THE PLANET VENUS 



525 



cessive images of what is contained by the slit are presented arranged 

 according to their wave-lengths. In practise the rays of light from the 

 slit enter a small telescope called the collimator, and are there rendered 





\ 



/ 



-JL„ - - 





i , /\ 



t 



i 



•^ — _ % 



*% 



/ 



-/j-ttzcims ;6y S/^'Va/^ 



£4" /£>■?*■ 





/ 





Sketches of the Planet Venus. 



Sketches of different observers showing agreement, made at Tacubaya, 

 Mexico, on February 7, 1897. 



