237 (#309) ############################################ PRINGIPLES AND PRACTICE Example : A (48's quality) cross-bred roving is to be spun to the maximum count. What is the maximum spinning draft which may be employed, the average fibre length being 6" ? 1 + 3.14 X Vo = 8.7 draft required. This rule may also safely be applied to shorter stapled wools. As a rule for these the draft so ascertained will not be the maximum. Especially may the drafts for short fibre be increased when mule spinning is in ques- tion. Under these circumstances the formula given for maximum "drawing draft " then applies. Thus with a 2" fibre = 5.4 draft under the last given rule. But under the drafting rule using F (the average fibre) 31.4 F This latter method may safely be adopted in worsted mule spinning It la IOTT 15.7 draft. 2 With the draft decided the weight of roving to spin to any given count is also readily decided, for Count of yarn = Count of roving required. Draft decided upon Unfortunately count of yarn is given in yards per pound and rovings must be stated in drams per 40 yards. Thus the count of roving required must be further dealt with as follows :- 256 x 40 18-3 dram roving, and as C. of R. C. of R. X 560 C. of R. Count of yarn required is therefore the problem and Draft decided on formula will stand- 237