In Plate V, page 112, are given six figures representing various cracks and fissures. No. 1 represents the cracks in the glaze of Japanese pottery, magnified. No. 2 shows the mud cracks on the edge of a lake, to the extent of two feet. No. 3 is a series of cracks in an asphalt pavement, covering about two feet. No. 4 shows the form of cracks in the surface of a mesa in Arizona, the result of the summer heat, the length being about ten feet. No. 5 is a tracing from a drawing by Professor W. H. Pickering showing cracks in the lunar crater Eratosthenes, with an extent of fifty-five miles. The original drawing represented a much greater widening of the lines which Professor Pickering believes to be due to vegetation. I endeavored to trace the centre of each line and Professor Pickering said in regard to my tracing: "In one or two instances you have assumed that a crack went through the middle of a broad space, whereas, for aught we know, it may have gone along either edge, but otherwise the tracing obviously follows the outlines of my drawing." It evidently gives a _cachet_ of what appears to be veritable cracks on the surface, and it is interesting to compare this drawing with the cracks in the asphalt. In No. 6 are two drawings; one marked A represents cracks in a region of the Moon known as Flammarion's Circle, the other B represents the great rift in southern Africa, probably the most stupendous phenomenon in geological history. This rift has been traced from the Valley of the Jordan through the Dead Sea, into the Gulf of Akaba, thence into the Red Sea, which it follows the entire length, then turning southwesterly into Africa and branching, one branch takes in Lake Tanganyika, and the other branch Lake Nyassa. A portion north of Nyassa is still problematical. Here is a crack 1,500 miles long, most of it filled with detritus, water, or forest. It would be an interesting question whether such a fracture would be visible even from the Moon. A glance at these various figures will give one a conception of the similarity of cracks, their irregular contour, their indeterminate origin, and ending. Cracks arising from shrinkage vary only in the material in which the crack takes place; the conditions resulting from shrinkage or pulling apart are precisely the same. [Illustration: PLATE VI 1. RAILROADS, ILLINOIS 37 MILES 2. STREETS, MONTREAL 1/2 MILE 3. IRRIGATION CANALS, ARIZONA 1-1/3 MILES 4. CANALS, GRONINGEN, HOLLAND 10 MILES 5. MARS, SCHIAPARELLI'S MAP 6. MARS, LOWELL'S GLOBE ARTIFICIAL LINES RAILWAYS, STREETS, CANALS, ETC.]