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Contents 1 Rewrite 2 Where's the science? 3 Expansion/contraction vs. pressure changes 4 Contradiction?

[edit] Rewrite

The reason I'm proposing a rewrite is in part to address the questions and ambiguity listed below, as well as properly writing this article. A lot of the text and information has been taken from the article published in Eur. J. Physics (1984), pp.195-197 and has only undergone a slight rewrite that I feel is akin to plagiarism.

Also note that the clock is no longer situated in the "foyer" but as of early this year resides in the common room of the Physics Department at the University of Otago. JT 03:38, 16 August 2007 (UTC)

[edit] Where's the science?

If this is the contender for the "longest continuously running science experiment", what is the science? What's the hypothesis being tested? (Its clear what the science is for the pitch drop experiment: its a measure of viscosity). linas 01:32, 14 November 2005 (UTC)

The "longest continuously running science experiment" is in referral to the three experiments published in the 1984 European Journal of Physics, namely the Pitch drop experiment, the electric bell and the aforementioned Beverly clock. Also remember that many experiments do not need to "prove a hypothesis" as such. Experiments are also performed as a proof of principle -- in this case, the fact that you can build a clock that runs purely from temperature fluctuations and can therefore function without being manually wound up. -JT 03:38, 16 August 2007 (UTC)

[edit] Expansion/contraction vs. pressure changes

Linas has reverted an edit of mine, where I changed "daily temperature variations … cause the air in a one cubic-foot air-tight box to expand and contract" to "daily temperature variations … cause the air pressure in a one cubic-foot air-tight box to increase and decrease", which he claimed was "obviously wrong". The reason I made the change is because the volume of the air clearly cannot change; after all, it is in a one-cubic-foot airtight box, so its volume is always one cubic foot. Since the volume cannot change, the air is not expanding or contracting. By Gay-Lussac's law, then, the pressure inside the box must vary. If I'm misunderstanding something, please let me know, but barring any disagreements, I will redo my edit in a few days. —Bkell 23:15, 28 November 2005 (UTC)

What makes you believe that the "volume of the air clearly cannot change", or that the "volume is always one cubic foot"? How do you propose that energy can be extracted from a pressure change, if no device or mechanism is allowed to move? Or rather, how do you propose that some device or mechanism shall move without also altering the volume of the contained air? linas 23:24, 28 November 2005 (UTC)

That's a good point. If the box is acting as the cylinder for a piston, or something like that, then the article's wording is a little confusing, since the image that comes to mind when I read "a one cubic-foot air-tight box" is certainly not a piston (I was envisioning something along the lines of a sealed aquarium, but I couldn't figure out how that could provide power to the clock). If you have a more complete description of the clock mechanism, perhaps you should include it in the article to alleviate its current vagueness. —Bkell 23:31, 28 November 2005 (UTC)

I was unable to find a diagram. I presume the mechanism is identical to that of a mechanical aneroid barometer, but with a larger active volume. I updated the text based on what I could find. linas 03:55, 29 November 2005 (UTC)

"It runs on both pressure and temperature, but temperature seems to be the most important factor." [1]. It appears that the clock does not rely primarily on pressure. "Ambient temperature fluctuations expand and contract the air in an air-tight box. ...a volume of one cubic foot of air expanding under a 6° diurnal variation of temperature. " Just to clear confusion. I have not modified the text itself. -- Martian 23:08, 26 March 2007 (UTC)

It turns out that all of you are right in some sense but miss the point. If you look at the article link, you will find a schematic for the winding and unwinding mechanism of the clock. The air-tight chamber pushes against a layer of oil, which in turn pushes a float that turns a sprocket that winds the clock up. Gravity winds the clock down, allowing it to "tick" by means of a torsional pendulum. - JT 03:38, 16 August 2007 (UTC)

[edit] Contradiction?

The article says, "Whilst the clock has not needed winding since it was made by Arthur Beverly in 1864, it has stopped [...] on occasions when the ambient temperature has not fluctuated sufficiently." If it stopped because the mechanism that winds it wasn't able to provide enough energy, how can it be said that it didn't need winding? 67.158.72.8 04:04, 17 February 2007 (UTC)

eventually, when the temperature difference increases, the clocks mechanisms will resume, hence, no outside intervention "winding" is required to keep it functioning. Cypher Aod 04:00, 13 April 2007 (UTC)

I suppose in the same way, my battery operated alarm clock has never needed winding either. It's really a pointless application of the word. I'd also argue that it can't really be considered to be continuously running if "it has stopped on a number of occasions, when its mechanism needed cleaning, when there was a mechanical failure, when the Physics Department moved to new quarters". talk) 14:19, 24 June 2008 (UTC)