Permalink Submitted by Anonymous (not verified) on Tue, 2010-08-24 12:07.
I think the monuments that you are referring to are obelisks. One is located off Shek O Road past the Cape Collinson Road turn-off. The other is located at the entrance to Tai Tam Bay opposite Red Hill.
The two obelisks are believed to have been erected by the Royal Navy and refer to the same line of longitude. In other words, the obelisks are 'in line' and were used by RN boats for geographical reference.
I heard there are actually two of these, built by the Royal Navy back then (but I don't know exactly when). It's for navigation, I think. There is some Chinese messages in some forums saying if you align your boat from the south with the two monuments into a straing line, the straight line will be going North-South. I am no sailor so you may find me saying nonsense. You might need some sea going person to exlain this to you.
I can add the following Map of Tai Tam Bay (which is mentioned in the article), which pinpoints both Beacons and there is a line of sight from the sea 'Beacons in Line' (lower centre)
The process of determining the deviation of the ship's magnetic compass by placing a vessel or an aircraft on various headings and comparing magnetic compass readings with the corresponding but previously determined magnetic directions
So it looks as though the obelisks' job was to provide a 'previously determined magnetic direction'.
Permalink Submitted by HO Lim-peng (not verified) on Wed, 2011-06-15 03:20.
Great research, amazing this answer was missed for so long. The two obelisks, viewed in line from seaward,would make a transit bearing, which would have been marked on Admiralty charts. During swinging, larger ships are often secured to a buoy, and towed round through 360 degees while bearings are taken. I wonder when these obelisks were last so used.
Re: monument
I think the monuments that you are referring to are obelisks. One is located off Shek O Road past the Cape Collinson Road turn-off. The other is located at the entrance to Tai Tam Bay opposite Red Hill.
The two obelisks are believed to have been erected by the Royal Navy and refer to the same line of longitude. In other words, the obelisks are 'in line' and were used by RN boats for geographical reference.
Moddsey
Re: Monuments near Shek O road
Hi there,
I heard there are actually two of these, built by the Royal Navy back then (but I don't know exactly when). It's for navigation, I think. There is some Chinese messages in some forums saying if you align your boat from the south with the two monuments into a straing line, the straight line will be going North-South. I am no sailor so you may find me saying nonsense. You might need some sea going person to exlain this to you.
Thanks & Best Regards,
T
re: Obelisk Hill
Dan Waters wrote an interesting piece about them here: http://sunzi.lib.hku.hk/hkjo/view/44/4400865.pdf
Map of Tai Tam Bay
@80sKid, Thanks for the related article.
I can add the following Map of Tai Tam Bay (which is mentioned in the article), which pinpoints both Beacons and there is a line of sight from the sea 'Beacons in Line' (lower centre)
High resolution image http://www.brianseed.com/zoom/taitambay.html
Images hosted on gwulo.com
Panoramio snaps
http://www.panoramio.com/photo/2921217
What the obelisks were for...
The Report of the director of Public Works for 1910 might have the answer:
19. Naval Land - Permission was granted for the following encroachments by the Naval Authorities on Colonial Government Land, viz:-
(a.) A pair of iron rods on Ma Kong Island marking the Western end of a measured course.
(b.) A pair of iron rods on Tytam Peninsula marking the Eastern end of a measured course.
(c.) A pair of obelisks, Tytam Bay, for swinging ships.
This online definition for 'swinging' a ship explains it as:
The process of determining the deviation of the ship's magnetic compass by placing a vessel or an aircraft on various headings and comparing magnetic compass readings with the corresponding but previously determined magnetic directions
So it looks as though the obelisks' job was to provide a 'previously determined magnetic direction'.
Regards, David
Great research, amazing this
Great research, amazing this answer was missed for so long. The two obelisks, viewed in line from seaward,would make a transit bearing, which would have been marked on Admiralty charts. During swinging, larger ships are often secured to a buoy, and towed round through 360 degees while bearings are taken. I wonder when these obelisks were last so used.
Words in the map
Would someone tell me the words beside "Obelisk Hill" and whether two tiny circles indicate the obelisks' locations on the map?
On the other hand, if the survey was conducted in 1893, is it contradictory to the information provided in the water works document (dated 1910)?
I suppose the document reports the works completed or being constructed in the year 1910.
Thanks in advance.
Another link to Dan Waters' article
Another link to Dan Waters' article: http://hkjo.lib.hku.hk/archive/files/3ee1f9e302d05759a1e029cc791bbfe7.pdf