The equation U-ms/U-mf = (H/H-m)(1-(0.5H/Hm)) was critically examined for spouting both in small conical-cylindrical columns (D-c < 0.5 m) and large cone-base or flat-bottom cylindrical columns (D-c >= 0.5 m). For small columns, a data base of 36 points with experimental measurements of both H-m and U-m(= U-ms at H = H-m) afforded some insights into the components of this equation and to the merits of the equation itself. For large columns, in the absence of verifiable methods of predicting Hm, correlation of U-ms/U-mf as a function of H/H-m, using the available experimental data on U-ms, has not been achieved.