ABSTRACT
193. Measurements and Errors.—Under the heading of Experimental Methods will be set forth the elements of experimental measurements and the instruments already mentioned will be described. A measurement is never absolutely correct; an error, no matter how small, always exists, no matter with what care the measurement is carried out, or however perfect the instruments. The art of measurement consists in knowing how to reach the extreme limit of experimental exactitude, or the smallest error. The difference between the value found and the real value is called the absolute error. Suppose, for example, it is desired to determine the exact weight of a man of 65 kilogrammes. If the scales indicate 64·900 kg., there i.s an absolute negative error of 0·100 kg. If they indicate 65·100 kg. there is again an absolute positive error of 0·100 kg. The reduction of absolute errors depends on the degree of perfection of the instruments. https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780429399459/94a4526a-9352-4743-b7a9-38ee3e829d09/content/pg261-1.tif"/>
