ABSTRACT
D d… The operator for the first derivative of a function or variable in several
formulas. d2… The operator for the second derivative of a function or variable in several
formulas. d’Alembert, Jean Le Rond See hydraulics. Dam A barrier constructed across a watercourse for impoundment, diversion,
navigability, or power generation purposes. See also dike; embankment. Dams may be classified according to their functions, according to design considerations, or according to the materials used in their construction. See the following types of dam: arch; arch gravity; buttress; check; coffer; crib; debris; detention; diversion; earth; earth fill; embankment; gravity; hydraulic fill; impounding; masonry; rock fill; rock filled crib; roller compacted concrete; single arch; spillway; storage; timber; timber crib; wicket.
