JOURNAL AND PROCEEDINGS. 45 
‘The other error was that all these visible movements were 
in exact circles. So evident did this seem to all who took any 
interest in the matter, that the circle came to be thought an 
attribute of Deity, a thing of beauty and a joy forever. What 
a rude shock to such enthusiasm it must have been, to discover 
that in the movements of the vast machinery of the universe 
there is no such thing at all as an absolute circle. It issaid that 
the satellites of Jupiter move in circles, but even that cannot be, 
except in an apparent or relative sense, for if the planet moves 
through space at the rate of nearly thirty thousand miles an 
hour, the actional motion of her satellites must be that of a 
long spiral. So if we take into account the movements of bodies 
through space, there may be nowhere an exact circle. 
To go back to the first of these errors, that the earth was 
the centre of planetary motion. Pythagoras taught the sun 
should have the honour. His only or chiefest argument seems 
to have been that as fire is superior to dead matter and 
the sun was a ball of fire, therefore it should control. Nicetus, 
his immediate follower was more bold and claimed that the 
apparent motion of the heavenly bodies was caused by the 
earth’s revolution around the sun. Hipparchus argued that if 
the sun and moon moved in exact circles then the earth could 
not possibly occupy their centres. After Hipparchus caiue Ptol- 
omey who strongly affirmed and taught the old doctrine that 
the earth was the great centre around which the sun, moon, 
planets and stars all revolved. By an ingenious system of 
circles and epicycles, he was able to explain the seeming irreg- 
ularitiesin the movements of the sun and planets. Hissystem, 
full of error as it was, held mankind in its strong hand for 
fourteen hundred years. 
Copernicus of Poland, after long and patient observation 
was convinced that Mercury and Venus revolved about the 
sun on which the earth was just as dependent for light and 
heat as they. If these two revolving bodies had the sun for 
their centre, then why not the earth also? For long ages the 
perturbations and apparent irregularities of the planets had 
plagued the minds of astronomers more than any other thing 
