Set into an elegant brass porthole are four instruments to give you an at-a-glance guide to the prevailing conditions - a barometer, with aneroid movement and scale in inches and millibars, a thermometer in C and F, a hygrometer, and a clock. Measures 12 inches across. Clock requires 1xAA battery.
Quartz silicon dioxide crystals possess the remarkable property of oscillating at a very regular and predictable frequency when subjected to an electrical current. The first commercially available clocks to exploit this appeared in the late 1920s, and went on to supersede mechanical movements thanks to their accuracy and reduced need for maintenance.