of the well known book on project management The Mythical Man-Month. Buys Ballot's law is concerned with the notion that the wind travels counterclockwise around low pressure zones in the Northern Hemisphere. Named for C. H. D. Buys Ballot, who published an empirical validation of an existing theory, in 1857. Byerlee's law gives the stress circumstances in the Earth's crust at which fracturing along a geological fault takes place. C–D Campbell's law: "The more any quantitative social indicator is used for social decision making, the more subject it will be to corruption pressures and the more apt it will be to distort and corrupt the social processes it is intended to monitor." Named after Donald T. Campbell (1916–1996) Casper's Dictum is a law in forensic medicine that states the ratio of time a body takes to putrefy in different substances – 1:2:8 in air, water and earth. Cassie's law describes the effective contact angle θc for a liquid on a composite surface. Cassini's laws provide a compact description of the motion of the Moon. Established in 1693 by Giovanni Domenico Cassini. Celine's laws are a series of three laws regarding government and social interaction attributed to the fictional character Hagbard Celine from Robert Anton Wilson's The Illuminatus! Trilogy. Chargaff's rules state that DNA from any cell of all organisms should have a 1:1 ratio (base Pair Rule) of pyrimidine and purine bases and, more specifically, that the amount of guanine is equal to cytosine and the amount of adenine is equal to thymine. Discovered by Austrian chemist Erwin Chargaff. Charles's law, one of the gas laws in physics, states that at constant pressure the volume of a given mass of a gas increases or decreases by the same factor as its temperature (in kelvin) increases or decreases. Named after Jacques Charles. Chekhov's gun states that nonessential elements of a story must be removed. Cheops law: Nothing ever gets built on schedule or within budget. Chesterton's fence states that reforms should not be made until the reasoning behind the existing state of affairs is understood. Child's law states that the space-charge limited current in a plane-parallel diode varies directly as the three-halves power of the anode voltage and inversely as the square of the distance separating the cathode and the anode. Named after Clement D. Child; also known as the Child–Langmuir law (after Irving Langmuir). See also Mott–Gurney law. Chladni's law