The Library Shelf

For a solution of a problem in practical engineering to be of any value it must be capable of concrete numerical computation at the design stage; and, moreover, it must be such that definite results can be arrived at in a reasonable time. It is seldom necessary for the solution to be exact, since the data and conditions of engineering problems are rarely precise. But what is expected of a solution to a practical problem is that it should give a fairly good approximation to the values observed experimentally or known from experience.