Wigan Album

Can someone explain why is this in the CENTRAL PARK topic? Is there some significance?

Can someone explain why is this in the CENTRAL PARK topic? Is there some significance?

Ordnance survey Marks
That's what this denotes.

Hello Harry,
I apologise unreservedly for putting this photo on here my excuse is that i was trying to start to upload photo's as i have not done it before so again im sorry i will try and put it right in the future i do hope this has not upset you too much G.B.

,,

Take no notice of harry.

Memories! when I was training to be a Civil engineer M6 (McAlpines) s a junior one started off on the bottom rung of the ladder so the 1st few months of my training was with an experienced surveyor ( most were ex NCB guys from the mines in the north west.) I held the levelling staff and these type of OS bench marks were a swine to get an accurate reading from unless you had a bracket. Our trick was a thick cardboard held into the groove of the masonry or brickwork to keep the staff vertical and still whilst the surveyor/engineer read the height from the dumpy level. The height of this one on Rose Bridge is given as 49.230m AOD based at Newlyn. Some older maps of the area give it in feet. Other types of bench marks are called Flush bracket as they were metal fixed to the structure and a special levelling plate was attached to them. Nowadays, with modern technology and satellites most construction works hardly use the bench marks now.