In the year 1st century CE, Hero of Alexandria published schematics for a steam device that rotated a ball on a pivot. The machine used heat from a cauldron to push steam through tubes toward the ball. It produced roughly 1500 rpm but never became practical for industrial use. Labor costs to operate and maintain the heat were too high. Human power remained the most readily available source for ancient machinery. Mechanical devices like windlasses used ropes and pulleys to move heavy objects. Multiple people pushed or pulled handspikes attached to cylinders to generate force. Animal power drove transportation across the empire. Oxen farmed land and moved large goods due to their strength and low maintenance cost. Horses provided speed for cavalry units and scouting parties on battlefields. Donkeys and mules carried passengers or light materials because they were faster than oxen and cheaper on fodder. A schematic known as De rebus bellicis described a ship powered by oxen walking in circles on deck. This design spun paddle wheels on either side of the vessel. Such ships likely never existed due to the difficulty of controlling animals on watercraft. Water power generated energy through water wheels with two main designs: undershot and overshot. Undershot wheels turned when flowing water hit submerged paddles. Overshot wheels received water from above, often via aqueducts. Overshot wheels could be 70 percent more efficient than undershot versions. Economic costs prevented widespread adoption of the more complex system. Primary uses included milling operations and raising water above natural heights. Evidence suggests water wheels also powered saws, though descriptions remain scant.
Engineering And Construction Materials
The Pantheon dome was constructed between 113 and 125 AD using Roman concrete mixed with lime and volcanic powder called pozzolana. The mortar did not require complete drying to cure, making it ideal for thick walls. Delaine estimates that building the structure required about 400,000 man-days of labor. Stone blocks weighing approximately 1000 tons have been found quarried near construction sites. Romans punched holes into stone lines at desired lengths and widths. Wooden wedges were hammered into these holes before being filled with water. Swollen wedges split the rock block free from the earth. Saws developed during the Imperial age cut stone initially by hand, later by water power. Lime mortars varied in mixture ratios depending on sand source location. River or sea sand required two parts sand, one part lime, and one part powdered shells. Inland sand needed three parts sand and one part lime. Limekilns were underground pits designed to block wind during preparation. Pozzolana mortar formed a substance as hard as natural rock when mixed with two parts pozzolana and one part lime. This material could form underwater and provided increased tensile strength compared to pure lime mixtures. The Hagia Sophia built in 537 AD used pozzolana mortar containing crushed brick dust instead of volcanic ash. Engineers removed decorative walls to allow the mortar time to cure properly. Wide mortar joints in the structure indicated designers understood its high tensile strength properties. Cranes capable of lifting 6 to 7 tons operated via treadwheels according to relief carvings on Trajan's Column. Fireproof wood was created by coating timber with alum. Quarries situated close to construction sites reduced transportation costs significantly.