O pinion by

Mb. Justice Mestrezat,

This action was brought by Patrick Henry McKenna against the Citizens Natural Gas Company to recover damages for personal injuries sustained by himself and for the loss of his wife, which the plaintiff alleges were caused by an explosion of natural *38gas at his residence in New Brighton, Beaver county, on the night of December 27, 1897. At that time Mr. McKenna was supplied with natural gas for fuel and illuminating purposes by the Bridgewater Gas Company whose mains were laid in the streets of New Brighton. The Citizens Natural Gas Company also had laid its mains in the streets of New Brighton, but they were not connected with the pipes on Mr. McKenna’s premises by which the gas was conveyed from the mains of the Bridge-water Gas Company to his residence. Charles T. Miller was an employee and inspector of the defendant company, but he had no connection with the Bridgewater Gas Company. On the morning of December 27, 1897, desiring to force some water out of the defendant company’s low pressure line, he by mistake entered a box of the Bridgewater Gas Company and opened the valves of the by-pass contained therein connecting the high and low pressure lines of the latter company. Mr. Miller thought this was the box of the Citizens Natural Gas Company and did not discover his mistake until the following morning. That night at 11 o’clock the explosion occurred at the residence of the plaintiff by which he and his wife were seriously injured and from the effects of which she died a few days afterwards. By Miller’s action in opening the valves of the by-pass, the gas in the mains of the Bridgewater Gas Company was freed from the control of the regulator and passed directly from the high to the low pressure line which carried it to the plaintiff’s house. This would equalize the pressure in the two lines and cause an excessive pressure on the low pressure line. Owing to a break in the line, the gas was turned off, and there was but little gas in the mains of the Bridge-water Gas Company during the day of December 27. Between 6 and 7 o’clock that evening the gas was turned on again. About 9:30 o’clock there was a pressure of twenty-two and one half pounds on the high pressure line. The low pressure line usually carried about ten or twelve ounces.

The plaintiff alleges that Miller’s action in opening the bypass in the Bridgewater Gas Company’s mains while he was in the service and under the direction of the defendant company, was negligence, and caused the explosion in the plaintiff's house which resulted in the injuries to the plaintiff and his wife.

The first and second assignments of error relate to the recep*39tion of the testimony of Samuel Henry offered for the purpose of showing the expectancy of the lives of Patrick Henry McKenna and Mary McKenna, his wife. He testified from a life table in a book entitled “ Handy Guide to Premium Rates, Applications and Policies and American Life Insurance Companies.” The book was not offered in evidence and all we know of it is what the witness testified to. It contained two mortality tables. In testifying to the expectancy of life, he read from the one designated “ Combined Actuaries Experience ” table. On what this table is based, or from what material it was constructed, is not disclosed by the evidence. Whether it was founded on selected or insurable lives or upon general population, or upon either, is not shown by the testimony. The character of the table and its value as a basis from which to determine the expectancy of life were not shown. Tiie witness testified that the table was used for ascertaining lates, and that from this table he could calculate the expectancy of life at a given age. The competency of the witness and the weight of his testimony depended entirely upon the value of the table as evidence to establish the expectancy of life. Had the table itself been offered, under the facts disclosed at the trial, it would have been rejected. The witness, therefore, should not have been permitted to testify from it to the expectancy of life of the plaintiff and his wife. The first and second assignments of error are sustained. The admission of such testimony as complained of in these assignments, its value as well as the care with which it should be submitted to the jury, have been fully discussed and determined by our Brother Dean in the very recent case of Kerrigan v. Penna. R. Co., 194 Pa. 98, and the subject needs no further elaboration at this time.

The third and fourth assignments are not sustained. If the testimony covered by these assignments had been admitted, it would not have convicted the plaintiff of negligence. Without some evidence tending to show that the unsafe condition of the meter and regulator contributed to or was the cause of the explosion, the condition of these appliances was immaterial and irrelevant to the issue, and the testimony offered for the purpose of showing it was properly excluded.

We are at a Joss to see how the fifth assignment can be sus*40tamed. Assuming that the Bridgewater Gas Company was negligent in the construction and maintenance of its lines, it does not exculpate the defendant company from its negligence. Where two parties are each guilty of negligence contributing to an injury, the tort of the one is no defense to an action against the other. In the case at bar, McKenna’s house would not have been wrecked notwithstanding the Bridgewater Gas Company’s defective appliances, had not Miller opened the valve in the bypass. Without his negligence, therefore, it is too clear for argument that the plaintiff would not have sustained the injuries for which he sues in this action.

The seventh assignment relates to a part of the charge devoted to the question of damages. The learned judge in his charge said: “ In determining damages for personal injuries resulting from negligence you will allow .... for the pecuniary loss he (the plaintiff) has sustained, and is likely to sustain, during the remainder of his life, from his disabled condition. When we speak of pecuniary loss we refer to earning power, what he was able to earn, or likely to be able to earn, and such loss as he might sustain of being unable to continue the exercise of that earning power.” The probable earnings of the plaintiff, therefore, was an element to be considered in determining the damages recoverable in the action. It was conceded and so stated in the charge, that there was no evidence in the case as to the earning power of the plaintiff before or after the accident. Yet the court directed the jury to take it into consideration in determining the damages. This was error. As the plaintiff asked damages by reason of his diminished earning capacity, it was his duty to introduce testimony from which the jury could ascertain such damages. Failing in this the learned judge should not have submitted to the jury as a basis for their verdict the pecuniary loss to the plaintiff occasioned by the injuries received in the explosion. “ But it is also true,” says Justice Williams in McHugh v. Schlosser, 159 Pa. 486, “ that when the probable earnings of the deceased are to be taken into account in fixing the damages, it is the duty of the plaintiff to show the earning power of the deceased or give such evidence in regard to his business, business habits and past earnings as will afford some basis from which his earning capacity may be fairly estimated.”

*41The first, second and seventh assignments of error are sustained, the judgment is reversed and a venire facias de novo is awarded.