Temperature is always measured based on the freezing and boiling points of water. In 1948 the Centigrade scale, renamed it the "Celsius" temperature scale and most countries use the Celsius scale. Indian, and several other countries, use the Fahrenheit system of temperature measurement mainly because from the British time only Fahrenheit thermometers were available in India. It is only after the invasion of Chinese thermometers that we have flat ones that show both centigrade/ Fahrenheit scale. Digital ones coming from western world gave Indian doctors their first exposure to centigrade scale thermometers