Sonic Nozzles are also known as âCritical Flow Venturisâ or âCritical Flow Nozzlesâ. What is a Sonic Nozzle? A âsonic nozzleâ (also known as âCritical Flow Venturiâ or âCritical Flow Nozzleâ) is a flow meter that can be used as a calibration standard for gas flow meters or any flow measurement device. By design, sonic nozzles are a constant volumetric flow meter.
The Abacus: A Brief History. Abacus is a Latin word that has its origins in the Greek words abax or abakon (meaning table or tablet) which in turn, possibly originated from the Semitic word abq, meaning sand. The abacus is one of many types of counting devices which are used to count large numbers.
The earliest archaeological evidence for the use of the Greek abacus dates to the 5th century BC. Also Demosthenes (384 BCâ322 BC) talked of the need to use pebbles for calculations too difficult for your head.