence<br />
once again. The second range of time is the solar or lunar calendar<br />
which determines the days, weeks, months and seasons. The third<br />
rank, the smallest unit of duration, is horologic time. To achieve<br />
accuracy in calculation, the span of a day was converted into<br />
smallest atoms of time. Thus, a day is conceived of as lasting for<br />
86,400 seconds and is further divided into 46,656,000,000<br />
moments, a number arrived by the following time-scale: 1<br />
day = 60 Ghatika (or 24 hours comprising 60 units of time); 1<br />
Ghatika = 60 Vig-Ghatika; 1 Vig-Ghatika = 6o Lipta, 1 Lipta = 60<br />
Vilipta; 1 Vilipta = 6o Para; 1 Para = 60 Tatpara; therefore, 1<br />
day = 46,656,000,000 Tatpara or moments.<br />
Among various methods to ascertain the mean position of a<br />
particular planet in its revolution, one of the most frequent of the<br />
Hindu calculations, known as the equation of the centre, is perhaps<br />
the most illuminating. The calculation entails considerable skill,<br />
but can be explained simply as being determined on the basis of<br />
assuming epicycles. The mean position of the planet is calculated in<br />
relation to the number of revolutions during a yuga, or age. In<br />
order to find the 'true place' of a planet certain epicyclic motions<br />
were assumed, that is, the planet was hypothesized as moving in a<br />
second circle whose centre is carried round the circumference of<br />
the mean circle. Errors were further corrected by obtaining results<br />
from combining two equations arrived at from two separate<br />
epicycles. They were the equation of conjunction (when two<br />
bodies have the same celestial longitude) and the equation of 'apsis'<br />
(the point of greatest or least distance from the central body). In<br />
this way the average is obtained by combining the results of these<br />
two equations and correction could compensate for discrepancy.