So That's What It Is

I rescued this as it was about o be thrown out by people who should have known better.

It is an instrument for measuring the power developed in the cylinder of steam engine. You can then, in conjunction with another device for measuring the power output, work out the mechanical efficiency.

It is such a beautiful piece of precision instrument making that I couldn't bear to see it destroyed.

I also got a rather better and later model suitable for internal combustion engines