A VISIT TO AN OBSERVATORY. 103 



very unsteady to-night." As long as this lasts the value 

 of his observations is appreciably impaired ; sometimes 

 the unsteadiness is so great that he must desist from 

 working altogether. 



To escape from the pernicious influences of the atmo- 

 sphere is at present the pressing need of practical 

 astronomy. In this respect of course there will be great 

 differences between one climate and another. But the 

 best method of evading the severe tax which the atmo- 

 sphere imposes on every astronomer's time and the injury 

 that it inflicts upon his measurements is to carry his 

 observatory to the top of a lofty mountain. 



The ocean of air that lies over our heads is perhaps one 

 hundred miles or more in thickness. It is, however, in 

 the lowest mile or so that most of the mischief is done of 

 which the astronomer so sadly complains. A lofty mountain 

 peak which reared its head a mile above the earth's surface 

 would protrude through the most troublesome portion of the 

 atmosphere. An observatory perched on the summit of 

 this mountain will therefore be in a position to observe the 

 stars almost free from the atmospheric anxieties of the 

 astronomer at the bottom of that turbid atmospheric 

 ocean on which the mountain astronomer can now look 

 down. 



At the present moment the attention of the astro- 

 nomical world is largely fixed on the bold experiment 

 which has been made in America to locate a telescope of 

 perhaps unsurpassed optical perfection on the top of a 

 mountain in one of the most exquisite climates on the 

 globe. 



Mr. Lick, a Californian millionaire, committed to the 



