Description

Late Victorian engineers slide rule calculator. Strong sound thick card instrument with good sliding action. Stained, slightly grubby overall, small surface loss to the back left edge. Length 6,3/8 or 162mm Guaranteed old and original. *********************** Description from THE POWERHOUSE MUSEUM 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 calculating the Horse Power that may be applied to Reddaway belting when used in driving machines with belt and pulley arrangements, given the diameter and the rotation rate of the pulley. It is very similar in style to the slide rules designed by C.N. Pickworth around the end of the 19th century. Many of the Pickworth type cardboard rules were intended as promotional items to be given away to manufacturing engineers and other customers of the belting and rope manufacturers of the period. It would have been used by engineers in the construction of factory production capacity when most factories had to supply their own power as a central resource which was distributed through the building via long crank shafts and transmitted to various machines via belts and pulleys. · Description Slide rule, Horse Power Calculator, closed frame, single slide, printed paper on card laminate, made by Reddaway & Co Ltd, Manchester, England, late 1800s The Reddaway Belting and Pulley Calculator. F Reddaway & Co. Ltd, Pendleton, Manchester Scales for: Upper stock: Horse Power of “Camel” Brand or Reddaway Belting Upper Slide: Width of Belt – Inches, Revolutions per Minute, Belt Speed – Ft. per Minute Lower stock: Pulley Diameters Instructions for use on face of rule and continued on reverse. Advertising for Reddaway belting on reverse. · Production date 1875 – 1899