What is a map?

Humans have always needed to find their way from place to place and their most common way of doing this and providing information about their surroundings has been through pictures or models. So, amongst the oldest pictures are cave paintings depicting the animal life around cave dwellings such as Lascaux in central France and the stick and shell models of wave patterns used by some Pacific island communities for travel between islands which are not intervisible. Maps of the stars were a vital aid to navigation long before maps of the ground were produced. Increasingly at the start of the twenty-first century car drivers and sailors use electronic maps and charts for navigation. All of these are forms of picture communication. Maps of the past as well as today are part of that tradition of a very useful and universal means of communication.

Maps in all their diversity can therefore be described as a form of picture communication. The map provides a scaled down version of the environment, be it a small portion of our environment or the entire planet. It does, however, only provide an interpretation of the environment, because it selects the information it provides.

Cartography through the ages

Today it is almost impossible to go through a single day without coming into contact with, or using in some way, the multitude of maps that today’s society has grown to depend upon.

Map use has undergone a revolution since the times when stone tablets and pictorial representations of trade routes were both rare and unexplored as a means of information communication. Charts of coasts and islands, especially showing newly discovered lands, became important, especially from the thirteenth century onwards, because they allowed navigators to repeat voyages with some degree of certainty. More importantly, they allowed the European monarchs to have documents, which showed their newly acquired and colonised lands. They depended on simple survey methods and equipment, such as the mariner’s compass, and charts were designed from the late sixteenth century to allow compass directions to be drawn as straight lines.

Maps were not only political tools, but also in England, following Henry VIII’s dissolution of the monasteries, provided information about the properties for sale. In 1538, Robert Benese explained in English ….”the maner of measurynge of all maner of lande….” and so provided a set of standards for measuring the area of land being sold. The tool for ensuring that measurements were accurate took rather longer to provide. However, in 1623 Edmund Gunter described his chain as being “fouire perches in length, divided into an hundred links” in groups of ten. It combined the well-tried English methods of land measurement based on the number 4 (the chain equalled four rods) and the then recently described Dutch system of using decimals, based on 10. Furthermore, 10 square chains equalled one acre. Land surveying now had a tool which dominated surveying so much that most of the land divisions of North America are based on multiples of chains.

Since these modest beginnings, maps have pervaded almost every aspect of our modern life. The morning paper, if not describing the location of the latest foreign or domestic incident via the use of a small map, almost invariably uses a map to convey the weather forecast. The road map, underground map, and train timetable map all represent a fundamental part of our daily life. Even more recent widespread utilisation of satellite and aerial photography has not only been accepted by the public, it has been positively embraced. Marine charts (See Theme 1 Topic 4 Dorset’s Underwater World) show a similar evolution, although joining together maps of the land and the sea is still proving difficult (See Theme 1 Topic 5 Visualising the Seabed: Accessing the Inaccessible).

Modern map use underlines several important facts about maps in general, not least the vast variety of roles maps play and the almost unending variety of form they adopt. Maps can be designed to meet a specific need or be more general in nature. They can be found in a variety of scales and sizes incorporating specific detail or stylised representations of perceived or imaginary phenomena. The maps and associated spatial information included in the DCDA reflect this rich diversity.

Cartography as a language

Although maps are pictures, they, like other pictorial means of communication such as written music, have their own language and rules.

The Grammar of Cartography

When reading a map the user must utilise a specific language divorced from, although not entirely separate from, the written language. The written text requires the reader to start at the beginning and follow a prescribed route through sentences and paragraphs to a pre-determined finishing point. The map is far more flexible. The map reader can start almost anywhere on the map and follow any number of routes through the information, be it the entire volume of information available or more likely the selected information required at that time.

However, like the written language the cartographic language can be divided into grammar and vocabulary: the former consisting of fundamental concepts of scale, orientation, reference grids and projections, with the cartographic vocabulary consisting of the symbols (or conventional signs) used by map makers.

Scale
The concept of scale is fundamental to the understanding of maps. To truly appreciate the relationship between the map and the environment it portrays, the reader of a map must come to grips with scale. Fortunately it is a very simple concept to understand. The scale of a map indicates the proportional relationship that exists between a distance on the map and its corresponding distance in reality.

