and between loom size and floor space occupied, this last being the product of length of lay and loom depth. An investigation of the Crompton and Knowles "Providence" cotton loom, the Stafford "Ideal" loom and the "New Standard" and "Print Cloth " looms of the Mason Machine Works, shows that for these looms the above dimensions are included within the extremes shown in the diagram. FORMULAE FOR LENGTH OF LAY AND DEPTH. The length of lay is different for different makes of machine and is also dependent on the size of the shuttle box and the number of filler forks, but with these conditions fixed the length of lay for different loom sizes can be expressed by a simple formulae of the following type: L=S+K. in which L is the length of lay in inches, S is the rated size of loom in inches and K a constant. In the following table the constant for this formulae is given for different makes or models. The conditions represent maximum and minimum values for the constant K, for each type of loom. In the drawing (Figure 10) showing representative conditions for 40-inch looms, the length of lay is 92 inches which corresponds to a value of 52 for the constant K, and this may be considered a representative value for all sizes up to 70 inches, disregarding the Draper type F looms in sizes from 66 to 70 inches. Beyond 70 inches, a more representative value for K is 55. Assuming these constants, therefore, the formulae for the length of lay are as follows The depth of loom differs with the manufacture and model and also depends on the diameter of the warp beam. Figure 8 shows the relation between this dimension and the rated size for Draper and Whitin looms, and practically this dimension for other makes lies between the extremes shown. The depth of the wide Whitin looms has been taken as representative, and the formulae, therefore, are as follows: D=48 where D is the depth of the loom in inches. AREA OF FLOOR SPACE COVERED BY LOOMS. As previously pointed out the area of the rectangular floor space taken by a loom is the product of the length of the lay and the depth. The formulae for the area are, therefore, as follows, where A equals the area in square feet. STANDARD WEAVE ROOM DIMENSIONS. Figure 10 is a plan of a weave room equipped with 40-inch looms, and shows conditions assumed standard in this paper. The looms are arranged in groups of four which arrangement gives greater spacing between looms than a grouping of six or eight looms to a group and consequently should be chosen for the lighting study for the same reason that the maximum dimensions of looms were chosen. The alley dimensions are given below, together with the variations likely to be found in actual installations. The back alleys are alternately wide and narrow, the wide alleys containing the supporting pillars. The clearance between the lays of looms in the same group is one inch, which dimension is practically standard. From the dimensions of alleys given above and by means of the formulae already given for the length of lay and depth of loom for different rated sizes, formulae can also be obtained for the area of floor space per loom including the alleys. In order to obtain these last mentioned formulae we must take as one dimension the length of lay plus the average distance between lays, or, in other words, the average separation of the looms on centres parallel to the lays. With four looms to a group the distance between lays is alternately one inch and sixteen inches, (see Figure 10) except that at considerable intervals a wider cross alley than sixteen inches is required. It is hardly necessary, however, to consider these occasonial wide. alleys in figuring the area per loom. The formulae for separation on centres parallel to lays, then, are as follows: For 26 to 70 inch looms, C=S+52+81⁄2 or C-S+602. For 72 to 124 inch looms, C=S+55+81⁄2 or C=S+632. For our other dimension of the area we must add together |