Grid references

Have just amended the title of this thread as its gone into unexplored territory.

Blundered across this useful document whilst researching ROF factories in Cumbria. Lots of military entries.

www.english-heritage.org.uk/publications...za/NW_RCZAS_2009.pdf

There is a large database at the end which gives Northings and Eastings for each site. They're not NGR or Lat/Long.

Help! - any ideas.

Graham

The Fielden converter should do it:

www.fieldenmaps.info/cconv/cconv_gb.html

(But I can never get it to work:))

I know it's far from convenient, but you can put Easting & Northings directly into Old Maps. It takes forever though.

norwichpaul;66800 wrote:

Its a bit vague on the 20th C military stuff, looks like a desk based assesment looking at some kind of mapping with little knowledge of whats on the ground. Then to leave out NGRs smacks of using Google maps etc. In other words almost completely useless!

I've just spent an hour with this document and am at my wit's end!

In an effort to solve this NGR issues I've attempted to cross reference an entry in the text (giving an NGR), with a datebase entry giving northings and eastings. I failed completely. In addition couldn't find a single 'HER' which cross referenced.

Then tried entering the NGR of a known item, (e.g. range, decoy, airfield, WWII factory etc) into the Fielden converter and seeing if it produces anything remotely like the numbers in the database. No chance!

Noted there are several references in the text to Moricambe Bay.

Then found this beauty:

An important WWI feature on the north side of the Wirral peninsula is a sound mirror (SJ 32165 38915; HER 2189-025 M). This was used as a Royal Observer Corps post, designed to give advance warning of approaching enemy Zeppelins.

Didn't know we had the ROC when the Zepplins were around, and regarding the quoted NGR it locates to a point in Wales, 7 miles south of wrexham and some 30 miles south of the northern end of the Wirral peninsula.

Still haven't given up - there could be some good stuff in this report, but initial results are very disappointing.

Just what is the system used for eastings and northings?

Graham

I tried a couple of the references but couldn't find the subjects. I lived in Wirral for quite a few years, still have a house there, but never heard of a Sound Mirror in the area. Now I have to divert and look!!

Thanks guys - the easiest way I've now found, is to use the online Fielden converter mentioned by PtE (The downloadable one I've used for years doesn't have this conversion)

www.fieldenmaps.info/cconv/cconv_gb.html

Checked this with the Mawbray bombing marker.

You enter the 'northing' and 'easting' into GB National Grid - Full Coordinates, and result appears in Grid Ref 2-letter square ID.

I had a few problems with Old Maps and GetMapping.

There was a lot of stuff on the web about how to write a Javascript or Python prog to do these conversions. Very complex stuff - especially when you haven't a clue what Python is

Now need about three weeks to check some of these out .

Graham

Just discovered that my downloadable Fielden performs the required conversion very neatly - its a matter of ticking/unticking the NGR box in the Great Britain National Grid field.

This reveals that the conversion is really very simple, and that no maths is required at all. Forget Javascript and all that.

The first digit in each northing and each easting becomes the two letter modern NGR prefix. The remaining five digits stay the same. In the case of Cumbria:

312345 467890 becomes SD 12345 67890 thus 3xxxxx 4yyyyy gives SD

312345 567890 becomes NY 12345 67890 thus 3xxxxx 5yyyyy gives NY

212345 567890 becomes NX 12345 67890 thus 2xxxxx 5yyyyy gives NX

I couldn't find anything on the web which explained it this simply. Just applying for a job at GCHQ. (they are advertising for cleaners) .

Also 3,3 = SJ. One day I'll do the rest.

Graham