CEN 



CEP 



touches the cogs of another in a vertical 

 position ; so that by the aid of a double 

 winch, the whole machine is moved round 

 with very great velocity. Near the bot- 

 tom of the perpendicular part of the tube 

 is a valve opening upwards ; and near the 

 two extremities, but on the contrary sides 

 of the arms, or cross part of the tube, are 

 two other valves opening outwards. These 

 two valves are kept shut, by means of 

 springs, till the machine is put in motion, 

 when the centrifugal velocity of the wa- 

 ter forces them open, and discharges it- 

 self into a cistern or reservoir placed 

 there for that purpose. On the upper 

 part of the arm are two holes, which are 

 closed by pieces that screw into the metal 

 of the tube. Before the machine can work, 

 these holes must be opened, and water 

 poured in through them, till the whole 

 tube be full : by these means all the air 

 will be forced out of the machine, and 

 the water supported in the tube by means 

 of the valve at the bottom. The tube 

 being thus filled with water, and the 

 holes closed by their screw-caps, it is 

 turned round by the winch, when the 

 water in the arms of the tube acquires 

 a centrifugal force, opens the valves near 

 the extremities of the arms, and flies out 

 with a velocity nearly equal to that of the 

 extremities of the said arms. 



If the men who work the machine be 

 supposed to turn the winch round in three 

 seconds, the machine will move round its 

 axis in one second ; and, consequently, 

 each extremity of the arms will move 

 with a velocity of 18.8 feet in a second. 

 A column of water, therefore, of three 

 inches diameter, will issue through each 

 of the valves with a^ velocity of 18.8 feet 

 in a second ; but the area of the aperture 

 of each of the valves is 7. 14 inches; which, 

 being multiplied by the velocity in inches 

 = 125. 6, gives 1610.784 cubic inches, the 

 quantity of water discharged through one 

 . of the apertures in one second ; so that 

 the whole quantity discharged in that 

 space of time through both the apertures 

 is = 3221.568 inches ; or 193294.08 cubic 

 inches in one minute. But 6U812 cubic 

 inches make a tun, beer-measure ; con- 

 sequently, if we suppose the centrifugal 

 machine to revolve round its axis m one 

 second, it will raise nearly 3 tuns 44 gal- 

 lons in one minute ; but this velocity is too 

 great, at least to be maintained for any 

 considerable time ; so that, when this 

 and other deficiencies in the machine 

 are allowed for, two tuns are nearly the 

 quantity that can be raised by it in one 

 minute. As the water is forced up the 



perpendicular tube by the pressure of 

 the atmosphere, it is evident that this 

 machine cannot raise water above thirty- 

 two feet high. 



CENTRIPETAL force, that force by 

 which a body is every where impelled, or 

 any how tends towards some point as a 

 center; such is gravity, or that force 

 whereby bodies tend towards the center 

 of the earth ; mag'uetical attraction, 

 whereby the load-stone draws iron ; and 

 that force, whatever it be, whereby the 

 planets are continually drawn back from 

 right-lined motions, and made to move in 

 curves. 



The greater the quantity of matter in 

 any body is, the greater will be its centri- 

 petal force, all things else alike. If a 

 body laid upon a plane revolve at the same 

 time, and about the same center with that 

 plane, and so describe a circle ; and if the 

 centripetal force, wherewith the body is 

 drawn every moment towards the center, 

 should cease to act, and the plane should 

 continue to move with the same velocity, 

 the body will begin to recede from the 

 center about which the plane moved. See 

 CE \TIIAL for ces. 



CENTRISCUS, in natural history, a 

 genus of fishes, ranked among the bran- 

 chiostegous order of Linnaeus, but by Dr. 

 Shaw among the Cartilagenei. Generic 

 character : snout lengthened ; body com- 

 pressed, carinated beneath ; ventral fins 

 united. There are but three species ; 

 viz. the scutatus, scolopax, and the veli- 

 taris. All are found in the Indian seas, 

 and the scolopax is likewise a native of 

 the Mediterranean. 



CENT ROG ASTER, in natural history, 

 a genus of fishes of the order Thoracici. 

 Generic character; head compressed, 

 smooth ; gill-membraned, mostly seven 

 rayed ; body depressed, smooth ; fins spi- 

 nous ; ventral connected by a membrane, 

 with four sharp spines, and six soft rays. 

 There are four species. 



CENTUNCULUS, in botany, a genus 

 of the Tetrandria Monogynia class and 

 order. Natural order of Rotacese. Lysi- 

 machiae, Jussieu. Essential character : 

 calyx four-cleft ; corol four-cleft, spread- 

 ing: stamina short ; capsules one-celled, 

 opening horizontally. There is but one 

 species, viz. C. minimus, bastard pimper- 

 nel, is an annual, and a native of Italy, 

 France, Germany, and Denmark with us 

 on Hounslow-heath, Ashibrd-common, 

 near Hampton Court, Chiselhurst; &c. It 

 flowers from June to August. 



CEPHAELIS, in botany, a genus of 

 the Pentandria Monogynia class and or- 



