experiments were made on ring nozzles, resulting in the
following formula:

f = 0.001135v squared.

f being loss of head in feet owing to resistance of nozzle, and v the
velocity of the contracted vein in feet per second.

Thirty-five experiments were made with smooth nozzles, resulting in the
following formula:

f = 0.0009639 v squared.

f being the loss of head in feet owing to resistance, and v the
velocity of efflux in feet per second.

Experiments show that a prevailing opinion is incorrect that jets will
rise higher from ring nozzles than from smooth nozzles.

Box's formula for height of jets of water compares very favorably with
experimental results.

* * * * *

IRON PILE PLANKS IN THE CONSTRUCTION OF FOUNDATIONS UNDER WATER.

The annexed engravings illustrate a method of constructing subaqueous
foundations by the use of iron pile planks. These latter, by reason of
their peculiar form, present a great resistance, not only to the vertical
blow of the pile driver (as it is indispensable that they should), but
also to horizontal pressure when excavating is being done or masonry being
constructed within the space which they circumscribe. Polygonal or curved
perimeters may be circumscribed with equal facility by joining the piles,
the sides of one serving as a guide to that of its neighbor, and special
pieces being adapted to the angles. Preliminary studies will give the
dimensions, form, and strength of the iron to be employed. The latter, in
fact, will be rolled to various thicknesses according to the application
to be made of it. We may remark that the strength of the iron, aside from
that which is necessary to allow the pile to withstand a blow in a
vertical direction, will not have to be calculated for all entire
resistance to the horizontal pressure due to a vacuum caused by the
excavation, for the stiffness of the piles may be easily maintained and
increased by establishing string-pieces and braces in the interior in
measure as the excavation goes on.

[Illustration: FIG. 1.--CONSTRUCTION OF A DOCK WALL BEHIND PAPONOTS IRON
PILE PLANKS.]

The system is applicable to at least three different kinds of work: (1)
The making of excavations with a dredge and afterward concreting without
pumping out the water. (2) The removal of earth or the construction of
masonry under protection from water (Fig. 1). (3) The making of
excavations by dredging and afterward co