A Machian interpretation of Kaluza-Klein gravity is outlined, wherein
the fifth coordinate is related to mass. It is shown that with an appr
opriate form for the metric, the usual law of inertial motion is obtai
ned together with a cosmological variation of particle masses. This va
riation, however, is slow enough to be compatible with observation. Wh
en the 5D theory is reduced to 4D general relativity, a cosmological c
onstant appears which is of acceptable size.