
9 F.2d 525 (1925)
ERIE R. CO.
v.
MURPHY.
No. 65.
Circuit Court of Appeals, Second Circuit.
November 16, 1925.
*526 Stanchfield, Collin, Lovell & Sayles and Halsey Sayles, all of Elmira, N. Y., for plaintiff in error.
Mortimer L. Sullivan, of Elmira, N. Y., for defendant in error.
Before HOUGH, MANTON, and HAND, Circuit Judges.
HOUGH, Circuit Judge (after stating the facts as above).
The uncontradicted facts adduced by both sides of this controversy presented a situation from which a jury could infer negligence. The case is one of a recognized class "where the circumstances of the occurrence (causing injury) are of a character to give ground for a reasonable inference that, if due care had been employed," what is popularly called an accident would not have happened. Central, etc., Co. v. Peluso (C. C. A.) 286 F. 661; Sweeney v. Erving, 228 U. S. 233, 33 S. Ct. 416, 57 L. Ed. 815, Ann. Cas. 1914D, 905.
It is regrettable that this situation has been so often spoken of as governed by the rule of res ipsa loquitur, for that can hardly be called a rule which depends for existence on a court's view of possible facts; nor is the matter made clearer by concealing the difficulty of definition in a tag of Latin.
Nothing, not even a man, speaks until experience and observation have given it or him power to speak and say something; and the phrase really means that what metaphorically speaks is experience, and experience that leads observing judges to hold that reasonable laymen may infer negligence from facts which experience teaches do not follow due exercise of care and skill. The standard illustration of the so-called rule is a boiler explosion, and since experience teaches observers that steam boilers, well made and properly cared for, do not explode without warning, the inference is justified that an exploding boiler failed either in construction, upkeep or management. Rose v. Stephens, etc., Co. (C. C.) 11 F. 438; The Rambler (C. C. A.) 290 F. 791.
But observation must rely on experience confidently to hold this, no court would have announced such doctrine if the engine that 100 years ago pulled the first train on the Stockton & Darlington road had exploded; nor was there place for it, had one of the first gasoline explosion engines that took to the open road in competition with each other in 1894 similarly behaved.
But now there are 30 years of experience with gasoline engines of many kinds and under all conditions of use and misuse, and it has become common knowledge that such apparatus, made with ordinary care and managed with ordinary skill, does not either explode or burst into flame. Hence we can draw the same inference from the facts here shown as have long been drawn from an exploding steam boiler.
An inference is not legally the same thing as a presumption, though both may connote a reasoning process, for a presumption may measurably take the place of proof, while the inference we have stated "does not relieve from the burden of proof but does put the burden of evidence  i. e., of explanation  on" (in this case) the defendant below. Kraljer v. Snare, 221 F. 255, 137 C. C. A. 108.
This distinction the trial court did not observe in the original colloquial charge, nor can we think that the explanation of the objection conformed to (especially) the decision last cited, nor to the other before-mentioned ruling cases, for it failed to point out directly that there was no presumption presently existing, but only the right to infer something insisted on by the Supreme Court of the United States, although the words have been used without proper distinction in many cases, as may be seen in 20 R. C. L. p. 184 et seq.
This was error; the question remains whether it was harmless. What is harmless error must, we think, always remain something dependent on circumstances never to be foreseen, and often not easily understood, when removed from the setting of the particular trial under investigation.
To render error harmless it must be held that it could not prejudice the rights of the party complaining (Vicksburg, etc., Co. v. O'Brien, 119 U. S. 99, 7 S. Ct. 172, 30 L. Ed. 299, followed in this court Austro-American Co. v. Thomas, 248 F. 231, 160 C. C. A. 309, L. R. A. 1918D, 873), and it has been held that, when the error is in giving instructions *527 to the jury, the defendant in error must bear "the heavy burden of showing that, under the undisputed facts as applied to proper instructions, the verdict could not have been other than was returned." Farmers', etc., Bank v. Newton, 154 Iowa, 49, 134 N. W. 436. We think this fairly states the substance of the best of many decisions, and that "could not" must be read to mean could not be different if the jury were intelligent men.
This jury was erroneously told, in substance, that the facts created a presumption, but was also most pointedly informed at last that the burden of proof was not shifted to defendant. Since the vice of calling the matter a presumption lies in the inference as to burden of proof, we are of opinion that defendant in error has borne the heavy burden of showing that, had this jury been instructed in the very words of the ruling cases first above cited, they could not, if reasonable, have strayed from the very proper and reasonable result they did reach.
Judgment affirmed, with costs.
