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Map measurers

For many decades of navigation, anyone that required a map was also using a map measurer. The military use them, sailors use them, motorists use them, town planners and draughtsmen use them, and still, just a few walkers use them. You run a little wheel along a route, a path, a road, a river, a line on a drawing, then either read off the result or measure against a standard.

My much used German made map measurer

The much used German made map measurer that is still pulled into action by Three Points of the Compass


The first England and Wales road atlas was published in 1675. This seminal work, Britannia, comprised 100 maps and was created by map maker John Ogilby. It was the first to use a scale of one inch to the mile and to use the Statute mile of 1760 yards. Each vertical strip map in the atlas showed compass orientation and distances in miles and furlongs. Such accurate measurements had been made possible by surveyors measuring the roads. A favoured and accurate method was walking the ground with a surveyor’s measuring wheel, otherwise known as a perambulator or waywiser. Paying homage, both man and instrument were depicted in Ogilby’s Britannia, shown on the frontispiece and on two maps within.

Surveyor and his waywiser are shown on plate number 21- the Road from London to Holyhead. c1698

Surveyor and waywiser are shown at the head of Ogilby’s ‘The Road from London to Holyhead’ map. c1698


The idea of map measurers is an old one, probably as old as ‘to scale’ maps themselves. Beyond simple calipers, early map measurers, or opisometers were very simple affairs indeed- little wheels on a threaded bar that could be pushed along a line. More expensive designs that incorporated a dial scale didn’t really appear in any great numbers until the later nineteenth century.

An opisometer is easy to use with irregular lines on a map or drawing

An opisometer is easy to use with irregular lines on a map or drawing

Once a scale map has been published, it is then relatively simple for the user to scale up by using a further instrument. At its simplest, another measuring wheel could be used. An opisometer is a wheel on a fine threaded rod. With the wheel wound to one end of the rod, the operator can run the wheel along any line on a map, and, if aware of the scale to which the map is produced, work out by the number of revolutions the distance travelled.

Opisomers were being made by fine instrument makers as early as the mid-nineteenth century and probably earlier still. Now uncommon, opisometers are still available new today, but seldom applicable to map reading purposes. For a tool with such a long history, it is perhaps a little surprising that they are still required and made today.

One of the very earliest of opisometer manufacturers, Francis Barker & Son Ltd., were still listing opisometers in their 1982 catalogue, though they appear to be unavailable from Pyser-SGI Ltd. of Edenbridge in Kent, England, who now bear the Francis Barker name, despite their continuing to manufacture high end prismatic compasses.


Morris's Patent Chartometer

Morris’s Patent Chartometer, circa 1875

The word ‘chartometer’ was described in Scientific Instruments 1500 – 1900 An Introduction, by Gerard L’Estrange Turner, with Andrew Turner (first published in 1980 as ‘Antique Scientific Instruments‘) thus:

“The opisometer is a small device for measuring the lengths of roads, rivers, walls etc., on maps. It is a milled wheel on a screw thread with a handle. The wheel traces the route, and is then wound backwards on the scale at the edge of the map. The chartometer is the same but has a dial and pointer to give the measure immediately.”

Englishman Edward Russell Morris, of the Morris Patents Engineering Works, High Street, Birmingham, began manufacture of his Patent Chartometer in the 1870s, the design being patented in 1873. It is a handsome measure and came with a range of interchangeable cards that provided differing scales. There is a link to a closer look at this particular measure below.

Newspaper advertisement for Morris's 'Wealemefna', a 'new design of map measurer'

Newspaper advertisement for Morris’s ‘Wealemefna’, a ‘bijou’ map measurer. The Graphic, 1880

Map measurers can be sweet little pocket watch style affairs that were tucked into the waistcoats of the gentry, or simple little wheeled opisometers, like the one below, sold in the likes of Stanfords map shop in the mid-twentieth century.

Simple opisometer

Measures could be made of plastic, bakelite or metal. They have handles incorporating bone or ivory. Cheap versions were given away at petrol stations, or combined into all-singing all-dancing measurer/compass/thermometers made in China by the thousand. That said, they still work. The cheapest will do the same job as the most expensive gold plated measurer ever made. They even make incredibly expensive digital versions today. I look on them with dismay, much preferring my little analogue measurers.

Plastic map measures sold to readers of a popular motoring magazine

A huge array of different measurers have been produced over the past century and more. Some different types are explored below. In recent years however, as digital mapping comes to the fore, they have very much fallen out of fashion. Not completely though- in 2019 compass manufacturers Silva began to include 1:25 000 and 1:50 000 scales on their compass lanyards. A potentially handy addition, these scale lanyards can be lined up directly on a map route to give a distance indication. Unfortunately Silva not only made these soft and bendable, but also slightly stretchy. This stretch leads to inaccuracy but is certainly good enough as a rough indication on trail.

Three Points of the Compass has had a closer look at some particular makes and models of map measurers from my collection. Links for these are below:

So what does Three Points of the Compass use? I have employed a simple little map measure for decades. This is a cheaply made one produced in Western Germany and has been pulled down off the bookshelf hundreds of times over the past twenty years when planning routes. It replaced another that gave equally lengthy service that eventually died the death.

This measure never goes on actual hikes with me. Three Points of the Compass is one of a seemingly dying breed who still likes, appreciates and takes hard copy maps on trail. But if I wish to measure a distance on the map while sitting in a tent, pub or hostel lounge, I either guesstimate, infrequently use a roamer scale on my compass baseplate, use a strip of paper which is then measured against the scale at the bottom of my map, or, most frequently, I use a length of thin cordage. This is usually a small hank of 2mm yellow cord just visible in the image at the head of this page. It is one of the two I carry for attaching my Katabatic Palisade quilt to my sleeping pad.

Box for 'Self-Registering Rotameter', giving detail on how to use

Box for ‘Self-Registering Rotameter’, provides detail on scale and how to use

Along with thousands of other hikers I rely very much on my online O.S. Maps when planning my routes. This will give me not only distance but also daily elevation. However I still like to use a map measurer on my paper maps when I can. It forces me to look at the terrain, the twists and turns, the type of country being crossed- across bogs, through woods, traversing moorland, traipsing through the backstreets of towns.

While a piece of cord or length of paper will simply measure a length, more complicated versions can measure in many units- multiples or sub-units of inches or feet, centimetres or metres, versts, miles or kilometres. Also to different scales- The two-faced French made measurer below has scales for 1:20 000, 1:25 000, 1:40 000, 1:50 000, 1:75 000, 1:80 000, 1:100 000 and 1:200 000. Made almost a century ago, it is still an effective and useful piece of kit that cost me less than a tenner. Not that I ever use it of course, I still pull down the old favourite from the bookshelf.

Map measurer by Henri Chatelain, with Quarter-Inch Ordnance Survey map to The Border, 1935

Map measurer by Henri Chatelain, with “Quarter-Inch” Ordnance Survey map to The Border, 1935

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