a town of Somersetshire, in England, on the north-east side of Wincanton, where Kenwald a West Saxon king so totally defeated the Britons, that they were never after able to make head against the Saxons; and where, many ages after this, Edmund Ironside gained a memorable victory over the Danes, who had before, i.e. in 1001, defeated the Saxons in that same place.

little instrument, usually formed of a quill, serving to write withal.

Pens are also sometimes made of silver, brass, or iron.

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

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

The fountain pen is composed of several pieces. The middle piece, fig. 1, carries the pen, which is screwed into the inside of a little pipe, which again is soldered to another pipe of the same bigness as the lid, fig. 2, in which lid is soldered a male screw, for screwing on the cover, as also for stopping a little hole at the place and hindering the ink from palling through it. At the other end of the piece, fig. 1, is a little pipe, on the outside of which the top-cover, fig. 3, may be screwed. In the cover there goes a port-crayon, which is to be screwed into the last-mentioned pipe, in order to stop the end of the pipe, into which the ink is to be poured by a funnel. To use the pen, the cover fig. 2, must be taken off, and the pen a little shaken, to make the ink run more freely.

There are, it is well known, some instruments used by practical mathematicians, which are called pens, and which are distinguished according to the use to which they are principally applied; as for example, the drawing pen, &c. an instrument too common to require a particular description in this place. But it may be proper to take some notice of the geometric pen, as it is not so well known, nor the principles on which it depends so obvious.

The geometric Pen is an instrument in which, by a circular motion, a right line, a circle, an ellipse, and other mathematical figures, may be described. It was first invented and explained by John Baptist Suardi, in a work intitled Nuovo Instrumenti per la Descrizione di diverse Curve Antiche e Moderne, &c. 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 first reduced it to practice. It has been lately introduced with success into the steam-engine by Watt and Bolton. The number of curves this instrument can describe is truly amazing; the author enumerates not less than 1273, which (he says) can be described by it in the simplest form. We shall give a short description of it from Adam's Geometrical and Graphical Essays.

Fig. 1 represents the geometric pen; A, B, C, the stand by which it is supported; the legs A, B, C, are contrived to fold one within the other for the convenience of packing. A strong axis D is fitted to the top of the frame; to the lower part of this axis any of the wheels (as i) may be adapted; when screwed to it they are immovable. EG is an arm contrived to turn round upon the main axis D; two sliding boxes are fitted to this arm; to these boxes any of the wheels belonging to the geometric pen may be fixed, and then slid so that the wheels may take into each other and the immovable wheel i; it is evident, that by making the arm EG revolve round the axis D, these wheels will be made to revolve also, and that the number of their revolutions will depend on the proportion between the teeth. FG is an arm carrying the pencil; this arm slides backwards and forwards in the box cd, in order that the distance of the pencil from the centre of the wheel h may be easily varied; the box cd is fitted to the axis of the wheel h, and turns round with it, carrying the arm fg along with it; it is evident, therefore, that the revolutions will be fewer or greater in proportion to the difference between the numbers of the teeth in the wheels h and i; this bar and socket are easily removed for changing the wheels. When two wheels only are used, the bar fg moves in the same direction with the bar EG; but if another wheel is introduced between them, they move in contrary directions.

"The number of teeth in the wheels, and consequently the relative velocity of the epicycle or arm fg, may be varied in infinitum. The numbers we have used are 8, 16, 24, 32, 49, 48, 56, 64, 72, 80, 88, 96.

"The construction and application of this instrument is so evident from the figure, that nothing more need be pointed out than the combinations by which various figures may be produced. We shall take two as examples:

"The radius of EG (fig. 2) must be to that of fg as 10 to 5 nearly; their velocities, or the number of teeth in the wheels, to be equal; the motion to be in the same direction.

"If the length of fg be varied, the looped figure delineated at fig. 3 will be produced. A circle may be described by equal wheels, and any radius but the bars must move in contrary directions.

"To describe by this circular motion a straight line and an ellipse. For a straight line, equal radii, the velocity as 1 to 2, the motion in a contrary direction; the same data will give a variety of ellipses, only the radii must be unequal; the ellipses may be described in any direction." See fig. 4.

Penstock. See PENSTOCK.

Sea-Pen. See PENNATULA, HELMINTHOLOGY Index.