With the introduction of engraving and printing to European cartography the practice became convention with a scale bar becoming an integral part of the map. The distances themselves, however, were anything but conventional with each European country having its own measure of distance. A French eighteenth century map by R.J.Julien takes the prize for the most complex scale system with no less than twenty separate scales. Each separate province of France prior to the 1789 revolution had its own unit of measurement for distance; a league subdivided into a greater, middle and lesser league! Unfortunately this was not just a French problem: Robert Morden’s 1695 map of Dorsetshire has a greater mile (2430 yards: 2220 m), a middle mile (2200 yards: 2010m) and a lesser mile (1830 yards: 1672m).

Orientation
In order to facilitate map reading the cartographer has to orientate a map to a particular bearing. Modern practice is to have north at the top of the map. This is now almost universal for all maps except for specific and specialised examples where it is deemed necessary. This can cause problems when, for example, maps are all drawn with north at the top but are used to show places such as beach zoning where the map itself is placed facing seawards (and southwards), reversing the relationship between the map and the ground.

This was not always the case. The earliest maps found on the Babylonian clay tablets had East at the top. This tradition was continued throughout the medieval period where the cartographers (often of monastic persuasion) orientated maps so as to preserve the venerated position of the holy lands at the top of the map – i.e. to the Orient – hence ‘Orientation’.

Orientation to the north (a contradiction in terms) first came about as a tradition of navigational charts in the fourteenth and fifteenth century and has stuck ever since. A single orientation to the north coincided with the development of magnetic compasses and the use of lodestones. Even then it was necessary to allow corrections between geographical and magnetic north.

Reference systems
The ability to locate a specific feature on a map, and to find it quickly and efficiently, is an important element of cartography. Without an adequate reference system, it can be a long and tedious task to search every piece of information and name on a map to find a particular one. The inclusion of a gazetteer in many early maps helped to speed this process up by referencing the smaller less well known locations via the larger better known ones. Hence Wareham could be referenced as so many miles or kilometres west of Poole which itself could be referenced with respect to London.

A far more efficient means of referencing any point on the globe is by means of the graticule i.e. the network of parallels and meridians that arbitrarily encompass the Earth. Thus a location can be defined as so many degrees east of a prime meridian and so many degrees either north or south of the equator. Whilst Nevil Maskelyne, Astronomer Royal, published the Nautical Almanac first in 1767 in which distances from Greenwich were listed, the use of Greenwich as the location of the Prime Meridian was by no means universal. Most European and American capitals were used with Paris, Lisbon, Madrid, New York and Washington all having at some time or other laid claim to a prime meridian.

Whilst for many local, regional and, in some respects, national cartographic undertakings the adoption of any number of prime meridians did not unduly affect the map’s usefulness, it often resulted in maps of neighbouring regions being projected in such a way as to make their comparison or amalgamation impossible.
In order that this issue might be resolved, and at the behest of the President of the United States of America, 41 delegates from 25 nations met in Washington, DC, USA in October 1884 for the International Meridian Conference.
At the Conference the following important principles were established:
1. It was desirable to adopt a single world meridian to replace the many different meridians already in existence.
2. The Meridian passing through the principal Transit Instrument at the Observatory at Greenwich was to be the 'initial meridian'.
3. All longitude would be calculated both east and west from this meridian up to 180°.
4. All countries would adopt a universal day.
5. The universal day would be a Mean Solar Day, beginning at the Mean Midnight at Greenwich and counted on a 24 hour clock.
6. Nautical and astronomical days everywhere would begin at Mean Midnight.
7. All technical studies to regulate and extend the application of the decimal system to the division of time and space would be supported.
The modern system used by the Ordnance Survey for the UK is the National Grid based on a point of origin in the south west just off the Isles of Scilly. The grid is divided into 500km squares each of which is given a prefix letter. Each 500km square is split into separate 100km squares and again given a letter. Within each 100km square 10km, 1km and 100m squares further subdivide the area with locations being given with reference to each of these progressively smaller squares position within the larger 100km square. As a result any location in the UK can be described by an exact coordinate measured from the point of origin. These are called the eastings and northings.

Projections
The most difficult and consistent problem faced by cartography since the world was first perceived as a sphere has been to transform that spherical surface in such a way as to make it fit the flat surface of a piece of paper. This is not an easy task. For practical purposes a small area of the Earth’s surface can be treated as flat without introducing any serious errors. Once the area under consideration grows to a point where the earth’s curvature comes into play the cartographer’s task suddenly becomes very complex. Over the last 2000 years geographers, astronomers, mathematicians and a whole host of others have wrestled with this problem producing an array of methods known collectively as map projections that allow the graticule of the spherical Earth to be displayed on the flat surface of the map.

