y of the Stevens Institute of Technology.

Its value in furnishing a side-light on the subject of habit, to
which the preceding chapters have been more directly applicable,
lies in its emphasis on the importance of the inventor (or
designer, if you prefer) having clearly before him at all times
the effect of habits of thought and action both in himself and in
all others. These modes must be both conserved and combated in
himself when building up favorable mental state. He must build on
habit in order to have his mind continue in its application to a
chosen subject, and he must combat any tendency to follow habit
lines of thought that may have been established by observation of
the older forms or methods. His inventions must be of a kind that
will be readily made, sold, and used by men whose habits of
thought and action he cannot readily change.

This should be of value not only to the designer, but also to
those who direct or co-operate with him.

In designing the parts of a machine, the need of trimming here and
there, of giving up this or that ideal form just to get things
together, must be seen and done unflinchingly. And in the same way
the whole scheme must be made to conform to the economic
conditions.

If the machine under consideration is like a machine tool, and is
to be offered for sale, then the manufacturing, selling, and use
must be taken into account. In machine-tool design a wholly new
invention is an exceedingly rare thing, and a successful new
machine is still more rare.

We must remember our own tendency to follow precedent, and we must
make an effort to see the problem in its natural form without
being misled by the solutions evolved by others.

Be Practical.

The toughened idealist may not look or act like an idealist,
but in reality his idealism is one of the practically-wise
construction. He allows his memory to hold all that is helpful of
the past, both of the blunders or successes.

The dreamer who has been toughened by experience is one who lets
his rational brain have control. He ranks next to the stalwart
knight of the eraser, because he has the courage to arrest the
endless tinkering of design in order to get something done. He
will not let the family freeze while he is thinking up some grand
scheme of sawing and splitting wood by magic.

A most cursory glance at the machinery in use in the world will
show that the work has been done by imperfect machines. A study of
the des