1905-6.] Mr T. Oliver on Take-up in Twisted Threads. 197 
spiral, and not one, as shown in fig. 8. Hence the solution 
becomes identical with the one I have given. 
We must now consider the experimental side of this subject. 
The apparatus shown in fig. 10, which I have used in this in- 
vestigation, was invented by Mr George R. Smith of Bradford for 
the purpose of the commercial testing of the strength and stretch 
of yarns. But as the amount of twist in the yarn under test 
may also be varied, I have found the apparatus, with only slight 
modification, admirably suited to my requirements in the present 
research. 
The thread A is stretched between two clamps B and C. C 
Fig. 10. 
forms the end of one arm of a bell-crank lever pi voted at G, whose 
other arm F carries a can E. Water may be run into E from a 
reservoir D, and thus the thread may be twisted under any tension. 
H is an adjustable counterpoise to balance E when can E is 
empty. The twist in the thread may be varied by turning the 
wheel M, the turns being indicated on dial T. The thread can 
be kept throughout the experiment at the same tension by turning 
wheel I, which communicates motion by a train of wheels to shaft 
Iv. K moves the clamp B so that the lever F always remains 
horizontal. The take-up in the length of the thread may be 
obtained by taking the difference of the readings on scale S. 
I took seven yarns at random — viz., 2/1 Os* cotton ; 2/12s ; 2/1 6s, 
* 2/10s means two threads, each measuring 10 hanks per lb., twisted 
together. 