The vocabulary of cartography

Symbols
A map as a whole symbolises an area of the real world; it is a model. The same map will usually have many smaller symbols placed within it, each of which symbolises a particular element of the world depicted by the map. What symbols are used, how they are used and in what context they are designed to interpret a particular element of the environment, varies from map to map.

The use of symbols needs interpretation, so maps usually have a key explaining the symbols or conventional signs as they are usually known. Few early maps include such a key. Treswell’s sixteenth century estate maps explain symbols in a listing of “characters” and Emmanuel Bowen’s 1749 map of Dorset has an “Explanation” for his symbols for Borough Towns, Market Towns and Post Stages. More recent maps often have very detailed information.

Anomalies, peculiarities and lies
All languages need translation and sometimes the meaning of the original can be lost or distorted in translation. Maps by their nature reduce features from their true size: they also select information. They can also be used to spread specific information. Like all forms of communication, the ways in which they modify reality need to be recognised. A road map used for locating yourself, planning a route and avoiding traffic jams is a good example of a map that has undergone specific forms of generalisation in order to better fulfil its intended role. Roads aren’t really that wide! If they were there would be no room for paths, houses, shops and almost anything else that is usually found within 50ft (15 m) of a road. To put this into figures, a 1/50 inch (0.5 mm) line on a map at a scale of 1:100,000 relates to a road almost 167ft (51 m) wide!

Plate 1 – Example of Cartographic generalisation showing the exaggerated road width at Owermoigne.

Clearly this is not a true representation of reality and yet it has been developed as a means by which the map can function efficiently. How? Well, many features that a map needs to portray to the user are simply too small or too closely bunched to enable the map to work efficiently. It is due to this that map makers have established a series of generalisations that enable a map to function.

The first distinction in map generalisations has to be whether the generalisation is to be of a graphical or conceptual nature.

A graphical generalisation deals with existing symbology being based around the five processes of simplification, enlargement, displacement, merging and selection. It is important to note that with graphical generalisations the symbols do not change – dashes remain dashes, dots remain dots etc.

Conceptual generalisations are also characterised by the processes of selection and merging but also deal with the generalisation processes of symbolisation and enhancement. Whilst graphic generalisation processes deal with the geometric component of spatial data, conceptual generalisation affects the attribute components.

Property mapping
The majority of cartographic enterprise throughout recent history has in some way at least involved, if not been driven by, ownership. Consequently, along with roads and rivers, boundaries have proven to be the closest things to constants in our endeavours to describe our geographical space. With such prevalence within cartography it is not surprising that property mapping, i.e. the demarcation of land ownership by the individual, the community or nation state has often formed the impetus for great works of cartography, undertakings that are synonymous with the artistic and scientific advancement of mapmaking.

Property mapping is often described in terms that, at their loosest, encompass all mapping that has in some way depicted the graphical distinction between two or more land parcels. Equally broad are the reasons why such mapping has come about. Maps of this nature, known collectively as cadastral maps, may be born from a variety of individual, social or economic reasons, ranging from a private land owner’s desire to marvel upon an ancestral estate, through parliamentary Enclosure Acts, to reasons of tithe or taxation based on land evaluation (See Theme 2 Topic 1 Growth and Development of Settlement).

Whatever the reason for its creation, property mapping comes in a multitude of styles, sizes, scales and orientations, employing an equally varied degree of artistic license. The cadastral maps (encompassing enclosure maps and tithe maps) are readily identifiable as ‘series’ employing a modicum of consistency in both the approach to survey and draughtsmanship. By contrast, estate maps were ‘one-offs’ unshackled by the need to conform and as a result vary greatly in style, artistic flair and accuracy.

Estate Maps
Estate maps form a subgroup of property maps. As with all property maps, estate maps do not have a defined start point in history. Indeed cartography is, by virtue of the delicate nature of the originals, impossible to pigeonhole into strict timeframes. Attempting to establish when the first estate map was produced is therefore a meaningless and ultimately frustrating task. That said there is a clear concentration of estate mapping in the later half of the eighteenth century and the early part of the nineteenth century.

