Jules Verne Forum

<jvf@Gilead.org.il>

JanFebMarAprMayJunJulAugSepOctNovDec 19961997199819992000200120022003200420052006200720082009

Re: Ingenieur des Mines and illustrations

From: Garmt de Vries <G.deVries~at~phys.uu.nl>
Date: Thu, 5 Aug 2004 09:53:59 +0200 (CEST)
To: Jules Verne Forum <jvf~at~Gilead.org.il>

Hi Norm,

> As you know I have the french SDD up on Project Gutenberg. I have a copy of
> the "Supplement" which is a pretty good xerox of the Recontre edition.

Unfortunately, Rencontre didn't include all the figures. I have a low
resolution scan of the original, which contains 9 figures. In Rencontre, I
believe fig. 6 or 7 and fig. 9 are missing (but I'd have to look it up).

I'm still hoping someone can send me good quality scans of the original!

> What really needs to be done is to recreate the diagrams in a
> reproducible format using a graphics program.

You mean, something more compact than just a tif, gif or png?

> It is hard to make out the letters. Also I need a copy of the french
> text, I have a rough copy extracted from the pdf file on the web, but it
> needs to be cleaned up. I will be glad to email it to you if you want to
> clean it up; then I will add it to the PG text (assuming you agree).

Cleaning up is correcting OCR errors and interpunction? Sure, send me the
text. I can't promise I'll finish the job within a few days, though. I
just think that it wouldn't make sense to include the text of the extra
chapter without including the figures as well.

> We also need a commentary on the physics involved, which is not too
> transparent in the original. That will be easier to do with adequate
> figures.

I went through all the calculations, and they're all completely correct.

> First it needs to be established the units he is working in. If in
> metric he seems to assume g=1, where it should be 9.8 m/s/s.

He is working with SI units, as a French scientist in that time would, and
as most scientists do today.

He doesn't assume g=1. See the remark in section 5, about the orbit of the
cannonball. He says: if v_0 = 11180, the orbit is a parabola. From his
earlier formula for the "equation des forces vives", you found that v_0 =
sqrt(2 g r_0) gives you a parabola (this is the escape velocity also
needed in De la Terre a la Lune). With g = 9.82 m s^-2 and r_0 =
40000000/(2 pi) m, we find v_0 = 11180 m/s.

What is a bit odd, is the following: "The cannonball is 1,000,000 times
heavier than the 180 kg ball used by the French navy. Its mass is
180,000,000/g = 18.10^6." He does the same thing for the mass of the Earth
(finding 625.10^21 rather than 625.10^22), and goes on using these "masses
divided by g" for his calculations. The cannonball's impulse, for example
is 18.10^6 times its initial velocity, the Earth's moment of inertia is
2/5 625.10^21 R^2, etc.

Apparently Badoureau uses a different concept of mass. But because the
results only depend on the ratio of masses, it doesn't really matter.

Badoureau is also a bit sloppy in writing the units he works in: "the
initial velocity is 2,800,000 metres", "v_0 equals 11180", etc.

> Also did you confirm that the original Hetzel contained the Supplement? I
> was of the opinion that only the small in-8 edition had the supplement, not
> the larger illustrated edition, which could be a reason for the poor
> illustrations.

According to the bibliography at Zvi's site, only the in-18 had the extra
chapter.

Cheers,
Garmt.
Received on Thu 05 Aug 2004 - 10:54:05 IDT

JV.Gilead.org.il
Copyright © Zvi Har’El
$Date: 2009/02/01 22:36:11 $$