227 



TABLE 204.— VARIATION OF THE RIGIDITY MODULUS WITH THE TEMPERATURE 



m = n„ (1 — at — pt 2 — yt 3 ), where t = temperature Centigrade 



TABLE 205.— INTERIOR FRICTION AT LOW TEMPERATURES 



C is the damping coefficient for infinitely small oscillations ; T, the period of oscillation in 

 seconds ; N , the modulus of rigidity dynes/cm 2 . 



Substance Cu Ni Au Pd Pt Ag Quartz 



Length of wire in cm 22.5 22.2 22.3 22.2 23.0 17.2 17.3 



Diameter in mm 643 .411 .609 .553 .812 .601 .612 



100°C C 24.1 1.34 27.5 1.67 2.98 55.8 — 



T 2.381 3.831 3.010 2.579 1.143 1.808 — 



N X 10"" 3.32 7.54 2.55 5.08 5.77 2.71 — 



0°C C 5.88 .417 4.82 1.25 4.60 7.19 4.69 



T 2.336 3.754 2.969 2.571 1.133 1.759 1.408 



N X 10-" 3.45 7.85 2.62 5.12 2.87 2.26 



— 195°C C 3.64 .556 6.36 .744 3.02 1.64 1.02 



T 2.274 3.577 2.902 2.552 1.111 1.694 1.425 



AT X 10- 11 3.64 8.65 2.74 5.19 6.10 3.18 2.20 



TABLE 206.— RATIO, p, OF TRANSVERSE CONTRACTION TO LONGITUDINAL 

 EXTENSION UNDER TENSILE STRESS 



(Poisson's Ratio) 



TABLE 207.— A SCALE OF HARDNESS BASED UPON THE RELATIVE HARDNESS 



OF SELECTED MATERIALS 



Each material will scratch the one following it in the table. 



10 Diamond 

 9 Corundum 



8 Topaz 

 7 Quartz 



6 Feldspar 

 5 Apatite 



4 Fluorite 

 3 Calcite 



2 Rock salt 

 or gypsum 

 1 Talc 



SMITHSONIAN PHYSICAL TABLES 



