Historically, the definition of a scientific instrument has varied, based on usage, laws, and historical time period. Before the mid-nineteenth century such tools were referred to as "natural philosophical" or "philosophical" apparatus and instruments, and older tools from antiquity to the
Middle Ages (such as the
astrolabe and
pendulum clock) defy a more modern definition of "a tool developed to investigate nature qualitatively or quantitatively." In a description of the use of the
eudiometer by
Jan Ingenhousz to show
photosynthesis, a biographer observed, "The history of the use and evolution of this instrument helps to show that science is not just a theoretical endeavor but equally an activity grounded on an instrumental basis, which is a cocktail of instruments and techniques wrapped in a social setting within a community of practitioners. The eudiometer has been shown to be one of the elements in this mix that kept a whole community of researchers together, even while they were at odds about the significance and the proper use of the thing." By World War II, the demand for improved analyses of wartime products such as medicines, fuels, and weaponized agents pushed instrumentation to new heights. Today, changes to instruments used in scientific endeavors—particularly analytical instruments—are occurring rapidly, with interconnections to computers and data management systems becoming increasingly necessary. ==Scope==