Looked at from its practical side, a brooch is a contrivance for fastening together temporarily any two points on a garment. It is obviously a higher development of the pin. Going back to first principles, the pin may have been suggested by the natural spikes, or thorns, found in the vegetable world. It would not require much intelligence to see that a small knob added to the blunt end of the pin would facilitate its removal from the fabric when it was required to be withdrawn, and would also prevent the pin going further than was desirable through the fabric. The problem which was solved by the invention of the brooch, however, was one of much greater complexity, namely, how to secure the pin in position so as to prevent it from slipping out of the fabric in the direction of the head. This might have been effected either by fixing a removable knob, or stop of some kind, on the pointed end after it had been inserted in the fabric, or by connecting the head with the point temporarily, so as to form a complete ring for the time being. In the brooch the latter alternative is chosen. The pin must necessarily be straight, so as to pierce the fabric with the least amount of resistance, and the temporary connection between the head and the point has to be approximately semicircular, the whole forming a ring shaped like a bow, the pin corresponding to the string and the body of the brooch to the bow. [Illustration: SILVER PENANNULAR BROOCH FROM IRELAND; NOW IN THE BRITISH MUSEUM SCALE ¾ LINEAR] In order to be able to remove the brooch from the fabric at pleasure, some contrivance must be hit upon by which a gap, or break, can be made in the ring, and be closed up again whenever it is desired to do so. The opening is attained by placing a hinge where the head of a pin joins the body of the brooch, and the closing by having a groove-shaped catch at the opposite extremity. A spring is also required to prevent the pin coming unfastened accidentally from the catch. These different contrivances constitute the essential parts of a brooch, which, divested of its ornamental appendages, is represented by the ordinary “safety-pin” of the present day. If the rigid bow-like connection between the head and point of the pin be doubled we get an annular brooch, and if the central portion of the ring be filled in we get the discoidal brooch. In these cases the ring or disc is placed parallel to the plane of the fabric instead of at right angles to it.