This page has been validated.
Wave Motion and Interference
13
A beautiful instance of such interference occurs in a soap film. Ordinarily, however, such films have the form 
FIG. 13of a soap bubble; and, while the disturbing causes usually in operation enhance wonderfully the beauty of the appearance, they do not permit the accurate investigation of the 
FIG. 14phenomenon. These disturbing elements are very much diminished in the arrangement which follows:
