Lack of technological progress in late Roman Empire

[Thiudareiks Flavius]

but it is broadly true that a large source of manual labour in slaves did have something of a retardant effect on the widespread use of mechanical power, for example.

Have you looked up the article conon394 offered in this thread as pdf
?
I can say that it quite radically reversed my opinion about the Roman attitude to mechanical power. Horizontal water wheel, vertical undershot wheel, vertical uppershot wheel, underwater turbines, archaeological evidence for water-powered trip hammers, large scale use of water power in mining - the only thing the author left out was the possible existence of Roman tidal mills. Not so bad after all. See:

"Machines, Power and the Ancient Economy" Andrew Wilson
The Journal of Roman Studies, Vol. 92 (2002), pp. 1-32

I've read it before. The reason I wrote in my post that the effect of slave-power on technological innovation is 'often overstated' is that there has been a tendency to claim that the Romans relied on muscle and animal power almost exclusively. This is simply not true, and recent research into Roman technology (such as that summarised by Wilson) has gone a long way towards correcting this.

Many of the sources of mechanical power widely implemented in the Middle Ages were not actually 'innovations' per se - they had existed for quite a while (eg overshot waterwheels). The thing that made them special in terms of medieval technology was the extent to which they were utilised. Even given the paucity of our evidence, there were very few watermills in Roman Britain, for example. But by 1100 AD there were 5624 documented mills in England alone, and that number increased vastly as the population of medieval England rose steadily.

I'm a bit sceptical about the evidence for Roman trip-hammers, however. They were definitely used in China (for hulling rice) as early as the Fifth Century AD, but we don't get definite evidence of their use in Europe until the Thirteenth Century.

A good overview of the history and development of water power, including up-to-date analysis, is Terry S Reynolds' Stronger than a Hundred Men: A History of the Vertical Waterwheel (2003).

We know that several monks were working on how to get a mechanical clock to run using a weight-driven escapement. We have one letter from one monastery to another where the idea is being discussed and the writer says he hopes someone would find a way to get such a mechanism to work. Not long afterwards the first such clocks began popping up all over Europe, so obviously someone found the solution.

Could you give a source for that correspondence? I am really interested in the history of clocks.

I didn't quite remember the reference properly. The attempts to create a true weight-driven escapement are actually documented in a treatise by Robert the Englishman in 1271 AD:

'Artisans are trying to make a wheel or disc which will move exactly as the equinoctial circle does, but they can't quite manage the task. If they coul, however, they would have a truly accurate timepiece worth more than the astrolabe or any other astronomical instrument for noting the hours.'
(Quoted in Lynn Thorndike, 'Invention of the Mechanical Clock Around 1271 AD', Speculum, XVI, (1941), pp. 242-43.)

Robert goes on to describe their (as yet unsuccessful) experiments with a wheel mounted on an axle driven by a weight mechanism.