Harnessing the Power of Water
When it comes to water, there aren't many simple solutions. Leonardo had to investigate many different aspects of underwater mechanics. On dry land, Leonardo spent a lot of time studying and designing aircraft, including elaborate helicopters, gliders, and parachutes. Never one to limit himself, he was also fascinated with water and devoted years to designing machines that worked with water. Given the sheer amount of water surrounding Italy, he picked a great hobby! It is likely that he was first exposed to aquatic engineering while apprenticed to Verrocchio, who was, among other things, a hydraulics engineer.
The Appeal of H2O
So why the interest in aquatics? From his observations, Leonardo knew that water was inherently contradictory. He described it as the vetturale di nature (vessel of nature). And it's only fitting that such a force of nature would have intrigued Leonardo. Studying for its own sake was never enough for Leonardo; he had to be making something. Between about 1485 and 1490, Leonardo developed several schemes for machines that worked in water. One design was for a type of water pump that could actually drain an entire port. This pump would have been useful when pylons had to be driven into water, or when a building's foundation had to be built underwater. He also developed pumps that could remove water from a ship (or anyplace else) through a valve.
Leonardo's Codex Atlanticus contains many designs for water-controlling devices. For example, he came up with several ideas for sluice gates, or movable panels, that could drop down to divert the flow of a river or canal. He also made detailed three-dimensional sketches for dredges (machines that could clean the bottom of locks and canals), which used mooring ropes to wind up the dredge and force it along the shoreline to the next point.
Leonardo also invented a variety of devices for his experiments with water, including a machine that measured the expansion of hot water during the production of steam. The device consisted of a bucket for cold water that, when heated, expanded and caused an exterior weight to fall. These sorts of measuring devices helped his experiments succeed.
Some of Leonardo's drawings show machines that use water to achieve another purpose. He sketched a hydraulic saw that used water to power the blade; this device could have been used for cutting logs and other large objects.
He also worked on a design that improved the Archimedean screw. This was an ancient device that used a turning handle to pump water out of a well or uphill. It was reportedly developed by Archimedes (287–212 B.C.), a Greek mathematician who many consider to be the father of modern mathematics. Like Leonardo, Archimedes had an intense interest in water and developed the first principle of buoyancy. He also created designs for levers, and these combined interests led to the development of the water-pumping screw.
Leonardo's take on the Archimedean screw was similar to both his helicopter studies and a later waterwheel design. He designed a very large screw which terminated in a handle; inserted into a well or lake, water would be pumped up at a moderate angle. Variations of his design are actually still in use in some countries; the Archimedean screw provides an inexpensive way to irrigate crops, and it can be powered by either people or animals.
Waterwheels were developed years before the Renaissance. A waterwheel is essentially a very large wheel with paddles mounted around its circumference. Water was used to spin the wheel, thereby moving the paddles. Writings from as early as 400 B.C. mention the waterwheel, which was used in those days to irrigate fields and provide fresh potable water. They were also used for grinding up grains and for other productive tasks.
As Leonardo probably realized, there were several different ways to use a wheel in the harnessing of energy. One used a vertical wheel, like those in Leonardo's designs. A variation on this design was actually used to transport objects vertically, more like a lifting tool. Yet another variation used a horizontal wheel that drove a millstone, which traveled vertically through the wheel.
Waterwheels in general were of great interest to Leonardo. They had the capacity to quickly replenish supplies (such as the local water tower) that could be exhausted during battle, and therefore had a utilitarian purpose; Leonardo was always keen on inventions that had immediate practical applications. He used the idea of the waterwheel in the design for a mill which rested on either side of a canal; the paddles on the waterwheel therefore had a naturally occurring power source (the canal), which could operate for as long as the canal held water at a sufficient height.
Telling Time with Water
Leonardo also created a water clock, which set off an alarm based on the amount of water flowing from one container to another. The history of timepieces is, compared to the history of the universe, relatively short; people don't seem to have had much of a desire to know the time until about 6000 years ago. Around 4000 B.C., as cultures started coming together more and creating standards for government, it became necessary for people to have set times for meeting each other.
There is evidence of obelisks dating back to around 3400 B.C. These sun clocks were basically just large monuments; as the sun cast a shadow from the obelisk onto the ground, people could plan their schedules around group meetings. Obelisks were also useful because as the sun started traveling lower in the winter, people could tell which were the long and short days—very useful for farming and other outdoor activities.
Of course, it wasn't always practical to have a clock that relied on the sun. What happened during cloudy days? Or nighttime? While it appears that there was some Egyptian experimentation with water clocks, they were used more often in the Greek period, around 300 B.C. In full keeping with Renaissance tradition, Leonardo looked to his ancient Greek predecessors for a starting point.
At its most basic, Leonardo's water clock consisted of a stone jar or other container from which water dripped. A second vessel was filled at a continuous rate. As the volume of water increased, people could use markings inside the container to see how much time had passed. While Leonardo produced designs for other types of clocks, such as a sand clock, he focused his timepiece design on the water clock.
Leonardo's water clock might not have the cachet of an hourglass, but it apparently worked quite well if you didn't mind the sound of dripping water. What's interesting about Leonardo's method is that it was developed around the same time as the probably fictional “Chinese water torture.”