deal in a very short time, and, in the second place, it is a subject of the greatest satisfaction and gratification to the man by whom it was evolved.

Principle IV.

There is an inherent sense of fitness in the mind of a well-trained and well-balanced metal-work designer, which sense of fitness is of the greatest importance in all that he does.

It is this sense of fitness which enables him often, when inspecting the work of other designers, to see at a glance faults and flaws that would escape the observation of an untrained man. This faculty of rapid and correct judgment is one which can be developed, and one that should receive constant attention throughout an engineer's entire career. It is of special value in an office which employs a large number of draftsmen and computers, all of whose work has to be checked by the head of the office or by a reliable assistant. Nor is it only in connection with the work of others that this faculty is valuable, for it is often serviceable to an engineer on his own personal work, perhaps even without his being conscious thereof, saving him from making errors which pure theory might not enable him to detect, or which the authorities in his line have not yet recognized as errors. An example of this occurred some years ago in the author's practice which will serve to illustrate the point.

In proportioning reinforcing plates at pinholes, especially for hinged ends, the author has made a practice of instructing his draftsmen to extend these plates considerably beyond the length required by the theoretical number of rivets necessary for the connection, without his being able to give any valid or scientific reason for so doing. By some experiments made upon the ultimate strength of certain columns with hinged ends, the results of which were published in the Transactions of  the Engineers'  Society  of

Western Pennsylvania, Mr. Thomas H. Johnson has shown that such pin-plates, unless extended beyond the length required by the theoretical num-