CHAPTER XXVIII

ABOUT TELESCOPES.

aes next day Uncle Nat
told the boys about
telescopes.

“There is a very fine
one at Cambridge, in Mas-
sachusetts. The  object-

glass, and that is the
glass at the telescope-end,
next to the object looked
at, measures fifteen inches

 

 

 

 

 

 

 

 

 

|. across. Here is a picture
of it. You see that the
roof over it is shaped like

 

 

 

 

 

 

a dome, and a hole in the
dome allows any observer
to point this telescope at
the heavens. Then the
dome is made to turn by

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

TELESCOPE AT CAMBRIDGE, U. S.

means of machinery, so
that the telescope can be pointed at different parts of the sky.
Look at the chair, too, where the man sits; for that can be moved
about on rails you see encircling the telescope, and there is a con-

262