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THE POPULAR SCIENCE MONTHLY 



Lick Observatory from the West. 



majority of the nights of a 3'ear, and many nights yield "seeing" that 

 might be considered perfect. A glance at the illustrations showing the 

 mountain as seen from the east and from the west will make it evident 

 at once why these conditions obtain. With the exception of a saddle 

 running eastward, the land slopes away rapidly from the summit down 

 into deep valleys, so that there is but little opportunity for heat waves 

 radiated from surrounding land to mount to the atmosphere above the 

 observatory and create atmospheric disturbances. The mountain is not 

 so very high (4,209 feet above mean sea level), but it is high enough to 

 hold the observatory in an atmosphere free from dust, smoke and fog. 

 Being near the ocean, fogs are very frequent at certain seasons over the 

 valleys in this region. It is seldom, however, that they mount high 

 enough to envelop the observatory. Many evenings and early mornings 

 fog completely fills the surrounding valleys, so that the observatory seems 

 to rest on an island in a vast sea of fog. Often peaks only a few hun- 

 dred feet lower than Mount Hamilton are covered by the fog, yet the 

 work with the great instruments is uninterrupted. The picture "Fog 

 in the Valleys at SuUvSet" gives a better idea of this condition than I 

 can describe. In such a location as this the 36-inch refractor can be 

 used with its maximum power a large portion of the time. In less 

 favorable localities even larger instruments would not be so efficient. 



It is one thing to have an excellent plant, and it is another thing 

 to have men skillful enough to operate such a plant effectively. A very 

 proficient marksman can not do very much damage with a blunderbuss, 



