"There lies, spiked and forgotten, in the vicinity of the signal station on Mt. Victoria, Wellington, an old carronado, which, away back in 1876, served as the official herald of noon. It may have had other functions, but its primary purpose was to hold the citizens in the town below to some unanimity of agreement as to the "right time." The "Dominion" says that it had a very short reign. Every noonday for about three week its "boom! gave out the hour, and then the Defence Department, aghast at the unseemly waste of powder, ruled it out of action. It was allowed to remain there, its black muzzle pointing disconsolately across the harbour, until it fell upon evil days. The bad boys of the town, having resisted temptation until they could resist it no longer, took to firing the gun at irregular intervals. Then the authorities decided that there would be no peace in the community until the gun was rendered useless altogether. So it was spiked, and its degradation was completed. A similar method of recording "noon" was used in Nelson, from a cannon placed on Britannia Heights."
I can add that the shine on the top of the barrel is the result of many small boys' and girls' backsides sitting astride the gun - including my own on many occiasions as a kid living in Wellington until age 10.
Also of some navigational interest is the triangular monument which appears in the background of one of the photo links David C provided. That is a monument to Rear Admiral Richard E Byrd, the polar explorer.
