Harvill (17) states that the graph as a means of communication was first used by William Playfair, an English statistician, in a book published in 1786. Playfair applied the principles of geometry to matters of finance in an attempt to convey the most information in the most economical manner. Since that time the graph has spread from the realm of technical statistical material into all areas of visual mathematical communication, including television. We find graphs in our daily paper, our magazines and in our children's school books in ever-increasing numbers. In 1942, Eagle (13) quoted from the Progressive Education Report of 1938, "The graphic method of presenting data has recently become so prevalent that the ability to interpret the common types of graphs occurring in newspapers, magazines and books may be considered as a necessary extension of the basic reading skill."