144 CELESTIAL PHENOMENA. 



according to Struve's most recent investigations, is 166072 

 geographical miles in a second a velocity almost a million 

 times greater than that of sound. From all that we learn 

 from the measurements of Maclear, Bessel, and Struve 

 of the parallaxes and distances of three fixed stars of 

 very different magnitudes, a Centauri, 61 Cygni, and 

 a Lyrse, a ray of light from each of these three bodies 

 requires respectively 3, 9J, and 12 years, to reach the 

 Earth. In the short but memorable period between 1572 

 and 1604, from the time of Cornelius Gemma and Tycho 

 Brahe to that of Kepler, three new stars suddenly appeared 

 in the constellations of Cassiopea, Cygnus, and in the foot 

 of Ophiucus. A similar phenomenon shewed itself in 

 the constellation of Vulpis, in 1670, but in this case 

 the light of the new star was intermitting. In very 

 modern times, Sir John Herschel, at the Cape of Good 

 Hope, saw the star r) Argus increase in brightness from the 

 second to the first magnitude ( 12 ) . But such events or occur- 

 rences in the vast regions of cosmical space belong, in their 

 historic reality, to other epochs than those at which the 



i phenomena of light first reveal them to the inhabitants of 

 the Earth ; they reach us as voices of the past. It has 

 been justly said, that with our large telescopes we penetrate 

 at once into space and time. We measure space by 

 time; the ray of light requires one hour to travel 592 

 millions of miles. Whilst in the Hesiodic Theogony, the 

 dimensions of the universe were expressed by the fall of 

 bodies, and the iron anvil was only nine days and nine nights 

 in falling from heaven to earth, it was thought by the elder 

 Herschel ( 121 ), that the light of the most distant nebula? disco- 



I vered by his forty-foot refrnctor requires two millions of 

 years to reach our eyes. Thus, much may have 



