BENCHMARKS continued
Two for the price of one. This pair is located on the base of the Martello Tower at Sandymount, Dublin. The one to the left is a true benchmark; Benchmarker has not yet discovered the role of the other one (with its associated writing and numerals) but it and many of its kind are a common feature on the 25 inch maps.
Below: The 'marks on the Martello Tower, Sandymount.
Above: Viewed from St John's Road, the Martello Tower, Sandymount, with the ‘marks at its base, near the centre.