In a dentist's operating room on a fine August morning in 1896. Not the usual tiny London den, but the best sitting room of a furnished lodging in a terrace on the sea front at a fashionable watering place. The operating chair, with a gas pump and cylinder beside it, is half way between the centre of the room and one of the corners. If you look into the room through the window which lights it, you will see the fireplace in the middle of the wall opposite you, with the door beside it to your left; an M.R.C.S. diploma in a frame hung on the chimneypiece; an easy chair covered in black leather on the hearth; a neat stool and bench, with vice, tools, and a mortar and pestle in the corner to the right. Near this bench stands a slender machine like a whip provided with a stand, a pedal, and an exaggerated winch.