Re: Why only crap in this NG? (was Wolter claims ...)
- From: David Johnson <trolleyfan_nospam@xxxxxxxxxxxxx>
- Date: Wed, 1 Jun 2005 19:15:07 +0000 (UTC)
nospam@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx wrote in
news:t6gr91588jgu1gi71nm6n9r23t1skc933a@xxxxxxx:
> Apparently on date Wed, 01 Jun 2005 13:31:50 GMT, Philip Deitiker
> <Donevenask@xxxxxxxxxxxxxxx> said:
>
>>nospam@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx says in
>>news:ke9r91t75hj6kg3i391spg06quf16th30l@xxxxxxx:
>>
>>> No it doesn't, I gave you the example showing why it doesn't and
>>> what Columbus did. All he had to know what what time an eclipse
>>> took place.
>>>
>>> Let me spell it out again for you, try not to snip it all and
>>> repeat your wrong assertion, as you did last time:
>>
>>Oh just wonderful, another one
>>[Snip]
>>
>>I have the exact calculation for you right here.
>>http://home.thegrid.net/~lllove/net-loon_index.html
>
> It's no wonder that you pollute the newsgroup with trash about the KRS
> and that, then, Philip, as you don't seem mentally equipped to discuss
> perfectly good science / history connections. You have to just snip it
> all and deny it.
>
> How do you score on the crackpot index? Quite high, I should imagine,
> with your obsession with racism.
>
> Still, it does seem that the newsgroup only deals with scandinavian
> fantasies these days.
>
> Anything that actually tries to discuss real history is discarded as
> crackpottery. Strange that.
>
> Anyone other than Philip feel capable of discussing the question of
> Columbus?
>
> I realise he's not a mythical figure and it's not some weird theory
> about stuff that never happened, but what's the problem otherwise?
Main problem? That he probably made up the whole finding his latitude by
an eclipse story:
------------------
Columbus and Longitude
Columbus twice claimed to have found his longitude by timing lunar
eclipses. These claims are probably false.
Before the invention of accurate clocks, it was nearly impossible for
sailors to find their longitude. This did not stop them from trying,
however. Columbus made two attempts in his lifetime to measure his
longitude. Both results were pretty bad, even by the standards of his
day.
The only practical method for determining longitude in the fifteenth
century was the well-known method of timing lunar eclipses. This method
had been in use since ancient times, but since eclipses are rare, it is
of limited use. A recent suggestion (Molander 1992) that Columbus used
planetary conjunctions to determine his longitude on the first voyage has
been shown to be incorrect (Pickering 1996). [See the bibliography.]
The eclipse timing method is simple: first, you determine the local time
that the lunar eclipse starts or ends by direct observation. Then you
compare your local time for that event against the local time at some
distant place. The difference in the two times is the difference in
longitude. For example, if the eclipse starts at 8:00 p.m. where you are
(say, in Virginia), and the same eclipse starts at 1:00 a.m. in London,
you find that there is five hours difference between Virginia and London;
or you might say five time zones, which is the same thing. This works out
to 75 degrees of longitude.
We now know that observers can tell the moment a lunar eclipse starts or
ends to within a few minutes. That means that the biggest source of error
for Columbus would have been finding the correct local time. But this is
also easy: in the tropics, the sun rises at nearly 6:00 a.m. and sets
nearly 6:00 p.m. every day. Also, sailors used a device called a
nocturnal which was used to determine the time of midnight from the
positions of the circumpolar stars.
Using these clues and a sandglass, Columbus should have been able to
determine the correct local time of an eclipse to within about ten
minutes, if he was careful. The problem is that both of Columbus's
eclipse timing longitudes are off by much, much greater amounts than
this. His 1494 longitude was recorded as 5 hours 23 minutes west of
Cadiz; at the time, he was 4 hours 10 minutes west of Cadiz, so his error
is an hour and 20 minutes. Columbus's error in 1504 is even worse: from
Jamaica, he claimed a longitude of 7 hours 15 minutes west of Cadiz,
while his actual longitude was 4 hours 45 minutes west of there -- an
error of two and a half hours!
The best way to explain the errors is to assume that Columbus didn't
really use the lunar eclipses at all. We know that Columbus believed that
one degree of the Earth's surface was 56 and two-thirds miles long. Using
this formula, it's possible to convert Columbus's transatlantic distance
(1142.25 leagues -- see the first voyage summary) into a longitude. When
we make this conversion, the transatlantic distance measured by Columbus
on his first voyage comes out to 5 hours and 23 minutes -- the exact
figure he reported on the second voyage as his longitude.
The 1504 longitude can be explained in a similar manner. On his fourth
voyage, Columbus reported that the distance from Puerto Rico to a place
in western Cuba was 400 leagues. This is the longest east-west distance
within the Indies that Columbus ever recorded in his lifetime. If we add
this 400 leagues to the transatlantic distance from the first voyage (the
longest transatlantic distance that he recorded in his lifetime), we get
1542.25 leagues. Converting this to a longitude using Columbus's own
formula yields 7 hours and 15 minutes, exactly the figure that Columbus
reported.
So Columbus didn't really use these lunar eclipses to find his longitude.
He really used his dead-reckoning distances, and claimed that they were
celestially determined. This was probably done to make his results look
scientifically respectable
from: http://www1.minn.net/~keithp/longi.htm
-----------------------
David
--
David Johnson http://home.earthlink.net/~trolleyfan
"You're a loony, you are!"
"They said that about Galileo, they said that about Einstein..."
"Yeah, and they said it about a good few loonies, too
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