. Carnegie Institution of Washington publication. 72 DISPLACEMENT INTERFEROMETRY. an even more sensitive micrometer, with the advantage that the telescope may be shifted, there being no fiducial line within it. If Ae refers to dis- placement of fringes measured along this scale, the standardization showed that io3AW/Ae = 101. Triplets for the loads 1-2-1 kg. gave a mean value of Ae/AP = cm., whence io4A7VYAP = cm. and£ = ~12 as above. The change is cyclic, the graphs are curved. The mean E, even above 3 kg. of load, will not exceed io12. Triplets gave in succession P=I-2-
. Carnegie Institution of Washington publication. 72 DISPLACEMENT INTERFEROMETRY. an even more sensitive micrometer, with the advantage that the telescope may be shifted, there being no fiducial line within it. If Ae refers to dis- placement of fringes measured along this scale, the standardization showed that io3AW/Ae = 101. Triplets for the loads 1-2-1 kg. gave a mean value of Ae/AP = cm., whence io4A7VYAP = cm. and£ = ~12 as above. The change is cyclic, the graphs are curved. The mean E, even above 3 kg. of load, will not exceed io12. Triplets gave in succession P=I-2-I i o3A£/AP = 27 EXio12/AP= 2-3 — 2 17 3-4-3 13 4-5-4 kg. 9 cm. cm. which is no marked improvement over what has preceded. There seems to be little hope of further increasing the effective rigidity of the apparatus. Measurements for E will therefore have to be made differ- entially. For this purpose the constants of the apparatus (here with elas- tic brass bifilar) are to be determined by a relatively thick steel rod, as has just been done. An example of this has been put in figure 51, a, showing the behavior of a fresh, hard-rubber rod treated in successive cycles of loads between i and 5 kg. Hysteresis and viscous deformations appear very clearly, as usual. The mean moduli for the ascending branches will not much exceed 2Xio10, and in triplet observations they ran from this to about 6Xio10 for loads up to about 50 kg. per , also in the manner found above. As a contrast to these results the behavior of the steel rod of the same dimensions (zL= 5 cm., 2r = cm., nearly), for which data have just been given, is also inserted in the lower curve b of the same figure. Both curves are cyclic, but on an enormously different scale, even though the true steel moduli can not be approached to more than one-quarter. The true steel line is shown at c. We admit that the hysteresis in curve 6 is possibly in the apparatus, which is a compound elastic body; but
Size: 1418px × 1761px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorcarnegie, bookcentury1900, bookdecade1900, bookyear1902
