Dotting Instrument

This 2-1/4" German silver drawing instrument consists of a teardrop-shaped plate to which is attached a mechanism that links a serrated wheel to a bar that holds a pen point. When the wheel is rolled along the edge of a T-square or straight edge, the pen point bounces up and down to make a line of dots. Draftsmen would then retrace and fill in the line, if desired, while they were finishing an engineering drawing.

Underneath the uniformly serrated German silver wheel is a brass wheel with a pattern of three and one serrations. This wheel is marked: 6. It could be interchanged with one of four other brass wheels to change the dotting pattern. The instrument originally had six pattern wheels, but the one numbered with a "2" is missing.

The back of the plate is marked: 1050. The instrument is in a rectangular wooden case covered with brown and black leather and lined with dark blue velvet and satin. The Eugene Dietzgen Co. of Chicago and Technical Supply Company (TSC) of Scranton, Pa., sold a similar dotting instrument in the early 20th century for prices ranging from $4.20 to $5.15. According to the 1904 Dietzgen catalog, E. O. Richter of Germany made the instrument sold at that time. Unlike the Dietzgen and TSC instruments, this example has a screw that allows the pen point to be removed from the bar. Compare to 1982.0147.01.

References: Catalog of Eugene Dietzgen Co., 7th ed. (Chicago, 1904), 88; Catalog of Eugene Dietzgen Co., 12th ed. (Chicago, 1926), 84; Technical Supply Company, Complete Catalog and Supply List, 5th ed. (Scranton, Pa., 1912), 91.

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