A PRACTICAL METHOD OF SPONGE CULTURE. 563 
sponge. This gave a small surface of attachment which, while sufficient at first, 
became proportionally smaller as the sponge grew. The attached area, and con- 
sequently the strength of the attachment, grew proportionately to the diameter 
of the sponge, while the forces acting to loosen it grew in proportion to the surface 
exposed to the impact of the waves. The consequence was that in rough water 
sponges 5 inches in diameter were generally torn loose, and, once started to 
rotate or oscillate, a large hole was soon worn about the wire to the detriment of 
the quality of the sponge and the retardation of its growth. In sheltered places 
sponges were successfully grown on wires until they reached a diameter of 7 
inches, but eventually they also must have become loose. 
To correct this tendency to loosen, the shape of the wire was modified to 
assist the strength of the attachment by mechanical resistance to the rotation of 
the sponge, longitudinal slipping on the wire being negligible after the attach- 
ment of the cutting is once established. A galvanized iron ribbon three-eighths 
inch wide and one-sixteenth inch thick was incased in a tight-fitting lead jacket 
one thirty-second inch thick, the whole making a flat band one-eighth inch thick 
and not quite one-half inch in breadth. This appears satisfactorily to prevent 
rotation in sponges as large as 8 inches in diameter. 
This lead-incased ribbon is durable so long as the casing is not mechanically 
broken or punctured. At the cut ends the iron rusts away slowly, but the con- 
tact between the iron and the lead is so intimate that the water at a depth of 
10 or 12 feet penetrates but an inch or two at most, and electrolysis is, therefore, 
strictly localized to the open ends. It has to be handled with care, however, as 
the thin lead is easily punctured and the slightest hole becomes the seat of electro- 
lytic action to the speedy destruction of the iron and the consequent breakage 
of the ribbon. When carefully put out this material has lasted for three years 
with no other sign of impairment than the rusting away of about one-half inch 
of the iron where exposed at the ends. Its strength is great, as was demonstrated 
at Biscayne Bay during the great hurricane of 1906 when a piece of wreckage 
fouled some of it, pulling up deeply embedded stakes and flattening a 14-inch 
wrought-iron ring without injuring the ribbon. It is heavy and difficult to 
handle when planting from a small boat and there is also some difficulty in 
attaching it at the stakes. It, of course, can be bent in but one plane, and it 
can not be attached directly to the rings owing both to the electrolytic effect upon 
the latter and to the abrasion of the lead casing of the ribbon. 
In the experimental work porcelain insulators were attached to the rings 
by means of galvanized wire, the ribbon being bent over them, with a piece of 
thin sheet lead interposed, and secured by means of a flattened seine lead or 
piece of lead piping as shown in figure 2. In a commercial application a 
special insulator similar in general shape to that shown in figure 1 could be 
employed. In any case it is necessary to place a piece of sheet lead or asbestos 
