A VISIT TO GREENWICH OBSERVATORY. 115 



with those of others. When will it be possible 

 to obtain a "personal equation " that will enable ns 

 to reconcile the differences which prevail amongst 

 men in their views of truth ? The astronomer is 

 to be envied by the moralist. 



Then the equatorial of small degree was seen, 

 and after it the standard clock which gives time 

 to the world. Every day at one o'clock the great 

 ball drops, but, alas ! it cannot rise till it is wound 

 up by a windlass turned by hand. Some day, 

 when the price of a hundred-ton gun can be spared, 

 this may be done automatically. 



The altazimuth instrument enables the observer 

 to sweep any meridian of the sky. It is used 

 mostly for watching the moon, and the dome over 

 it opens at any point by means of machinery. 

 To sailors these observations are of the utmost 

 importance, for, with the astronomer's results before 

 him in the Nautical Almanac, the moon becomes 

 a kind of hand upon the giant dial of the sky, of 

 which the figures are the stars, and he can thus 

 ascertain his whereabouts in any part of the world. 



The great equatorial telescope is the largest 

 instrument at Greenwich. Its object glass is a 

 little more than a foot across. What a pigmy 

 compared with those mighty instruments possessed 

 by our enlightened transatlantic cousins ! Perhaps 

 some princely Lick will one day give England a 

 refractor with a diameter of three feet ; or, better 

 still, we may some time be able to sell an ironclad 

 for the purpose. There is, however, we are glad 

 to state, a twenty-eight inch refractor being now 



