CO M 



237 



COM 



of commutation of a planet is measured 

 by the difference between the sun's longi- 

 tude and the geocentric longitude of the 

 planet. 



COMPANION, the covering over a ladder 

 or staircase in a ship. 



COM'PA.VY 1. In military affairs, a sub- 

 division of a regiment under the command 



of a captain. 2. In commercial affairs, 



a n umber of merchants associated together 

 in one common interest and for some 

 special purpose. When there are only a 

 few individuals associated, the concern is 

 called a cojtarttttry, leaving the term com- 

 pany to be applied to larjre associations, 

 as the East India Company. 



COMPARATIVE A.NAT'OMY, the anatomy 

 of all organised bodies, animal or vege- 

 table, compared with a view to illustrate 

 the general principles of organisation. 

 See ANATOMY. 



COMPAR'ISON. 1. Ingrammar, the form- 

 ation of an adjective in its several de- 

 grees, as good, better, best. 2. In rhe- 

 toric, a figure by which two things are 

 considered with reference to a quality 

 possessed by both, as "a hero is like a 

 lionincowrrtfje." The distinction between 

 comparison and similititde is, that the for- 

 mer has reference to the qtuintity, and the 

 latter to the quality. Comparison is be- 

 tween more and less ; similitude is between 

 good and bad. 



COMPARTI'TION, division into parts. Ap- 

 plied in architecture to the distribution of 

 the ground plan of an edifice into rooms 

 and passages. 



COMPART'MENT, a separate part or divi- 

 sion of a design, as a compartment ceiling, 

 a ceiling divided into panels ; compartment 

 tiles, an arrangement of white and red 

 tiles. In gardening, compartments are 

 assemblages of beds, plots, borders, walks, 

 &c. In heraldry, a compartment is called 

 & partition. 



COM'PASS, from con and passus, opening. 

 An instrument used in surveying, con- 

 structed In the main like the mariner's 

 compass, but the needle is not fitted into 

 the card moving with it, but plays alone, 

 the card being drawn upon the bottom of 

 the box, and a circle divided into 360 

 on the limb. The mariner's compass con- 

 sists of a circular card or fly, on which 

 are drawn 32 points of direction, called 

 the points of the compass, and a small 

 bar of steel magnetised, called the magnetic 

 needle, and which (excepting the varia- 

 tion) always points to the north, and the 

 box or framework which contains the 

 card and needle. The card and needle 

 are fastened to each other in such a man- 

 ner, that the north pole of the magnet 

 coincides with the northern point of direc- 

 tion marked on the card, and turn on the 

 point of a pin fixed in the centre of the 



COMPASSES, or pair of compasset, a rot 

 thcmatical instrument for descriWnsj 

 circles, measuring figures, &c., consisting 

 of two pointed legs made of iron, brass, 

 or steel, and jointed at the top by a pivot 

 on which they move. There are several 

 sorts of compasses in use, as the triangular 

 compasses, which resemble the common 

 compasses, with the addition of a third 

 leg, which has a motion every way, and 

 which suits the instrument for laying 

 down triangles on maps, <&c. ; the cylin- 

 drical and spherical compasses, which have 

 four branches joined in a centre, two of 

 which are circular and two flat: their use 

 is to take the diameter of cylindrical and 

 spherical bodies; the German compasses 

 are common compasses with the legs 

 bent ; the hair compasses are adjusted with 

 a fine screw in one of the legs, so as to 

 take an extent with great exactness; the 

 proportional compasses have the joint, not 

 at the ends of the legs, but between the 

 points terminating the legs : they are 

 convenient for reducing designs, for what- 

 ever space is measured by one end, a pro- 

 portionate space will be marked by the 

 legs at the other end. The elliptical com- 

 passes are intended to be used in drawing 

 ellipses, but are very inconvenient. Spring 

 compasses are more commonly called di- 

 viders (q. v.) Beam compasses consist of a 

 beam with a fixed point at one end and a 

 moveable one at the other. 



COMPASS-SAW, a saw with a broad edge 

 and thin back to cut in a circular form. 



COM'PASSING. In carpentry, bringing a 

 piece of timber into the form of an arch. 



COMPITA'LIA, Lat. compitwn, a street. A 

 Roman feast in honour of the Lares and 

 Penates. 



COM'PLEMENT, from complementum, a 

 filling (con andpleo, to fill). In astronomy, 

 the distance of a star from the zenith, 

 otherwise called the co-latitude. In ma- 

 thematics, the complement of an arc is what 

 that arc wants of 90, or of a quadrant ; 

 the complement of an angle is what that 

 angle wants of being a right angle. The 

 arithmetical complement of a logarithm is 

 what that logarithm wants of 10,000,000, 

 &C. Complements of a parallelogram are 

 the two smaller parallelograms, formed by 

 drawing two right lines parallel to the 

 sides of the quarter, through a point in 

 the diagonal. In fortification, the comple- 

 ment of the curtain is that part of the in- 

 terior side which makes the demigorge. 



COMPLB'VIUM, anciently an area in the 

 centre of Roman houses, so constructed 

 as to receive the water from the roof. 



COMPOS'INO STICK, an instrument used 

 by compositors in setting types. 



COMPOS'IT^;, one of Linmrus's natural 

 orders of plants, comprising thosn which 

 have composite or compound flowers, as 

 the sun-flower, dandelion, &c. 



