In the face of the verdict, which is not challenged by the appeal, it- would be singular if the plaintiff should also recover in the instant case. One who causes or contributes to- an injury by his own negligence is not entitled to damages therefor. Neither plaintiff nor defendant is permitted to recover for injuries resulting from a collision when the negligence of each contributed thereto as a proximate cause. Construction Co. v. R. R., 184 N. C., 179, 113 S. E., 672. It follows, therefore, that the judgment of nonsuit on plaintiff’s cause of action, which seems correct upon the evidence, must, upon its own merits and for this additional reason, be sustained. In any view of the ease, the *254plaintiff has failed to overcome the presumption against error. Jackson v. Bell. 201 N. C., 336, 159 S. E., 926; Bailey v. McKay, 198 N. C., 638, 152 S. E., 893. To prevail on appeal, he who alleges error must successfully handle the laboring oar. Frazier v. R. R., ante 11; Poindexter v. R. R., 201 N. C., 833, 159 S. E., 926.