The work described in this paper was carried out in an attempt to clarify the problem of determining the effects of elastic foundations under rotating machines on the resonant speeds of those machines. Nonrotating models were used as a medium for studying this problem for reasons of expediency in construction, manipulation, and measurement. These models consisted of a “rotor” mounted in “bearings” from a rigid stator which in turn was supported through a foundation, the stiffness of which could be varied. The behavior of uniform rods and models of turbo-driven alternator rotors was studied in this apparatus. Results showed a wide variation of certain resonant frequencies of the model system with foundation stiffness, emphasizing the need for careful consideration of the effect of this factor on the resonant speeds of full-sized machines when run on their permanent foundations.