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It's probably an inking compass (for drawing circles in ink). You would attach a type of dip-pen to the knob nearest the right and can set the spacing very accurately using the protruding knob. The two strips of thin steel ensures that when the size is adjusted, the pen nib stays perpendicular to the paper - which is important for old-fashioned pensWhen drawing a circle, you can push down hard on needle part (via the steel shaft) to stop the compass slipping, and the weight of the compass body (brass part) applies the correct pressure to the pen-part.

To halve the strength of the steel you need to get it to 500 - 700 degrees, and a candle burns at ~1000 degrees. So in theory, you could use a candle to heat a bolt up to glowing red so you could forge it. However, there's a reason why people use forges powered by coal, gas, and that is ... safety. In order to heat up the bolt, the air around it has to be hotter than your desired temperature. Paraffin auto-ignites at about 250 degrees. So if you have a candle in a space hot enough to soften the steel, your candle would have long since turned into a flaming puddle.There's also the issue of the thermal output: it would take a long time for a candle to heat up a bolt (A candle outputs about 40W of heat, and steel takes 0.5j to heat one gram up one Celsius. So with 100% efficiency, it takes j…

To halve the strength of the steel you need to get it to 500 - 700 degrees, and a candle burns at ~1000 degrees. So in theory, you could use a candle to heat a bolt up to glowing red so you could forge it. However, there's a reason why people use forges powered by coal, gas, and that is ... safety. In order to heat up the bolt, the air around it has to be hotter than your desired temperature. Paraffin auto-ignites at about 250 degrees. So if you have a candle in a space hot enough to soften the steel, your candle would have long since turned into a flaming puddle.There's also the issue of the thermal output: it would take a long time for a candle to heat up a bolt (A candle outputs about 40W of heat, and steel takes 0.5j to heat one gram up one Celsius. So with 100% efficiency, it takes just over a second to heat up a 100g bolt by one degree. To go from 20 degrees to 500 degrees would therefore take around 8 minutes. By the time you allow for the fact that 99.9% of your energy goes around your bolt you'd be there for a very long time).That said, I like the idea of using a bolt, they're a nice source of available material - but I think you'd need a gas torch to work with one. A bolt is likely to be higher quality steel than a nail - I know I put dents into the rail-road track I was using as an anvil while trying to flatten a screw, so make sure you don't ruin your work-surface when hammering on a bolt.

The link should be fixed now. Thanks for letting me know.

There we go, I've added another drawing on the last step. The story now has an ending.

You do have to alter the circuit, you have to remove a capacitor and a diode. There's a nice writeup about the mod here:http://rimstar.org/science_electronics_projects/cfl_powered_by_electric_fly_swatter_racket_zapper.htm

Here's a small version: 10cm cubed. Got an LED, powered over USB, checks time over Wifi and acts as an alarm clock.