A series of measurements of wire diameter, length of side, and area of holes, hasbeen made on new and used sieves, all of which were originally of the“100 mesh” size, i.e. thesquare holes were supposed to be ·01″ in length of side and thewire to be ·01″ in diameter. The measurements have been expressedas frequency curves.

In the case of unused sieves woven to the I.M.M. specification, the sieve on thewhole compared well with the specification, but in used sieves the variationswere much greater. The divergence from specification in the new and old sievesis shown by Tables I and II respectively.

In one sieve (No. 2) the holes elongated more in one direction than the other. Infact in one direction the alteration which has taken place is a contractionrather than a stretch. This effect was probably connected with the manner inwhich the sieve was attached to its metal framework, and also to difference intempering of the wires and the tension in weaving.

A number of the frequency curves showed double peaks, and the actual observationsshowed that there was a systematic distribution of values corresponding to thesetwo peaks. It is probable that some of the guides in one of the combs throughwhich the warp wires are led during the weaving were displaced sideways, thusgiving alternate strands of wire and narrow holes. This was particularly thecase in the single weave.