Care was taken to so adjust the turnbuckles or swivels that proper
and proportionate initial tension occurred in the diagonal tie- rods.
Provision is made for dissipating charges of electricity due to
atmospheric disturbances, to which elevated metallic structures are
more or less liable. Heavy iron wire cables, placed within flue
spaces built in the masonry, connect the metal work of the dome
with certaiu water pipes laid under ground adjacent to the tower,
thus acting as conductors for the passage of any electric charges away
from the dome. The efficiency of the device was made apparent
during the erection of the structure, when several severe electrical
storms were experienced.
All water from rainfall or snow is gathered by a cast-iron electro-
plated gutter placed at the base of the dome, and on top of the
marble cornice. The gutter extends around the dome, is about 3
feet wide and 18 inches deep, lined inside with 64-ounce
sheet copper with expansion joints, and laid upon a Portland cement



Schumann — The Dome of the City-Hall Tower, Philadelphia. 75

base, graded from each corner of the tower down to the middle of a
side, where funnel-shaped copper outlets lead to 6-inch diameter iron
pipes that connect with the sewers of the building. The inside edge of
the gutter, which extends up back of the lower sheets forming the
shell of the dome, is three inches higher than the outside edge, so that
in the event of a possible overflow from a stoppage of the down pipes
the flow would be outward, and away from the tower.
DISCUSSION.
