The Centennial Pipe Vise

1877 Scientific American  
titutifit �tutritau. In order to verify this, a tear was half inclosed in plaster, The properties hitherto noted in Batavian tears, may be as in Fig. 2 . The tail was attacked with'hydrofl uoric acid, and found in tempered glass, and they are present in degree pro. the large end was cut with a saw. After rupture, the fragportionsl to the temper. If, however, the glass is but par ments were held in place by the plaster, and their position tially tempered, it is no longer possible to determine
more » ... de and form could thus be conveniently studied. The tear usu-I gree thereof by rupture. Recourse must then be had to ally remains as in Fig. 3 , and on separating the fragments I another characteristic presented by all tempered glass, with it is found to be composed of numerous truncated cones i out regard to the intensity of temper ; namely, the action of mutually imbedded. Fig. 4 shows a tear, the tail of which I the glass upon polarized light. The tempering process, by has been destroyed by acid. The summits of the cones are producing in the glass changes of elasticity in various direc. turned in the direction of the tail. In Fig. 5 the tear has tions, causes phenomena of double refraction which may be
doi:10.1038/scientificamerican01131877-19 fatcat:rmmvxd3kpnhg3l6ifmbfekhvn4