  We supplement our previous observations of the shell effect in alkali-metal
nanowires (Li, Na, K) with data extended to the heavy alkalis Rb and Cs. Our
observations include: i) a non-monotonous dependence of conductance-histogram
peak heights on atomic weight, ii) a rapid transition to an atomic shell
structure at elevated temperatures, and iii) a ''reverse'' atomic-electronic
shell transition, caused by the closeness to the liquid state.
