The ordinary means by which an easement of light can be obtained are by grant or covenant, express or implied, or under the provisions of the Prescription Act, 2 & 3 William IV. c. 71.

Theoretically, all easements may be considered as founded on grant or covenant, according as they are positive or negative in their nature.

The theory is that a dominant owner could not legally acquire a burdensome right over a servient tenement unless the owner of that tenement had voluntarily burdened his estate with the easement.

When the easement is positive, such as a " Right of way," for example, the owner of the tenement over which it is intended to create a "right of way" may-create that right in favour of the owner of another tenement by a deed of grant ; or if the easement to be created is a negative one, such as an easement of light or air, the owner of the land across which the light or air passes binds himself by covenant in a deed not to do acts which will interrupt the access of light and air to buildings on the land of another. In either case a relationship of dominant and servient tenements and owners may be thus created, and the general principles of law applicable to the subsequent rights of all parties who may be, or afterwards become, owners or occupiers of the tenements will be the same.

It is well, however, to keep in mind the general distinction between those easements which are classed as positive and conveyed by grant, and those which are negative and reserved by covenant.

The positive easement implies a right for a dominant owner to make active use of the land of another by doing something on, or in, or under the land, as of right, which would ordinarily be acts of trespass, and the right to do things can be conveyed by deed of grant ; whereas the negative easement does not confer any active rights on the owner of the dominant tenement, and all that the dominant owner requires is that the servient owner or persons deriving title from him shall not do certain things which under ordinary circumstances he or they would be entitled to do. The servient owner must therefore be bound by covenant to abstain from doing what would otherwise be lawful acts. I neither case it is the servient owner who must execute the grant or be bound by covenant. Except by Act of Parliament, no other person than an owner can voluntarily create an easement over land to run with the land and to be a burden upon it for ever ; but other persons in possession and holding subordinate interests, such, for example, as a life interest or a long lease, may bind themselves and the land to the extent of their interest, but not beyond, while even an owner of the fee who has parted with possession of his tenement on long lease cannot create easements over his property to the prejudice of the tenant in possession under the lease.

Sometimes owners or occupiers of neighbouring tenements enter into parole agreements relating to what they will and will not do for each other's comfort and convenience, or for mutual advantage, and such agreements are not infrequently reduced to writing and signed by the parties. In such cases the parties may be bound as by any other ordinary agreements, and if the agreement in any case is of such a character as to amount to an agreement to grant an easement, the other party may be able, on the strength of it, to compel the subsequent execution of a proper deed to create an easement; but it is important to bear in mind that mere agreements or contracts not under seal cannot create an easement, and the utmost they can do is to confer a personal right to demand a regular deed to bind the land, or a right of action for breach of contract if the terms are not observed by the parties bound by them.

The benefit of mere personal contracts may be lost when the tenements pass into the ownership or possession of strangers.

The acquisition of easements by particular description in a deed is the most satisfactory of all methods, and the least likely to favour subsequent disputes or litigation.

An easement may also have been acquired under the general words in an old deed of conveyance, or, when land is transferred under the Conveyancing and Law of Property Act, 1881, all easements appurtenant to the land at the time of transfer will be conveyed with the land without the use of any particular description or general words. This Act only came into operation after the 31st December 1881, and therefore all easements to be conveyed needed to be described by particular description or general words before that date.

It is not thought necessary to attempt to enumerate or discuss the technical rulers of law and practice affecting the drafting and interpretation of deeds by which easements are or may be created or transferred.

Any such attempt would lie outside the general range and intention of this work, and require more space than can be spared.

Professional advice and assistance are nearly always necessary, or at least desirable, in the interest of parties concerned when deeds of conveyance or express grants or particular covenants need to be drafted or considered or interpreted, and little if any good would result from attempting to deal with such matters here, even if space did permit.

There is, however, one general principle of great importance to be always remembered, which is, that A grantor may not derogate from his own grant.

The application of this principle will often be of much assistance to grantees of property, by enabling them to use, and preserve as easements, rights which have not been specifically granted, but the enjoyment of which could not be prevented by the grantor without derogation from some grant.

What are called implied grants of easements in favour of the grantee frequently arise out of actual grants or conveyance of houses. A grant of supplementary easements over the land of the grantor will often be presumed in favour of a grantee, to assure to him the full value and use of his grant as against the grantor, but very rarely indeed will it happen that any sort of reservation (or grant by the grantee) will be implied in favour of the grantor of property.