270.WHAT IS CRYPTOGRAPHY?
Suppose you and your friends wanted to set up a system of sending secret messages to each other You might say, “Instead of using letters, let’s use numbers.” Each number will stand for a certain letter of the alphabet.
You would then have a code. Cryptography is writing using a secret code. Sometimes the word “cipher” is used instead of code. Did you know that Julius Caesar used a cipher to keep his message secret from enemy eyes? In modern times, ciphers and codes are used by both government and business for important and secret messages.
269.WHAT ARE THE CATACOMBS?
The catacombs were underground tombs near Rome where the early Christians were buried. These tombs were cut in soft rock in a sacred area surrounding the city of Rome.
When Emperor Nero began his persecutions of the Christians, they gathered in the tombs to worship. This was because every citizen was safe from attack in the burial grounds. Later, in the middle of the third century, even the burial grounds were not safe. The Christians then blocked up the regular entrances and made secret ones. They extended for miles in the underground galleries. It is said that the catacombs would be longer than the peninsula of Italy if the passages were in a straight line!
268.HOW WERE THE EGYPTIAN PYRAMIDS BUILT?
No one knows exactly how old the pyramids are. A thousand years before Christ, they were already old and mysterious. The Great Pyramid at Giza has been attributed to King Cheops of the fourth dynasty(about 2900 B.C.).
The pyramids are tombs. The ancient Egyptian kings believed that their future lives depended upon the perfect preservation of their bodies. The dead were therefore embalmed, and the mummies were hidden below the level of the ground in the interior of these great masses of stone. Even the inner passages were blocked and concealed from possible robbers. Food and other necessities were put in the tombs for the kings to eat in their future lives.
