File talk:Spring balance (Steam and the Steam Engine, Evers).jpg

This is also an example of a Newtonmeter which measures the force of something.

No, they would have a simple spring balance. This one also has an adjusting nut on the top, so it's a device for applying a force – in this case, as a safety valve. Andy Dingley (talk) 20:15, 16 December 2012 (UTC)