333 



THE SERIMETER. 



By Philip Walker. 



The first experiments, having in view the determination of the fact 

 that silk is elastic, were made near Paris in 1836, They were executed 

 h. "MM. Delbare, sr., Paroissien, and Boucher. Two years later, M. Rob- 

 iij-fet, " Member of the Royal Academy of Medicine and Professor of a 

 coarse on the Silk Industry," took up the work and it occupied him 

 for several years, during which he announced his results in a series of 

 memoires. It is to be regretted that only the first of 

 these, entitled a "Memoire on the Silk Filature," 

 published in Paris in 1839, is at present in the library 

 of the Agricultural Department, for it is, to this 

 learned experimenter that we owe nearly all of the 

 earlier knowledge of the physical properties of silk. 

 He invented the serimeter, the instrument employed 

 in determining the tenacity and elasticity of raw silk. 

 The perfected form of this machine, as used by him, 

 is shown in Fig. 74. It was the outcome of several 

 tentative models described in the memoire cited. 

 The principle of these was one by which a very light 

 cup was suspended to the thread to be tested. This 

 cup carried a pointer which glided along a scale. 

 The silk in place, the cup was gradually filled with 

 sand, the addition stopping only with the rupture 

 of the thread. This apparatus only measured the 

 elasticity. 



After having obtained, by means of the apparatus 

 of the cup and sand, a certain number of results which 

 demonstrated that silks had, to very different degrees, 

 the faculty of stretching, Robinet constructed a more 

 accurate machine of a high degree of sensibihty and 

 capable of giving results that might be compared with 

 one another. His first idea was to replace the uncer- 

 tain and unequal descent of the cup charged with a 

 variable weight by a fixed weight, the action of which 

 would be moderated and regulated by means of a 

 pendulum or balance-wheel absolutely like that of a 

 clock. The silk was attached by one end to a fixed 

 point ; the other end was seized by a pair of pincers 

 fastened to a weight which gave motion to a chain 

 wound round the drum of the clock. Then by means 

 of a very simple mechanism of an escapement and a balance-wheel 

 the descent of the weight could be regulated so that each oscillation of 

 the balance-wheel would make it descend one millimeter and stretch 



u 



4^ 



Fig. 74.— Robinet's 

 Serimeter. 



