NavList:

Robin, about how long does that Port Chalmers time ball take to fall? Is it on the order of two seconds, like the video Rafael linked from Greenwich? Or is it slower? 

Nearby observers, on land near a time ball, would have no problem spotting the instant of the exact fall, either upon release from the top of the mast or arrival at the bottom. Given that these events were supposed to be observed from vessels possibly as much as a mile or two away, it seems to me that a faster fall would be more useful. It's easier to see. The Greenwich time ball video seems to show a braking mechanism engaging about halfway down. The ball bounces slightly. Is there some sort of pneumatic piston offering resistance? 

Decades ago at Mystic Seaport Museum there was a working time ball. It was smaller and less elaborate, but it appeared to be a real mechanism from the late 19th or early 20th centuries. It dropped quickly, only a little slower than gravity, and "clanged" a bit when it struck the base. The ball itself was hollow so there seemed to be little chance that it would cause any wear to the mechanism even if it was operated every day. In the end the mechanism froze too often so they gave up on it. 

Rafael, you mentioned that the observatory "staff was too busy measuring the Sun’s meridian transit to drop balls." Was that really the issue? I had always heard that it was for the convenience of ships in harbor. Why 13:00 and not 14:00 or 09:00, I don't know, but avoiding noon probably had more to do with the work routine aboard ship than the astronomy of the Sun's meridian passage, which, after all, would only occasionally have happened within a minute of 12:00 local mean time. And you could miss a noon observation in a known harbor with no cost. But noon was also the time for the all-important principal work shift change during the day. Officers aboard ship were supposedly too busy assigning tasks and making sure everyone was on-duty to spend a few minutes studying some distant time ball through their telescopes.

It seems that time balls had marginal value. They appeal to us today on many levels, including a romanticism for such a visual representation of the flow of time. Yet even in the era, they were not especially common, and they were often shut down after a few years or decades of use. In the photo Robin included of the signage, this Port Chalmers time ball operated six days a week from 1867 to 1877. Then the service was stopped for five years. From 1882 the ball was dropped once a week. Not exactly high demand!

So how were chronometers checked in most ports if not by time ball?

Frank Reed