Opinion by

It is not material for the purposes of this case whether the appellant’s right in plaintiff’s building be called an irrevocable license or an easement, for it must rest on the principles and be decided on the footing of an easement by prescription. That' the joint erection and occupation of the stairway and the area in which it is located were by agreement is known here just as it is implied in a prescription, but in the absence of any evidence either written or oral as to the terms of the agreement, the court can only determine what it was by what was done without dispute by the parties on the land at the time and subsequently. That is the test of the nature and extent of an easement by prescription and it must be the test here. The inference from the evidence is not that each party gave the other an unlimited right to use the common area for such purposes and in such manner as he might desire or even for general use for a stairway, but that the right was definitely confined to the common area as it was established by the parties at the time and as it continued to be jointly used.

The alterations in the stairway and building made by defendant are admitted. Some of them, such as the building of the wall an additional story in height on plaintiff’s side of the area, and the alteration of the front wall over the area, were corrected before the decree and are now out of the case. But there still remain the removal of the stairway farther front at the ground floor, the reduction of the headway at points in the stairs and landings, the consequent interference with the light from the front windows, the cutting of new holes in plaintiff’s wall to support the new landings, and the opening of a door to the elevator on the ground floor of the area, which though in defendant’s own building subjects the common area to the new and additional use of persons going to the new upper stories erected by defendant. All these, and perhaps some others less mani*397fest, are new or more extensive burdens on tbe area and stairway than have been used heretofore.

That the changes inflict little or no damage on plaintiff is not material. Even a conceded benefit by an improvement cannot be imposed without consent, for plaintiff’s right is to have the status quo maintained, independently of any actual present injury by the change. The legal injury which plaintiff is entitled to prevent is the permanent change in the conditions agreed upon as shown by the past user.

Decree affirmed with costs.