Page:Smith - Number Stories of Long ago (1919).djvu/113

NUMBER STORIES many travelers at this great port on the Mediterranean. So Heron grew up in very interesting surroundings and at an interesting time in the world's history — about the beginning of the Christian era.

When Heron went to school he found that he needed another kind of fraction than the one used by Ahmes. When he came to the very careful measurements used in making machines or in finding the position of the stars, he found that he needed certain other fractions that had come into use in Alexandria long after the time of Ahmes. These fractions had 60, or 60 x 60, or 60 x 60 x 60 for their denominators, and since everyone knew this, it was not necessary to write the denominators. When we write 0.5 we mean 5/10, and it is not necessary to write the denominator. To use our modern terms we may say that 23 minutes meant 23/60 of something that was being measured, and 23 seconds meant 23/60 of a minute, or 23/3600 of the thing that was being measured. In the same way the next 23 meant 23/60 of a second, and so on. In this way it was possible to have fractions without writing the denominators at all. 86