By the 18th century, the average mechanical clock was more than
sufficiently accurate to meet the general public's civil and
personal timekeeping needs. The scientific community, however,
required a much higher level of precision in their laboratories
and observatories. In response to this demand, clockmakers
sought to make ever more precise clocks. By the early 18th
century, it was already widely know that temperature affects
clock metals, diminishing timekeeping accuracy. In 1715, George
Graham did a great deal of research into the thermal reactions
of different metals, hoping to find two metals whose rates of
expansion would "compensate," or cancel one another out. He
found such a relationship between steel and the viscous metal
mercury, and went on to introduce a mercury-compensated pendulum
in 1722. Graham's work helped usher in a new era of precision
timekeeping. As clockmakers coupled a growing understanding of
metallurgy with new technological designs, timekeeping accuracy
continued to improve through