182 
Proceedings of Royal Society of Edinburgh. [sess. 
The Relation between Normal Take-up or Contraction 
and Degree of Twist in Twisted Threads. By Thomas 
Oliver, B.Sc. (Lond. & Edin.), Carnegie Research Eellow. 
Communicated by Dr C. G. Knott. 
(MS. received February 5, 1906. Read February 5, 1906.) 
The “ take-up ” in twisting threads together is a factor of very 
great importance in the manufacture of every textile material. 
The manufacturer wdio considers this matter so trivial that he 
makes no allowance for it in his calculations will undoubtedly 
suffer pecuniary loss. Since many lines of textile work at the 
present day are cut very keen, the thin fringe of profit which the 
manufacturer imagines himself to he making may actually have 
assumed a negative value entirely in consequence of this seeming 
trifle. The fact that the elementary rule usually employed in the 
estimation of the size number of a twist takes no account of any 
contraction which may arise in the process of twisting fosters the 
idea that this quantity is negligible. I shall only quote one 
example selected from many which came under my notice during 
the long period I was engaged in woollen mill work. A cloth 
made from 36 cut 2-ply hard twisted yarn w 7 as calculated to 
finish at a weight of lOJ ounces per yard, and was specified as. 
such to the merchant. This cloth invariably came into the 
warehouse 11 \ ounces per yard, thus entailing an extra expendi- 
ture of 10 per cent, on the cost of the material. The solution of 
the difficulty simply lay in the fact that no account had been 
taken of the contraction due to the twisting. The weight per 
unit length of the 2-ply thread was equal to that of a single 
thread measuring 16 J cuts per standard weight of 1J lbs., instead 
of 18 cuts as estimated. 
Twisted threads may he classified under one or other of 
two general categories, viz. — (1) Normal twists; (2) Abnormal 
twists. 
Under the first heading which I have termed “ normal ” may 
