A court of equity or of common law, as the case may be, is called the court of construction with regard to wills, as opposed to the court of probate, whose duty is to decide whether an instrument be a will at all. Now, the court of probate may decide that a given instrument is a will, and yet the court of construction may decide that it has no operation, by reason of perpetuities, illegality, uncertainty, etc. Wharton
