COMPASSES 



COMPETITION 



Mo- '} 

 .-, o. 



supporting needle. Hence the ' friction error ' can 

 be made very small in fact, if it is found that a 

 card can be made to rest even half a degree out of 

 the magnetic meridian, the supporting point is 

 rejected for a sharper one. 

 The weight, such as it is, 

 being mostly in the rim, 

 the period of vibration of 

 the card is long ( 40 seconds, 

 or so ), which makes the card 

 very steady. The bowl is 

 saved from violent oscilla- 

 tion by having in the bottom 

 a quantity of castor-oil. The 



fimbals are supported on 

 nife edges, and their being 

 made of brass wire-rope dis- 

 penses with the not very 

 durable india-rubber pads 

 otherwise used. A simple 

 device prevents the card 

 from jumping off the pivot 

 when heavy guns are fired 

 a matter of some importance 

 in an engagement. The bin- 

 nacle has complete provision 



for stowing away the magnets, soft iron bars, and 

 spheres used to counteract the magnetism of the 

 iron of the ship. 



_ Along with Thomson's compass is supplied a 

 piece of apparatus for converting it into an azimuth 

 compass, which is a compass for finding the angle 

 subtended at the observer's eye by the projections 

 of two objects on the horizontal plane. 



For the earth's action on a magnetised needle 

 suspended free to move horizontally and vertically, 

 see the articles MAGNETISM, DECLINATION. 



The great difficulty connected with the use of 

 the compass arises from the disturbing influence 

 of the ship's magnetism, of which part is con- 

 sidered permanent, and part due to the soft iron 

 is temporary, and varies with the position of 

 the ship. Various methods are in use to regulate 

 this difficulty, which in iron vessels is some- 

 times so great as to make an ordinary compass 

 almost useless. The principal are ( 1 ) counter- 

 acting the permanent induced magnetism by pro- 

 perly placed permanent bar magnets ; and (2) 

 supplying about the compass soft iron masses in 

 such a way that, however the ship turns, the 

 transient induced magnetism on the left of the 

 compass shall be exactly equivalent to that on the 

 right. Many of the best ships carry a standard 

 compass placed as far as possible from the iron of 

 the ship, especially from vertical masses like iron 

 masts and funnels. When it is mentioned that an 

 error of one point ( 11J) in steering means an error 

 of about one mile in five, the necessity for the 

 various precautions will be readily recognised. For 

 details on this subject, see the Admiralty Manual 

 on the Deviations of the Compass, and the references 

 there given. 



Compasses, instruments for transferring and 

 marking off distances, or for drawing circles, &c. 

 The common compasses are simply two rods or 

 ' legs ' joined together at one end by a pivot-joint, 

 and pointed at the other ; when used for draw- 

 ing circles, the lower part of one of the legs is 

 replaced by a pen or pencil. Spring dividers 

 are much in use by workmen ; in these, the legs 

 are united by a strong steel spring, the action 

 of which is to stretch them open ; but half-way 

 down, a screw passing between the legs, regulates 

 by means of a nut, the degree of opening. The 

 value of these depends upon the permanency with 

 which they retain any degree of opening given 

 to them, pivot compasses being liable to slip. A 

 more delicate variety of the spring dividers is 



also made for use in mechanical and architectural 

 drawing. 



Beam Compasses consist of points sliding on a 

 long bar, to which they may be clamped at any 

 distance from each other. They are used for 

 greater openings than pivot compasses can safely 

 span, and, when delicately made, for more accurate 

 dividing. See GRADUATION. 



Proportional Compasses have a point at each end 

 of each leg and the pivot between, thus forming a 

 double pair of compasses opposite to each other, 

 end to end. The pivot is a clamping screw moving 

 in an elongated slit in the legs, by means of which 

 any proportion between the ends may be attained. 

 They are usually provided with scales of proportions 

 for lines, solids, cubes, and circles. They are very 

 useful in making reduced or enlarged copies of 

 drawings, especially mechanical drawings. 



Triangular Compasses have three legs, so that 

 the points of a triangle may be all transferred at 

 once. For Calliper Compasses, see CALLIPERS. 



Compensation is used in both English and 

 Scottish law to denote the claim which arises to the 

 owner or occupier of land which is taken for the 

 purposes of a public undertaking under statutory 

 powers, or which is injuriously affected by the 

 execution of public works. The question is gener- 

 ally referred to arbitration, under the Lands Clauses 

 Act, and the award is final as to the amount 

 of damage. The claim includes such matters as 

 loss of profits from shop, interference with access 

 and amenity, nuisance from smoke, &c. Formerly, 

 fifty per cent, used to be added for compulsory 

 purchase, but latterly awards have been more 

 moderate. Compensation is also the name given 

 in recent statutes to the right of an outgoing tenant 

 in respect of certain classes of unexhausted im- 

 provements which are scheduled to the acts. See 

 AGRICULTURAL HOLDINGS ACT. The word is 

 loosely applied to any claim of damages arising 

 in respect of injury. Thus in event of legisla- 

 tion interfering with the business of the publicans 

 (in the way of limitation or prohibition), it is 

 strongly affirmed by some, and as strongly denied 

 by others, that the publicans are entitled to com- 

 pensation. In Scots law its proper meaning is 

 that mutual creditors and debtors may set off 

 one debt against another. This applies, as it 

 did in the civil law, to most pecuniary obliga- 

 tions, but in order that one debt may extinguish, 

 another, so as to stop interest, &c., compensation 

 must be pleaded. Even where an unliquidated 

 claim of damages is opposed to an ascertained debt, 

 time will be given to constitute, if the claims arise 

 under the same contract. 



Compensation of Errors, in Physics, a 



method of neutralising errors which cannot be 

 avoided, by introducing others into the experiment 

 or observation, of an opposite nature, and equal in 

 amount. The compensation pendulum illustrates 

 the principle. See PENDULUM. 



Competition ( Lat. , ' a seeking together ' ) has 

 been well defined by Dr Johnson as ' the act of 

 endeavouring to gain what another endeavours to 

 gain at the same time. 1 In political economy it 

 is simply the form taken by the struggle for exist- 

 ence as applied to industry. Formerly, prices and 

 generally the economic relations of men to each 

 other were regulated by custom or authority. 

 The growth of freedom has now brought it about 

 that these relations are determined by individual 

 effort. The general rule is that each man must be 

 responsible for his own economic well-being. The 

 workman brings his labour to the market and gets 

 what he can for it. The capitalist engages labour 

 on the terms most favourable to himself, and sell* 

 his produce at such price as it can bring. 



