IN FOCAL PLANE OF TELESCOPE. 347 



which approximately represent the appearance of such a dark 

 disc seen within the luminous source, as observed by means of a 

 telescope. 



We have thus arrived at the probable explanation of the drop- 

 formation during the transit of inferior planets. If the dark space 

 be taken nearly equal to the luminous source and have small 

 protuberances, we can by a similar process obtain a result, which has 

 close analogy with Baily's beads, observed during the solar eclipse. 



