even as the amount of coal required for any particular application fell. Jevons argued that improvements in fuel efficiency tend to increase (rather than decrease) fuel use, writing: "It is a confusion of ideas to suppose that the economical use of fuel is equivalent to diminished consumption. The very contrary is the truth." At that time, many in Britain worried that coal reserves were rapidly dwindling, but some experts opined that improving technology would reduce coal consumption. Jevons argued that this view was incorrect, as further increases in efficiency would tend to increase the use of coal. Hence, improving technology would tend to increase the rate at which England's coal deposits were being depleted, and could not be relied upon to solve the problem. The Jevons effect is perhaps the most widely known pitfall in environmental economics. Although Jevons originally focused on the issue of coal, the concept has since been extended to the use of any resource, including, for example, water usage and interpersonal contact. Although the concept of rebound effect was developed from the original theory by Jevons, the contemporary economics have traversed, to expand the scope of what is meant by rebound effects and to provide Jevons' effect a more concise definition. The concept of rebound effects has taken various iterations in different disciplines and has come to encompass several spheres of challenges and negative externalities. Walnum et al. carried out a systematic study of rebound effect research and observed the presence of seven viewpoints in which each provides unique interpretations and suppositions on the phenomenon: psychological study, ecological economics, energy economics, ecological economics, socio-technological discipline, evolutionary economics and urban planning. An eighth important position, that of industrial ecology, was also identified in further studies. The expansion of slavery in the United States following the invention of the cotton gin has also been cited as an example of the effect. The Jevons effect is also found in socio-hydrology, in the safe development paradox called the reservoir effect, where construction of a reservoir to reduce the risk of water shortage can instead exacerbate that risk, as increased water availability leads to more development and hence more water consumption. Cause Economists have observed that consumers tend to travel more when their cars are more fuel efficient, causing a 'rebound' in the demand for fuel. An increase in the efficiency with which a resource (e.g. fuel) is used causes a