Yogurt stands in for mayonnaise, and veggies such as celery, onions or bell peppers add a bit of crunch. One serving of egg salad made with two egg whites, 1/2 ounce of plain, fat-free yogurt and 1/4 stalk of celery has 60 calories, less than 1 gram of carbohydrates and 0.5 grams of fat.
The Amazing Inventions of Heron of Alexandria. Heron, also known as Heron of Alexandria, developed many machines and mechanical devices with practical uses, showing that it was possible to take theory and put it into practice. Some of his devices were: 1  A coin operated 'Holy Water Dispenser'. 2  A water organ. 3  The Aeolipile, a steam-powered device.
Books have been around for thousands of years. When ancient civilizations first started developing writing systems, they would write on just about anything, from stone to tree bark. Ancient Egyptians were the first to use paper-like materials, called papyrus, which they made by pounding flat the woven stems of the papyrus plant. It was not long before the ancient Egyptians began gluing together papyrus sheets to form scrolls, which were the first steps toward books as you know them.