Help and Advice

Why are Cassini Maps so useful?
Who are Cassini Maps?
What are site-centred maps?
How do I download a site-centred map?
What historical maps does Cassini Mapmaker provide?
What is a map series?
Is Cassini going to be adding other series to its range?
How can I find out more about historical Ordnance Survey maps?
What is a scale?
What scales are Cassini's maps?
What is a map projection?
How have the maps been joined together?
What about the railways? Sometimes a line suddenly stops half-way across the sheet.
Why does the background colour of the maps sometimes vary?
Why does the style, such as the type, sometimes change across the map?
Why do the maps sometimes show a range of dates (such as 1845-49)?
Why are there no map legends on the printed Old Series maps?
Do historical maps show rights of way?
Who owns the copyright of the Cassini maps?
Can I reproduce the maps I have bought?
Can I license your historical mapping data to use in a GIS system?
How can I be kept informed of new products that you offer?

If you’ve come this far into our site you probably already have a good reason for being interested in historical maps. They appeal to many people: local historians, genealogists, home owners with an interest in the history of their area and property, walkers and cyclists who want to see how the landscape they’re exploring has changed, metal detectors who are interested in discovering old paths on which valuable items might have been dropped centuries before: the list could go on and on. Surveyors, architects, archaeologists, planners, solicitors and farmers also often need, and are frequently obliged, to know how the landscape has changed.

But enough of everyone else – what’s your reason for being interested? CLICK HERE and tell us why you’re exploring the landscape of the past. We want to know so that we can produce more maps in different formats to satisfy as many people’s needs as possible. Every response will earn you a discount voucher.

Who are Cassini Maps?

Cassini Maps are part of Cassini Publishing Ltd which was founded in 2005 with the aim of providing something unique – reprints of historical Ordnance Survey maps of England & Wales that matched the scale, projection and coverage of present-day Ordnance Survey 1:50,000-scale Landranger maps. This would let people compare the past and the present quickly and accurately for whatever reason they needed. Since then we’ve published over 500 historical maps. All are available on this web site and also at all good bookshops.

Mapmaker is a web-based service that puts you in control of producing your own historical map. You can choose what area the map covers, how much it’s enlarged and what format it’s provided to you in. More options are being added all the time.

From the early 19th century, Ordnance Survey made a succession of surveys and re-surveys of Britain which resulted in maps being printed of the whole country. Depending on the scale, these ran to several hundred or several thousand sheets. Each of these series of maps was, at the time or later, given a name to distinguish it and we have used these names in our editions. Each series not only showed the landscape at different stages of development but also showed evolving styles of the maps themselves, including the increased use of colour, symbols and contour lines.

For more information on the various series we have published, click on the appropriate button below:

• Old Series
• Revised New Series
• Popular Edition
• New Popular Edition
• Seventh Series
• Scottish First Edition
• Scottish Third Edition
• Scottish Popular Edition
• County Series

The scale of a map shows by how much it has been reduced. These days it is normally expressed as 1: followed by a larger number: 1:50,000, for instance, means that one unit on the map represents 50,000 of the same units on the ground; which, in this example, can be converted to 2cm = 1km.

The smaller the number after the 1:, the more detailed the map is. Somewhat perversely, the smaller the number – and thus the more detailed the map – the larger the scale. A 1:10,000 map would therefore be described as being at a larger scale than a 1:50,000 map.

We have four series that were originally drawn at a scale of one inch to the mile, with others being added soon: the more detailed six inch to the mile maps will be the next.

Since the late 1960s, small scale Ordnance Survey maps have been produced using metric scales (such as 1:50,000), rather than at the old Imperial scales (such as one inch to the mile): old maps and modern maps cannot, for this reason and others, be compared with any accuracy. We have therefore enlarged the historical maps so that they match the scale used by maps today. One inch to the mile, for instance, is equal to 1:63,360. The nearest present-day map in the Ordnance Survey Landranger, which is at 1:50,000. We’ve therefore enlarged the old one-inch maps to this scale. All our printed and folded maps (available elsewhere on this site) are at this scale. As well as making them easier to read, they’re also easier to compare. In Cassini Mapmaker, you can enlarge these still further if you wish.

In the same way, the six inch to the mile scale equals 1:10,560. We’ve enlarged all these to 1:10,000.

If you’re using Mapmaker, the maps you create can be enlarged still more if you wish.

Because the surface of the earth is curved and a map is flat, cartographers have to employ a controlled distortion when drawing maps – skin an orange and try to flatten out the peel and you’ll see the problem. These ‘distortions’ are very precisely calculated and involve complex mathematics. Each different method is known as a projection, most of which have names, such as Cassini, Transverse Mercator and Peters. Maps of the same area drawn using different projections can look very different from each other. In particular, the shape of the coast and other features will vary from map to map and locations such as towns will appear in different positions. The larger the area of coverage and the smaller the scale, the worse this problem becomes.

As mentioned above, Ordnance Survey’s small scale maps have, since the 1960s, been produced using metric scales rather than at the old imperial ones. They are also produced using different projections (The current system is based on a Transverse Mercator projection on what is called the “National Grid”). Taken together, these factors make comparing old maps and new ones next to impossible. We have enlarged the maps to match modern scales: this was a comparatively simple operation. Vastly more complicated was re-projecting the old maps to match the modern projections used today. As a result, you can compare maps from different periods with each other, and with present-day ones, to an extent not previously possible. Ordnance Survey’s larger scale maps have been produced on the National Grid since the 1940’s – these superseded the Ordnance Survey’s County Series which were based different scales (e.g. 1:10,560 rather than 1:10,000, Imperial measurement and the Cassini projection system.

The short answer is ‘with great difficulty.’

