Sadie and Rosie attended.
A "mask and shadow dance" is as important a function to girls of Sadie's and Rosie's class as a cotillion is to girls of your class.

Such affairs are possible only in large dance halls, and to do them impressively costs the proprietor some money.

The guests rent costumes and masks and appear in very gala fashion indeed.

They dance in the rays of all kinds of colored lights thrown upon them from upper galleries.

During part of a waltz the dancers are bathed in rose-colored lights, which change suddenly to purple, a blue, or a green.