Does this court have the power to reverse a finding in favour of a plaintiff in a civil case?

Defendants claim that this court has the power to reverse although there is substantial evidence to support the findings in plaintiffs' favor, because the trial court which made them on the basis of a written transcript was in no better position than this court to appraise the credibility of the witnesses. That point was so thoroughly canvassed in Tupman v. Haberkern, 208 Cal. 256, 261--263, 280 P. 970 that any further discussion is unnecessary.