338 



C. Barus — Apertures of Coronas. 



so sweeping that a ratio can only be inferred for the small 

 coronas. 



10 cm 



11 14- 16 18 



Chart. — Curves 1 and 2, relations of apertures computed from successive 

 exhaustions (s) and directly measured (s'). Tall cylindrical receiver, 13 cm in 

 diameter. Curve 3, the same for plate glass apparatus 20 cm deep. Coronas 

 were difficult to place. Order numbers, z, attached to curves. 



Curves 4 and 5, relation of diameter of fog particle computed from succes- 

 sive exhaustions (d), and from measurements of aperture (d"), both given in 

 centimeters. Tall cylindrical receiver. The types of coronas are marked 

 gr (green centered), cr (white- crimson centered). Curve 5 dropped , 0002 cm . 

 Small dots refer to a special series. Numbers on the curves show the orders 

 (z) of the successive coronas. 



