We are now in a position to realize why scientific discoveries were made very slowly, and at long intervals apart, in early times. Facts had to be accumulated, studied, grouped, and compared. Accounts of these studies had to be pictured and stored away for future use. Only exceptionally learned men did this. But when alphabets were invented and education increased, numerous minds became active and there was a great extension of thought, experimentation, and philosophical contemplation. This was followed by the establishment of new religious houses, schools, and philosophical academies, at all of which the ablest men of the day emulated the scholars in formulating theories and making inventions. Soon after the perfecting of cuneiform writing in Babylon, characters were devised for representing numbers. A vertical, arrowlike wedge represented the figure 1, while a horizontal wedge stood for 10. A vertical and horizontal wedge, placed together, signified 100. Other arrangements of these characters meant that they were to be multiplied, subtracted, divided, or added together. In this simple manner all kinds of arithmetical results could be recorded. The Babylonian mathematicians were familiar with decimals, integers, and fractions, and their tables and records of astronomical and engineering calculations reveal a remarkably high degree of mathematical ability, indicating that peoples who preceded us by several thousands of years were familiar with the more important calculations requisite in trade and industry as well as for astrological computations. Babylon was a great world metropolis. It occupied a position similar to that occupied by London to-day. Its merchants were engaged in world-wide commercial operations which needed good systems of bookkeeping and accountancy. These, in turn, presupposed a highly developed arithmetical system. Practically all the arithmetical calculations used in commerce to-day were employed by them. Their accountants, like those of China to-day, used the abacus, or calculating machine. A lucid illustration of the accuracy of ancient calculations, the efficiency of their reports, and the confidence with which they executed intellectual duties is afforded by the following translation of a Babylonian astronomer's official report: "To the King, my lord, thy faithful servant, Mar-Istar. "... On the first day, as the new moon's day of the month of Thammuz declined, the moon again became visible over the planet Mercury, as I previously had predicted that it would to my master the King. My calculations were accurate." The records of Babylon furnish us with a wealth of documents of this character.