Plate 2 – Example of a late eighteenth century Estate map of farmland near Marshwood. It records both the name of the field and its area.

Why they were created can only truly be answered on a map-by-map, estate-by-estate basis and is a topic much in debate. In Frederick Emmison’s opinion, estate maps were produced for the ‘inventory, management or improvement’ of the estate although many, Emmison included, concede that, for many a map, the reasons for creation are far less noble, simply being produced ‘for the information and pleasure’ of the individual landowner.

A particularly good example of the art and skills of the early makers of estate maps is the survey of Studland parish by Ralph Treswell in 1585-6. He also produced a map of Poole harbour which is one of the earliest detailed maps of the harbour itself.

The Treswell map of Studland parish
Ralph Treswell (c 1540 to 1616) was an Elizabethan land surveyor whose surveys of country estates, and also London, provided detailed information about individual properties, fields and tenements. The map of Studland parish, reproduced here by permission of the National Trust, is of particular interest for several reasons. First it provides detailed information about the land holdings and coastal features of a site which has been much studied by geographers and includes one of Britain’s most important coastal dune systems. Second, it provides a baseline against which the historical changes on this coast can be estimated. Third, it is a very good example of the detail which was included in estate maps as early as the end of the sixteenth century. Finally it also illustrates well the importance of understanding the language of cartography.

The map is drawn with east at the top of the map. In the lower left hand area of the map there are TWO linear scales, framed by a drawing of open dividers. The first is “ A Scale of perches at 15 foote 9 inches”, the other “A Scale of perches at 16 foote ½ to ye perche”. A perch was a measure of length which is the equivalent of 5.5 yards or 5.1 metres. The title to the map reads “A Survey of the Mannor of Studlande in the Isle of Purbecke in Countie of Dorset measured at 15 foote 9 inches to the pche”. If we look closely at the map we can see fields, each of which is marked by a symbol. The symbols (“Caracter”) are explained in a table in the top left hand part of the map.

The areas of the holdings are given in acres, roods and square poles, a rood being one quarter acre which equals 40 square poles. Thus, Edith Wilshire had 11 acres and 2 roods in arable and 2 acres, 3 roods and 20 square poles in meadow and pasture. The table also records the rent and related matters, but these are difficult to decipher.

In 1585-6, the date of the survey, Studland parish had 2130 acres, of which 1210 were “The Heathe grounde” and 173 “ The Downe or sheepe pasture”. 419 acres, 2 roods was arable and just over 138 acres was in pasture and meadow. There were 24 tenants, of whom 6 were women. The largest holdings were with “Elizabeth , Wife of Ric’ Squibb” who had 75 acres of Studland Wood, 180 acres of arable and a little over 16 acres of meadow and pasture. Many tenants’ land was divided between several plots. Phillipp Forde, for example, had a plot in Studland village and two at Salterns at the southern end of Little Sea.

The map shows that by the late sixteenth century there was already a spit, named as “Burnet poynte”, enclosing “Litle Sea”, around which there were fourteen fields held as tenancies. Treswell shows a narrow ridge extending northwards to the mouth of Poole Harbour where it forms a large recurve. Its tip was 128 perches (641 m) from Brownsea Castle. Today, a low inter-tidal gravel and sand ridge, known as Stone Island, reaches to within 500 m of Brownsea Castle. Four small headlands, shown as ‘Rede orde’, ‘Coke orde’, ‘Geries orde’ and ‘Rickmans orde’ coincide in position with the modern Redhorn Quay, an unnamed ridge, Jerry’s Point and Gravel Point. Salt-making was recorded at Studland in the Domesday Book of 1086. It is likely that it took place at the area shown as Salterns on Treswell’s map. Although the seaward shoreline of Studland parish changed considerably in subsequent centuries, Treswell’s map shows that the south-eastern shore of Poole harbour changed very little.

Despite the lack of detailed information about how the map was surveyed and compiled, it provides a very detailed insight into the land surveyor’s skills and the landscape of the time.

