Opinion,

The coal companies are the owners of the coal under a large body of land in Westmoreland county, the surface of which belongs to others. In granting the coal, the owners of the land released their right to the support of the surface, so that the *532coal companies have the right to remove all the coal without regard to the effect of such removal on the surface. ' The gas company desires to lay its main line foi’ the transportation of natural gas or fuel upon and across -these lands. The transportation of natural gas has been declared a public use and the right of eminent domain conferred upon companies organized for the purpose of providing transportation for it, by the act of May 29,1885. The gas company appears to have entered lawfully upon the surface for the purpose of laying its line of pipe, and to have proceeded on the theory that the owners of the underlying estates in the coal were not injured by their entry upon the surface, and had no right to be heard. The learned judge who heard the case adopted this view, and held that the gas company could not be required to give bonds to the coal companies for going over the surface which did not belong to them, but nevertheless sustained the plaintiffs’ bills, and made a decree regulating the manner in which the pipes should be laid on the surface, so as to guard against injury to the underlying coal, as well as it was practicable to do. Just how these positions are reconcilable, it might be difficult to see. Our present inquiry relates to the first of them.

If an entry had been made on these lands under the right of eminent domain before the coal had been separated from the surface by sale, the corporation making such entry would have acquired a right both to the surface and to the support of the surface by the underlying coal, or so much thereof as would be needed for that purpose. The loss in value to the tract by reason of the appropriation of part of the coal to the support of the surface is a proper subject for compensation by the viewers appointed to assess damages: Searle v. Railroad Co., 33 Pa. 57; Reading etc. R. Co. v. Balthaser, 119 Pa. 472. This is to be ascertained, not by a calculation of the quantity of the coal, but by the effect of the appropriation on the tract as a whole. The railroad company, as was said by Lowrie, C. J., “ gets no title to the coal further than it is needed to support the surface,” but they did acquire, beyond all question, the right to such support, without which the right to the surface would have possessed but little value. It was, so to speak, appurtenant to the surface, and was acquired with it.

What is the effect of the severance of the coal from the sur*533face ? If- the sale of the coal be made in the usual manner, the purchaser takes it subject to the burden of surface support, and cannot remove it without leaving a sufficient quantity to support the surface: Jones v. Wagner, 66 Pa. 429; Carlin v. Chappel, 101 Pa. 348. An entry in that case upon the surface has the same effect as though made before the sale of the coal, and the right to surface support residing in the owner of the surface passes to the corporation when it appropriates the surface. If, in addition to severing the coal from the surface by a sale, the owner releases his vendee and the underlying estate from the obligation of surface support, the release is binding upon him and those taking title from him, but it cannot bind the state, or its grantee, entering by virtue of the title paramount residing in the sovereign. The right of eminent domain cannot be abridged or defeated by the contracts between private owners, or by the release of the owner of the surface. An entry by the state upon the surface is an entry upon the subjacent strata so far as they are necessary to support the surface for the purposes of the canal, railroad, pipe line, or other structure to be built thereon. If the corporation making the entry has no knowledge that the right of support has been released, or if it fails for any reason to tender a bond to the owner of the coal, the remedy of the owner is by bill to restrain, or by a proceeding to obtain an assessment of the damages sustained. If the latter mode be adopted, the amount of support needed, the probable length of time the structure may remain in place, the possible danger from its use, are elements that enter into the calculation of the damages to the extent that they may affect the market value of the underlying estate, but not otherwise. If the proceeding by bill be chosen, we see no reason why the owner of the subjacent stratum has not a right to require security to be given, before the appropriation of his coal to the support of the surface is made by the corporation entering upon the surface for the construction of its railroad, canal, or other line of transportation.

As we have already said, the character of the structure to be put upon the surface, the use to which it is devoted, the depth below the surface at which the vein of coal is found, and the regularity of the geological formation, are circumstances to be taken into account in determining the amount of support *534needed and of the compensation to which the coal owner is entitled. If the corporation feels that its works are of such a character, or of so temporary a nature, or for the transportation of a commodity so soon to be exhausted, as to render appropriation of the underlying estate to the support of the surface unnecessary, it may file a stipulation agreeing to be bound by the release of the owner of the surface, and to accept the risk of subsidence which such release involves. If it does not do this, support is acquired as matter of law by an entry under the right of eminent domain, and is a proper subject for compensation, not by estimating the value of the coal in place that may be needed for support, but by the effect of the appropriation on the price or value of the underlying estate.

Upon the other question, that of the precautions necessary to be taken in laying the pipe so as to secure the coal owners from danger, the order made would seem, for the present at least, a sufficient protection. If it shall hereafter appear inadequate, there is no reason to doubt that such further order will be made as may then seem necessary. The only error of the court below was in holding that the owners of the coal had no standing, and no right to be heard on the question of compensation, because the pipe was not laid on their estates, but on the surface which was owned by others. The court should have granted the injunction prayed for, unless the corporation joined in, or agreed to be bound by the release of support by the owners of the surface, or gave security, as required by law, for the payment of the damages to be assessed for such support. The decree is reversed, so far as relates to this subject, and the learned judge is directed to proceed to a disposition of the motion for a preliminary injunction upon the principles now laid down; refusing it, if either security or a release be given, and granting it, if both be withheld.

The rule of this court is not to file an opinion in cases relating to preliminary injunctions. These cases are made an exception because the question involved is new, and because it has seemed probable that an expression of our views at this time might simplify, if it did not wholly save future litigation in them.