Patent Model - Improvement in Indicators for Mining-Shafts

Maker and role
Calvin Richardson, Patentee
Production date
Jul 24 1877
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Object detail

Metal, fabric
20 x 17 1/4 x 1 1/2" (50.8 x 43.8 x 3.8cm)
Richardson's "invention consists of a bell having a spring tongue or clapper that vibrates easily, so that when the bell is attached to the hoisting-rope of a mining-shaft, and the tub or cage descending, the clapper will strike the bell when there is a slight checking or variation in speed, which is caused by the momentum of the clapper overcoming the slight resistance of the spring-tongue." (Patent Number 193,462)
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