NUMBERS 4 & 5

BENCHMARKS continued

These two are located at the base of one of the pillars of a gate on Benburb Street, Dublin.

Below. Looking west. The 'marks are on two sides of the base of the pillar at left.

Above. Looking east towards the city centre. One of the 'marks is on the right at the base of the pillar nearest.

NUMBERS 2 & 3

BENCHMARKS continued

 

Below: These two are each located on the bases of the pillars of a gateway at the junction of Temple Street West and Wolfe Tone Quay, Dublin. Benchmarker suspects that training for mapping/surveying work was carried out by personnel attached to the nearby Royal Barracks (later Collins Barracks, now part of the National Museum). Therefore these particular benchmarks, and others close by, may have been used for training exercises. It's only a theory.

Above: Wolfe Tone Quay, looking east towards the city centre. The 'marks are at the bases of the pillars of the entrance on the left.

 

NUMBER 1

BENCHMARKS
 

Benchmarks - the original kind rather than those applying in recent years to workers in the Public Service etc. - can be seen at many locations throughout Ireland and the United Kingdom. They date from the time of the first ordnance surveys of these islands. It appears that the first survey commenced in the 1820s, with others following in later years. (So if you discover one in its original location then you can be almost certain that the wall or building or bridge on which it is positioned is at least 100 years old, but probably much more than that.) Carved into stone surfaces the horizontal line was the slot against which the leveling instrument was placed. The three lines underneath represent an arrow head pointing to the measuring slot. I had originally believed that they were used solely as triangulation points for map making, and while they indeed had that function, I now understand that primarily they were points where height above sea-level was measured. Many old maps feature a symbol of a benchmark with a number beside it – the height (altitude) in feet above sea-level. For many years in the United Kingdom they were protected structures but in modern times with the advent of satellite technology for map making, they are effectively redundant.

The intention with this website is to record the locations of at least 1,001 of them, or die in the attempt (no flowers please, house private). They will be posted here at intervals over the coming days, weeks, months, years, decades, centuries .... Anyone who wishes to contribute can send photos and location descriptions of any benchmarks they may find and would like to have included on this website to mfbourke@gmail.com Write 'benchmark' in the subject box.
Happy hunting,
Benchmarker
 

Perhaps an appropriate way to kick-off this site is by posting as NUMBER 1 the benchmark which may be the one that is closest to my house – a small but perfectly formed mansion in Dublin 8. It is located about 200 yards away on Bow Lane West.

Below: The 'mark on Bow Lane West.

Above: Bow Lane West, looking east towards the city centre. The 'mark is on the base of the pillar on left. Someone has outlined it in white paint.