(_a_) If rubber is weighed in the box, and the average tare of the case deducted from the gross weight (in order to obtain the nett weight), any loss in the weight of the timber would appear as a deficiency of rubber at the distant port. (_b_) Whether the same effect would be produced eventually in the case of rubber which is weighed before packing will depend upon the method of weighing at the warehouse. If the rubber is weighed in the box, any observed deficiency would be attributed to a loss of weight in the rubber. PART III MACHINERY AND BUILDINGS CHAPTER XIII _MACHINES_ The number of manufacturers of machines for preparing rubber would seem to be on the increase, and there can be little doubt that this competition will result in a continued improvement in the design of machines. It cannot be denied that there has been room for such improvement, and it is believed that manufacturers will display judgment in putting only their best quality into the work. While design and finish are very excellent in their way, it is to be regretted that in a number of cases in the past the material of rolls has been found to be of inferior quality. Generally, the complaint seemed to be that the rolls were too soft, and that the "grinding" effect was far too great. The damage to pale rubber in such cases is considerable, as it is impossible to keep the rolls free from fine dark powder. The effect is generally noticed more in the smooth rolls with which a finish is put upon the crepe. Cases have occurred frequently in which rolls have been returned, because of the injury caused to pale rubber, and there can be little doubt that the life of quite a large number of rolls is even now far too short in comparison with the expense involved. It is a moot point, however, in many instances how far the quality of the rolls is actually responsible for the damage done to the rubber. In the experience of the writers it is certain that complaints regarding the rolls were unjustifiable, and that the injury had been caused by carelessness in the "feeding" of the machine. Especially in the case of smooth finishing rolls, it is clear that if the rolls are allowed to run idle for more than the briefest possible interval grinding must take place.