24:6 · A circle with several vertical lines was used in some meteorological systems to denote varying degrees of cloudiness, the actual degree indicated by the number of lines.
    Dalton, in his nineteenth century system of signs for chemical substances, used the similar to represent soda or the metal sodium.
    Another similar sign, , appears as a military sign for anti-aircraft gun, the sign being a combination of for the element of air, and for gun or cannon.