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the universe. This theory, to which Ptolemy gave his name and 

 influence, regarded this planet to be the centre, round which 

 revolved the sun, moon and all the celestial bodies. The 

 Ptolemic doctrine continued down to 1543, when Copernicus 

 assigned to the sun his j)roper position in the Solar System. 

 The laws of the planetary motions were discovered by Kepler in 

 1609, and in 1610 Gahleo supported the Copernican theory, and 

 also discovered the moons of Jupiter. Newton's great discovery 

 of universal gravitation came about the year 1687. At the 

 beginning of the present century the French Astronomer, 

 Laplace, propounded the theory now designated the Nebular 

 Hypothesis. In affirming the truth of the above theory the 

 lecturer directed the attention of the members of the club to the 

 fact of the present incandescent state of certain members of the 

 Solar System (Jupiter and Saturn). In imagination he placed 

 his audience on the equator of the Sun itself : stating that the 

 central orb was 866,000 miles in diameter, moving once round 

 its axis in 26 days, with a direct motion in space of 18,000 miles 

 an hour towards the constellation, Hercules : his vast incandes- 

 cent body enshrouded in a highly heated gaseous envelope. 

 One important fact urged in support of the hypothesis was the 

 axial and centripetal motions of the planets agreeing with the 

 motion of the Sun ; the direction of all being from west to east. 

 The flattening of the poles of the planets was affirmed to arise from 

 the once gaseous and incandescent particles flying largely towards 

 the equator in consequence of the centrifugal motion of each 

 body. No other reason he maintained had been given to account 

 for the polar compression of all members of the Solar System. 

 The distances, magnitudes and densities of the planets were 

 minutely described with their degrees of inclination to the plane 

 of the ecUptic. From Mercury to Neptune their rotations and 

 velocities were given, with their equatorial directions and affinities 

 to the equator of the sun. 



This continuous whirl of planets round the equator of the 

 central orb in thek various stages of condensation was claimed 

 by the speaker as supporting the Nebular Hypothesis. After 

 carrying his hearers to the distant planet, Neptune, on the out- 

 skirts of the Solar system, he stated that he had no doubt that 

 all the matter now contained in the sun and planets, was origin- 

 ally one vast nebulous cloud, filhng a space far beyond the 

 extensive orbit of Neptune. 



This gaseous cloud would be more than 5,000,000,000 of miles 

 in diameter, and Uke all true Nebulae at the present time, revolving 

 as it were on an axis. Our Nebulae would also revolve ; condens- 

 ation would go on at a certain rate, the heavier particles falling 

 towards the centre, and the more volatile atoms flying to the 

 surface. The law of gravitation would crowd these (once attenu- 



