HOW TO OBSERVE THE HEAVENS. 



the object, it will have returned to the meridian, without having 

 gone below the horizon or disappeared. 



In thus passing from an elevated point of the meridian to 

 another point much lower, the object in question will appear to 

 move over a semicircle of the heavens, of which the part of the 

 meridian between the point from which it departed and the point 

 at which it arrives is the diameter. 



If the same object could be seen during the succeeding twelve 

 hours, it would be observed to move over the corresponding 

 semicircle to the east of the meridian, that is, to the right of the 

 observer ; and, at the end of this second interval of twelve hours, 

 the object would return to that more elevated point of the 

 meridian from which it started. 



Such an object, therefore, never rises or sets; and if the 

 presence of the sun did not render it invisible during the day, it 

 might be seen to revolve continually in a circle of the heavens 

 divided into two equal semicircles, east and west, by the meridian, 

 completing its revolution in such circle, and therefore returning to 

 the same point of the meridian, after an interval of about twenty- 

 four hours. 



What has been here stated respecting a single object, is true, 

 with certain qualifications, of an immense number of objects visible 

 to an observer looking to the north, as here supposed. All such 

 objects like that described appear to revolve in circles, but not all 

 in the same circle. Some will be found to revolve in greater, and 

 some in lesser, circles ; but all such circles are characterised by two 

 most remarkable circumstances, the first of which is, that they all 

 have the same centre, which is a certain point on the celestial meri- 

 dian ; and the second is, that all the objects which move in them, 

 complete their revolution in precisely the same time. 



Such being then the general character of the changes which the 

 scene presented by the heavens to the observer undergoes, let us 

 consider some other important circumstances attending it. 



6. After attentively contemplating this spectacle for several 

 nights, the observer will not fail to be struck with the fact, that 

 the relative position and configuration of the objects upon it, 

 remains always unchanged. This remarkable circumstance is 

 rendered the more easily observable by the fact that the objects 

 themselves differ greatly in apparent splendour, some being 

 exceedingly bright and conspicuous, while others are barely dis- 

 tinguishable. The observer soon becomes familiar with the 

 relative arrangement and configuration of the brighter and more 

 conspicuous ones ; and, grouping them in his imagination, retains 

 their forms so as immediately to recognise them upon their 

 successive reappearances, 

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