These scales are also provided with a paper tape, and by means of a lever, which is pulled when the correct point is reached for each portion of the charge, the actual weight on the scales is stamped on this tape, which is locked up in the scale box, entirely inaccessible to the operator. At any interval desired, generally once a day, this tape may be taken out and examined to see the accuracy of the weights actually obtained, as compared with those called for by the pointers.

The moral effect of this on the scale-car operator is tremendous, and vastly better results can be secured by the use of such an apparatus.

The writer became general superintendent of the plant mentioned between the time that this experimental apparatus was ordered and the time it was put in operation. The change produced in the accuracy of the weights obtained was almost beyond belief and the work of the furnace on which the scale was used immediately improved very much.

Since that time the American Kron Scale Company has brought out a similar device by which the same results may be obtained. The practical importance of this matter is so great, and the moral effect upon the scale-car operator caused by the knowledge that a continuous record is being made of the way in which he is doing his work, is so important that it is doubtful if any furnace is justified in doing Without such equipment.

The scales on scale cars are subjected to a very severe service. They not only have to receive the impact and shock of the incoming material, but they have to stand the much more serious shocks arising from irregularities in the track on which the scale car runs. The great inertia of the charge on a loaded scale car causes enormous stresses on the knife edges even with apparently insignificant irregularities in the track. For this reason switches, cross-overs, and other breaks and irregularities in scale-car tracks should be avoided to the greatest possible extent. Moreover, these cars should always be provided with springs over the axle boxes, or in other suitable location. These springs should be the softest, that is, have the maximum travel for a given change in stress, permitted by the conditions, as in this way the springs absorb the shocks arising from the irregularities of the track and keep them off the knife edges.

I have seen scale cars built entirely without springs, and at the same time heard the furnace managers complain bitterly that it was impossible to get his scales to stand up and give accurate service, without his realizing the reason.

Means have been provided whereby the weight of the charge hopper was lifted off the knife edges except during the time that it was actually being weighed. But it is ordinarily difficult to get scale-car operators to use this device. There seems no reason why it should not be made to interlock with the traversing motor of the car, so that the latter could not be moved except after relieving the knife edges of the scales from weight.

This may seem a matter of too little moment to deserve such serious mention, but when the importance of accurate weighing previously mentioned is considered, and when it is realized how utterly unreliable the best scales become when their knife edges are even slightly worn, it is believed that the stress laid on this subject will be justified.