In the past few years, lapidaries and gem-workers have learned to cut stones and gems with steel disk-wheels, the cutting edges of which are furnished with carborundum or emery powder or insets of diamonds. The pyramid builders knew this method of sawing and cutting stones. They actually employed bronze saws set with diamonds to cut the huge blocks of granite, syenite, diorite, and basalt used in the construction of the pyramids. They also set the cutting ends of their rock drills with diamonds, and bored rocks as we do to-day with diamond core drills. The art of making these tools was afterward lost. Only within the past half-century have mechanical rock saws and diamond drills been reinvented. This brilliantly indicates the inventive ability of the engineers at the dawn of Egypt's history. The builders of the splendid monument of Rameses II in the Memnonium, at Thebes, which weighs 887 long tons, transported the huge stone by land from the quarries at E'Sooan, a distance of 138 miles. Such tasks appear never to have deterred early Egyptian engineers and architects. They were so sure of their ability to carry their great operations to satisfactory completion that they never hesitated in agreeing to the severest penalties for nonfulfillment of contract. Their cranes, levers, wedges, rock drills, pumps, air blowers and compressors, and building tools all showed how well mastered was their knowledge. Their quarrying methods were similar to those used in the best practice to-day. When huge blocks and slabs of stone were needed the required dimensions were marked on the rock and channeled out. Metal wedges were forced into the channels and struck at once by a large number of hammers. The constant vibration, in time, broke off the stone with clean-cut surfaces. When these were to be carved into statuary or ornamental shapes it was often done at the quarries, so as to reduce transportation difficulties. Water transportation was used when possible. When the stone had to be moved over the desert sands it was lifted by cranes and set on sleds drawn by men or animals, or driven forward by levers, just as heavy steel machinery is moved by modern engineers. The principle of the siphon was known to the Egyptians at an early period. It was employed daily in many homes for supplying water and for drawing off wine from barrels and tanks into domestic utensils. Its principal use, however, was in civil engineering works. Siphons were constructed on a large scale for furnishing water to villages, draining land for farming, and for irrigation purposes. They were built, in many known instances, for carrying large quantities of water, in high lifts, over hills. Herodotus tells us that the science of geometry was discovered by the Egyptians as a result of the necessity for making annual surveys of the farming lands in the Nile valley.