Signedon top disc: COPYRIGHT. 1902, CARL G. BARTH.
Inscribedon top disc: BARTH'S SPEED SLIDE RULE.;
on top disc: FOR LATHES, BORING MILLS, DRILL PRESSES, ETC.
FunctionFor calculating the revolutionary speed setting consistent with a given surface speed on a lathe or similar machine.
First loosening the clamping nut on the center bolt, the user rotates the top disc such that the appropriate value on the "DIAMETER OF WORK" scale aligns with the desired surface speed (bottom disc). He then tightens the clamping nut and reads off the speed in revolutions per minute, using the innermost arrow on the top disc.
Historical AttributesThis is part of a set of slide rules for machine shops designed by Carl G. Barth under Frederick Winslow Taylor's system of scientific management. Given the characteristics of a particular machine and a depth of cut, for example, a shop manager could quickly calculate the most efficient speed and feed settings using one of Barth's speed and feed slide rules. Other objects in the collection include slide rules for helical springs, belts, and gears, as well as jigs for making slide rules.
Primary Sources"Barth's Lathe Speed Slide Rules," American Machinist 25 (November 20, 1902): 1684-5.
Carl G. Barth, "Slide Rules for the Machine Shop as a Part of the Taylor System of Management," Transactions of the American Society of Mechanical Engineers 25 (1904): 49-62.
Frederick W. Taylor, "On the Art of Cutting Metals," Transactions of the American Society of Mechanical Engineers 28 (1908): 31-432.
ProvenanceThe papers and slide rules of Carl G. Barth and his son, J. Christian Barth, were transferred to the Baker Library of the Harvard Business School by J. Christian Barth in 1961.
The slide rules were transferred from Harvard Business School to the Collection of Historical Instruments in 1980.