The phases of the moon.

Moon Phases

The phases of the moon.

"The various phases of Venus." -Comstock 1850

Phases of Venus

"The various phases of Venus." -Comstock 1850

"...represents two sets of sound waves with like periods and phases but different amplitudes." -Avery 1895

Waves with Different Amplitudes with Equal Periods

"...represents two sets of sound waves with like periods and phases but different amplitudes." -Avery…

"...represents two such wave systems meeting in opposite phases." -Avery 1895

Waves with Opposite Phases

"...represents two such wave systems meeting in opposite phases." -Avery 1895