Longitude miniseries
Hello All: Last night the four hour long TV miniseries, Longitude was shown on AE channel (in US). This fabulous program detailing the struggles of Harrison to perfect a mariners clock and win the prise for determining the longitude at sea should not be missed by anyone who is interested in the history of time, clocks, or engineering. I have a couple of questions about its contents. 1. In the scenes showing the meetings of the Longitude Board with Harrison, on the wall is a large round map of northern Europe with London at the center. Around the perimeter of the map are the cardinal points of a compass. A single moving metal hand is attached at the center. I'm wondering is this might be a mechanical device attached to a weathervane used to indicate the direction of the wind. Or it might be some sort of indoor sundial which shows the sun's hour angle. Does any body have a clue what this instrument does? 2. To determine longitude at sea, Harrison's clock was carried on board a ship traveling west. The clock was set before the journey to show apparent solar time in Greenwich. The difference between local solar time on the ship and the time on the clock was used to determine longitude. To determine local solar time on the ship, Harrison used a sextant to look at the sun. How can a sextant, by itself, indicate the time? To determine high noon, wouldn't he only need a compass to know when the sun souths at high noon? 3. Where are the four Harrison clocks today? Are they still functional? Thanks John Carmichael Tucson Arizona
RE: Longitude miniseries
On 10 July 2000 15:15 John Carmichael wrote: From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] To: sundial@rrz.uni-koeln.de Subject: Longitude miniseries 1. In the scenes showing the meetings of the Longitude Board with Harrison, on the wall is a large round map of northern Europe with London at the center. Around the perimeter of the map are the cardinal points of a compass. A single moving metal hand is attached at the center. This is indeed an internal weathervane driven by a shaft and gears from the actual vane on the roof. Several British buildings have or had them, including the East India Company offices and even some private houses (very large ones!) 2. To determine local solar time on the ship, Harrison used a sextant to look at the sun. How can a sextant, by itself, indicate the time? By determining times of equal altitude either side of noon and indeed the time when the sun reaches its highest altitude, noon is obtained (as well as the latitude, knowing the date). A compass would a) need to be accurate and corrected for magnetic deviation and b) would only be useful as described if the sky were clear at noon, whereas observations of altitude a short time either side of noon can be reduced to find the actual time of noon even if no sight is possible at that moment. For taking sights either side of noon of course a watch (a deck watch) is necessary but it is only its reasonable accuracy in the short term that matters, not its timekeeping over many days. Such a watch was used anyway to carry the time information to and from the chronometer(s) which were never moved from their resting place below deck. 3. Where are the four Harrison clocks today? Are they still functional? The four timekeepers H1 to H4 are all on show at the Old Royal Observatory, Greenwich, London, where they are indeed functional. H1 to H3 are kept running. However H4 requires lubrication - unlike H1 to H3 - and this means dismantling, cleaning, lubrication and reassembly every few years. The risk of damage inherent in this process, even though - in the hands of the most skilled and careful watchmakers to whom alone it would be entrusted - it may be slight, and the slight wear which running might cause, are nowadays felt to be good reasons why H4 - arguably the most important watch in the world - is no longer kept running. It was running until a few years ago. There are videos and simulation of its fascinating action. Several copies have been made of H1 over the last 50 years, and Malcolm Leach has almost finished a copy of H2, while Don Unwin has very recently made a copy of H3 which I saw running a week ago along with the H2 copy at Upton Hall, the British Horological Institute headquarters. The copy of H4 which Harrison made, H5, almost identical except with much less decoration, is in the Collection of the Worshipful Company of Clockmakers at Guildhall, London. It is also in working order though I am not sure whether it is now kept going - I rather think not. Harrison's late regulator clock is also at Greenwich in the same room as H1 to H4. One of his early wooden clocks was in the Time Museum and is now in the Chicago Museum. Another of his clocks is in Guildhall together with another clock movement. Apologies that all this is a bit off sundials but the Longitude film and story IS very interesting! Andrew James
RE: Longitude miniseries
3. the Harrison clocks are at the National Maritime Museum in Greenwich. They are functional, but are kept unwound in order to avoid wear-and-tear. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Sent: Monday, July 10, 2000 10:15 AM To: sundial@rrz.uni-koeln.de Subject: Longitude miniseries Hello All: Last night the four hour long TV miniseries, Longitude was shown on AE channel (in US). This fabulous program detailing the struggles of Harrison to perfect a mariners clock and win the prise for determining the longitude at sea should not be missed by anyone who is interested in the history of time, clocks, or engineering. I have a couple of questions about its contents. 1. In the scenes showing the meetings of the Longitude Board with Harrison, on the wall is a large round map of northern Europe with London at the center. Around the perimeter of the map are the cardinal points of a compass. A single moving metal hand is attached at the center. I'm wondering is this might be a mechanical device attached to a weathervane used to indicate the direction of the wind. Or it might be some sort of indoor sundial which shows the sun's hour angle. Does any body have a clue what this instrument does? 2. To determine longitude at sea, Harrison's clock was carried on board a ship traveling west. The clock was set before the journey to show apparent solar time in Greenwich. The difference between local solar time on the ship and the time on the clock was used to determine longitude. To determine local solar time on the ship, Harrison used a sextant to look at the sun. How can a sextant, by itself, indicate the time? To determine high noon, wouldn't he only need a compass to know when the sun souths at high noon? 3. Where are the four Harrison clocks today? Are they still functional? Thanks John Carmichael Tucson Arizona
Longitude, the miniseries
Hi All, In case you missed it, the four hour show on Longitude will be shown again on AE. 8 to 12 pm Tuesday July 11. Be sure to see it. Bob
RE: Longitude, the miniseries
B.T. In case you missed it, the four hour show on Longitude will be shown again on AE. 8 to 12 pm Tuesday July 11. For other procrastinators like myself, my guide shows another full length AE showing Saturday, July 15 from 1 to 5PM. There are also several other listings for 1Hr segments scattered throughout the week (one is shown from 8 to 9PM Tuesday July 11, like Bob's). I also heard? one weekend evening may show it twice thru the night. Check your local TV guides as these times may vary? The preview Behind the Scenes look at the making... was very interesting, so I'm looking forward to the weekend! Enjoy, Fritz
Re: Longitude, the miniseries
Left Coasters, Note: AE is now a dual feed station. So when the adverts say 8pm/7 central that means its on at 8:pm on the pacific coast. (Not 5 as it used to be). ++ron - Original Message - From: Fritz Stumpges [EMAIL PROTECTED] To: sundial@rrz.uni-koeln.de Sent: Monday, July 10, 2000 1:23 PM Subject: RE: Longitude, the miniseries B.T. In case you missed it, the four hour show on Longitude will be shown again on AE. 8 to 12 pm Tuesday July 11. For other procrastinators like myself, my guide shows another full length AE showing Saturday, July 15 from 1 to 5PM. There are also several other listings for 1Hr segments scattered throughout the week (one is shown from 8 to 9PM Tuesday July 11, like Bob's). I also heard? one weekend evening may show it twice thru the night. Check your local TV guides as these times may vary? The preview Behind the Scenes look at the making... was very interesting, so I'm looking forward to the weekend! Enjoy, Fritz
