a little instrument, usually formed of a quill, and serving to write withal. But pens are sometimes made of silver, brass, or iron.

Dutch Pens are made of quills which have passed through hot ashes, to take off the grosser fat and moisture, and render them more transparent.

Fountain Pen is a pen of silver, brass, or other metal, so contrived as to contain a considerable quantity of ink, and let it flow out by degrees, to supply the writer a long time without his being under the necessity of taking fresh ink.

The Geometric Pen is an instrument by which a right line, a circle, an ellipse, and other mathematical figures, may be described by a circular motion. It was first invented and explained by Suardi, in a work entitled Nuovo Instrumento per la Descrizione di diverse Curve antiche e moderne. Several writers had observed the curves arising from the compound motion of two circles, one moving round the other; but Suardi first realized the principle, and reduced it to practice.