The small pencil markings at the edges of this drawing were used as reference points by the draughtsman from which to plot the area accurately. The road to Earl Stoke is marked "TG", meaning toll gate. The precision with which the survey records the road network is testimony to the military imperative of the Survey and is a major advance on earlier county maps. Running diagonally across the drawing is the Roman road from Bath, indicated by grey lines. The Kennet and Avon Canal and the Wiltshire and Berkshire Canal are shown in aquamarine, with each lock recorded, most notably on the section leading into Devizes. The canals were opened in 1810 to better exploit the resources of the Somerset coalfield, and are therefore contemporary with the survey of this drawing. The paper is watermarked JAMES WHATMAN TURKEY MILL KENT 1807.
This drawing highlights Bath and the River Avon. Major communication routes are coloured yellow/buff, according to military cartographic convention. Shading and 'hachuring' denote relief and give an overall impression of the undulating landscape. The Somerset Coal Canal is clearly visible leading into Bath. It was established by Act of Parliament in 1794 and welcomed by the mine owners of north Somerset as a cheaper way of transporting coal to Bath and the surrounding areas, curbing fears of an influx of Welsh coal. The canal was one of the most successful in the country, carrying over 100,000 tons of coal per year. That success was to be checked, however, by the expansion of the local rail network, in particular, the opening of the line between Radstock and Frome, which hastened the canal's closure in 1898. At the time of this survey, the canal was fully operational. Crocker, Edmund
1 : 31680 Although this drawing was surveyed six years before the obligatory inclusion of archaeological sites on drawings, several are featured. The most famous of these is Stonehenge, to the right of the drawing. Ancient camps, earthworks, castles and grave mounds ('tumuli') pepper the area, indicated by concentric shapes and a title in neat script. Their inclusion reveals the meticulous nature of the survey. To the right of the drawing, opposite Wishford, a trigonometrical station is indicated by a dot within a circle (annotated 'Col. Mudge's station' - Major-General William Mudge was Superintendent of the Ordnance Survey). This station denotes a point from which angular measurements were taken. In the right hand margin of the drawing a point titled "End of Base" marks the end of the Salisbury Plain baseline: an important measurement allowing for the triangulation of the area. Crocker, Edmund