But nobody is perfectly wise, and those who have not much time to get knowledge, and learn science and political economy, will often not see the effects of what they demand. They may ask for something which is impossible, or would cost so much as to stop the trade altogether. In all such matters, therefore, working-men should proceed cautiously, hearing what their employers have to say, and taking note especially of what the public opinion is, because it is the opinion of many who have nothing to lose or gain in the matter. #48. The Regulation of Hours.# One of the principal subjects of dispute is usually the number of hours in the day that a workman should work. In some trades a man is paid by the hour or by the work done, so that each man can labour a longer or shorter time as he prefers. When this is the case, each man is the best judge of what suits him, and no trades-union ought to interfere. But in factories, generally speaking, it would not do to let the men come and go when they liked; they must work while the engines and machines are moving, and while other men need their assistance. Accordingly, somebody must settle whether the factory is to work for twelve, or ten, or nine, or eight hours a day. The employer would generally prefer long hours, because he would get more work and profit out of his buildings and machines, and he need not usually be on the spot all the time himself. It seems reasonable, then, that the workmen should have their opinion, and have a voice in deciding how long they will work. But workmen are likely to be mistaken, and imagine that they may get as much wages for nine hours' work as for ten. They think that the employer can raise the price of his goods, or that he can well afford to pay the difference out of his own great profits. But if political economy is to be believed, the wages of workmen are really the value of the goods produced, after the necessary rent of land and interest of capital have been paid. If factories, then, produce less goods in nine hours than in ten, as is usually the case, there cannot, in the long run, be so much wages to receive. On the other hand, as machinery is improved, labour becomes more productive, and it is quite right that those who are sufficiently well paid should prefer, within reasonable limits, to lessen their hours of work rather than increase their earnings. This is a matter which depends upon many considerations, and it cannot be settled in this Primer. What I should conclude is, that when workmen want to lessen their hours of work, they ought not to ask the same wages for the day's work as before. It is one thing to lessen the hours of work; it is another thing to increase the rate of wages per hour, and though both of these things may be rightly claimed in some circumstances, they should not be confused together.