To Ryan Weh and to all are interested to the matter
In late april 1999 I published an article on matter , in the bulletin of the Italian Diallists. Open the file.
<>I Hope you 'll understand my English (The basic of the basic). If anyone will correct it, and send back to me.
Alessandro
This is real cookery! As an alternative to etching face down in a flat
dish, it is simple to use a vertical tank as supplied for etching PC boards.
These are tall and very thin - about 1.5 cm wide, and big enough to take the
plate that is being etched. Easy to make with two sheets of perspex
Roger Bailey wrote:
the Longitude Problem became critically important for navigation.
Time is the essence of the determination of longitude so knowing the
difference between solar time and star time was the first step.
An interesting and readable book on this subject is Dava Sobel's
Roger Bailey wrote:
[...] When was the axial gnomon invented? The hemispherium was
used by the Babylonians and the armillary sphere by the Alexandrian Greeks.
It is a small step from these instruments to the equatorial dial with an
axial gnomon, but who first used the axial gnomon with the
At 20:02 19-11-99 -, you wrote:
-Original Message/Oorspronkelijk bericht--
...
The key is to get a good quality photoresist that doesn't fail - the aerosol
type has a very limited shelf-life, I've found.
any experience with a 'permanent' marker pen? If you use this for
Fellow Shadow Watchers,
While recently making a reproduction of a 10
octagonal Victorian??? dial (the client wishes to replace the flimsy
original with a more robust version in phosphor bronze) I've taken JPEGs
at various stages of the etching process. The first three
