Measurements of multilayer adsorption of solid 4 He on graphite have been made for 0.965 K^ T^ 1.24 K at intervals of ~ 15 mK using fourth sound in He II as a probe. The first observation of the increase of the two-dimensional critical temperature T cj with increasing layer number j is reported. We extrapolate our values of T cj for j -• oo and obtain the bulkroughening transition temperature, confirming a prediction of current theories. The modeling of the acoustics including effects of the solid-liquid interface is also presented.