The solar cycle variations of geomagnetic indices are compared for the last two solar cycles. It is found that the midlatitude as index and the ring current index, Dst, exhibit a markedly different relationship to one another in the two cycles. During solar cycle 20 the yearly averaged aa has been shown to be linearly related to either the yearly averaged ‖Bz‖v2 or v2, where Bz is the north-south component of the interplanetary field and v is the solar wind velocity. However, the yearly averaged Dst is well represented by a linear function of Bzv and not by a function v2. A combination of regression formulas for Dst and aa allows estimates to be made of the annual average v and Bz from 1957 until 1965, when in situ measurements of the solar wind became available. Most interesting, however, is the point that the dependence of aa and Dst on different functions of solar wind parameters implies that the ring current is not directly produced by substorm injections. This result is in agreement with models of magnetospheric processes in which the increased ring current and substorm activity are two separate aspects of increased magnetospheric convection.