(After stating the foregoing facts.) This case is in this court on the grant of a petition by the defendant for the writ of certiorari, to review the decision of the Court of Appeals, which was adverse to the defendant. The only grounds of alleged error are those set out in the fifth, tenth, eleventh, and fifteenth grounds of the motion for new trial, which are set out in extenso in the statement of facts.
In the tenth ground it is alleged that the court erred in permitting a witness for the plaintiff, over objection of counsel for the defendant that it was irrelevant, to testify that rocks had fallen off from its side into the cut where the plaintiff had been injured. The court admitted this evidence to show notice to the defendant of the dangerous condition of this cut. It does not appear, from the facts stated in this ground, when these rocks had fallen into this exeavation. In the application for certiorari, and in the brief of counsel for the director-general, it is asserted *507that this witness fixed the date of the falling of these rocks at a period prior to the time the government took over the control of this railroad; and we are referred to the brief of evidence for the substantiation of this assertion. If this occurrence had taken place after the director-general had assumed management of this railroad, it would have been admissible as tending to bring home to him the dangerous condition of this cut. If this occurrence happened before this officer began to operate this road, it would not have been admissible for the purpose for which it was offered, and should have been rejected. The burden was on the movant to show error. Hunter v. State, 148 Ga. 566 (97 S. E. 523). Each assignment must be complete in itself. Jenkins v. State, 150 Ga. 1111(102 S. E. 830). This court will not look through the brief of evidence to ascertain whether evidence, set out in a ground of a motion for new trial, was illegally admitted. The illegality of its admission must appear from the averments contained in the ground of the motion. McMichael v. Atlanta Envelope Co., 151 Ga. 776 (3) (108 S. E. 226). For these reasons we can not say that the trial judge erred in admitting this testimony.
In the eleventh ground it is urged that the trial judge erred in allowing the plaintiff, over objection of defendant’s counsel that it was immaterial, to testify that men, who had not been in the service as long as he had been, had been promoted by seniority and gone ahead of him as engineers, since this accident. What was meant is, that firemen who had been in the service of the company for shorter terms had been promoted to engineers over the plaintiff, due to the fact that the latter had been injured. Was this evidence admissible? In Richmond etc. Railroad Co. v. Allison, 86 Ga. 145 (12 S. E. 352, 11 L. R. A. 43), this court held that it was improper to allow proof of a particular possibility, or even probability, of any increase of wages by appointment to a higher public office, especially where the appointment is somewhat controlled by political reasons. This ruling was put on the ground “ that Allison’s promotion was too' uncertain, and the possibility of an increase of his salary . . too remote to go to the jury and for them to base a verdict thereon.” In the opinion Justice Simmons said: “We believe the rule of most of the railroads in this State is to promote their employees. An employee com*508menees at the lowest grade; and if he is competent, capable, and efficient, he is likely to be promoted upon the happening of a vacancy above him. If one occupying a lower grade of service were injured, would he be allowed to prove, unless he had a contract to that effect, that his prospects of promotion to a higher grade and better salary were good, and would the jury be allowed to base their calculation and estimate of the damages upon a much larger salary which he had never received . . ? It is to be observed that the testimony in this case shows that there were two others in the same class with Allison, equally competent and efficient as he was, and it is by no means certain that Allison would have been preferred to each of them in ease of vacancy, and promoted above them; so it could not be said that he was in the direct line of promotion.” From this language it might be inferred that the injured employee, if he were working under a contract which entitled him to promotion, could prove such fact as an element of
his damages. In Central of Ga. Ry. Co. v. Perkerson, 112 Ga. 923, 926 (38 S. E. 365, 53 L. R. A. 210), this court said: “It is pretty well established that in proving the value of the life of a deceased employee it is not competent to prove that he was in the line of promotion in his calling, and the increased rate of wages which he would have received if promoted. 8 Am. & Eng. Enc. L. (2d ed.) 943 and cases cited. See also Richmond & Danville R. R. Co. v. Allison [supra]. The reason for the rule is that the chances for promotion are too remote, and dependent upon too many contingencies to be considered.”
But counsel for the plaintiff insist, that, under the facts of this case, the promotion of the plaintiff was not dependent upon uncertain factors and contingencies. This contention is based upon his testimony that “promotion on the railroad is by seniority;” but the plaintiff did not testify that promotion was dependent solely upon seniority. At the time he was hurt he was in the employment of the director-general of railroads; and “ Supplement No. 7 to General Order No. 27” was in force. Art. 12 of this supplement declares: “ Promotions shall be based on ability, merit, and seniority; ability and merit being sufficient, seniority shall prevail.” So promotion of the plaintiff depended at last upon the presence of these three factors. So we cannot say that the ruling laid down in the above-cited cases is not applicable to *509this cáse by reason of its peculiar facts; and under that ruling the court erred in admitting this evidence.
