Another History Mystery

[1st ade]

Another of the things I've seen for years but never noticed or paid attention to.

 

Bridge 70 at Wolverton (a dual purpose bridge carrying both a road to the newish development and a rail line to the works) has a plaque on the side facing the railway station.

 

I guess the arrow symbol is the War Office and that OS might be Ordnance Survey but what does it mean? No other bridges (or any other structures) in the area have one.

 

Might it be a height reference, either for the canal or the railway above?

[Batavia]

It is an Ordnance Survey Bench Mark, used to provide an accurate local reference height above OS datum.

 

Chris G

[Phil Ambrose]

I have half a memory of being told as a child that the arrow was a indicator of sea level, that's al I have to offer.

Phil

[lockedout]

OS Bench Marks are established by the Ordnance Survey to provide height references. They are usually carved into stonework or other stable material that is unlikely to be disturbed.

The centre of the horizontal groove is the height reference.

They don't actually indicate sea level, but their height can be reduced to Mean Sea Level.

IIRC the number is purely an identifier.

[Mac of Cygnet]

You'll find that sign on thousands of trig points all over the country, usually on tops of hills, but I did pass one in the Fens last summer which was marked on the OS map as 4 metres above sea level. I was cruising past about 7 metres below it!

[Phil Ambrose]

You'll find that sign on thousands of trig points all over the country, usually on tops of hills, but I did pass one in the Fens last summer which was marked on the OS map as 4 metres above sea level. I was cruising past about 7 metres below it!

Yes that sounds about right for the Fens.

Phil

[Beaker]

If you keep your eyes skinned, you'll often see these carved on the walls of stone buildings, as stated above, it's a benchmark.

 

http://www.ordnancesurvey.co.uk/benchmarks/

[Ace 01]

Another website is : bench-marks.org.uk. Don't know if it's connected to the previous site.

 

 

David

[1st ade]

Thanks for the two links - the un-official on has the ability to search by number (the Ordanance Survey one can only be searched by location.

 

Ace 01's link confirms "Flush Bracket 656: Wolverton.Flush Bracket on N.E. face of railway bridge over canal, S.W. end of Recreation Ground, Wolverton [2GL]; railway bridge parapet, E side"

 

Another way for me to waste many an evening as the site also links to other nearby marks...