Scripta clarissimi mathematici M. Ioannis Regiomontani, de torqueto, astrolabio armillari, regula magna ptolemaica, baculo[que] astronomico, & observationibus cometarum, aucta necessariis, Ioannis Schoneri ... additionibus. Item observationes motuum solis, ac stellarum tam fixarum [qua ...] erraticarum. Item libellus M. Georgii Purbachii de quadrato geometrico ...

but I refrained, lest the crowd of technical terms weary the mind of the reader, who is perhaps far removed from affairs of this kind. This is especially true since I desire to present this work, produced with my own hands, to that prince to whom this little writing of ours is directed, and to whom we are perpetually indebted for what we are and whatever we are able to do. We shall, however, explain the use of such a distinguished organ, omitting its mechanical description, most accurately if its parts are first marked with suitable names. Therefore, this remarkable machine has long been called the Torquetum, from the word torquendo twisting/turning, as I suspect, because the celestial figure represented by this image is not seen as a whole or extended in the form of a sphere in every direction, as in the annular astrolabe, but consists of circles gathered and twisted into a certain flat shape. For nothing can be borrowed from the word torques necklaces/collars regarding the etymology, since it neither preserves a similarity to the thing nor a sufficient derivation of the name. It should perhaps have been called Torquatus if room were given to grammatical formulas. However, whether Torquetus is legitimately derived from torquendo or not is of little concern to us, as we do not profess the task of a grammarian at present. We shall therefore use the ancient name as if it were a fortuitous one, so that we may not seem to have despised the antiquity that is the parent of the good arts. The foundation of the Torquetum is a quadrangular board, which we shall call the Horizontal Board, because it is destined to perform the functions of the horizon everywhere. A certain straight line cuts through its center, which shall be called the Meridian. Finally, another quadrangular board adheres to this, which we shall call the Equinoctial Board, because it is held as if it were a fixed equinoctial, and it must be raised in every region according to the position of the equinoctial circle which is in the heavens. On the face of this board, a circle is divided into three hundred and sixty degrees, as is customary, and letters are added to count the equal hours; this circle will not unjustly be called the equinoctial circuit. Attached to this board again is the equinoctial circle, on whose rim a small tooth projects, which may be called the equinoctial index.