|By 某某人 on Wednesday, March 22, 2006 - 12:41 pm: Edit|
|By laism57 on Sunday, March 26, 2006 - 11:18 pm: Edit|
It was built by the SMO of Lands Dep.
They were not built at the same time.
It is not only with level but coordinates also.
They are called Trig.Station. The surveyor put the survey equipment on the pillar & carry out surveying.