Barth's speed slide rule
Datecopyright 1902
Inventory Number1990-4-0017
ClassificationSlide Rule
Subject
Maker
Carl G. Barth
1860-1939
Associate Name
Frederick W. Taylor
1856-1915
Cultural Region
Place of Origin
Dimensions1 × 16.8 × 16.8 cm (3/8 × 6 5/8 × 6 5/8 in.)
Material
DescriptionTwo off-white circular paper discs joined by a brass bolt with moveable clamping nut.
Two scales are printed around the circumference of the bottom disc. The outermost scale, for "REVOLUTIONS PER MIN.," has values ranging from 0.1 to 500. The innermost scale, "CUTTING SPEED IN FEET PER MINUTE," carries values from 0.3' to 500'.
The irregularly-shaped top disc is printed with two arrows and one scale. The point of the outermost arrow falls outside either scale on the bottom disc. The innermost arrow, approximately 30° clockwise from the first arrow, points into the "REVOLUTIONS PER MIN." scale on the bottom disc.
Around the circumference of the top disc is a scale for "DIAMETER OF WORK," carrying values ranging from 1'' to 300''.
Two scales are printed around the circumference of the bottom disc. The outermost scale, for "REVOLUTIONS PER MIN.," has values ranging from 0.1 to 500. The innermost scale, "CUTTING SPEED IN FEET PER MINUTE," carries values from 0.3' to 500'.
The irregularly-shaped top disc is printed with two arrows and one scale. The point of the outermost arrow falls outside either scale on the bottom disc. The innermost arrow, approximately 30° clockwise from the first arrow, points into the "REVOLUTIONS PER MIN." scale on the bottom disc.
Around the circumference of the top disc is a scale for "DIAMETER OF WORK," carrying values ranging from 1'' to 300''.
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.
Curatorial RemarksRecords indicate that Barth was working in Philadelphia in 1902;
Identical to 1990-4-0018, 1990-4-0019, 1990-4-0020, 1990-4-0021, 1990-4-0022, 1990-4-0023,and 1990-4-0024;
Similar to 1990-4-0025, 1990-4-0026, 1990-4-0027, 1990-4-0028, 1990-4-0029, 1990-4-0030, 1990-4-0031, and 1990-4-0032 in function and arrangement, though range of values on scales is different, and this instrument incorporates neither a scale for "time in minutes for 10 revolutions," nor one for diameter values below 1''.
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.
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.
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.
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.
Carl G. Barth
Date: 1902
Object number: 1990-4-0023
