It was nine o'clock at night, and the thirty huge dynamos of the Societe Generale Electrique of Paris were nearly all at work. In the great glass-roofed hall of the Mont Parnasse Central Power Station blue-bloused workmen moved quietly over the shining floors of white concrete, pausing now and then by this or that purring, spitting monster, scrutinising the whirring, glittering copper drums, listening with experienced ears for the slightest variation in the deep wasp-like hum, touching a lever here, adjusting a screw there, or oiling a bearing with tin cans beaked like a snipe."