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Author Topic: OS Trig Points and Bench Marks in Kent  (Read 38198 times)

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BONZO

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Re: OS Trig Points and Bench Marks in Kent
« Reply #29 on: October 02, 2012, 14:11:16 »
Gosh - this brings back memories!

I used to be the Land Survey Technician for Polytechnic of the Southbank/Brixton School of Building.

Somewhere at the back of my shed with old surveying instruments I should have a Trivet plate for the top and a "L" shaped bracket for the Levelling staff.

Most of the student practicals were held down at Seaford, nothing in Kent I'm afraid.

Offline 101sean

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Re: OS Trig Points and Bench Marks in Kent
« Reply #28 on: December 06, 2011, 20:56:00 »
The Bench Marks are shown on 1:1250, 2500 and 10,000 OS plans along with their value, they were originally located roughly every 1/4mile in built up areas. The OS has a list of them but no longer maintains or install them, the coming of digital mapping, total stations and differential GPS has taken over. I used to use them a lot when surveying, it was frustrating to go on site and find the BM you were planning to use has been removed!

The bronze plate ones are fundamental BMs and are more widely spaced, they are designed to have a bracket inserted so you can rest the staff on it. On the incised ones, the staff holder uses something like a credit card to get the staff on the horizontal bar.

I can thoroughly recommend Map of a Nation by Rachel Hewitt if you want to learn more about the OS.

Offline kyn

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Re: OS Trig Points and Bench Marks in Kent
« Reply #27 on: December 06, 2011, 18:11:46 »
St Peter and St Paul, Aylesford

Offline kyn

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Re: OS Trig Points and Bench Marks in Kent
« Reply #26 on: November 21, 2011, 22:02:58 »
St John the Baptist, Penshurst

Offline kyn

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Re: OS Trig Points and Bench Marks in Kent
« Reply #25 on: November 18, 2011, 13:03:53 »
St Margaret's Church, Horsmonden


Offline unfairytale

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Re: OS Trig Points and Bench Marks in Kent
« Reply #24 on: June 25, 2011, 23:24:03 »
On Martello Tower no.15. Hythe.
When you've got your back to wall, there's only one thing to do and that's to turn around and fight. (John Major)
http://www.flickr.com/photos/unfairytale/sets/

Offline Paul

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Re: OS Trig Points and Bench Marks in Kent
« Reply #23 on: December 13, 2010, 20:15:30 »
Trigonometry :)
Maybe it's big horse I'm a Londoner. :{

Guest

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Re: OS Trig Points and Bench Marks in Kent
« Reply #22 on: December 13, 2010, 17:13:01 »
I wonder why we still call them 'trig' points, when officially they've been 'triangulation' points for decades? Even my old 7th Series 1" map shows them as such.

Offline kyn

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Re: OS Trig Points and Bench Marks in Kent
« Reply #21 on: December 13, 2010, 11:27:50 »
Teynham Church

Offline unfairytale

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Re: OS Trig Points and Bench Marks in Kent
« Reply #20 on: August 07, 2010, 21:17:13 »
Im guessing this is a rather old trig point. It is located at East demi bastion east of Dover castle close to the cliff edge.

It is something to do with the Battery. A mount for a gun sight or something. There's one at Dover's shoulder of mutton battery:


 and one at the hospital battery at Dover castle:
When you've got your back to wall, there's only one thing to do and that's to turn around and fight. (John Major)
http://www.flickr.com/photos/unfairytale/sets/

DoverDan

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Re: OS Trig Points and Bench Marks in Kent
« Reply #19 on: August 07, 2010, 18:38:38 »
Trig point at Tolsford Hill near Folkestone.

Offline Glen

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Re: OS Trig Points and Bench Marks in Kent
« Reply #18 on: July 27, 2010, 23:26:56 »
Trig point at Rowdow Hill above Otford (204 metres)



Glen

DoverDan

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Re: OS Trig Points and Bench Marks in Kent
« Reply #17 on: July 09, 2010, 22:46:34 »
I'm guessing this is a rather old trig point. It is located at East Demi Bastion east of Dover Castle close to the cliff edge.



DoverDan

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Re: OS Trig Points and Bench Marks in Kent
« Reply #16 on: May 20, 2010, 21:22:43 »
This trig point is on top of Shakespeare cliff near Dover overlooking Samphire hoe.

Offline Jason

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Re: OS Trig Points and Bench Marks in Kent
« Reply #15 on: April 26, 2010, 21:22:36 »
can i ask what a trig is?

Its a Triangulation point,For measuring distance. :)..........http://en.wikipedia.org/wiki/Triangulation_station
Its from Trigonometry...http://en.wikipedia.org/wiki/Trigonometry.

I saw a programme on these once (and they say I don't know how to live! :) ) and it said that Brigadier Martin Hotine's work was so accurate that working through all the trig points from the west country to the north of Scotland, the total inaccuracy was less than 18 inches.  That's pretty good considering they were using manual instruments to measure all of the angles between the points.

They also had to carry the cement and moulds to cast the trig points up hills and mountains to wherever they were needed.

It seems it was a much tougher job than it seems at first :)

Mind you, we shouldn't be too surprised - Mason and Dixon (of Mason Dixon Line fame) were British, and they did a pretty good job of surveying that - maybe it's something in the water ;)

Jason

 

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