30 POLITICAL ECONOMY mean the price attained after the employer had taken every possible step to increase his output, on the assumption that meanwhile no new machinery had been constructed, no new mines had been opened up, and no new labour had been specialized. The long-period effect on price would be the alteration in price ultimately reached after full time had been given for the change to work out its complete consequences, provided that no other change bearing upon the situation took place mean while. The three ends distinguished above are not found in independent existence in the actual world, because all the tendencies to which we have referred are unceasingly act ing together. The ends actually met with are the intermixed effects of compounded forces with shorter or longer time periods. It is in particular true of the long-period tendencies that their full economic results arc never actually attained. Other changes, set ting on foot other tendencies, are bound to intervene before a given change can eventuate in its final outcome. We may, therefore, be led to question whether a study of long-period phenomena fulfils any useful purpose ; but a brief deliberation should lead us to an affirmative answer. The study is of value