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Frank Reed referred to my comments about a BBC animation about navigation,
in Navlist 3335.

You will find that animation on-

http://www.bbc.co.uk/history/british/empire_seapower/launch_ani_navigation.shtml-

and neither those comments nor Frank's reference will make much sense to you
unless you have taken a look at it. It's quite short, and you can work your
way through it within 5 minutes. The list of 11 items in which I had
detected errors is appended below.

With a map of the Northern sky, the text had stated- "The Pole Star is near
a group of stars known as the Plough, or big dipper- and is itself part of
the Great Bear."

and my comment (item 3) was-.

"Not that near, it's about 10 degrees away, and it is NOT part of the Great
Bear [that's the same thing as the Plough or Big Dipper or Ursa Major]  but
is part of the Little Bear or Ursa Minor, as the picture shows. As for the
Great Bear, its stars are in the wrong positions, completely jumbled about."

Frank refers to that last sentence, and points out-

| Nope. Tain't so. Ursa Major (the Great Bear), as well as Ursa Minor,
Draco,
| and Cepheus are all portrayed about right, in the correct relative
| locations, shapes, and sizes. You don't see most of the stars of the Great
| Bear because they're simply off the map (the southern limit as drawn is
| about 57 or 58 degrees declination). Of the bright ones, only Alpha UMa
| should be present, and in fact, it's in just about the right spot. On the
| other hand, the stars of Cassiopeia are missing. It looks like the
animator
| ran out of time or money when he got to that part of the star chart,
ranging
| from 0h RA to 8h RA. But I don't see that it matters anyway. The diagram
and
| the animation that follows make their small point: the circumpolar stars
go
| round and round Polaris which remains basically motionless.

He is, of course, quite right; the Great Bear is almost entirely off that
star map, and I had misunderstood the scale on which it is drawn. My
mistake. It shouldn't have happened. Indeed, the Plough is all of 28 degrees
from Polaris at its nearest, rather than the 10 degrees I had mentioned.

That sentence was part of the third item, of the 11 items I had picked out
as errors. Frank does not criticise the remainder of that item, or the other
10 on my list of errors, copied below, and I presume that they pass his
scrutiny.

So what does Frank conclude, from this detection of my error?

| I think you put far too much energy into attacking this simple little
Flash animation.

I will expend my energy as I choose, without asking permission from Frank
Reed.

| It's just a beginner's introduction to the 18th century history
| of navigation. There are a number of minor editing errors (e.g. "and is
| itself a part" should have been "which is itself a part"), but it really
| doesn't affect the educational effectiveness, which is rather minimal
| anyway, no matter how perfectly it is rendered. This animation was just a
| small part of the "online content" that accompanied that rather annoying
| "reality show" re-enactment of part of Cook's voyage called "The Ship"
that
| was filmed back in 2001 which explains its over-emphasis on James Cook. I
| assume it's been available online for some five years.

What is the relevance of who it's intended for, and how long it's existed,
to whether it's correct or erroneous? Frank claims to have unearthed a
"minor editing error", but mine were errors of fact, major and minor. Read
the list below.

Next came this gem-

| By the way, you recently recommended a diagram for the Wikipedia lunar
| distance page. And it's a nice diagram, but the stars in that diagram are
| "jumbled about" even more so than they are in the BBC Flash animation. I
| don't think it's a serious flaw there. Do you?

Unlike that BBC map, it did not set out to represent a particular night sky,
which would have been irrelevant to its purpose. If Frank thinks he can
recognise certain features, that's his own interpretation. And why raise it
here?

| I ask because if you're going to "play critic", it's important to be
even-handed.

Don't moralise at me, Frank Reed.

======================

Here is my list of errors, which will make sense only to those that can
bring themselves to look at that website.

1. "The Polynesians could calculate their positions from the currents of the
waves". What on earth are "the currents of the waves"? And how could anyone
"calculate" position that way?

2. "Ptolemy's maps were rediscovered in the 15th century and were used until
the 18th". I can't class this one as an error, but I'm very surprised by the
claim that a Ptolemy map was used until the 18th century. Is there any
backing for that claim?

3. "The Pole star is near a group of stars known as the Plough or the Big
Dipper, and is itself part of the Great Bear"  Not that near, it's about 10
degrees away, and it is NOT part of the Great Bear [that's the same thing as
the Plough or Big Dipper or Ursa Major]  but is part of the Little Bear or
Ursa Minor, as the picture shows. As for the Great Bear, its stars are in
the wrong positions, completely jumbled about.

4. The backstaff illustration shows the observer looking toward the Sun.
That isn't the way it was used. The Sun was behind the observer's back,
throwing a shadow, which is why it was called a backstaff. That's the whole
point of the instrument. The text mentions only looking at the horizon,
saying nothing about the Sun and shadow.

5. The text describing an octant is illustrated by another picture of the
backstaff, not an octant.

6. Compass. Did the ancient Greeks have a compass? I don't believe it.
Evidence, please.

7. The king's complaint resulted, not from ignorance of longitude, but the
fact that his mapmakers HAD CORRECTLY measured the longitudes of the
boundaries of France. However, that was by a method that was unusable at
sea. And it was Louis XIV, not Louis XVI.

8. Cook didn't visit Tasmania on his first voyage. (He did on his third).

9. There were various ways of spelling Maskelyne, but never, I think,
Meskalyne.

10. Lunar table method. The "several hours for a lunar calculation" applied
BEFORE Maskelyne's lunar tables were published. But those tables were there
to bypass nearly all of that work, reducing the calculation to less than
half an hour. This is a common mistake, told by many that should know
better. It seems to gain authority at each retelling. But it's quite wrong.

11. 1884 conference. Map has Rio de Janeiro spelled wrong.

=========================

No doubt, you could unearth your own additions to that list. Since it was
originally posted, Wolfgang Koberer has added others.

George.

contact George Huxtable at george@huxtable.u-net.com
or at +44 1865 820222 (from UK, 01865 820222)
or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.


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