[15]Ceres was the goddess of grain.
[16]In the thirteenth century wind-power began to be used for turning mills, and in some countries windmills were as common as water-mills.
[17]About the year 1700 elliptical springs were invented, but they did not find their way into general use until more than a hundred years later.
[18]A spirited account of life on a Roman galley is found in Wallace's "Ben Hur."
[19]Wood, "Curiosities of Clocks and Watches."
[20]The illustration is taken from Keary's "Dawn of History."
[21]In the payment of the postage no stamps were as yet used. Indeed the postage stamp is a late invention. Postage stamps were not used in England until the year 1840, while in the United States they were not regularly used until 1847.
[22]In 1840, the English government following the recommendations of Sir Rowland Hill, adopted throughout the United Kingdom a uniform rate of one penny for letters not exceeding half an ounce in weight, and after this cheap postage became the rule in all countries.
[23]The verb telegraph means to write at a distance afar off.
[24]As there are only 24 letters in the Greek alphabet, the last group was one letter short, but this did not interfere with the working of the system.