his rent, and by that means saved his 

 action. 



CIRCUIT also signifies the journey, or 

 progress, which the judges take twice 

 every year, through the several counties 

 of England and Wales, to hold courts 

 and administer justice, where recourse 

 cannot be had to the King's courts at 

 Westminster ; hence England is divided 

 into six circuits, viz. The home circuit, 

 Norfolk circuit, Midland circuit, Oxford 

 circuit, Western circuit, and Northern 

 circuit. In Wales there are but two cir- 

 cuits, North and South Wales. Two 

 judges are assigned by the King's com- 

 mission to every circuit. In Scotland 

 there are three circuits, viz. the Southern, 

 Western, and Northern, which are like- 

 wise made twice every year, viz. in 

 spring and autumn. 



CIRCULAR lines, in mathematics, such 

 straight lines as are divided from the 

 divisions made in the arch of the 

 limb, such as sines, tangents, secants, 

 chords, &c. 



CIRCULAR numbers, called also spheri- 

 cal ones, according to some, are such 

 whose powers terminate in the roots 

 themselves. Thus, for instance, 5 and 6, 

 all whose powers do end in 5 and 6, as 

 the square of 5 is 25, the square of 6 is 

 36, &c. 



CIRCULATION of the blood, the natu- 

 ral motion of the blood in a living ani- 

 mal, whereby that fluid is alternately car- 

 ried from the heart to all parts of the 

 body by the arteries, and returned from 

 the same parts to the heart, by the veins. 

 See PHYSIOLOGY. 



CIRCUMFERENCE, in a general 

 sense, denotes the line or lines bounding 

 A plane figure. However, it is general- 

 ly used^in a more limited sense, for the 

 curve line which bounds a circle, and 

 otherwise called a periphery ; the boun- 

 dary of a right lined figure being ex- 

 pressed by the term perimeter. 



The circumference of every circle is 

 supposed to be divided into 360 degrees. 

 The angle at the circumference of a cir- 

 cle is double that at the centre. For the 

 ratio of the circumference of a circle to 

 jts radius, see CIRCLE. 



CIRCUMFERENTOR, a mathemati- 

 cal instrument, used by land-surveyors 

 for taking angles by the magnetic nee- 

 dle. It is an instrument (where great 

 accuracy is not desired) much used in 

 surveying, in and about woodlands, com- 

 mons, harbours, seacoasts, in the work- 

 ing of coal-mines, &c. &c. where a per- 

 manent direction of the needle is of the 



must material consequence in surveying' 

 The instrument is made of brass, and, in 

 its most simple state, consists of the fol- 

 lowing parts ; a brass compass box, about 

 five inches diameter, or more ; on the 

 plate of the box are engraved and letter- 

 ed the principal points of the compass, 

 divided into four quarters of 90 degrees 

 each, two of the quarters being ligured 

 from the south point, and terminated by 

 90 degrees at the east and west ; and the 

 other two quarters from the north point, 

 terminating also at the east and west : on 

 the circumference of the plate is fixed a 

 ring, divided into 360 degrees, number- 

 ed from to 360; the observer may 

 therefore take his angles as bearing- 

 from the north and south towards the 

 east and west ; or, by that which is the 

 most usual method, the whole circum- 

 ference of a circle of 360 degrees, com- 

 mencing from the north point : a magnet- 

 ic needle of the usual kind turns upon 

 an iron point, fixd in the centre of the 

 compass plate ; a stop and trigger wire 

 is applied to the compass box, to throw 

 the needle off its centre when not in 

 use, in order to preserve the fineness of 

 the centre point : a glass and brass spring 

 ring covers the needle and closes the 

 box ; to the under side of the compass 

 box, at the N. and S. points, is connected 

 a bar about 15 inches long, from end to 

 end, to each end of which is fixed a per- 

 pendicular brass sight about five inches 

 long; each sight containing 1 a long slit 

 or perforation, and a sight line, so that 

 the observer may take his line of sight, 

 or observation of the line upon the sta- 

 tion mark, at which end of the bar he 

 pleases. 



CIRCUMSCRIBED, in geometry, is 

 said of a figure which is drawn round ano- 

 ther figure, so that all its sides or planes 

 touch the inscribed figure. 



CIRCUMSCRIBED hyperbola, one of Sir 

 Isaac Newton's hyperbolas of the second 

 order, that cuts its asymptotes, and con- 

 tains the parts cut off within its own 

 space. 



CIRCUMSCRIBING, in geometry, de- 

 notes the describing a polygonous figure 

 about a circle, in such a manner that 

 all its sides shall be tangents to the 

 circumference. Sometimes the term Is 

 used for the describing a circle about a 

 polygon, so that each side is a chord ; but 

 in this case it is more usual to say the 

 polygon is inscribed, than the ciycle is 

 circumscribed. 



C1RCUMVALLATION, or fc of dr. 

 cumvallation, in the art of war, is a trench 



