ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
103 
place! thi’ough the round aperture D. Thus the arms G H and I H, 
joining the two telescopes, can be contracted or extended. The form 
E F is placed upon H, and both arms G H I are held in place by a small 
nail passing through F and H. There the spiral part B C is placed 
through E. Now, if the head A of the nail A B C be turned this way 
or that, the arms G H and I H, joining the two telescopes, will be con- 
tracted or lengthened. 
‘ XIII. Cases to contain long binocular tubes should bo made of 
strong solid wood and the tubes within so firmly made that they cannot 
bend ; also that the glasses may at any time be taken out and the tubes 
differently placed, so as to be adapted to one vision or another. The 
upper part of the case must be so fitted with clasps that it can be closed 
or opened at pleasure. Long tubes of this kind can be made square 
like oblong beams, and may be made of plates of alloy of silver, lead, 
and iron, joined in several pieces, which can be easily separated from 
each other again. I saw a tube of this kind constructed by P. liheita. 
It was at the Castle of Herbipolensus. 
‘XIV. The longer the binocular the better, but the less convenient. 
How the inconvenience may be remedied I will show. Where these 
tubes are to be used they may be placed on long poles and easily ex- 
tended or contracted. Tubes of this kind are very useful in war for 
viewing the enemy from afar, &c. I have selected the construction of a 
tube of this kind which I have beard P. Rheita used in his wonderful 
binocular telescope, whose lenses were not fitted to tubes, but to a certain 
capsule which could be folded like a pair of bellows. The length of 
this was about ten hands when extended on a pole. They say that it 
made the moon of enormous size, which can easily be believed. The 
manner of constructing this kind of binocular tube is as follows: — In 
the first place, make tubes out of leather folded like paper lanterns, or 
like the leather pipes used by hunters and bird-catchers for alluring 
beasts and birds. Crumpled leather tubes of this kind can be fitted to 
transverse plates, in which are placed the glasses, as in A B C D E F, 
fig. VIII. These plates vary in number according to the length of the 
tube and hold the tubes perfectly straight, and also (since they have holds 
within) transmit to the eye a clear image, as is the case commonly in 
other telescopes. The transverse tablet is shown in G H in the figure. 
Again, that access may be had to the ocular glasses, some part of the 
transverse plate B and C can protrude on either side (as is seen in J K), 
to which are attached the leather tubes after the manner of a capsule. 
When the tubes are to be attached to the pole for use, cords or little 
chains abode are put through all the transverse tablets, and at each 
of these tablets a knot is made, or in some other way the exact length of 
the desired extension is kept. Then nails at a and / fasten the tube to 
the pole and hold it at the desired extension. It can be constructed as 
in M and inclosed in the capsule N (for it must not be kept stretched 
on the pole all the time), and thus conveniently carried about. Instead 
of a pole, a contrivance like that shown in V P can be used, which can be 
extended to any length and again folded together, as in fig. 2, and easily 
carried about ; also one large leather tube holding both telescopes can 
be made, which can be extended at pleasure like a pair of bellows. 
Many of the contrivances might be mentioned for showing the object 
right side up in astronomical binocular tubes, &c.’ 
