The table below shows the elements of these series both as regards current-velocities and maximum quartz-grain diameters carried off by each. In a great many cases, however, it is altogether unnecessary to go into such detail, and a subdivision into six or seven divisions is quite sufficient. Such a subdivision, based upon the doubling of grain-sizes instead of current-velocities, has been adopted by Prof. Milton Whitney, of the U. S. Department of Agriculture, and others. TABLE OF DIAMETERS AND HYDRAULIC VALUES OF SEDIMENTS. =============================================================== |Velocity per second,|Maximum diameter Designation of materials.| or hydraulic | of quartz | value. | grains. -------------------------+--------------------+---------------- | _Mm._ | _Mm._ | | Grit | (?) | 1-3 { | (?) | .5-1 { | 32-64 | .50 Sand { | 16-32 | .30 { | 8-16 | .16 { | 4- 8 | .12 { | 2- 4 | .072 { | 1.0- 2 | .047 Silt { | .5- 1 | .036 { | .25-0.5 | .025 { | 0.25 | .016 { | < 0.25 | .010 | | Clay | < 0.0023 | -------------------------+--------------------+---------------- _Results of such analyses._—A tabular presentation of the results of analyses made in accordance with the above plan will give a good idea of the differences between the various grades of soils recognized in farm practice, to any one accustomed to the study of figures. But a much more satisfactory showing is made by placing the several grain-sizes segregated, into small vials or tubes of identical diameter and placing them in parallel series alongside of each other.[26] The curves formed by the surfaces of the several sediment-columns in each series show to the eye very strikingly the relations of the several grades of soils to each other, and suggest at once that while gentle slopes or gently undulating curves belong to soils of intermediate, loamy character, steep grades and zigzags show soils of extreme types. This is exemplified in the subjoined Figures: [26] Convenient stands for this purpose, used by the writer since 1872, may be cut from L-shaped moldings of wood, such as can be readily ordered from any planing mill. The vials can be cemented, wired or tied.