As well as problems of different scales and projections, each mapping series was produced using its own sheet sizes and shapes. Sometimes these were square, sometimes rectangular. We scanned all the maps, being careful to find ones in good condition with no folds or creases, and then cut them down to the frame edge. Theoretically, they could then be joined together to form a vast seamless sheet .

Unfortunately, the edges rarely matched exactly. Particularly with the older maps, one sheet might have been produced using a different projection or point of origin from its neighbour. Some sheets had overlaps between them, which needed to be trimmed off. Furthermore, two adjoining sheets may have been surveyed by different people at different times, using different standards of accuracy, cartographic conventions and instructions as to what to include (no map can ever include everything). In a few cases, the surveyors made errors, with a road suddenly stopping at a sheet join, or continuing but from a different position.

In short, the maps were never designed to be joined up, and we were the first people to attempt to do this with the one-inch sheets. Although there are some problems, the overwhelming impression is of a stunning level of accuracy – and this without computers, vans to carry the equipment, GPS technology or even, in the case of the first maps, any previous maps to work from.

This is mainly a problem with the Old Series, the first one-inch series surveyed by Ordnance Survey. So massive was the task that it took over 70 years to complete. When it began, in 1805, railways hadn’t even been invented; when it was completed, in 1874, the rail network covered virtually every corner of the country. The surveyors were overtaken by the navvies.

To overcome this problem when it first appeared from the 1830s, the Ordnance Survey went back over the sheets they’d created and over-engraved new railway lines, but without changing other features or even the publication date, which made it very hard to know when the map had been altered. By the 1850s, the problem was largely solved by more flexible print technology and the fact that the mapmakers were, in general, surveying areas that already had their railways built and so included them from the outset. Future series (being in general revisions) were produced over a far shorter time period for the whole country, so reducing the problem still further. For this middle period of the Old Series maps, though, which mainly covered the middle part of the country (the surveyors started at the south coast and moved north), this problem does from time to time appear and is virtually impossible to solve.

All our maps, whether created for our printed and folded maps or using Mapmaker, involve combining various original sheets. These were often quite small and so on our printed and folded maps it’s not uncommon for parts of eight different originals to have been used, and sometimes more. Even an A4 Mapmaker map could easily have parts of four sheets used to create it.

These original sheets were never designed to be joined up and were often produced at different times, printed on different machines and stored in different places in varying conditions. These days, consistency and accuracy across a series of maps is taken very seriously and modern technology can help ensure that colours are the same for Land’s End as they are for John o’Groats. No such standards existed in the 19th and early 20th century. Also, some of the maps we scanned are over 200 years old, and small variations in light and humidity can cause changes to the inking. In some cases, these variations were beyond our power to correct and we sourced alternative sheets. In others, the variations didn’t become clear until we started to join them up. We’ve done our best to smooth out the worst inconsistencies but sometimes this would have been impossible without distorting some other aspect of the map.

All our maps were created from joining together several original sheets. Some of these were published several years apart and used different styles of type, symbols and the like. This is particularly the case with the first series produced, the Old Series. As nobody had ever mapped the country at this scale in such a single-minded way before, the surveyors and engravers would often find they were confronted with a problem or a choice on one sheet that hadn’t occurred on a previously published one. The earliest maps, of Southern England, were produced at break-neck speed because of fears that Napoleon was about to invade the country (as he so nearly did) and the map makers were not much concerned with features like ancient barrows or the names of mills that had no immediate military significance. Later, the maps began to acquire a more civilian aspect and such features tended to be added.

Also, the progress of the Old Series surveying and mapping took so long (over 70 years) in its progress from south to north that the mapmakers found they were describing an increasingly crowded landscape, particularly with the advent of the railways. Type tended to become smaller, abbreviations and symbols began to be used more freely and more choices needed to be made as to what to include or exclude, all with an eye to the increasingly wide range of uses (not only military ones) to which the maps were being put. New surveying and printing technology also played their part. As the 19th century progressed, the landscape could be measured more accurately and the results displayed more flexibly and, increasingly, more colourfully. A railway-free and largely empty country in 1805 was, within a few decades, anything but, and the mapmakers needed to reflect this as best they could, pushing the available technology to the limit in order to record it.

As described above, each series was produced and published over several years; several decades in the case of the Old Series. Often, two adjoining original sheets may have been published in different years, and the date range we provide reflects this.

For various reasons, particularly the rapid spread of the railways, maps may have had some (but not all) new features added before being re-published. This can cause confusion and uncertainty as to what the actual date of an original sheet is, and from what date the survey information comes. The dates we have provided are those of the first publication of that sheet for that series, even though it may have had other features (such as railway lines) added later.

The Old Series maps were produced over several generations in the 19th century during which time the complexity of the landscape, and thus the maps, grew. It was only with subsequent series that it became clear to Ordnance Survey that a consistent table of symbols, line styles and abbreviations would be necessary. Various cartographic scholars have produced a series of legends that describe the evolving use of such features, but this is impossible to reproduce on our maps which often combine parts of original sheets from more than one period. Most symbols and styles on the Old Series can be inferred from local knowledge or common sense.

No. Ordnance Survey was not and is not concerned with questions of land access or land ownership. Any right-of-way-data that exists on their present-day maps is licensed from other bodies such as local authorities.

That is not to say that old maps are of no use in indicating a right of way such as a footpath or bridleway. If a path or track existed in a rural area was used in the 19th or early 20th century it would almost certainly have been marked on the one-inch maps. Even if it has since disappeared from modern maps the right of access may still exist, and the old map may be able to be used as evidence. Because our maps match the scale and projection of modern maps such as Ordnance Survey’s Landrangers, this exercise of comparison is much easier than previously.

We also produce a newsletter which gives information, for retailers and consumers, about our new products. CLICK HERE and use the form under the left hand menu to add your name to our mailing list.