drop press (droppres)

A swaging-, stamping-, or forging-machine having either a regular or an intermittent motion. It is e entially a power hammer moving between vertical guides, and delivering a dead-stroke blow either from its own weight or by weight combined with power. In simple machines the weight is raised above the anvil by hand by means of a cord, and let fall; but as these machines are wasteful of labor they have been largely superseded by power-machines, in which the weight is raised by a strap wound over a drum, or by a wooden slat pre ed between two pulleys revolving in opposite directions, or by direct connection with a wrist disk-wheel. The weight is either released at any point of its path by some simple device controlled by a lever within reach of the operator's hand or foot, or it descends by the movement of the disk. If a spring is interposed between the weight and the lifting apparatus, whatever its form, to absorb the recoil, it is called stroke hammer or pre . In the drop-pre es employing a strap or other lifting device that is released at the will of operator, the blows intermittent. Where the connection with a wheel is direct, the blows are regular and uniform so long as the machine works. All things shaped from hot metals on a drop-pre , such as small parts of machines, are called drop - forgings. The drop pre is sometimes called simply pre , and sometimes drop-hammer. It should not be confounded with the stamping-pre , which, while it is allied to the drop-pre , differs e entially in its manner of working. n. In photog., a device for rendering the exposure of a plate in a camera very brief: used in instantaneous photography. The most simple form, also known as the guillotine shutter, and the one that gives a name to all other appliances of the kind, consists of two opaque pieces, each pierced with a hole, and arranged to slide one over the other. One of the pieces is fitted over the lens-tube, and when the openings in the two pieces are in line, the shutter admits light to the camera. When it is desired to make a very short exposure, the movable slide is raised till the opening of the tube is closed. On letting the slide fall, the opening in it pa es before that in the fixed piece, and for an instant light is admitted to the plate behind the lens. To accelerate the fall of the slide, various devices are used, as springs or elastic bands. Improved drop-shutters have the form of revolving disks actuated by springs, etc., or that of flap-shutters controlled by a pneumatic device, etc.; and in many the opening is made to take place eccentrically, or the holes in the shutters are cut of various shapes, with the object of distributing the light, and giving a greater volume of light to the foreground or the lower portion of the picture, which is naturally not so well lighted as the higher portions. dropsical (drop'si-kal), a. [ dropsical ne (drop'si-kal-nes), n. The state of being dropsical. Bailey , 1727. dropsied (drop's id), a . [ dropsy + -ed2.] Dis- eased with dropsy; unnaturally swollen; ex- hibiting an unhealthy inflation. Where great additions swell, and virtue none, It is a dropsied honour. IMG:content-0019.png:[blocks in formation] But the sad Dropsie freezeth it extream, Till all the blood be turned into fleam. Sylvester, tr. of Du Bartas's Weeks, ii., The Furies. 2. In bot., a disease in succulent plants caused by an exce of water.-3. In fish-culture, a disease of young trout. Before the food-sac is gone the trout are affected with a swelling over the sac, where a membrane forms, swells out, and is filled with a watery substance. An incision is sometimes made in the swelling to let out the water. Also called blue swelling. drop-table (drop'ta "bl), n. A machine for lowering weights, and especially for removing the wheels of locomotives. drop-the-handkerchief (drop'the-hang'kerhaving a handkerchiefrihe chif), n. A game player of the others, who are formed in a ring, and tries to escape within the ring before being ki ed.