An opisometer is an intuitive instrument. Give it to someone unfamiliar with such a tool and they could have a pretty good guess at how it is used. They are simple in design and simple to use. The two English examples shown here were made by Elliott Brothers between 1864 and 1916.
Elliott Brothers included their “Opisometer, or Map Meter, for measuring curved lines” on page four of their eleven page 1868 priced catalogue. Each instrument then cost three shillings. Despite being a simple instrument, they have to be carefully made to maintain accuracy. Both measures shown here feature a fine threaded axle on which a thin tracking wheel rotates. The finer the thread, the greater the distance that can be tracked. Prior to use the milled metal wheel is wound to one end of the axle and then rolled and rotated along a line on a map- a path, a road, stream, railway, canal, pretty much anything that required measuring. Opisometers have also been used by carpenters, engineers, surgeons and draftsmen. The opisometer is then wound back along the scale usually present on a scale map and the distance indicated. The tracking wheels turn easily on the thread and have a small pointer to aid in accurate measurement. Both examples shown here have bone handles, probably from a cow or ox, though handles could be made of other materials such as horn, ivory or metal. Each opisometer also has an attractive turned finial at the end. The shape of these finials indicates the country of origin and both shown here are English made. We would have known that anyway as the maker’s name is also etched into the length of the two handles- ELLIOTT.
Two sizes of Elliott opisometer are shown here. The larger weighs 11.4g and has extreme dimensions of 116mm including the 93mm handle x 17mm. This has a 18.80mm diameter tracking wheel. The smaller measure weighs 5.8g and has extreme dimensions of 96mm including 80mm handle x 17mm. This has a 11.50mm diameter tracking wheel. Wound to one end of the axle, the tracking wheel is then used to follow a line on a map. The larger will track up to 1500mm (59.05 inches) and the smaller will measure up to 1240mm (48.82 inches). Greater distances could be measured however that would require a second measurement.
William Elliott was born in Holborn, London 1780/81 and apprenticed to compass and drawing instrument maker William Blackwell in 1795. By 1804 he was working independently from 26 Wilderness Row, Goswell St. (-1817), 21 Great Newport St. (1817-27), 227 High Holborn (1827-33) and 268 High Holborn (1833-49) manufacturing drawing instruments, scales and scientific instruments under the trading name W. Elliott. When the firm moved to 56 Strand, London (1850-64) his two sons (from his third marriage) Charles and Fredrick joined him and they traded under the name William Elliott and Sons (1850-53) and the firm was awarded a Bronze Medal at the 1851 Great Exhibition.
The brothers continued the business following their father’s death in 1853 and the following year the firm was renamed Elliott Brothers (1853-1916). They added electrical instruments to their range of fine quality instruments which already included navigational and surveying instruments. The business again relocated, this time to 449 Strand, London (1864-1886). Charles Elliot retired in 1865 and the partnership officially dissolved in 1870, Frederick died in 1873 and his widow Susan inherited the firm. She was the last Elliott associated with the business and she went into partnership with the telegraph engineer Willoughby Smith.
Elliott Brothers, were also successors to Watkins & Hill, previously of 5 Charing Cross and 30 Strand, London. Francis Watkin founded the Watkins optical business at 5 Charing Cross, London in 1747. Watkins partnered with his son-in-law Addison Smith who was operating a nearby shop in Strand, London. Watkins retired and passed his part of the business to his nephews Jeremiah and Walter. This then passed on to Jeremiah’s son Francis until the foreman William Hill joined the business as a partner and the business name Watkin & Hill was adopted c1817.
Francis and William died within weeks of each other. The Watkin & Hill business struggled on for another nine years, managed by Francis’ widow Mary Ann and manager Abraham Day. The firm was sold to Elliott Brothers in 1856 who maintained both 5 Charing Cross and 56 Strand premises until combining both into a single shop at 30 The Strand in 1858. Elliott Brothers then began the additional manufacture of electrical instrumentation.
In 1876 production expanded and a new factory in St Martins Lane London began producing telegraph equipment and other instruments for the Admiralty and Royal Navy. Susan Elliott died in 1880. In 1892 the business was trading from 101 and 102 St. Martin’s Lane, London. Smith in turn brought his sons in to manage operations and the business relocated from London to Lewisham, Kent in 1898. A warrant to use the Royal Arms was awarded to Elliott Brothers in 1902. Many mergers and acquisitions took place and in 1916 the firm became a Private Limited Company, renamed Elliott Brothers (London) Limited. Their involvement in the development and manufacture of many important products continued, radar and computers amongst them. The company was renamed Elliott Automation Ltd. in 1957 and was subsequently merged into English Electric in 1967. The Elliott Brothers trading name disappeared in 1988 when absorbed into what is now known as BAE Systems. The importance of the Elliott Brothers manufacturing company has been lauded in recent times:
“one of the most important instrument manufacturers in Britain in the 19th and 20th centuries”Museum of the History of Science
Elliott Brothers were not the only ones producing or selling opisometers. A simpler all metal opisometer known as Philips’ Universal Simplex Map Measurer has been previously looked at in detail. Those measures were sold through London mapmakers Stanfords, though not exclusively so.
Three Points of the Compass has previously looked at another example of opisometer sold by Stanfords that has the same metal and bone construction as the two Elliott instruments shown here. This measure is shown below and it can be seen that there are subtle differences in design between this and the smaller Elliott measure, particularly in the finial. It is extremely unlikely that Stanfords actually produced this opisometer themselves and they would have sourced this from an instrument maker, possibly even Elliott Brothers.
Though fragile, all of these finely made opisometers are still capable of being used today to measure a line on a map, chart or drawing. There is little to go wrong and as long as they are protected from damp and ill treatment, they will continue to work for another hundred years.
Three Points of the Compass has looked at a few more Map Measurers in detail. Links to these can be found here.