Last February, we posted a blog about the manometer found next to the engine and how its scales were made of German silver (the same material that is possibly on the object Will discussed last week- see post of June 29).
Well, since this winter, more work was performed on this device and its treatment came to completion about a month ago.
Below are photos before and after treatment of the object showing how well the metal surface was preserved under the concretions, especially the scales inscriptions.
On the left the temperature scale goes from 102 to 180 degree F and one can read: “Wm Sewell Temperature John Powers Manufr New York”.
On the right the pressure gauge goes from 28 to 15 inches of Hg (the atmospheric pressure is about 30 inches). For saturated steam (which was used here), pressure and temperature are related: to each pressure belongs a definite temperature of the water and vice and versa (this relationship is compiled in steam tables). This gauge was indicating the vacuum maintained in the condenser, i.e. the engine’s efficiency. Really neat piece.