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ly, there is still the possibility that the difference between these estimates and our results is simply due to slow convergence or other peculiarities in the expansion procedure.Our results, which are expected to simulate for k 1^ 10" 2 an infinite two-dimensional kinetic Ising system 13,14 with nearest-neighbor interactions, lead to the following conclusions:(1) The divergences of r* and T (nI) * are predicted to be the same as those of the isothermal susceptibility [Eq. (11)]. Consequently, there is no evidence for a critical speeding up of fluctuations. The equality of A and A (nl) confirms the conjecture of Suzuki, 4 and A (nl) «y «?J-agrees with the result of Ogita et al. 12 (2) The critical exponent A A of slowing down of the order-parameter autocorrelation function is considerably smaller than that of the isothermal susceptibility [Eq. (11)].(3) Our results [Eq. (11)] do not confirm the estimates obtained from the high-temperature expansion and ratio method. 4,9,11 (4) Our data [Eq. (11)] imply that This result contradicts the prediction of the DSH, x = -\ [Eq. (9)], and the estimates from the hightemperature expansion and ratio method, which in turn confirm the DSH.To summarize, we have reported on computer simulations of critical slowing down in finite kinetic Ising systems which approximate an infinite system for le I £ 10~2, 13,14 as one expects from static scaling for the rounding effect. TheThe tunneling of electrons through an insulator into a superconductor is a powerful way of studying directly the electron-phonon interaction in the critical exponents deduced from these data disagree with the predictions of the DSH to such an extent that the failure of this hypothesis in the kinetic Ising model is probable. Our results also disagree with those obtained from a high-temperature expansion and ratio method.We acknowledge fruitful discussions with RTunnel junctions were fabricated on Nb 3 Sn films reacted on Nb substrates. Derivative measurements were made from 0 to 50 meV and above 18 K. From these tunneling results, the phonon spectrum of Nb 3 Sn is shown to have a strong low-energy peak at 9 meV, a broad peak centered around 17 meV, and a small peak at 25 meV. Using this shape of the phonon spectrum and taking /** = 0.11, a maximum T c of ~ 21 K is obtained for this class of superconductors. This result suggests that crystal transformations arising from instabilities do not limit T in this case.1082