Collection of pages from K&E catalogs for the 4251 Precision Polar Disc Planimeters
The 4251 is an Precision Polar Disc Planimeter. Refer to page 336 of the 1906 catalog for a good description of the instrument.
Of the catalogs available the 4251 polar disc planimeter first appeared in the 1906 catalog and was last shown in the 1936.
Links to catalog pages for the 4251 planimeter: