In an earlier paper2 I have published mechanical analyses of a number of samples of wind sediments and have described the conditions under which these samples were formed, classifying them into lag gravels, drifting sand, lee sand, and atmospheric dust. It was my purpose to present some reliable measurements on the mechanical composition of such deposits. It was evident from that study that wind sediments are less heterogeneous in their mechanical make-up than water sediments are. This fact is quite generally recognized. It is readily inferred from consideration of the physical forces and conditions involved. The lightness of the air prevents it from moving pebbles more than about one centimeter in diameter, except on occasions so rare that wind deposits of that coarseness are practically non-existent. Likewise, dust grains measuring less than one sixty-fourth millimeter in diameter are so easily held in the atmosphere that they are readily scattered . . .