When a subscriber called (by turning the handle of his magneto- 'generator), the shutter of the annunciator associated with his line dropped.
When there is no current the shutter covers the perforations and no light passes, but when a current traverses the wires they are depressed by electromagnetic action, carrying the shutter with them, and a quantity of light proportional to the current strength is admitted through the perforations.
- Shutter Weir with Foot-bridge, Port a l'Anglais, Upper Seine.
Sometimes it is a loosely-fitting shutter or windowframe, a hanging drawer-handle, or a lamp-shade which will rattle; the timbers in a roof may creak, or a group of wine-glasses with their rims in contact may chatter.
In a much larger /!w/ - Shutter '60' inch Reflecting Telescope Dome and Building, Solar Observatory Mount Wilson,Calif.