Choice of sieve sizes
In each of the standard series, the apertures of consecutive sieves bear a constant relationship to each other. It has long been realised that a useful sieve scale is one in which the ratio of the aperture widths of adjacent sieves is the square root of 2(~/~= 1.414). The advantage of such a scale is that the aperture areas double at each sieve, facilitating graphical presentation of results. Most modem sieve series are based on a fourth root of 2 ratio (4/2 = 1.189) or, on the metric scale, a tenth root of 10 (k~iO-1.259), which makes possible much closer sizing of particles. For most size analyses it is usually impracticable and unnecessary to use all the sieves in a particular series. For most purposes, alternative sieves, i.e. a x/~ series, are quite adequate, whereas over certain size ranges of particular interest, or for accurate