Now, when's the last time you saw that jackknife Claudia gave you last summer?
When S and S' lie on the same radius, taken along Ox, the Stokes' function can; be written down; and when S and S' coalesce a doublet is produced, with a doublet image at H.
These forms all agree in making the frequency negative when s falls below a certain value sp. Rydberg's second law states that if the main branch series is taken, the numerical value of np_I corresponding to sp_ I is equal.
If we wish to be more general, while still adhering to Deslandres' law as a correct representation of the frequencies when s is small, we may write n - A (s+ 1 1) 2 - - a Po+Pi(s + c) -F +pr(s+ c)r' where s as before represents the integer numbers and the other quantities involved are constants.
Equations of this form have received a striking observational verification in so far as they predict a tail or root towards which the lines ultimately tend when s is increased indefinitely.