Such association is authorized to enter upon, and construct, and maintain lines of telegraph through, along, and upon any of the public roads and highways, or across or under any of the waters within the limits of this state, by the erection of the necessary fixtures, including posts, piers, or abutments for sustaining the cords or wires of such lines: Provided, That the same shall not be so constructed as to incommode the public use of said roads or highways, or injuriously interrupt the navigation of said waters; nor shall this act be so construed as to authorize the construction of any bridge across any of the waters of this state: And provided, further, That this act shall not be construed to authorize any such association to injure, deface, tear, cut down, or destroy any tree or shrub planted along the margin of any highway in this state, or purposely left there for shade or ornament. Said association, instead of running or placing their wires on posts, may, if they choose, run or place the same under ground, with a suitable or proper covering for the protection of the same; and any part of this act, or any law made or to be made, providing for the appraisement of damages to any person injured by the construction or maintenance of such line or lines, shall be construed to include damages occasioned by the construction of said lines under ground, as provided by this act.