JOURNAL AND PROCEEDINGS. OI 
games at Olympia, at the time of first full moon after the summer 
solstice. For a long time Greecian months alternately comprised 29 
and 30 days, but as a Junation is not the exact mean of these num- 
bers, occasional corrections had to be made. The best known of 
such correctional devices, the cycle of Meton, covered a period of 19 
years, 7 of which had 13 and the rest 12 months to the year, a total 
of 235 months for the cycle. One hundred and ten of these months 
had 29 days each, and the remaining 125 months of the cycle had 30 
days to each month, making altogether 6940 days, 9 hours in excess 
of 19 tropical years, and 7 hours more than 235 lunations, leaving but 
a trifling discrepancy for future correction at the end of the cycle, 
between the three modes of reckoning time, by tropical years, calen- 
dar months and lunations. This cycle, called the golden number, 
because, it is said, the Athenians proclaimed it in figures of gold, is 
stili used to determine the time of Easter, as ecclesiastical authority 
has decreed the Sunday following the first full moon after the Vernal 
equinox shall be observed as Easter Sunday. Thus modern Christen- 
dom and ancient Heathendom both accepted the moon as an indi- 
cator of the precise time for holding their great festivals. 
Long years were given to the task of explaining the moon’s 
motion. But modern astronomers have succeeded in shewing that 
motion accords with, and lucidly illustrates the principles of their 
science. ‘The reasoning on which astronomical science depends is 
confessedly intricate, and its thorough mastery may well challenge 
the devotion of a lifetime. Nevertheless, it requires no special gifts 
or training to comprehend that the main links in that chain are: the 
conception of Copernicus that the earth has a daily axial rotation 
and an annual translation around the sun; and Kepler’s laws—that 
a planet’s orbit is an ellipse about its primary as a focus, that the 
areas swept by the radius vector of a planet are proportionate to the 
time of its motion, and that the squares of periodic times of planets 
are proportionate to the cubes of their distance from the sun. Add 
to these the discovery of Newton, which confirms them, that all 
bodies attract each other directly as their mass and inversely as the 
squares of their distance from each other, and we have the axioms 
on which the whole structure of modern astronomy is built. Kep- 
ler’s generalizations were epoch-making. ‘They compel all the more 
admiration that they were conceived in astrological times, and were 
