23-i ASTRONOMY. 



of the science of which we have any authentic account), by merely 

 observing that after ages of philosophic dispute whether the Ptolemaic, 

 the Tycho7iic, the Carles tan, and Copernican was the true one, and when 



-" Nature's laws lay hid in night, 



God said, let Newton be, and all was light.'' 



For he it was who laid down the laws of nature and motion ; and compar- 

 ing all the phenomena in the Heavens, discovered the true system of the 

 universe ; his discoveries confirmed the accuracy of the Corpernican 

 system of astronomy, and demonstrated, by irrefutable arguments, that 

 it was impossible to be otherwise, without subverting all the beautiful 

 regularity of the laws of Nature. 



THE SOLAR SYSTEM. 



THE sun is placed nearly in the centre of the orbits of all the planets, 

 and in those orbits they move round the sun, each in its periodical time. 

 The sun keeps always in or near the same place, but has a central motion 

 on his own axis from east to west, once in twenty-five days and a half, 

 which is evident from the macula: or spots on his disk, which are 

 always observed to move in the same manner ; but as the sun has no 

 circular motion he can have no orbit. 



The orbits of all the planets are nearly circular, having the sun for 

 their centre ; but to speak more accurately they are ellipses, having the 

 sun in thefocus of each. These orbits are not all of them alike ; although 

 they do not vary much, they intersect one another in lines that pass 

 through the centre of the sun ; and the places of the orbits where they 

 intersect are called the Nodes. 



All the planets move round the sun in the same way, which is from 

 nest to east, and are called primary planets. 



The number of planets at present known is eleven. They are Mercury, 

 Venus, Mars, Jupiter, Saturn, Herschel or Uranus, Ceres, Pallas, Juno, 

 Vesta. The first five are visible tot he naked eye, and have been known 

 from the earliest periods. Herschel is also visible to the eye without 

 the aid of a glass on a very clear night ; the remaining four can only 

 be seen by a telescope. By the Newtonian system, Mercury is placed 

 nearest to the Sun, and then in succession, Venus, the Earth, Mars, 

 Jupiter, Saturn, &c., and to these succeed the fixed stars, supposed to 

 be the centres of other systems. 



Mercury and Venus, moving within the orbit of the earth, are called 

 inferior planets, and as Mars, Jupiter, Saturn, &c., revolve in larger 



