Christiani Hugenii Const. F. Astroscopia Compendiaria, Tubi Optici molimine liberata

A decorative headpiece features a central human face surrounded by floral and foliate scrollwork.

TO THE READER.

A decorative drop cap 'V' features floral motifs.Our new Astroscopia astroscopy; the art of observing the stars seemed already complete and perfect in all respects; it had been printed, yet not yet published, when, as often happens, second thoughts occurred to us regarding certain ways in which it might be made better and more convenient. Since it seemed appropriate to append these here in the manner of a supplement, we advise that, as these were discovered later, they should be read last, after the rest of the description and illustration has been grasped.

When we first found spectators for our invention who were less accustomed to telescopic pertaining to a spyglass or telescope observations of the planets, experience taught that they indeed found it more difficult to locate a star by themselves, just as used to happen before, when they chanced upon larger tubes. However, the usual practice here—whereby the star is first found and, while the tube remains fixed, the spectator simply brings their eye to it—could not be imitated by us now, as the lens closest to the eye, when it was fastened, had no support. Therefore, we have now provided for this matter in a different way, as follows.

The support we prepared for the observer, upon which their arms may rest, has a square transverse beam on its upper part, two feet long. Above this, we placed another similar beam, but twice as short, parallel to it, though set a finger’s width apart from the first. Furthermore, we had a rule made, one foot in length, three fingers in width, and half a finger in thickness, in which a small channel or slot was carved, again one finger wide; this does not run the whole length of the rule, but leaves four fingers of space at one end. Within this space, one side is slightly hollowed out so that the handle made of brass sheet, which holds the ocular lens, can be conveniently inserted there; it is necessary that this be flat and straight, as is customary. Furthermore, with the rule erected and applied to the upper support, and a wooden screw passed through both slots—which is inserted on the other side into a small disk—the rule is tightened by turning this disk. Thus, the lens placed there is fixed in the position it occupied when the view of some star was attained. Then the spectator is easily assisted and steps into the place of the one who found it, enjoying the same view. For the thread connecting each lens ensures that the support maintains its position, even if it rests on only two feet.

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