pounds of coal, and can be supplanted by steam. The limitations and conditions are, however, that the task to be done must present uniform requirements over a considerable extent of time or place, so that it may be economically possible to apply machinery without intelligence. Some examples will make this point clear.
We see men employed in shoveling and carrying coal from the side-walk into the cellar. Are they paid for pure energy, or for intelligence? If it was the fact that the coal-bins of all houses were built in the same shape and in the same position relatively to the sidewalk, then coal carts could be fitted with apparatus for passing the coal into the bin without any shoveling or carrying. In fact, carts have been invented, and are in use, which do this in that great number of cases where the position and shape of the bins conform to a general plan of house construction. Or, if coal had to be put into the cellar every few days, apparatus could be arranged for each house, in spite of differences of construction, to put it in without hand labor. In fact, therefore, at the present time, the services of the coal-heavers are required to adapt the task to the varying circumstances of the different cases; that is, to apply intelligence where it cannot be dispensed with.
Another case, familiar to our notice, in which human beings expend much nerve and muscular energy, is in hod-carrying. Steam hod-hoisters are familiar, but it is obvious that their applicability and utility is limited to the cases where a large building is to be constructed at one spot; otherwise it does not pay to put up the apparatus. Therefore the case is that the task can be reduced to routine and machinery can be applied to it, if the amount of it is sufficient, within the limits of time and space, to give the machine simply machine work to
