BACK TO THE ARTIST   The Ballet Class, c. 1880           Details     Description     Artist EDGAR DEGAS An X3ƒ4ray analysis of this work shows that Degas made frequent changes to the positon of the dancers. Once satisfied, however, that these were correct, the artist painted several variations on the theme. This canvas was commissioned by Mary Cassatt for her brother Alexander, and the family’s correspondence reveals their frustration with delay in the painting’s delivery.   Date c. 1880   Institution Philadelphia Museum of Art     Medium Oil on canvas    Dimensions 82.2 x 76.8 cm