((Location of marker is approximate - can anyone identify the location?))
To establish the old HK Civil Time, what was needed was a regular transit check on HK's longitude. This was best done using the 67 'clock stars' and the transit instrument at the Observatory, but as a back up physical transit checks were established. The northern one was within the observatory grounds. The southern one, however, was 3.46 km away (11,354') on the 'side of a hill in Wantsai'. Our team at HKU's Dept of Real Estate and Construction is on the hunt for this, which was a white painted obelisk with, on its north face, two black circles with a vertical black line (I think between them - the description is not lucid!). We know to within 20-30m where it must have been - somewhere close to Bowen Road between 50m or so to the east of the junction with Wanchai Gap Rd and 50m or so west of the eastern exit of the steps coming up from Shu Fai Terrace. Our guess is that the obelisk will have been at least 1.5m tall (the telescope of the transit instrument had a c. 50x magnification) and so placed that it could not be washed away by a flood or zapped by a landslip, as well as being sufficiently firmly planted to be fixed very unbudgeably in position.
A scout the other day didn't spot anything (the big landslip of a couple of years back is perilous close to the most likely area), but that's probably because the obelisk has long since bitten the dust. We know it was in position until c.1941. We're fairly sure we shall be able to pinpoint where it was once we've translated all the old HK Datum based positions to today's WGS84, so that at least will identify the actual location (we have our suspicions).
Meanwhile, and anyway, if anyone can spot it on a photo or has ever come across an image of it, we should be delighted to learn whatever we can.
Perhaps a bit sad to admit this, but starting from Jan 1981 I calculate I have run over 10,000k on Bowen Rd. There have been a few efforts to renovate it over the years, railings, kerbs, slope stabilisation etc. The lights were installed late 80s and the land slip was 2003/4 I recall. I never noticed anything like you described in that area, but would it be on the hillside above the road, now overgrown? Also my legs tell me it is over 300m from the Shiu Fai steps to Wch Gap Rd so quite a large area to search.
Anyway, not as sad as the loss of the city boundary marker that used to be on Magazine Gap Road. I guess that is in a landfill now.
I was running on Bowen Road today and noticed a man climbing over the gate of the drainage gulley west of the steps leading up from Shui Fai Terrace. I stopped and asked him what was up there. He told me he'd been to see the historical structure up the hillside, which he said was for measurement purposes. He showed me a photograph of a large rectangular stone structure.
He told me there is a rough path up to it from the top of the steps and a rope has been fixed to help the climb up.
If your team has not yet located the obeilsik I can show you the way one day.
Obelisk HK Meridian
I visited the hillside today and there were more people (families) up there. They told me there is a video on the HK Observatory FB page about the HK Meridian (I located it later -13 December 2019). Shows that Stephen and his team located the obelisk, which must have been well known to the geotech engineers who reparied the Bowen Rd landslide in the early 2000s (2004?), as it's right above the new concrete steps.
I'll try to post photos.
There is a also a concrete trig station marker inscribed "WDTRIGSTN 1893"
Hong Kong Meridian
A link to the latest and last HKO video on the Hong Kong Meridian can be viewed here
The earliest HKGRO reference to Wanchai comes from the 1893 Observatory's Report: Para (21) "The azimuth of the meridian mark above Wanchai was determined three times." This statement appears to tie-in with the date of the trig station marker on the ground.
The 1894 Report: Para (16) "The azimuth of the meridian mark above Wanchai, which I (Dobcerk, Director of the Observatory) contracted in 1894 (?), has been determined 8 times, but it is not yet ascertained how much or to which side it deviates from the meridian, as that depends on the weight attributed to individual measures, and the unweighted mean result is below the probable error."
Obelisk HK Meridian
Just watched the video - well
Just watched the video - well done to all involved in tracking down the two pillars.