The teacher may introduce this subject to the class by reference to the meaning of "pressure" as used in mechanics. Explain to them that the gauge pressure in a steam boiler or auto tire refers to the number of pounds pressure on each square inch of inner surface. Sometimes a problem will make it clear.
©1928 by Iowa State Teachers College
Science Bulletin: Vol. 1:
2, Article 9.
Available at: https://scholarworks.uni.edu/science_bulletin/vol1/iss2/9