back loaded, he could just insert the crystal and retaining ring when the movement was out of the case, then make sure everything was dry, tight, and at room temperature before installing the movement again.
Ah, yes, the ancient water clock. IIRC, it was called the "clepsehydra" which meant "water stealer" in Greek.
Actually, a marvelous invention that eliminates the need for a drive train! There were even versions of it that had DIALS with an HOUR hand on them! Apparently, as the water slowly dripped out of a supply tank inside of the clock (the rate being adjusted by a small valve) into a seperate storage tank located at the bottom of the clock, a float inside of the supply tank would slowly descend and a cord attached to it would then make a counter balanced hour hand slowly revolve around the dial.
I wonder if this is when they first got the idea for putting 12 hours on the dial to represent 12 hours of daylight followed by 12 hours of night. Although such a clock would not be that accurate as far as being synchronized with the solar time was concerned, if everyone who owned such a clock in a certain locale were to reset them to a certain hour at the same time every day, then all of the clocks would, more or less, agree with each other and that, ultimately, is what really counts when it comes to timepieces.
At dawn one would empty the water that had collected in storage tank during the previous 12 hours back into the supply tank again and the hour hand would be manually turned counterclockwise back to the 6 am position again. Over the next 12 hours the water would drain slowly down into the storage tank, the float would descend, and the cord would again turn the hour hand clockwise through 12 hours until it was 6 pm.
At dusk, the process was repeated and the clock would continue to run all night until dawn of the next day at which time the clock was again "rewound". The nice feature of such a clock is that, unlike a sundial, it can continue to operate on cloudy days or at night.
Of courses, this type of clock is a bit of a pain because one must "rewind" it twice every 24 hours. But, then again, anyone with a clock like this back then could just assign a slave to do the work while he slept late! If the supply and storage tanks were big enough, then it would be possible to make such a clock run longer. Perhaps as long as a week! Then all one would have to do, aside from a weekly "rewinding" was occasionally replace any water lost through evaporation. If the tanks were made of copper, that would prevent algae from growing inside of the tanks and fouling everything up.