With respect to the extent of easements and the mode of their enjoyment, the following provisions shall take effect:--

Easement of necessity.--An easement of necessity is co-extensive with the necessity as it existed when the easement was imposed.

Other easements.--The extent of any other easement and the mode of its enjoyment must be fixed with reference to the probable intention of the parties, and the purpose for which the right was imposed or acquired.

In the absence of evidence as to such intention and purpose--

(a) Right of way.--A right of way of any one kind does not include a right of way of any other kind;

(b) Right to light or air acquired by grant.--The extent of a right to the passage of light or air to a certain window, door or other opening, imposed by a testamentary or non-testamentary instrument, is the quantity of light or air that entered the opening at the time the testator died or the non-testamentary instrument was made;

(c) Prescriptive right to light or air.--The extent of a prescriptive right to the passage of light or air to a certain window, door or other opening is that quantity of light or air which has been accustomed to enter that opening during the whole of the prescriptive period irrespectively of the purposes for which it has been used;

(d) Prescriptive right to pollute air or water.--The extent of a prescriptive right to pollute air or water is the extent of the pollution at the commencement of the period of user on completion of which the right arose; and

(e) Other prescriptive rights.--The extent of every other prescriptive right and the mode of its enjoyment must be determined by the accustomed user of the right.