DISTANCES OF THE FIXED STARS. 7 



seen from them, is only an indivisible point ; and it is only within 

 the last few years that instruments of a precision unknown to 

 former ages have at length brought a small number of them with- 

 in the reach of human calculation. In these immense regions 

 of space solar orbits are too small to serve as a unity of 

 measure ; we are obliged to travel on the wings of light, which 

 in a second leaves 200,000 miles behind, to be able to express, 

 in a few numbers, distances which exceed the utmost limits 

 of our conception. 



A ray of light emitted from our earth would require three 

 years and a half to reach the nearest fixed star ; twenty years 

 long it would have to dart through the fields of ether before it 

 reached Sirius, and thirty years would have to pass before it 

 rested on the Polar Star. 



Thus the distances of about thirty of the nearest fixed stars have 

 been measured ; but the remaining thousands which we are able 

 to see with the naked eye, and the millions which the telescope 

 reveals to our gaze, roll on at such immense distances from 

 our planet, that most probably no progress of astronomical 

 science will ever be able to bridge over the intervening gulf. 

 A reduction of stellar distances to a smaller scale will enable 

 us to form some faint idea of the enormous difficulties of their 

 calculation, and of the astonishing perfection of our instruments. 

 Supposing the sun to be of the size of an orange, and placing 

 it in the centre of the dome of St. Paul's, our pea-sized earth 

 will then be performing its orbit within the circumference of 

 the dome, while Neptune will be moving in the vicinity of the 

 Bank, and many of the comets extending their vagrant excur- 

 sions as far as Charing Cross. From these proportional distances 

 we may easily conceive how, the diameter of the cathedral dome 

 (which is here supposed to be the diameter of the earth's orbit) 

 being known, it must be comparatively easy to measure all the 

 angles necessary to calculate the distances of Neptune or any 

 other planet : but when we come to consider that, according to 

 the given proportions, the nearest fixed star would be sending us 

 its light from the vast distance of St. Petersburg, then indeed 

 we must be astonished at the perfection of the instruments 

 which from so narrow a basis have been able to measure the all- 

 but-imperceptible inclinations of the angles verging towards 

 that distant world. 



