COMPENDIOUS ASTROSCOPY.

it is also enclosed in a tube or short cylinder; it is likewise joined to a rod or tail, which furthermore has its own sphere upon which it rests. But in place of this, a small transverse axle can be used. A small weight is again appended below the rod, as much as is necessary to create the balance. Furthermore, the handle, which carries the sphere or axle, is grasped by the hand of the observer; the rod is directed toward the larger lens positioned high above, and tied to the same thread that descends from it. When the hand is moved and the thread is lightly taut, it is clear that the lenses become parallel to each other. But the thread is not attached to the extreme part of this rod in the same way as it is to the upper one, which directs the larger lens; rather, it is passed through a hole and then wrapped around a spindle, of the kind used to tune the strings of a lute; this spindle is fixed to the side of the middle of the rod. By turning this, during observation, the length of the thread is lengthened or shortened until the interval between the two lenses exactly suits the eye of the spectator, after it has previously been found near the true distance, which is very easy.

Furthermore, so that the observer can keep the lens closest to him motionless, which is especially necessary, a certain fulcrum made of light material is at hand, resting on two feet, and having a crossbar at its upper part upon which both arms, whether standing or sitting, may rest, while he supports the lens with the other hand. This method is much more expeditious and better suited to use than if a third leg were added to the fulcrum and the eyepiece lens were placed upon it.

So that stars may be easily found by our telescope at night and in the darkness, we use a light enclosed in a lantern, such as are now commonly known, projecting light far by the work of a convex lens or mirror. When its rays are directed to the mast and the lens sticking to it, once the circle containing it is sighted, the view is easily transferred so that the star is covered by the lens itself, and at the same time, with the smaller lens moved into place, it presents itself to be viewed through both. And truly, this is accomplished much more quickly than has been done hitherto with telescopes equipped with tubes. So much so that this new method of observing is far superior for this reason as well. For those wishing to contemplate the Moon, there is no need for a lantern, because the lens can be viewed by the light of the star itself...