CYC 



CYC 



and z. It is geometrical when its equation 

 is algebraic, and expressed in finite terms ; 

 and mechanical, when the equation is 

 not algebraic, but diflferential. 



CUS P {cuspis, a point). In Geometry, 

 the point where two parts of a curve 

 meet and terminate. In Astronomy it 

 denotes the tip or horn of the crescent 

 of the moon. In an eclipse of the sun, 

 the borders of the sun and moon make 

 two cusps at their point of intersection. 



CU'SPIDATE {cuspis, a spear). Spear- 

 shaped; tapering to a stiflf point; ab- 

 ruptly acuminate; a term applied to 

 leaves. 



CUTICLE (dim. of cutis, skin). In 

 Botany, a thin homogeneous membrane, 

 external to the epidermis, formed of or- 

 ganic mucus, and overlying every part 

 of plants, except the stomates and the 

 stigmatic tissue. 



CY'ANIC ACID. A volatile, corrosive 

 acid, procured from cyanogen, existing 

 only in combination. It is converted 

 spontaneously into a white solid matter 

 called cyamelide. 



CY'ANITE [Kvavo^, blue). Disthene. 

 A mineral occurring in the granite and 

 mica- slate of primitive mountains, and 

 used in India as an inferior kind of sap- 

 phire. Its principal colour is Berlin- 

 blue, which passes into grey and green. 



CY'ANO- {Kuavoi, blue). A Greek 

 term, denoting a clear bright blue colour. 



CYAN'OGEN {Kvavoi, blue, yewdu, to 

 generate; so called from its being an 

 essential ingredient in Prussian blue). 

 Bi-carburet of nitrogen ; a gas. It forms, 

 with oxygen, the cyanic, cyanous, and 

 fulminic acids; and with hydrogen, the 

 hydro-cyanic, or prussic. All its com- 

 pounds, which are not acid, are termed 

 cyanides or cyanurets. 



CYANO'METER (Kvavof , blue, fxerpov, 

 a measure). An instrument invented by 

 Saussure, for comparing the different 

 shades of blue in order to determine the 

 deepness of the tint of the atmosphere. 



CY'ATHIFORM {cyathus, a drinking- 

 cup, forma, likeness). Cup-shaped; as 

 applied to the form of certain corollas. 



CYCADA'CEiE. A family of Gymno- 

 spermous plants, named from the genus 

 cycas, and consisting of trees, with a 

 cylindrical trunk, increasing by a single 

 terminal bud. 



CYCLE (k«5k\op, a circle). A certain 

 period of time, in which the same revolu- 

 tions begin again ; a periodical space of 

 time. 



1. Cycle of the Sun. A revolution of 



twenty-eight years, at the expiration of 

 which the days of the months return 

 again to the same days of the week; the 

 sun's place to the same signs and degrees 

 of the ecliptic on the same months and 

 days, so as not to diflfer one day in 100 

 years ; and the same order of Leap-years 

 and of Dominical Letters returns ; hence 

 it is also called the Cycle of the Sunday 

 Letter. 



2. Cycle of the Moon. A revolution of 

 nineteen years, after which the various 

 aspects of the moon are, within an hour, 

 the same as they were on the same days 

 of the month nineteen years before. This 

 cycle was adopted on the 16th of July, 

 B.C. 433, by Meton, whose name it also 

 bears. 



3. Cycle, Paschal. The cycle of the 

 Sun consists of twenty-eight, and the 

 cycle of the Moon of nineteen years; 

 these cycles, multiplied by each other, 

 form a third, which is called the Paschal 

 Cycle, because it serves to ascertain when 

 Easter occurs. At the end of a revolu- 

 tion of 532 years, the two Cycles of the 

 Moon, the Regulars, the Keys of the 

 Moveable Feasts, the Cycle of the Sun, 

 the Concurrents, the Dominical Letters, 

 the Paschal Term, Easter, the Epacts, 

 with the New Moons, recommence as 

 they were 532 years before, and continue 

 the same number of years. 



4. Cycle, EcUptical. An unknown pe- 

 riod of time during which the angle be- 

 tween the ecliptic and the equator, con- 

 stituting the obliquity of the ecliptic, has 

 completed all its changes. The present 

 rate of diminution of the obliquity is 

 estimated at about 48 seconds of a degree 

 every century. 



CY'CLICA {kvkXo^, a circle). A section 

 of Coleopterous insects, with bodies of 

 a rounded or oval form. According to 

 Latreille, they constitute a subsection of 

 the section Tetramera. 



CY'CLINiE. A sub-family of the 

 Tellinidae, or Solid and Closed Bivalves, 

 named from the genus cyclas ; these 

 animals are generally fluviatile, and have 

 their shells covered by an epidermis. 



CY'CLOBRANCHIA'TA {kvkXo^, a 

 circle, /3pa7X'a> gills). An order of Gas- 

 teropods, in which the branchia form a 

 fringe around the body of the animal, 

 between the edge of the body and the 

 foot. The order consists principally of 

 the limpets. 



CYCLO-GANGLIATA (kiJkXop, a cir- 

 cle, 'yaffXiov, a nerve-knot). A terra 

 applied by Dr. Grant to the fourth sub- 



