This slide rule is from the collection of calculating instruments assembled by Assoc. Professor Allan Bromley. His collection provides examples of most forms of calculating devices made from the early 18th to the late 20th centuries. Slide rules constitute a substantial proportion of this collection.

Over the 19th and much of the 20th centuries the slide rule was the primary instrument for calculation used by many people engaged in the trades and in engineering. Although originally invented in the 17th century, and widely used for gauging (or estimating the quantities of certain products such as alcoholic spirits) it took until around 1850 for the slide rule to become generally popular.

Specialist slide rules of many kinds were developed over the period of their use. This example is a slide rule used in cotton cloth manufacture. It appears to be used to calculate the amount of cotton yarn required in various qualities of cloth and the cost of such cloth given the price of the warp and the yarn with which it is made.

Stephen Jones
March 2008

Mfr: C.N. Pickworth, Wh. Sc., Fallowfield, Manchester

C.N. Pickworth was a designer of specialist slide rules and wrote several books on how to use the slide rule. He also wrote the English language manuals for various European slide rule makers. These include:
Pickworth, C. N., "The Slide Rule: a Practical Manual", London: Whittaker, Treacher & Co.,
Pickworth, C. N., "The Indicator Handbook: a Practical Manual for Engineers", Manchester: Emmott and Co, 1906.
Pickworth, C. N., "Instructions for the Use of A. W. Faber's Improved Calculating Rule",
Newark, N.J.: A. W. Faber.
Pickworth, C. N., "Revised Instructions for the Use of A.W. Faber's Calculating Rule". Stein, Germany: Faber.

eg. http://archive.org/stream/sliderulepractic00pickrich#page/n5/mode/2up

Slide rule, Pickworth's Patent Cotton Cloth Computer, closed frame, double slide, celluloid laminate on wood, scales engraved into celluloid.


Scales for:
Upper stock: Weight of Warp or Weft in Piece
Price of Warp or Weft in Piece
Upper Slide: Counts of Yarn and Number of Hanks
Price of Yarn per Lb [Pound]
Lower slide: Picks of Reed per inch
Width in Inches
Lower stock: Length in Yards

Made: 1900 - 1925

Name and manufacturer notes on slide rule, in top center ' Pickworth's Patent Cotton Cloth Computer ', in left bottom ' C.N. Pickworth, Wh. Sc., Fallowfield, Manchester ', in right bottom ' Copyright - Ent'd. at Stationers' Hall '.

White paper label on reverse, handwritten in black ' Bromley 1982-147 '.

2010/1/312

1900 - 1925