CIR 



IR 



Vve are at a loss for the just proportion 

 betvreen the diameter and circumference 

 of a circle. 



Archimedes is the person who has come 

 nearest the truth ; all the rest have made 

 paralogisms. Charles V> offered a re- 

 ward of 100,000 crowns to the person 

 who should solve this celebrated pro- 

 blem ; and the States of Holland have 

 proposed a reward for the same pur- 

 pose. 



CIRCLE, great, of the sphere, that which, 

 having its centre in the centre of the 

 sphere, divides it into two equal hemi- 

 spheres ; such are the equator, ecliptic, 

 horizon, the colures, and the azimuths, 

 &c See EQ.UATOR, ECLIPTIC, &c. 



CIRCLE, lesser, of the sphere, that which, 

 having its centre in the axis of the sphere, 

 divides it into two unequal parts : these 

 are usually denominated from the great 

 circles to which they are parallel, as pa- 

 rallels of the equator. 



CIRCLE of curvature, a circle, the curva- 

 ture of which is equal to that of a certain 

 curve at a given point. 



CIRCLE, horary, on the globe, a brazen 

 circle fixed on every globe, with an index, 

 to shew how many hours, and consequent- 

 ly how many degrees, any place is east or 

 west of another. 



CIRCLE of perpetual apparition, one of 

 the lesser circles, parallel to the equa- 

 tor, described by any point touching the 

 northern point of the horizon, and car- 

 ried about with the diurnal motion : all 

 the stars included within this circle are 

 always visible above the horizon. 



CIRCLE of perpetual occultation, another 

 circle at a like distance from the equa- 

 tor, on the south, containing all those 

 starsr which never appear in our hemi- 

 sphere. 



CIRCLES, diurnal, are immoveable cir- 

 cles, supposed to be described by the se- 

 veral stars and other points of the hea- 

 vens, in their diurnal rotation round the 

 earth ; or, rather, in the rotation of the 

 earth round its axis. 



CIRCLES of latitude, or secondaries of the 

 ecliptic, are great circles perpendicular to 

 the plane of the ecliptic, passing through 

 the poles of it, and through every star 

 and planet. They serve to measure the 

 latitude of the stars, which is an arch of 

 one of those circles intercepted between 

 the star and the ecliptic. 



CIRCLES of longitude, are several lesser 

 circles parallel to the ecliptic, still dimi- 

 nishing in proportion as they recede 

 from it ; on these the longitude of the 

 -.tars is reckoned, 



CIRCLES of declination, on the globe, 

 are, with some writers, the meridians on 

 which the declination or distance of any 

 star from the equinoctial is measured. 



CIRCLES, horary, in dialling, are the 

 lines which shew the hours on dials, 

 though these be not drawn circular, but 

 nearly straight. 



CIRCLES, polar, are parallel to the equa- 

 tor, and at the same distance from the 

 poles that the tropics are from the equa- 

 tor. See ARCTIC. 



CIRCLES of position, are circles passing 

 through the common intersections of the 

 horizon and meridian, and through any 

 degree of the ecliptic, or the centre of 

 any star, or other point in the heavens ; 

 and are used for finding out the situation 

 or position of any star. 



CIRCLES, Dmidical, a name given to 

 certain ancient inclosures, formed by 

 rude stones circularly arranged. These, 

 it is supposed, were temples, or places 

 for solemn assemblies for councils, or 

 seats of judgment. These tern pies, though 

 generally circular, occasionally differ in 

 magnitude. The most simple were com- 

 posed of one circle. Stonehenge consist- 

 ed of two circles and two ovals, respec- 

 tively concentric. One near St. Just, in 

 Cornwall, is formed of four intersecting 

 circles. In magnitude these differ very 

 much : some are formed of only 12 stones, 

 while others, as Stonehenge and Abury, 

 contained, the first 140, and the second 

 652, and occupied many acres of ground. 

 These different numbers, measures, and 

 arrangements, are supposed to have had 

 reference, either to the astronomical di- 

 visions of the year, or some mysteries of 

 the Druidical religion. 



CIRCUIT, in electricity, denotes the 

 course of the electrical fluid from the 

 charged surface of an electric body to the 

 opposite surface on which the discharge 

 is made. 



CIRCUIT, in law, signifies a longer 

 course of proceedings than is needful to 

 recover the thing sued for : in case a per- 

 son grants a rent charge of 101. a year 

 out of his manor, and afterwards the 

 grantee disseises the grantor, who there- 

 upon brings an assise, and recovers the 

 land, and 20J. damages; which being 

 paid, the grantee brings his action for 

 IOL of the rent, due during the time of 

 the disseisin : this is termed circuity of 

 action, because, as the grantor was to 

 receive 201. damages, and pay 10/. rent, 

 he might only have received the Wl. 

 for the damages, and the grantee 

 might have retained the other 10A for 



