264 
Proceedings of the Royal Society of Edinburgh. [Sess. 
XXVI. — A New Method of determining the Degree of Twist in 
Single Threads. By Thomas Oliver, B.Sc. (Lond. and Edin.), 
Carnegie Research Fellow. Communicated by Dr C. G. Knott. 
(Read May 20, 1907.) 
The determination of the degree of twist in a folded or ply thread com- 
posed of two or more strands is an easy matter. It is merely necessary to 
stretch the thread between two clamps, one being fixed and the other 
forming the end of a bar which can be rotated about its axis. A counter 
is attached to indicate the number of rotations. Rotating the thread in 
the opposite direction to its twist ultimately brings the singles parallel to 
each other. This point is easily observed. If we apply this method to 
single yarns we are at once confronted with the difficulty that the fibres 
constituting the yarn cannot be reduced to exact parallelism with each 
other. A reason for this is that the fibres in the thread before twist is put 
in are not always parallel. In the formation of the worsted “ top ” in the 
combing process, the aim is to arrange the fibres parallel to each other : this 
object is attained within narrow limits of error. If, in the spinning opera- 
tion, it were possible to fix the fibres, with respect to their neighbours, so 
that there would not be any relative motion amongst the fibres in the 
thread, then, on untwisting the thread again, the fibres would be reduced to 
a parallel condition. But this end cannot be attained; the fibres in the 
thread are free in the initial stages of twisting to slip on each other, both 
longitudinally and circumferentially, within limits. This motion is, how- 
ever, not so great as to preclude possibility of the degree of twist being 
determined in combed yarns with a satisfactory degree of accuracy. 
Several pieces of apparatus have been devised from time to time, similar 
to that described above for ply threads, but more accurately constructed. 
It is usual to place one inch of thread between clamps at the focus of a 
magnifying lens, or the clamps and torsion apparatus are mounted on a 
frame so as to slide the thread across the field of a compound microscope 
fitted with a low-power objective. 
When the afore-mentioned methods are applied to carded woollen 
threads the results are very unsatisfactory. The reason is that, in the 
processes preliminary to spinning, the fibres of a woollen thread are never 
reduced to parallelism. The aim in forming the woollen sliver is to make 
the fibres include a maximum number of air spaces. The distinctive mossy 
