How can I find out when a trig pillar was constructed?

[Monument Man]

I was on Holyhead Mountain, Anglesey, North Wales on Sunday, 6 October 2019. There's an OS Hotine triangulation pillar on the summit at 220 metres (760 feet). It has the number S1633 on its cast 'level flush bracket' (I think that's what they call them?)
Can anyone tell me how I can find out on what date any particular trig point was constructed please?
Many thanks.

[agentmancuso]

According to the OSGB36 extract on T:UK, the pillar was computed on 01/06/1952, presumably very shortly after physical construction.

[eon]

The pillar was built on the 19th of November 1936 at a cost of £19 4s 6d. Last maintained by the OS in June of 1979.

[agentmancuso]

The pillar was built on the 19th of November 1936 at a cost of £19 4s 6d. Last maintained by the OS in June of 1979.

It never occurred to me that there would be such a long delay between construction and computation. I wonder why; the war maybe?

[eon]

It could well be that the war played a part in this, but looking through the list of pillars, most are computed not long - within a year, or two - of their construction. Even those built in the 30s/40s. But around that time, the sizable gap is more evident.

[Monument Man]

That's brilliant, thank you, much appreciated. Where are you getting such detailed information from please?

[agentmancuso]

That's brilliant, thank you, much appreciated. Where are you getting such detailed information from please?

Computation dates are given for most stations on the T:UK page iteself; there's a wealth of historical information in the files section of the TrigonomyYahoo! group, though you'll need to be quick as Yahoo are killing that off pretty soon.

[clochandighter]

There is work going on in the background to make sure these historic files remain available.

Yahoo! may well be deleting these files around 12th December but I will be hosting many of them on Dropbox.

Pillars18.xls has build completion dates for most of the pillars

Development still underway but here is your starting point:

https://www.dropbox.com/s/aoaesd8ui0wr6 ... M.pdf?dl=0


Rgds,

Graeme P.
clochandighter on TPUK