Robert Hooke – Elasticity’s Champion

While several of our process control regulators rely on a dome filled with compressed air or a gas to control pressure, others operate with the help of a spring. Born on July 28, 1635, in England, Robert Hooke and his research are responsible for helping us understand why a spring can accomplish the task.

Hooke’s Law

Hooke’s Law describes elasticity within a certain range: For small deformations of an object, the displacement or size of the deformation is directly proportional to the deforming force or load. Under these conditions the object returns to its original shape and size upon removal of the load. Hooke published the law in 1676, though he said he was aware of the condition as early as 1660.

The law is written as F = kx or sometimes F = -kx. F is force, measured in Newtons; k is a spring constant, usually appearing in Newtons/meter; and x is the length of the extension or compression in meters.

Hooke applied his new law to the balance springs of pocket watches. While most clocks used pendulums to keep time, a pendulum wasn’t practical in a pocket watch (and wristwatches weren’t popular among men until the 1800s). Hooke’s understanding of the relationship between force and displacement in the other workings of the watch made the watches of the time more accurate.

While we appreciate an accurate watch, in our shop, this law applies to our Burling Valve brand spring-loaded regulator, the direct-acting BS-Series. The Burling Valve dome-loaded BD4 also features a spring. The spring is adjustable within a range of force that equates to the range of desired pressure control – Hooke’s Law at work.

Beyond Springs and Elasticity

While his eponymous law is our clearest link to him, Hooke was a masterful scientist in many areas.

Early in his life, he was an employee of another well-known scientist, Robert Boyle. Boyle hired Hooke specifically to work on an air pump. Boyle’s Law came about during the time Hooke worked with Boyle; many credit Hooke for setting up the experiments – and possibly the mathematics – leading to that law.

Hooke’s early work came during a pivotal time in English history. The Royal Society, a group of elite philosophers and physicians, was founded in 1660. Hooke’s mechanical aptitude and eye for detail were well-regarded by his peers, who made him curator of experiments for the society. He held the position for 40 years. It allowed him to experiment in several fields, including biology, astronomy and physics.

It was in biology that he made some of his greatest contributions. After observing cork under a microscope, he coined the word “cell” to refer to the units that join to make larger organisms. This use of early microscopes led to his book Micrographia, a best-seller that also included early ideas on the nature of combustion and observations from telescopes.

He was also one of the first proponents of the theory of evolution. After studying fossils under a microscope, he identified them as the remnants of living things. He was among the first to identify Saturn’s rings. Additional work in physics included a new way to measure gravity, the wave theory of light and studying how matter reacts when heated.

Rivalry with Newton (and Everyone Else)

Hooke is also remembered for his rivalry with Isaac Newton. The disputes may have started with Hooke discrediting Newton’s theory that light was a particle. When Newton published Principia, his work that described the theory of gravity, the two argued about how much Hooke had influenced some of the content. Both claimed credit for the inverse square law relating the gravitational forces between celestial bodies.

The squabbles with Newton, and reportedly other scientists, may have contributed to his relative lack of fame today. Newton became president of the Royal Society the year Hooke died, and may have destroyed the only known portrait of his rival. The breadth of ideas he pursued could also be responsible.

Regardless of his potentially difficult personality, Hooke and his work play an integral role in how our products are built today.