It is not my purpose to belittle the great work that has been done in improving existing machines, for this, after all, is the real great work that must be done. It is the work to which the world owes its greatest debt for progress in material wealth. Furthermore, it is a phase that must be considered in connection with every invention before that invention can become of value to any one. But just now we must consider how the inventor must work while dreaming out the fundamental ideas of a mechanical scheme. The clear view of a mechanical scheme is more likely to come after a good night's rest, particularly if the schemer has retired with the problem in mind. There are times when invention comes under severe stress, hard physical work, and mental anxiety, but the most usual time is after a sleep which refreshed mind and body. After this the inventor brings his scheme to the drafting board, to patent office, to factory, and to the market, and in each case he encounters barriers. Designing by the Square Foot. The ordinary work of machine design, in which well-known parts are grouped to accomplish a given end, without much thought of attaining anything approaching the best,--such designing is like painting a fence, so many square feet of paper should be covered per day. But the real higher type of work cannot be measured in this way. It requires the forethought, the close application, the keen interest, and the comfortable idea building. Designing by the square foot is, however, a good preparation, and many a good brain has been developed by such work. The importance of designing a machine to meet all the conditions necessary to success from a mechanical and business standpoint is fully recognized by every one. But the grouping of the ideas in the mind while working out the various phases must not be hampered by the bewildering picture of all of these problems, each demanding consideration at every move. The phase in hand must have the concentrated attention, and the best conditions for its solution. The harmonizing is an after-process which must be worked out by a series of compromises after the various component elements have been almost independently considered. Problems to Consider. In taking up the problems of design of a machine, there will be found an almost endless number of elements to consider. The strictly mechanical problem of the best machine for the purpose never stands alone. What is the measure of the best machine? How much can be spent on its design and construction? How much work is to be done? An endless variety of questions at once crowd into the mind for answer. It is doubtful if all the elements could ever be tabulated in any form that would be a positive guide in shaping the final result, but in a general way the designer should make a fairly good guess at the kind of standard toward which he should work.