Antonius Maria Schyrlaeus de Rheita. 
Oculus Enoch et Eliae sive radius sidero-mysticus.  Antwerp. 1645.
Translated from Latin to German by Rolf Willach;
   and from German to English by Ilse Roberts and Peter Abrahams.


(page 338)   This viewing glass (by Joannes Lippensum Zelandus - Dutch), at 
first misshapen and unfinished, was then led to further refinement by the 
improvements of Galileo.  And now, after all these years, I hope that it 
will finally be completed in our time.  And even if, in comparison, the 
Galileo tube is much better on earth, it doesn’t seem to be especially 
useful for the stars, since it has an all too narrow field.  And we are 
also reminded of the problems that Kepler’s glasses have.  He connected two 
convex glasses of a certain ratio and mass with rather lucky results and 
installed them in a tube.  Their achievement is unbelievable (on the other 
hand, it does not lack anything agreeable of the disagreeable).  How much 
space is opened up and made visible with just a glance.  Indeed, we could 
with a long as well as a short telescope, sometimes exactly count more than 
20, 30, 40, and even 50 stars, so that this telescope shows at least a 
hundred times more space to the astronomer than the old tube.  This fact is 
surely not less useful than enjoyable.

But we were not satisfied with this monocular tube either.  We added the 
correct and opposite lens, and that was a successful enterprise, because we 
noticed such a difference between the one and the other, of the kind and 
manner that is common between the one eyed and the two eyed human being.  
Things appear more alive with the binocular telescope, doubly as exact so 
to speak, as well as large and bright.  With the monocular, they appear at 
most half dead, strongly unfocused, and made smaller.  How much one is 
better than the other can be found by anyone with their own eyes using the 
following example.  If you, with one eye, observe an object, and then watch 
it anew with two eyes, you will, if you compare the one with the other 
carefully, recognize that the object is larger, brighter and more full of 
expression, as I already said.  Consequently you can already decide about 
the value of both types of telescopes.

Because we finally know the size and measure of the hyperbolic form which 
is necessary to eliminate the unequal fraction of the lenses (also see the 
learned Descartes), we certainly hope that things which are now 
miraculously hidden in the sky, will be unveiled sometime soon.


(page 354) Instruction VII
About the manufacturing of the binocular tube.
Everything that we have said up to now about the manufacturing of the 
tools, glasses and dishes, leads to this binocular tube and serves it well.  
And it is surely not necessary to add anything but the method and manner of 
how to make a binocular tube and put the lenses within, in their correct 
order.

So, a tube in wider form is constructed so that, when placed in front of 
the eye, it covers both eyes with its large form.  From the upper rim, 
which goes in front of the eye, an arc should be cut out, so that it 
touches the forehead.  At the lower rim it should be caved in, at the 
middle, in similar fashion so that there is room for the nose.  In this way 
the eyes in relation to the convex oculars always have a solid hold and 
keep their position, which has to be totally guaranteed.  Then one of the 
tubes should be provided with its small oval glare shield, as we have 
learned above, this must occur in the binocular tube.  This done, you need 
to have two convex objectives, manufactured in the same dish, with 
completely equal quality, dimension and thickness, and also two oculars 
absolutely equal and also done in the same form.  These are put into the 
tube so that the centers of the ocular glasses coincide with each pupil of 
your eyes, so that the centers are as far apart from each other as one 
pupil is distanced in your eye from the other (which you can easily find 
out with the help of a compass and a mirror).  The two objective lenses 
should be a little closer together, depending on whether the object is 
closer or farther away from the position of the observer.  The farther it 
is, the more the convex objectives in the tube have to be distanced from 
each other, and the closer it is, so the objectives have to be closer, too.
But his can be achieved for each distance of the object more correctly and 
more comfortably with one little cogwheel between both lenses, which is so 
cleverly placed with its teeth at the top and the bottom, with a moveable 
disc, and the toothed protuberances pull them together or push them apart.  
In this way, the convex objectives, fastened to the little disks made of 
brass or other hard material, can easily be distanced or pulled together 
for any distance of the objectives.  And by chance, in this way even the 
distances of the objectives are accurately measured by the eye.
Consequently, the four convex lenses in this binocular tube (or two concave 
and two convex, in the usual way and for the viewing of terrestrial 
objects), have to be positioned so that each of the two light cones, which 
are to be sent through those glasses, from the object side on both sides 
into the eyes, is collected outside the tube in a wider cone and in a 
single focus and so all points of the object are not doubled, but unitedly 
viewed, as also happens with the usual telescopes.
Through such a tube, made by us, we really have seen objects two, three, 
and even four times larger, brighter and clearer, than through the 
monocular tube.  If we had not experienced ourselves what we wrote about, 
we would certainly be ashamed to write something that doesn’t stand up in 
practice.


Conclusion
Remember that plano-convex glasses in longer tubes are superior to biconvex 
ones.  Whether, in hyperbolic optics, this is true for plano-hyperbolics or 
rather for the hyperbolic-hyperbolic, is not yet proved.

Convex-concave oculars (but those where the concave arc has to be ten to 
twenty times larger than the convex) widen the object to be viewed in a 
kind of viewing cone, which is sent through the tube.  If you position two 
convex objectives with identical or different curves in the tube so that 
they can be approached or distanced within the tube (which you can easily 
do by placing one at the outermost, another in the middle of the tube,) 
then you will have to your great joy, ten or twenty tubes of different 
length in one tube, so that, the more you distance the tubes, the larger 
and larger the object will appear, and vice versa.  But note that in such a 
case the ocular glass (the third glass in this case) has also to change its 
distance from the middle convex objective, as experience will show you.  
The same effect is accomplished by replacing the middle convex objective 
with a halfmoon-like objective or a concave-convex.

Objects, reversed by two convex lenses, are uprighted beautifully by three.  
Of course, this through two oculars and one objective, which are placed in 
the correct ratio and distance from each other and to each other.  Such a 
tube is to be used for the things on the earth, but also shows in one view 
nearly a hundred times more space than the concave-convex.





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