This is a close up of the medallion at the top of the proscenium.  The figure is of a Muse. Her name is Calliope and she is the eldest and most distinguished of the nine  Muses. She is initially identified with philosophy and poetry. Calliope means "beautiful voice". Her emblems are a stylus and wax tablets, a roll of paper or a book. This image is a fine example, she is holding a stylus or quill pen in her right hand and a book or tablet in her left hand.