Tithe Maps (National, Dorset)
The tithe surveys of the late 1830s and early 1840s were one of the most ambitious cadastral surveys undertaken in this country. They were prepared as a method of settling longstanding grievances about tithes, but the range of data collected has great interest 160 years later. The methodology was interesting in that parishes were given a set of standards to work with, but were largely left to arrange the local surveys themselves. Dorset’s surveys were consistently the highest quality with a high proportion of ‘First Class’ maps and of lithographed schedules that closely followed the methodologies suggested. In many ways, the Tithe surveys represent an early form of Geographical Information System (GIS), comprising as they do consistent and systematically measured spatial data cross-referenced against the ‘attributes’ of the property described in the tithe apportionment (or schedule). Thus they lend themselves particularly well to rendering in an electronic format.

Plate 3 – Example of a Tithe map from the Osmington Parish showing associated apportionment information for one of the land parcels.

Plot 127, Puzzard Orchard was owned by Thomas Hare and occupied by Miller and Croad. It had an area of 1 acre, 3 roods and 1 square pole: just over 1.75 acres or about 0.73 hectares

The maps and books of reference are vital mapping resources for a range of heritage interests from general family, local and topographical research to more specialised uses such as definitive footpath research, archaeological surveys and mining investigations. In addition there is extensive personal and place-name data plus detailed information on land-type and land-use. Their value is enhanced by their pre-dating Ordnance Survey at large scale, the fullness of their coverage and content, and by the consistency of mapping with regard to quality and scale. They are a uniquely full audit of rural property in the nineteenth century.

The DCDA includes fully transcribed apportionments for all the coastal parishes along with the rectified and mosaiced Tithe maps ( See Interactive maps – Tithe Apportionments). The apportionments represent a table of ownership, occupier and the state of cultivation for each of the numbered land parcels depicted on the respective parish Tithe map.

Mapping on a national scale
Coordinated national surveys and map series came into being in Britain with the establishment of the Ordnance Survey (OS). The OS, in common with other national surveys, grew out of the need for armies to have good maps upon which to base their strategy and tactics both at home and abroad. The development of national topographic maps began in Scotland with William Roy’s 1747 survey and at the same time Cassini’s survey of France. Roy was appointed Surveyor-General of Coasts and Engineer to make military surveys of Britain in 1765 and just two years later James Rennell was appointed Surveyor-General of Bengal. The first map, at a scale of 1 inch to 1 mile (1:63360), was published in 1801 and covered Kent in four sheets. OS plans of Ireland at a scale of 6 inches to 1 mile (1:10560) were produced between 1825 and 1840, but the Six-Inch Plans for Dorset were not completed until the 1880s. The work of the Ordnance Survey gradually expanded the coverage and plans of urban areas at the very detailed scale of 1:1250, with a standard of survey and draughtsmanship which meant that lines on the map could represent 5 inches (127 mm) on the ground.

Plate 4 – Example of First Edition Six-Inch (1:10560) Ordnance Survey map of Bridport.

Surveys of specific features of Britain such as geology, soils and land use have also been carried out either by specialist agencies such as the British Geological Survey or through national efforts such as the Land Utilisation Survey of the 1930s (See Theme 2 Topic 2 Life on the Land and in the Town).

Post-1945 aerial photography
Unlike historical cartography with its defined series or epochs of maps, aerial photography has traditionally been produced on a smaller, ‘project-by-project’ basis or as part of more recent county and national coverage exercises as optimised by the GetMapping enterprise. However, from an historic environment perspective we find there is a whole series of post 1945 aerial photographs. Some of these give complete (or near complete) national coverage whilst others have been taken of specific regional or local areas.

Perhaps the most widely used of the historic aerial photographic series was taken immediately after the Second World War. Between 1946-48 the RAF photographed almost all of the country as part of their National Survey. Done initially as an aid to the revision of highways and to help coordinate planning work, the photographs offer a unique and valuable resource recording as it does the landscape of post war Britain.

Like many other County Councils throughout England, Dorset holds a copy of the county Aerial photography from the RAF 1946-48 National Survey. This access has provided for the DCDA an opportunity to create a ‘snap-shot’ of the coast in 1947. A later Flight in 1972 provides stark contrast for these earlier photographs and affords a unique picture history of the Dorset coast over the later half of the twentieth century.

Plate 5 – Example of change in the Dorset village of Chickerell between 1947 and 1970.

This extract from the Map Viewer compares two aerial photographs, on the left dated 1947 and on the right 1970. The pattern of fields which is still clear in 1947 has largely been obliterated by the growth of the settlement by 1970. If you go to this location in the Map Viewer you will be able to see how these patterns appear on the earlier cartography