Known as Coston lights after their inventor, William Coston, the four lights at the flagpole—white, red, green, and white in descending sequence—serve as a night signal to identify the Eastern to members or visiting yachtsmen sailing into the harbor.  The EYC Coston lights are first mentioned in the 1875 yearbook, but were probably issued by the U.S. Navy when the Club was founded, in 1870. These night signal codes were adopted in 1878 by the leading U.S. yacht clubs.

Coming into use around 1840, Coston lights were made by burning chemicals to make "pyrotechnic flames" of a certain color or sequence.  At that time they were often used by the various steamship companies as identification: a certain sequence of colors, sometimes even including "throwing stars" of different colors!

Photo Above:
These colored lights identify the EYC.

The lights hanging from the flagpole.