Logitude

[Greenheart]

Can anyone remember the question?

I'm dismayed by the levity on show, here. Surely, logitude is a matter of great importance for safe navigation?

 

[superheat6k]

I thought the final decision on where the primary meridian was placed was made on 21st October 1805.

Incidentally the same date that the World adopted English as THE International language.

 

[Graham_Wright]

I'm dismayed by the levity on show, here. Surely, logitude is a matter of great importance for safe navigation?

Blame it on my cold!

 

[AntarcticPilot]

I thought the final decision on where the primary meridian was placed was made on 21st October 1805.

Incidentally the same date that the World adopted English as THE International language.

Yes, except that it isn't at the precise location defined at that time any more. As I pointed out previously, the zero longitude is no longer defined by a mark on the ground, but by a model of the earth's form that is fixed to a network of geodetically located stations (orginally VLBI observatories; I think it may include others these days). There are more precise models that WGS84 (the one in general use); the ITRF series are used by those interested in plate tectonics, and take into account the relative motion of the "fixed" observatories.

 

[rogerthebodger]

I'm dismayed by the levity on show, here. Surely, logitude is a matter of great importance for safe navigation?

Is that the captains log ?

 

[Dan Tribe]

Thinking about the accuracy achieved in the early years using comparatively primitive instruments. I realise that Ian Dury was right.
"There ain't half been some clever... chaps"

 

[PuffTheMagicDragon]

I'm dismayed by the levity on show, here. Surely, logitude is a matter of great importance for safe navigation?

The only danger to "safe navigation" that is posed by that log would be a 'tripping hazard'. It seems to be sitting in water that's only a few centimetres deep!

 

[Hydrozoan]

Thinking about the accuracy achieved in the early years using comparatively primitive instruments. I realise that Ian Dury was right.
"There ain't half been some clever... chaps"

What also amazes me is that more simply technical abilities were so great in early times. In one way, the fine jewellery of the ancients should make such achievements as the Antikythera mechanism less surprising, but its accuracy of scale marking and gear cutting was not ISTR achieved again (in Europe, anyway) until perhaps the C16th.

 

[AntarcticPilot]

What also amazes me is that more simply technical abilities were so great in early times. In one way, the fine jewellery of the ancients should make such achievements as the Antikythera mechanism less surprising, but its accuracy of scale marking and gear cutting was not ISTR achieved again (in Europe, anyway) until perhaps the C16th.

I've read that while the theory behind the Antikythera mechanism was highly advanced, the actual implementation was not fine enough for it to work as a practical tool; more an intellectual toy (like the orreries of the 18th and 19th century). However, it was still a very striking achievement for its time. However, the preservation of the mechanism is such that it is difficult to be certain about the accuracy of it's gears and divisions; it is only recently (for exampel) that new techniques have revealed various inscriptions on it.

 

[Hydrozoan]

I've read that while the theory behind the Antikythera mechanism was highly advanced, the actual implementation was not fine enough for it to work as a practical tool; more an intellectual toy (like the orreries of the 18th and 19th century). However, it was still a very striking achievement for its time. However, the preservation of the mechanism is such that it is difficult to be certain about the accuracy of it's gears and divisions; it is only recently (for exampel) that new techniques have revealed various inscriptions on it.

Sure, and whilst some of the major inaccuracies were down to the limitations of Greek astronomical theory, it is accepted that its conceived design way exceeded its engineered capacity. But Wiki quotes Marchant (2009) for the assertion that ‘... the calculations used and the technology implemented ... predated that of the first known clocks found in antiquity in Medieval Europe by more than 1000 years’. But it doesn’t much matter – we agree that it was a striking achievement, and I wished only to make the point that ancient craftsmen were skilled enough to turn much of the cleverness of their contemporaries to practical use.

 

[superheat6k]

Yes, except that it isn't at the precise location defined at that time any more. As I pointed out previously, the zero longitude is no longer defined by a mark on the ground, but by a model of the earth's form that is fixed to a network of geodetically located stations (orginally VLBI observatories; I think it may include others these days). There are more precise models that WGS84 (the one in general use); the ITRF series are used by those interested in plate tectonics, and take into account the relative motion of the "fixed" observatories.

Modern technology has indeed adjusted the precise position of the primary meridian, but it is still a lot closer to its original historic position in Greenwich than it is to Paris, despite the bureaucratic and politic efforts of the French to move it away from London.