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Authors' AdditionsThe above-titled article originally appeared in PE&S, 20 (5), 339-348. It is regretted that, owing to postal delays, it was not possible to incorporate proof corrections, among which are the following: P. 340. Second paragraph ("The only . . .") should be transposed to top of right-hand P. 343. Equation 9. Should read )IM = Y, + ail., ( V . U )~ dV; Equation 11. Denominator P. 344. Equation 16 should read: column on p. 339. should read: variational derivative of 1,. ( V . B )~ dV /,(V.U)~ dV [ 2.rr ps ' ' x channel volume over one pitch I € = P. 345. Right-hand column, line 4: for II P. 346. Appendix. Equation A-5: for d e 2 , r e a d d m . P. 347. Nomenclature. At Y entry, delete R ( l -r ) / H ;

Finite element solutions are presented for developed, isothermal, power‐law flow in an extruder channel, based on a variational formulation in helical co‐ordinates. The success of the method in handling non‐Newtonian flow in a deep, highly‐curved channel is tested by comparison with experimental results. Operating characteristics were determired under virtually isothermal conditions for a screw with depth to diameter ratio 0.25 pumping an aqueous glucose solution containing high molecular weight hydroxyethyl cellulose. Shear stress and first normal stress differences of this solution were determined in a rheogoniometer. It was both highly shear‐thinning and elastic. Computed and experimental screw operating characteristics agree well, except near closed discharge, where effects due to viscous heating and elasticity are tentatively suggested.