1851 Great Exhibition: Official Catalogue: Class X.: Henry Baker
396. BAKER, HENRY, 90 Hatton Garden — Inventor and Manufacturer.
Steam gauge, upon the compressed air principle, showing the pressure per square inch, and also the temperature of the steam at various pressures. (See fig. 1.)
Vacuum gauge, with sliding scale; the glass tube is protected by a bronze covering. The same in a brass case, showing a scale of 22 inches and upwards, intended for sugar boiling, or situations where space is an object. (See fig. 2.)
New steam gauge. Rain gauge, upon a simple plan.
Thermometric alarum, for giving an alarm at any required temperature; useful in case of fire, overheating, etc. It consists of a bent glass tube, with a bulb at each end, one of which is open to the external air, a certain quantity of mercury is poured into it. The ether vapour in one bulb acts as a thermometer, and by its expansion displaces the mercury, which flows into the other; the tube rests upon a pivot, and is by this movement overbalanced. The brass tube over the glass one contains a ball, which then rolls down and falls upon a lever in the upright pillar, which sets the clockwork in motion, giving an alarm which will continue for some time. It will also act as a thief-alarum, by means of wires being fixed from it to the doors and windows.
Horticultural and other thermometers.
Barometers, for the working classes.
Glass hydrometer for testing the strength of spirits, in a box, with a thermometer.
Glass saccharometers, for testing beer.
Glass lactometer, for showing the quality of milk; also the percentage of cream by measure.
Urinometers, fitted up in various ways, with bottles, lamps, and test tubes.