The actual rate of output of this installation is the capacity of the last smooth machine. This is about 180 lbs. per hour, while the output of the macerator is approximately double this amount. Thus the macerator only works for about half the time. This applies also to the two intermediate machines. After a study of the preliminary remarks, it would not be difficult to suggest methods for improving the condition of affairs. It would appear that, in order to obtain a uniform rate of working in such a battery, the relative peripheral speeds of the several machines should be--(1), (2), and (3) 100; (4) 150; (5) and (6) 200. The remarks on the practical limits of speed should be borne in mind. In this case the smooth rolls travelled at 23 revolutions per minute. As already stated, it is not intended to lay down definitely that, _e.g._, horizontal grooving alone should be cut on macerating rolls. Some estates employ with satisfaction a deep square-cut spiral 1/4 inch by 1/4 inch by 1/4 inch or 1/2 inch spacing; others use a large diamond pattern. Similarly various types of grooving are cut in the intermediate rolls. [Illustration: A BATTERY OF MACHINES. On the left, light marking rolls for sheet rubber; on the right, heavy machines for crepe preparation. In the middle background, "scrap-washing" machines outside the main building.] It has been remarked in the chapter dealing with crepe preparation that much depends upon the condition of the coagulum. There is no necessity, or desirability, for having a standard higher than 2 lbs. dry rubber per gallon, and it has been argued that it would be better to select a standard of 1-1/2 lbs. The tougher the coagulum, the more the power required, and the slower the rate of output of the leading machines. In ordering machines for crepe-making, only large rolls should be considered--_e.g._, rolls having a diameter of 12 inches to 18 inches and from 15 inches to 18 inches face. ROLLS RUNNING HOT OR "FREE."--If the rolls are found to become hot, work on that machine should be stopped, and an examination made, otherwise there is the possibility of the crepe becoming sticky and "tacky" when dry. Although comparatively cold water may be flowing upon the rubber and the rolls, little alleviation may be noticed, inasmuch as the source of heat lies generally at the bearing ends of the rolls. This may be tested by placing the hand on the top of the "standard" of the machine. The development of the heat may be due to lack of lubrication, worn bearings, or sometimes faulty setting-up of the machines. Allusion has been made to the necessity for avoiding the running "free" of rolls--_i.e._, in the absence of rubber. The grinding of the rolls, when working close together, produces a fine powder, which causes a more or less pronounced deposit on pale crepe. When the rolls have been in action for some time and become slightly worn, this deposit may be confined only to the edges of the rubber.