Constant capital, the means of production, considered
 from the standpoint of the creation of surplus-value, only exist to absorb
 labour, and with every drop of labour a proportional quantity of surplus-labour.
 While they fail to do this, their mere existence causes a relative loss
 to the capitalist, for they represent during the time they lie fallow,
 a useless advance of capital. And this loss becomes positive and absolute
 as soon as the intermission of their employment necessitates additional
 outlay at the recommencement of work. The prolongation of the working-day
 beyond the limits of the natural day, into the night, only acts as a palliative.
 It quenches only in a slight degree the vampire thirst for the living blood
 of labour. To appropriate labour during all the 24 hours of the day is,
 therefore, the inherent tendency of capitalist production. But as it is
 physically impossible to exploit the same individual labour-power constantly
 during the night as well as the day, to overcome this physical hindrance,
 an alternation becomes necessary between the workpeople whose powers are
 exhausted by day, and those who are used up by night. This alternation
 may be effected in various ways; e.g., it may be so arranged that part
 of the workers are one week employed on day-work, the next week on night-work.
 It is well known that this relay system, this alternation of two sets of
 workers, held full sway in the full-blooded youth-time of the English cotton
 manufacture, and that at the present time it still flourishes, among others,
 in the cotton spinning of the Moscow district. This 24 hours’ process of
 production exists to-day as a system in many of the branches of industry
 of Great Britain that are still “free,” in the blast-furnaces, forges,
 plate-rolling mills, and other metallurgical establishments in England,
 Wales, and Scotland. The working-time here includes, besides the 24 hours
 of the 6 working-days, a great part also of the 24 hours of Sunday. The
 workers consist of men and women, adults and children p246of both
 sexes. The ages of the children and young persons run through all intermediate
 grades, from 8 (in some cases from 6) to 18. [60]