celerity
The speed of symbol transmission, now called baud rate.
celerity: how fast symbols moved down the wire
Celerity was the term electrical engineers used to describe the rate at which symbols or pulses were transmitted through a telegraph wire or early communication line. It measured transmission speed in symbols per second, counting each distinct electrical state change as one unit. In modern terms, this is what we now call the baud rate, though celerity fell out of use by the mid-20th century as standardized nomenclature settled around baud and bits per second.
The word comes from the Latin celeritas, meaning swiftness or speed, and it appeared naturally in technical writing when engineers needed to distinguish between the actual physical speed of electricity through copper (which remains constant) and the rate at which meaningful information pulses were being sent. A telegraph line might operate at 20 or 30 symbols per second; later teletype equipment pushed this to 110 or 300 baud. Celerity measurements directly affected how many characters could be transmitted in a given time window.
Celerity declined as telecommunications standardized around the baud unit, which itself was named after Émile Baudot, the French inventor of the five-unit telegraph code. By the 1960s, with digital computing becoming dominant, the industry converged on baud rate as the universal specification. Bits per second (bps) later became the preferred metric for data communication, since it directly counted binary units rather than abstract symbols. The older term lingered in academic texts and patent documents but disappeared from working engineers' vocabularies.
Understanding celerity matters for anyone reading historical technical documentation, maintenance manuals for vintage telegraph or teletype equipment, or studying the evolution of communication standards. It also clarifies why baud rate is not simply "bits per second": a single baud may represent multiple bits if the modulation scheme encodes information across several voltage or phase states. This distinction becomes critical when specifying modems or analyzing legacy system performance.