Taylor’s map of 1759 is the first map to show us the canal and the spit across the estuary as we would recognise it today. All earlier maps, including Kinchin’s map of 1751 depict an open estuary. There is another chart, believed to have been drawn about the same time as the Taylor map, which also depicts the canal and the closure of the mouth of the estuary. What are we to make of this?
The map of 1759 conforms to our modern knowledge and there is no reason to dispute its accuracy. The two maps shown below (Norden 1607 and Speed 1611) show an open estuary and also conform to our expectations.
We begin to encounter a problem with the publication of three late 17th century maps – Bleau in 1645, Jannsen in 1646 and Modern in 1695. Each of them depicts an open estuary to the River Meon and these maps are repeated in this form until the 1759 map noted at the outset. We could conclude, on the basis of this visual evidence, that the Canal was not constructed until the middle of the 18th century, during the period in fact when serious canal building started in this country.
However, we should be circumspect. Many of these maps were drawn from earlier publications rather than from original survey and it may be that the open estuary at the mouth of the Meon became convention. The river was still navigable, and that was perhaps all travellers needed to know. Changes start to appear in maps in the early 18th century when road travel assumes some importance. As can be seen from the 17th century maps, roads and tracks were not depicted, although they must have been present. Local knowledge would suffice. The 1759 map is the first to show a network of local roads, which probably underscores the fact that those local roads had become an important feature of the economy.
The evidence from the maps is inconclusive. I am advised by experts non cartographic history that we can place no reliance on a map unless we know that a survey had taken place. We are only able to say with certainty that the canal had been constructed by 1759, but that does not necessarily mean that it was not built in 1611.