LABORATORY SUPPLIES AND CHEMICALS 



295 



COMBINATION POWER YARN AND CLOTH TESTER 



3997C This tester is a combination of the machines listed 

 on the previous page. The addition of the 

 automatic recorder has greatly enhanced the 

 value of the tester. By the use of the recordjer 

 a chart line indicative of stretch and strength 

 of the material is automatically recorded. The 

 chart line shows the exact relation of stretch 

 to the tensile strength, at every point of the 

 test. Aeroplane wing fabric and other mate- 

 rials whose elongatiln under certain tension 

 is of vital importance can be accurately tested 

 only by this means. 



Can be supplied in sizes of 50 to 600 pounds 

 capacity depending upon the kind of material 

 to be examined. 



3997C 



Weights Used for Cotton Yarn 



24 grs. (Troy) 



109 3-8 grs. or 4 dwts. 13 3-8 grs. 



218 3-4 grs. or 9 dwts. 2 3-4 grs. 



437 1-2 grs. or 18 dwts. 5 1-2 grs. 



7000 grs. (Troy) 



= 1 dwt. (Troy). 



= 1-4 oz. (avoir'pois). 



= 1-2 oz. 



= 1 oz. 



= 16 ozs. (avoir.) or 1 Ib. 



Measurements Used for Cotton Yarns 



54 inches = 1 thread or circumference of hank. 

 4,320 inches = 80 threads = 120 yards 1 lea. 

 30,240 inches = 560 threads = 840 yards = 1 .hank. 

 No. of yards-=-8.33 grains=counts of yarn. 

 1 bundle usually = 10 Ibs. weight. 



Worsted Yarns 



In its general features the system of numbering worsted yarns are similar to those 

 of cotton. The worsted reel is two yards in circumference, and the table of measure is: 

 2 yds. = 1 thread. 

 80 yds. = 40 threads = 1 lea or warp. 

 560 yds. =280 threads = 7 lea or warp = 1 hank. 



12 hanks = 1 doz. 

 144 hanks 12 doz. = 1 gross. 



THE COUNTS OF YARN is the number of hanks required to weigh 1 Ib. avoirdupois 

 (or 7,000 grains Troy). 



RULE FOR COUNTS Reel off and weigh a suitable number of leas, add 3 cyphers 

 to number of leas weighed, and divide by number of grains (Troy) the 

 yarn weighs; the result gives the counts. 



