The range ro of the residual central forces in nucleus is discussed. The splitting of two-particle configurations and binding energies of n particles in a j-level are shown to be most sensitive to the range ro. From the corresponding data analysis in the lead region the value ro = (1.8 - 2.0) fm is obtained. It is found that levels with J = 0 and 1 are especially sensitive to the tensor forces. Possible density dependent types of the residual interaction are discussed. © 1968.