Thanks for all the comments,
William,
Galadriel and
Zigūr!
William, you might be right in terms of Tolkien not thinking through the issue of the barometer being an aneroid one.
Galadriel, you asked the question, '
Is it possible to make a clock like that with mostly wooden pieces?' The answer is 'Yes'. It can be seen if we look at the life of the great John Harrison (1683-1776), the self-educated English carpenter and clockmaker, who invented the marine chronometer. Early in his career, he built wooden clocks, one being in Nostel Priory, Yorkshire, made by him in 1717:
http://www.bbc.co.uk/bradford/conten..._feature.shtml
Harrison was the son of a carpenter for the estate, who was trained by his father for the same trade. He found himself repairing, then making clocks. In terms of the one shown, the wooden mechanism enables it to keep accurate time centuries later, this being due to the woods used, including lignum vitae, not needing any lubrication like a metal clock would.
Zigūr, thanks for the references you have pulled out regarding clocks from
The Hobbit and
The Lord of the Rings. I would add to this by saying that, in Chapter 2 of the first book, hobbits appear to be, as a society, used to the idea of accurate time, due to the existence and plentiful nature of clocks. Those who don't have one at home might be able to at least see one, hear one, or both.
Even if the dwarves don't have clocks, they are aware that hobbits do; so the contract they leave for Bilbo has the term that it would be accepted by him if he turned up at the Green Dragon Inn at '
11 a.m. sharp', with a reminder to him to be '
punctual'. (Their emphasis)
Bilbo has 10 minutes to get there, and does so '
just on the stroke of eleven'. Can this imply that there was a clock nearby, perhaps in the Green Dragon? I can imagine it being of service for travellers. Balin was keeping a look out for Bilbo at the door, and congratulated him for arriving on time with a '
Bravo!'
Bilbo then apologised for arriving at the last minute, explaining that he hadn't got their note (or rather contract) '
until after 10.45 to be precise'.
Zigūr, you then wondered if clocks were peculiar to hobbits, and only used in the Shire and in Bree-land. If that was the case, were there all kinds of local times, or some kind of agreed universal time, approximating to Greenwich Mean Time, if Pippin was able to make reference to '
Nine o'clock we'd call it in the Shire'?
It would, I suggest, make sense for the existence of a 'Shire time', originally introduced to facilitate the postal service. A common time would make it easier for those using it, in terms of knowing when the post offices would be open, and when the post would be delivered. What do people think?