TANACETUM, TANSEY; a genus of the polygamia æqualis order, belonging to the syngenesia class of plants. There are eight species; the most remarkable of which is the vulgare, or common yellow tansey, which grows naturally on the borders of fields and on dry banks in many places of Scotland and England. The stalk is three or four feet high, erect, stiff, and branched; the flowers are yellow, and terminate the branches in flat umbels. It has a bitter taste and aromatic smell. It is esteemed good for warming and strengthening the stomach; for which reason the young leaves have obtained a place among the culinary herbs, their juice being an ingredient in puddings, &c. It is rarely used in medicine, though extolled as a good emmenagogue. A drachm of the dried flowers has been found very beneficial in hysterical disorders arising from suppressions. The seeds and leaves were formerly in considerable esteem for destroying worms in children, and are reckoned good in cholics and flatulencies. In some parts of Sweden and Lapland, a bath with a decoction of this plant is made use of to assist parturition.
TANGENT of an ARCH, is a right line drawn perpendicularly from the end of a diameter, passing to one extremity of the arch, and terminated by a right line drawn from the centre through the other end of that arch, and called the secant. See GEOMETRY.