336 



as the pendulum rises the clip e, which is indirectly attached to the 

 bell crank at its upper end, descends. To indicate this descent the 

 quadrant bears a second scale &, upon which the same pointer d shows 

 the motion of e in millimeters. This motion must be deducted from the 

 motion of the lower clip /to obtain the real stretch of the silk. 



The lower portion of the instrument is simi- 

 lar to Robinet's apparatus minus the dyna- 

 mometer. The clij) / carries a pointer g, which 

 indicates upon the scale c the amount of stretch 

 at the moment of rupture. In the instrument 

 of to-day, howev^er, the distance between the 

 initial position of the clips is but 50 centime- 

 ters, and as the scale is divided into centimeters 

 and millimeters the stretch there indicated must 

 be doubled to obtain the per cent, of elongation. 

 The instrument just described is that used 

 in all conditioning houses to-day. There is, 

 however, according to M. Quajat, Assistant Di- 

 rector of the Italian Experimental Station at 

 Padua, a great difference among instruments 

 in the time necessary for the descent of the 

 weight from the upper to the lower end of the 

 scale, a distance of 200'""'. In a recent pam- 

 phlet he calls attention to this fact, which is 

 important because the indicated tenacity of a 

 given thread may be altered by varying the 

 time to which it is submitted to the strain. The 

 weights of the serimeters in the following con- 

 ditioning houses descend (according to M. 

 Quajat) in the following periods of time: 



Seconds. 



Milan 15 



Turin 14i 



Turin (another establishment) 13 



Treviso 20 



Padua 16 



Lyons 16 



That in the silk laboratory at this Depart- 

 ment consumes thirteen seconds in the descent. 



In relation to the instrument in the New York Silk Conditioning 

 Works, the director of that institution writes : 



In answer to j our favor of the 17th instant, I beg to state that I have tested the seri- 

 meter used by us and find as follows : The average time it takes to run from zero to 

 the 200 mark is fifteen seconds ; after a thorough cleaning and when everything is 

 favorable it takes twelve seconds, but after a few hours on accouut of dust the speed 

 18 reduced to fifteen seconds, and if very dusty I find as low speed as eighteen to 

 twenty seconds. 



Fig. 75. — standard Serimeter. 



