A measuring instrument is a device for measuring a physical quantity. In the physical sciences, quality assurance, and engineering, measurement is the activity of obtaining and comparing physical quantities of real-world objects and events. Established standard objects and events are used as units, and the process of measurement gives a number relating the item under study and the referenced unit of measurement. Measuring instruments, and formal test methods which define the instrument's use, are the means by which these relations of numbers are obtained. All measuring instruments are subject to varying degrees of instrument error and measurement uncertainty.
Scientists, engineers and other humans use a vast range of instruments to perform their measurements. These instruments may range from simple objects such as rulers and stopwatches to electron microscopes and particle accelerators. Virtual instrumentation is widely used in the development of modern measuring instruments.
Water metering is the process of measuring water use.
In many developed countries water meters are used to measure the volume of water used by residential and commercial building that are supplied with water by a public water supply system. Water meters can also be used at the water source, well, or throughout a water system to determine flow through a particular portion of the system. In most of the world water meters measure flow in cubic meters (m3) or litres but in the USA and some other countries water meters are calibrated in cubic feet (ft.3), or US gallons on a mechanical or electronic register. Some electronic meter registers can display rate-of-flow in addition to total usage.
The term musical form (or musical architecture) refers to the overall structure or plan of a piece of music, and it describes the layout of a composition as divided into sections. In the tenth edition of The Oxford Companion to Music, Percy Scholes defines musical form as "a series of strategies designed to find a successful mean between the opposite extremes of unrelieved repetition and unrelieved alteration."
Musicologist Richard Middleton describes form through repetition and difference: difference is the distance moved from a repeat; a repeat being the smallest difference. Difference is quantitative and qualitative; how far different and what type of difference. According to Middleton, musical form is "the shape or structure of the work." In many cases, form depends on statement and restatement, unity and variety, contrast and connection.
Music notation or musical notation is any system used in sheet music in order to represent aurally perceived music through the use of written ancient or modern musical symbols.