1 янв 1848 г. - System Palmer

Описание:

French inventor J. Palmer receives a patent for the ‘System Palmer’, the first micrometer still recognizable today with its U-shaped frame. Modern micrometers closely follow the System Palmer’s basic design of a U-shaped frame, thimble, sleeve, spindle, anvil, etc. Besides, all micrometers and other hand tools must still be traceable to the International Standard.

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