This was sold to us as a bell push. Fortunately it is much more interesting than that. What it is is a time delay switch. Fully depress the brass plunger and over the next 25 to 30 seconds it gradually returns to its original position. When the plunger is pressed home a spring loaded arm completes the circuit. When the plunger reaches the top of its travel it pops up therby lifting the spring loaded arm and breaking the circuit. We have no idea if this is still legal to use today, altough the mechanism is about as simple as it can be. If you intend to use this for its original purpose, please consult a suitably qualified electrician. The above not withstanding, this is sold as a purely decorative collectors item.