We have assumed that capitals of equal size are invested in spinning and machine-building, that these capitals contain equal proportions of constant and variable, fixed and circulating capital, that the working-days are of equal length, in brief, that all conditions are equal except the duration of the working period. In the first week, the outlay for both is the same, but the product of the spinner can be sold and the proceeds of the sale used to buy new labour-power, new raw materials, etc.; in short, production can be resumed on the same scale. The machine-manufacturer on the other hand cannot reconvert the circulating capital expended in the first week into money and resume operations with it until three months later, when his product is finished. There is therefore first a difference in the return of the identical quantities of capital invested. But in the second place identical amounts of productive capital are employed during the three months in both spinning and machine-building. However the magnitude of the outlay of capital in the case of the yarn manufacturer is quite different from that of the machine-builder; for in the one case the same capital is rapidly renewed and the same operation can therefore be repeated, while in the other case the renewal of the capital is relatively slow, so that ever new quantities of capital must be added to the old up to the time of its renewal. Consequently there is a difference not only in the length of time of renewal of definite portions of capital, or in the length of time for which the capital is advanced, but also in the quantity of the capital to be advanced according to the duration of the labour-process (although the capitals employed daily or weekly are equal). This circumstance is worthy of note for the reason that the term of the advance may be prolonged, as we shall see in the cases treated in the next chapter, without thereby necessitating a corresponding increase in the amount of the capital to be advanced. The capital must be advanced for a longer time, and a larger amount of capital is tied up in the form of productive capital.