When a part of a parcel of land under one ownership is taken by condemnation, the value of the damages to be proved is often not the value by itself of the part taken but the difference between the value of the property as a whole before the proceeding and the value of the remainder after the condemnation proceeding has taken a part of it. This amount over and above the value of the part actually taken is known as consequential damages. That is to say, the value of the remainder has been reduced as a direct result of the proceeding. Should the proceeding be for a public improvement, such as a park, which would tend to increase all values in the neighborhood, such increment cannot be used as an offset to the amount of damages sustained by the owner by reason of the condemnation of his land.