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.
The invention of such portable sundials shows how important it was for the ancient Egyptians to keep time. At the same time, sundials were only effective given enough sunlight. To tell time at night the Egyptians invented the water clock. The first water clocks appeared during the reign of Amenhotep I. It was a stone bowl filled with water at precise time of the day. It had slanting sides and a small hole at the bottom trough which water dripped at a constant rate.