Final answer:
The short lines on a centigrade thermometer represent individual degrees Celsius, with each line denoting one degree on the scale that ranges from the freezing point to the boiling point of water, divided into 100 equal intervals.
Step-by-step explanation:
The short lines on a centigrade thermometer, also known as a Celsius thermometer, represent individual degree marks indicating temperature. On the Celsius scale, the temperature range between the freezing point of water (0°C) and boiling point of water (100°C) is divided into 100 equal intervals, with each short line representing one degree Celsius.
The spacing between these short lines allows us to measure temperature with precision. In comparison to the Fahrenheit scale, which has more degrees between the freezing and boiling point of water, Celsius degrees are larger because they are spread over fewer total degrees; hence, the short lines are spaced further apart on a Celsius thermometer.