CALYX (a term originally Greek), in botany, the outermost of the circles of modi fied leaves which surround the parts of fructification, and along with them constitute the flower. Within the C. there is generally at least a second circle of leaves, called the corolla (see COROLLA and FLowfai.); but this is sometimes wanting, and the C. is the only envelope of the parts of fructification. The leaves of which the C. is com posed are called sepals, when quite separate from each other; but they often grow together into a tube at the base, and the C.is then said to be monosepalous orgamosepalous (mono; one; gamos, union). The sepals are generally simple and without stalks; they are generally green, and differ much less widely from ordinary leaves than the petals or leaves of the corolla; sometimes, however, they are petaloid, and brightly colored, as in fuchsia. The C. and corolla of many endogenous plants resemble one another almost completely, and the common term perianth (q.v.) is then very generally employed. In some plants, the C. passes insensibly into the corolla, and it is not easy to distinguish the innermost sepals from the outermost petals. The C. is in such cases often com posed of more circles of leaves than one. The C.* occasionally falls off when flowering is over (deciduus), as in ranunculus; sometimes even when it commences (carlucolls), as in the poppy; generally it remains till the fruit is ripe (persistent), and is then much enlarged and more brightly colored, as in physalis. It often becomes fleshy, and forms the seeming fruit, as in the rose.—The glumes (q.v.) of grasses, etc., used to be regarded as a C., to which, however, they have no proper analogy.
CAM, or GRAISTA, a river of England, which, rising in Essex, flows n.e. through Cambridgeshire, and after a course of about 40 m., joins the Ouse 3+ m. above Ely. It gives its name to the town of Cambridge, which stands upon it, and below which it is navigable, and is classic on account of the boat-races on it by Cambridge students.
CAM, in machinery, a curved plate or groove, by which motion is communicated and controlled. The moving plate or groove is a driver; the rod, bar, or other thing moved, is called the follower. The follower is held against the driver by its weight or by a spring, or other device. The radii of the driver determine by their length the motion of the follower, and the angles which they make with some one, chosen as a base of calculation, fix the time at which change of motion occurs. For example, it may be desired that the follower shall move upward, and then downward, with a uni form velocity. From the center of the driver any convenient number of radii may be drawn, dividing equally the 360° of angular space. On one of these radii we mark the distance from the center of the driver at which the point of the follower will stand when in its position nearest to that center. Upon the opposite radius, distant 180° from the
first, the point is marked which gives the farthest position of the follower; the differ ence between these radii being divided into as many equal parts as we have made angu lar spaces in the 180°, we increase the length of each radius in succession, beginning with the shortest, by one of those parts, and we draw a curve connecting the ends of the radii so terminated. Of course the greater the number of parts chosen for the division of the angular space and of the difference of the first and last radii, the more accu rately will the curve be drawn. of the driving-plate being cut to this curve, the follower being made to press constantly,against it, and the driver being turned with a uniform rotation, the follower will move through its limited space with an equable motion, because the radii of the driver increase by constant amounts, at constant inter vals of time. If the curve is reversed, the second part being the symmetrical oppo site of the first part, the follower will descend as uniformly as it rose. The cam thus drawn is one of frequent use, and is called the heart-shaped cam. To avoid friction the end of the follower often carries a roller which works against the surface of the cam; in this case the cam-surface is found by drawing a line parallel to that above described, at a constant distance equal to the radius of the roller. If we wish the fol lower to rest at any part of a cycle of motion, the radii for that time will be made equal, and the corresponding cam-surface will be a circular arc; the time will be such a part of that of a complete cycle, as the angle between the radii of the ends of this arc, is of 360°. The cam-plate has sometimes a groove cut upon its flat side, and the end of the follower runs in the groove. A spiral groove may be cut into the surface of a cylin der as in a screw; if a follower be inserted in this groove it trill be driven forward as the cylinder turns; when the groove reaches the end of the cylinder, it may turn back, and cause the follower to return with the same motion, or if the pitch of the groove be made shorter or longer, the return of the follower will be changed accordingly. By a judicious construction and arrangement of cams, almost every variety of motion may be produced with the greatest precision as to time and amount. A cam-form which does not make a complete revolution, but after moving a short distance in one direction oscillates in the opposite direction, is called a wiper. familiar example may be seen in the engine-room of a steamboat, in the rocking arms which raise and let fall the valve rods.
CAM, Di000, a Portuguese navigator of the 15th c., who continued the w. African discoveries commenced by Don Henry. He had sufficient influence with the king of Congo to induce that monarch to permit the establishment of Christianity in his dominion.