In the nineteenth century, how did a farmer weigh his livestock in the field? He might have used a clever little slide rule known as "The Cattle Gauge & Key to the Weighing Machine" arranged by J Ewart, Newcastle on Tyne. These rules were often manufactured by James Tree of 22, Charlotte Street, Blackfriars Road, London. The method used involved measuring the length and girth of the animal and using a ready reckoner on the rule, giving percentage values of meat on the carcass, to calculate the weight using a series of gauge points. The rules are made mainly from box but sometimes with ivory slides and occasionally completely from ivory. The Tree family made rules at Charlotte Street from 1832-1895, according to the Directory of British Scientific Instrument Makers 1550-1851, but these rules probably date from the second quarter of the nineteenth century. Although this rule is uncommon, its just the sort of thing that turns up at the fair. Several dealers specialise in slide rules and calculators, notably David & Yola Coffeen, from Tesseract , Peter Delehar , and Desmond Squire .
A further note about the cattle gauge.
ReplyDeleteThe first slide rules for determining the carcase weight of cattle were made by William Cary (1759-1825) and were based upon the tables of George Renton who described his method of measuring cattle in 1798 (The Graziers Ready Reckoner, 2nd. ed., Berwick). The slide rule determined the weight from a knowledge of its length, girth and a multiplying factor.
John Ewart, a farmer and a writer on farming topics, realized that the shape and offal content of cattle are different for different breeds; nor was their fat content constant. He improved the rule in 1844 by introducing nine gauge points for various types of cattle (A Treatise on the Produce of Beef, Newcastle-upon-Tyne 1844). They were initially made by John Cail of Newcastle-upon-Tyne, but the majority of those seen were made by James Tree.
A year later Ewart received a letter from Lord Althorp (later Earl Spencer - ancestor of Princess Diana) in which he claimed to have devised, with the help of Dr. W.H.Wollaston (1766-1828) the cattle gauge made by Carey (sic), Ewart reproduces this in his book of 1878 (Meat Production, London p.116) in which he also describes a further modification of the rule whereby the carcass weight could be read by means of a sliding index either in stones of 14lbs. avoirdupois, in Smithfield stones of 8lbs. (Smithfield was the location of the London meat market), in scores of 20lbs. in Edinbro' stones of 17.5lbs. or in Imperial stones of 14lbs. (ibid p.113) He also mentions a circular cattle gauge on the side of a box containing a tape measure. This was patented by John Chesterman in 1842 (No.9214) but the improvement he claimed as not in the slide rule but in the case for the tape measure to which he could affix, instead of the rule, either a compass, a sundial or a perpetual calendar. The slide rule itself was a retrograde step as it did not have any gauge points.
Peter Delehar.