delivered the opinion of the Court:

The claim of the complainants is undoubtedly too broad. They virtually claim a prospect, not the free access of light and air. They claim the perpetuation of existing conditions, when such perpetuation was not within the contemplation of the parties to the covenant. There is nothing in the covenant to sustain this claim. Neither in express terms nor by necessary implication does the covenant dedicate the strip of land between the Jackson house and the old frame building to the common use of the occupants of the two buildings for all time. Much *127less is there such a dedication for the exclusive use of the owners of the Jackson building. There is nothing in the covenant, from which it can reasonably and fairly be inferred that tho existing condition of tilings should be maintained in perpetuity; that the frame building was never to be replaced by a larger structure; that no structure of a greater height than 20 feet, was to be built upon tbe premises; tbat there was to be no occupation whatever of any part of tbe intervening lot for tbe erection of any structure. It would be an unreasonable construction of the covenant that would warrant such an inference.

Of course, it would have been competent for the parties to the covenant to stipulate for the maintenance of existing conditions in perpetuity; but sucb stipulation is not to be inferred from a covenant not to obstruct windows, not to interfere with the enjoyment of window lights as they then existed, and to permit ingress upon the land for the purpose of certain repairs. Such a dedication of vacant land to common use as would require it practically to remain vacant forever is not usually made in that way; and we see no reason for any construction that would give this covenant such far-reaching effect.

The complainants are entitled to the letter of the covenant reasonably and fairly construed, — to unobstructed windows, to the enjoyment of light and air through these windows unimpaired and substantially the same as when the easement was granted, and to the right of ingress upon the property for the purpose of repair. This right of the complainants would not only have been impaired, but it would have been actually desti*oyed by the course contemplated in the first instance to be pursued by tbe defendant; and this is candidly conceded by tho defendant, who at the time was evidently unaware of the existence and nature of the covenant, but wbo, of course, was chargeable with constructive notice of it. The injunction, therefore, was properly sued out, aud was properly granted, although perhaps too broad in its scope.

Tbat to wbicb tbe complainants are entitled is not the maintenance in perpetuity of the pre-existing condition of the land, *128but that their light and their right of access for a specified purpose should not be obstructed or substantially impaired. Unquestionably, this would necessitate that a sufficient portion of the land adjoining the house should be left vacant. But it is substantial impairment of their right, not the slight and unimportant impairment that would necessarily follow from any improvement of the premises, against which the complainants are entitled to be protected.

Two witnesses have been produced by the defendant, architects by profession, who testify that a space of 3 feet and 8 inches between the buildings would be ample for light and air. But if all the architects in Washington should swear that a space of 3 feet and 6 inches would afford substantially the same light and air for windows as a space of 21 feet, this court would not believe them. The witnesses, however, have not so sworn. They have only sworn to a custom or usage among builders, and the requirements of the building regulations of the city of Washington, neither of which have anything whatever to do with the covenant now before us for construction.

There is nothing in the record before us by which we can determine to what proximity to the Jackson house the defendant may build upon his own lot without substantially impairing the right reserved to the complainants by the covenant. There is both the matter of the substantial impairment of light and the matter of substantial interference with the right of access for the purpose of repair to be considered; and there is no testimony in the case, at least no sufficient testimony, upon which to base a decree that would secure the just rights of both parties. Either by a reference to the auditor of the court, or in some other way, it should be determined what amount of vacant land is necessary to the west of the Jackson house in order to secure to the complainants the unobstructed right to light and air and access to the land to which they are entitled before a decree can properly be entered.

We think that there was error in the decree appealed from, for which it must be reversed, with costs. The cause will be re*129manded to the Supreme Court of the District, with directions to vacate that decree, and for such further proceedings as may be right and just, in accordance with law and in conformity with this opinion. And it is so ordered. • Reversed.