[Illustration: FIG. 7. SHOWING CONSTRUCTION OF PLANK FRAME BARN, SIDE VIEW.] Figures 6 to 9 are side and end views, showing the detail construction and size of the timbers of the plank frame and mortise frame barns here figured. The detailed figures of the lumber bills for each of these barns were carefully worked out, but are too voluminous for publication here. The total number of feet of each kind of lumber required is given in Tables 1A and 1B. Since the proportion of the different kinds of lumber and shingles varied for the different barns, to draw an exact comparison it was necessary to base it upon the money value, and for this purpose the total cost of lumber has been figured in each case. The lumber values used thruout are the best average prices that could be obtained. As the same prices are used for the material of all the barns, the comparisons of cost are correct, altho these exact prices will not hold for all localities and all times. [Illustration: FIG. 8. SHOWING CONSTRUCTION OF PLANK FRAME BARN, END VIEW.] Since a silo cannot be economically built inside of a rectangular barn, the first comparison is made with the barns simply enclosed, altho one of the chief advantages of a round barn is the deep silo which it is possible to build so economically in the center. [Illustration: FIG. 9. SHOWING CONSTRUCTION OF MORTISE FRAME BARN, SIDE VIEW.] Another item of economy in the circular barn is less framing lumber. This form has the strongest possible construction with the least lumber in the frame, and the least bracing, not a single timber larger than a 2 × 6 being required above the sill. The arched circular roof requires no supports, and no scaffolding is needed inside during its construction. The accompanying tables show the comparative amount and value of lumber and cubical content in round barns 60 and 90 feet in diameter, and rectangular barns of equal area and height of posts. TABLE 1A.--A COMPARISON OF THE COST OF MATERIAL IN ROUND AND RECTANGULAR BARNS OF THE SAME AREA, _Not Including_ Foundation And Silos. A: Framing lumber, B: Sheathing, siding, and flooring, C: Shingles, D: Bolts, E: Total cost of lumber, F: Content, cubic feet,