Hampshire Waterways

Whitworth’s maps of the proposed canal

There are two maps produced by the engineer Robert Whitworth showing his proposals for the intended canal dating from 1770 and 1789. These appear on these two pages:

• Map of 1770 proposals
• Map of 1789 proposals

Bradshaw's Map

Below are two extracts from Bradshaw’s “Map of Canals, Navigable Rivers and Railways &c” published in 1830 covering the northern and southern parts of the canal.

Ordnance Survey field drawings

The surveys for the ‘Old Series’ One Inch maps were collated by the surveyors onto preliminary drawings on paper at a scale of two inches to the mile using pen and ink. It was from these that the copper printing plates were engraved by hand at One Inch scale. The first of these maps were surveyed along the south coast starting in Kent as a reaction to the threat of invasion by Napoléon Bonaparte.

These drawings were working documents, now over 200 years old, and in places are a bit the worse for wear. The British Library holds these documents and the links below provide access to images of the drawings covering the Southampton & Salisbury and Andover Canals. It seems that the Andover Canal was taken as the common edge between the two sheets south of Stockbridge.

Copies of these maps are available on Wikimedia Commons as normal image files albeit quite large. These files are licensed under the National Archives: Open Government Licence version 1.0 (OGL v1.0).

Ordnance Survey ‘Old Series’ maps

This series of maps were the first maps published by the Ordnance Survey. At a scale of One Inch to One Mile [1/63360], they were derived and engraved by hand on copper plates from the field drawings listed above. These are the only Ordnance Survey maps to show the canal when open. By the time that larger scale maps at 1/10560 [6 inch] and 1/2500 [25 inch] were surveyed in the 1870s, the canal had been closed and replaced by the railway. Although some of the route of the unconverted canal can be traced on these later maps, it lacks much detail.

The Andover Canal appears on two of these One Inch sheets:

Dimensions

The locks are said to have been big enough to take boats 65ft (19.8m) long with a beam of 8ft 6in (2.6m), although the 1789 Act of Parliament stated that boats should be a maximum of 60ft by 8ft (18.3m by 2.4m) with a draught of 3ft 6in (1.1m). Without archaeological investigations, it is not possible to confirm the dimensions. Unlike on the Itchen Navigation, there appears to be no pictures of the barges used on this canal. The only information to hand is that in 1794 a newspaper report refers to “A barge loaded with upwards of 20 tons burthen” and that in 1849 when the canal company started carrying goods on the canal themselves, they bought the sixteen 18-ton barges then working on the waterway.

Distance Table

Joseph Priestley’s “Historical Account of the Navigable Rivers, Canals, and Railways of Great Britain”, first published in 1831, states the finished canal was 22½ miles (36.2km) long, with a fall of 176⅓ feet (53.75 metres) by 24 locks. Other sources say the fall was 179 feet (54.56m). The distances in the table below have been carefully measured using Google Earth which indicate the true length of the canal was nearer 23.0 miles (37km). The position of the features marked with "?" are unconfirmed.

Bradshaw’s “Map of Canals, Navigable Rivers and Railways &c” published in 1830 (see above) names the locks from Andover to Redbridge and gives the height of the canal above each lock. These names and height values are shown in the table below. See the notes below the table about the height values.

The Height and Fall columns below show values in feet and inches. By using the Settings button (via the Page Links button on small screens) at the bottom of the page, it is possible to change the values to metres. NB - These are a conversion of Bradshaw’s values to metres - not values on the Ordnance Survey Newlyn datum. Similarly, it is possible to change the OS National Grid values to WGS84 (GPS) values.

Notes on the heights given by Bradshaw

The heights quoted by Bradshaw were said to be based on a level 6ft 10in (2.08m) below the Old Dock Sill in Liverpool Docks which Bradshaw states is "low water at Liverpool". This not the same as the Liverpool datum measured by Ordnance Survey in 1844 which represented Mean Sea Level. Modern Ordnance Survey heights are related to Mean Sea Level measured at Newlyn, Cornwall between 1915-21. The level of the Old Dock Sill is 4ft 6.5in (1.38m) below Newlyn datum. This means that Bradshaw’s height figures should be 11ft 4.5in (3.46m) greater than those based on Newlyn.

It should also be borne in mind that early 19th century surveying equipment / technology was not up to the task of accurately transferring a level from Liverpool to Redbridge. It is likely that the figures given by Bradshaw were derived from a local measurement or estimation of low water level and assumed that such a height would be the same as that at Liverpool. It was only confirmed in the early 20th century that mean sea level was not constant around the coast of Britain.

At first sight, Bradshaw’s heights given above appear to be very approximately 8 feet (2.4m) higher than levels based on Newlyn datum. However, upon more detailed examination of OS height data, this seems not to be a complete answer. It is difficult to be certain of the precise levels of water in the canal when it was in use as the structures that retained the water have been destroyed or amended over the last 160 plus years.

However, these levels are listed above as height differences between adjacent locks and these are possibly more accurate.