Barth's speed slide rule
Datecopyright 1902
Inventory Number1990-4-0032
ClassificationSlide Rule
Subject
Maker
Carl G. Barth
1860-1939
Associate Name
Frederick W. Taylor
1856-1915
Cultural Region
Place of Origin
Dimensions1 x 16.8 cm
Material
DescriptionTwo off-white circular paper discs joined by a brass bolt with moveable clamping nut.
Three scales are printed around the circumference of the bottom disc. The outermost scale, for "TIME IN MINUTES FOR 10 REVOLUTIONS," carries values descending from 50 to 0.01. Below this scale is a second, for "REVOLUTIONS PER MIN.," with values ranging from 0.2 to 1000. The innermost scale, "CUTTING SPEED IN FEET PER MINUTE," carries values ranging from 0.3' to 100'.
The irregularly-shaped top disc is printed with two arrows and two scales. The point of the outermost arrow falls within the "TIME IN MINUTES FOR 10 REVOLUTIONS" 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 are printed two vertically-stacked scales for "DIAMETER OF WORK." The outermost scale carries values ranging from 1'' to 300''. Values on the innermost scale range from 1/16'' to 1''.
Three scales are printed around the circumference of the bottom disc. The outermost scale, for "TIME IN MINUTES FOR 10 REVOLUTIONS," carries values descending from 50 to 0.01. Below this scale is a second, for "REVOLUTIONS PER MIN.," with values ranging from 0.2 to 1000. The innermost scale, "CUTTING SPEED IN FEET PER MINUTE," carries values ranging from 0.3' to 100'.
The irregularly-shaped top disc is printed with two arrows and two scales. The point of the outermost arrow falls within the "TIME IN MINUTES FOR 10 REVOLUTIONS" 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 are printed two vertically-stacked scales for "DIAMETER OF WORK." The outermost scale carries values ranging from 1'' to 300''. Values on the innermost scale range from 1/16'' to 1''.
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 RemarksProbably made in the same location as 1990-4-0033. See Engineering News v.50, No.24, pg.514.
Records indicate that Barth was working in Philadelphia in 1902;
Identical to 1990-4-0025, 1990-4-0026, 1990-4-0027, 1990-4-0028, 1990-4-0029, 1990-4-0030, and 1990-4-0031;
Similar to 1990-4-0017, 1990-4-0018, 1990-4-0019, 1990-4-0020, 1990-4-0021, 1990-4-0022, 1990-4-023, and 1990-4-0024 in function and arrangement, though range of values on scales is different, and this instrument incorporates two additional scales--for "time in minutes for 10 revolutions," and 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 outer "DIAMETER OF WORK" scale aligns with the desired surface speed (bottom disc). He then tightens the clamping nut and reads off the revolutionary speed, using the outermost arrow for a reading in units of time (in minutes, for 10 revolutions), and the innermost arrow for a reading in revolutions per minute.
For diameters smaller than 1'', the user performs the above using the inner "DIAMETER OF WORK" scale. He then multiplies the resultant revolutionary speed reading (in either time or revolutions per minute) by ten.
First loosening the clamping nut on the center bolt, the user rotates the top disc such that the appropriate value on the outer "DIAMETER OF WORK" scale aligns with the desired surface speed (bottom disc). He then tightens the clamping nut and reads off the revolutionary speed, using the outermost arrow for a reading in units of time (in minutes, for 10 revolutions), and the innermost arrow for a reading in revolutions per minute.
For diameters smaller than 1'', the user performs the above using the inner "DIAMETER OF WORK" scale. He then multiplies the resultant revolutionary speed reading (in either time or revolutions per minute) by ten.
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: copyright 1902
Accessories: bottom of storage box; Instruction booklet (belongs to a different instrument, a time slide rule)
Object number: 1990-5-0002