The court admitted two rules of the operating department of the Louisville & Nashville Eailroad Co., over the objection of .the defendant that they were irrelevant; and this ruling is complained of in the fifteenth ground of the motion for new trial. One of these rules requires that all accidents, involving injury to persons, or damages to property, track, structures, or rolling-stock, must be reported promptly by wire to the proper officers, and confirmed in writing on prescribed forms. The second’ of these rules prescribes, that section foremen 'must take every precaution during storms to prevent accident, that at exposed points a strict watch must be kept, and that particular attention, day and night, must be given to cuts, tunnels, and'other places where rock, earth, or trees are liable to fall upon the track, or fills that are settling. Were these rules properly admitted by the court? These rules prescribe the duties of employees of the Louisville & Nashville Eailroad alone. They have no application to employees of the Western & Atlantic Eailroad; and do not fix any duties to be discharged by the employees of this road. It does not appear that it was the duty of any employee of the Louisville & Nashville Eailroad to report this slide, and that he failed to discharge such duty. The complaint is that the engineer of the Western & Atlantic Eailroad, who was in charge of a passenger or troop train, which had passed through this cut a short time prior to this accident, and who saw some rock near the track in this cut, failed to -report it, when he reached Yinings. This rule did not apply to this engineer, and did not prescribe any duty to be performed by him. For this reason, the first of said rules was not admissible.
The second of the rules prescribes the duty of section foremen of the Louisville & Nashville Eailroad. It applies solely to foremen of that road. It does not fix any duty to be discharged by the section foremen of the Western & Atlantic Eailroad. Counsel for the plaintiff insists that the introduction of these rules was proper, because the suit was against the director-general as director of both the Nashville, Chattanooga, & St. Louis Eailroad and the Louisville & Nashville Eailroad. The director-general is to be treated as the director of each separate system of trans*510portation. 'The separate systems which were operated by him were separate and distinct parties. Smith v. Babcock & Wilcox Co., 260 Fed. 679; Davis v. Dantzler Lumber Co., 126 Miss. 812 (89 So. 148); Harmon v. Hines, 113 S. C. 179 (101 S. E. 925); Payne v. Coleman (Tex. Civ. App.), 232 S. W. 537; Payne v. Munroe, 28 Ga. App. 6 (110 S. E. 34). The Western & Atlantic Railroad Company is a separate and distinct corporation. Nashville etc. Ry. Co. v. Edwards, 91 Ga. 24 (16 S. E. 347); Branan v. Nashville etc. Ry. Co., 119 Ga. 738, 744 (46 S. E. 882). The relation of the Louisville & Nashville Bailroad to the Western & Atlantic Bailroad, in the operation of the particular train on which the plaintiff was injured, does not appear. It only appears from the evidence that the Louisville & Nashville Bailroad was operating this particular train over the tracks of the Western & Atlantic- Bailroad. It appears from the proof, that the latter company had not given complete possession of its tracks to the former company. Permitting the former company to run trains over its tracks would probably impose upon the latter company, with reference to the eniployees of the former, the duty to furnish a reasonably safe track for the running of such trains. Augusta etc. R. Co. v. Killian, 79 Ga. 234 (4 S. E. 165); Gregory v. Ga. Granite R. Co., 132 Ga. 587 (64 S. E. 686); Wadley So. Ry. Co. v. Durden, 142 Ga. 361 (82 S. E. 1055). It nowhere appears in the record that the section foreman of the Louisville & Nashville Bail-road had charge of any employees engaged in work on the tracks of the Western & Atlantic Bailroad, or were themselves employed in keeping in safe condition the tracks of the latter company; or had any connection whatever with these tracks. So we are of the opinion, that the court erred in admitting in evidence, over objection of counsel for the defendant, these two rules. The fact that the plaintiff was the employee of the Louisville & Nashville Bailroad Company did not render these rules-admissible when they applied to'servants who were in no way responsible for the condition of the track for alleged defect in which the plaintiff was hurt.
Upon an analysis of the charge complained of in the fifth ground of the motion for new trial, we do not think that it was erroneous on the ground that it placed upon the defendant a' greater burden than that imposed by law. This extract from the *511charge of the court lays down two propositions of law. In the first proposition the court instructed the jury that if they found that the director-general of railroads was in the exercise of ordinary care and diligence, through his servants and agents, and that by the exercise of ordinary care and diligence it could not have been discovered that this dirt and rock were upon the track of the railroad company operated by him, then the plaintiff could not recover. The second proposition embodied in this charge is, that if the slide on the track was due to causes over which the director-general had no. control, or if it came so suddenly, or was there for so short a time, or for any other reason which appears in proof it was impossible to have been discovered and prevented, and for this reason -the plaintiff was injured, the director-general being in the exercise of ordinary care and diligence through his agents and servants, then, notwithstanding the fact that the plaintiff may have been injured, the director-general would not be liable for such injury. The court did not instruct the jury that before they could render a verdict in favor of the defendant they must find that it was impossible for the defendant to have discovered and prevented this slide and the consequent injury to the plaintiff. The trial judge plainly instructed the jury that if the defendant exercised ordinary care and diligence in the premises, he could not be liable. He then instructed them in substance that if they found it was impossible for the defendant to have discovered this slide, and thus have prevented this injury, the defendant would not be liable. Surely if it was impossible for the defendant to have prevented this injury, he would not be liable. • So telling the jury was not error. So instructing the jury is quite a different thing from charging them that the defendant would be liable unless it was impossible for him to have prevented the injury. An instruction to this effect would have put upon the defendant a heavier burden.than the law imposes. The instruction as given accorded to the defendant a defense to which he was clearly entitled.
We reverse the judgment of the Court of Appeals on the ground that it erred in not reversing that of the trial court on its ruling in admitting evidence dealt with in the second and third divisions of this opinion. Does not even Homer sometimes nod?
Judgment reversed.
All the Justices concur. Gilbert, J., concurs in the judgment.