Old Bess (beam engine) facts for kids

Quick facts for kids Old Bess
Old Bess, as now preserved in the Science Museum, London
Origins
Type	Watt beam engine
Designer	James Watt
Maker	Boulton and Watt
Date	1777 (1777)
Country of origin	England
Former operator	Soho Manufactory
Purpose	Water-returning engine driving factory machinery
Measurements
Cylinders	1
Bore	33 inches (838 mm)
Preservation
Collection	Science Museum Group
Location	Science Museum, London
Working	No

Old Bess is a very old beam engine. It was built by the famous team of Boulton and Watt. This amazing machine was made in 1777 and worked for many years, until 1848.

Old Bess is special because it was one of the first engines built by Boulton and Watt. It was also the first engine designed to use steam more efficiently. This was done by cutting off the steam supply early. This allowed the steam to expand and do more work.

Today, Old Bess is kept safe in the Power Gallery of the Science Museum, London. It is the oldest surviving engine designed by James Watt. It is also the third-oldest beam engine still existing anywhere.

How Watt's Engines Developed

Watt's first engine was at Kinneil House in Scotland. It didn't work very well. Its parts were moved and used again at Boulton's factory. This factory was called the Soho Manufactory in Birmingham.

The reworked engine did much better there. This success made Boulton want to invest more in steam technology. He also believed in Watt's new ideas.

Powering the Soho Factory

The Soho Manufactory used a water wheel to power its machines. But sometimes there wasn't enough water in the river. This meant the factory couldn't always run.

To fix this, they thought of using a "water-returning engine." This was a steam pump. It could lift water to power the water wheel when the river was low. The Kinneil engine, which was a pump, was perfect for this job.

In 1777, Boulton and Watt decided to build a second engine for Soho. They wanted to try out Watt's new idea. This idea was about using steam more efficiently by letting it expand. This new engine was also a water pump. It couldn't directly power machines.

Old Bess's Working Life

Building the Engine

As early as 1769, Watt thought about using steam more efficiently. He wrote about it in a letter. Early engines couldn't do this. They used one valve for both steam entry and exit.

Watt started using separate valves for each job. This meant he could control when they opened and closed. He decided to build a new engine to show this idea. He was sure it would save a lot of coal.

Construction started in 1777. They ordered a large cylinder, 33 inches (84 cm) wide. The engine was set up and working at Soho by August.

Old Bess always worked as a water pump. It had two cast iron cylinders. One was for the engine's power. The other was for the pump. The pump cylinder was taller and thinner. It was 24 inches (61 cm) wide and 8 feet 3 inches (2.5 m) tall. It could pump water up 24 feet (7.3 m) high. The engine was later said to be 30 hp.

The engine's main beam was typical for early engines. It used wrought iron chains. These chains ran over curved parts at each end of the beam. Later, the beam was made stronger. This was done with extra wood and iron supports. You can still see these supports today.

Nicknamed Beelzebub

When the engine first started, it didn't work well. Watt was away. Boulton wrote to him, saying the engine was "very fierce." He thought the cylinder was too big for the work.

This made the engine run at a lower pressure. It was very jerky and violent. This strange behavior gave the engine its first nickname: Beelzebub.

Neither Watt nor Boulton knew how to fix the engine's wild actions. Watt suggested slowing down the steam supply. Boulton wanted to try more experiments with the valve timing. He thought they should take more scientific measurements. Boulton's idea was better for saving energy.

Fire and Rebuilding

One morning in July 1778, the engine house caught fire. The fire spread quickly. Within half an hour, the roof was gone. The engine's wooden parts and copper pipes were also damaged. Even the large wooden beam was ruined.

Luckily, the most important part, the cylinder, survived. Within three weeks, the engine was rebuilt. It was expected to be working again soon.

Watt was still away when the fire happened. He advised not to do too many repairs. He wanted to rebuild the engine in a better way. We don't know exactly what improvements were made.

By 1781, the engine had been working in its rebuilt form for years. But Watt and Boulton still agreed it was "one of the worst engines they had."

Old Bess Finds a New Home

The engine worked at the Soho Mint in Handsworth, West Midlands. It stayed there until the mint closed in 1848. It was sold for £48, then sold again for £58. Its new owner, Mr. Walker, put it on display. It was on an island outside his metal-rolling factory.

Most of the mint's coin-making machines were sold to the new Birmingham Mint. But this old engine was kept. It was one of the first old machines to be saved on purpose. This is called industrial archaeology.

Later, the engine was sold again. Then it was given to the Patent Office Museum. This museum later became the Science Museum. So, Old Bess is one of the museum's oldest exhibits. It was also one of the first items in its collection.

When it was first shown, the engine was in a pretend brick engine house. Now, it is displayed on its own wooden frame. This lets people see its parts more closely.

Even though it was once called "one of the worst engines," Old Bess worked for over 70 years. Its name also changed from the wild Beelzebub to the friendlier Old Bess. This shows it performed much better later on.

In 2009, Old Bess received an Engineering Heritage Award. This award came from the IMechE.

Clearing Up Confusion

There are some common misunderstandings about this engine.

Some people think Old Bess was Watt's second engine. They also think it was the first built by Boulton and Watt together. But several engines were built between 1773 and 1777. These include a large engine for John Wilkinson in 1775. Another was a pumping engine for Bloomfield Colliery.

The identity of Beelzebub is also sometimes confused. Some sources say it was the rebuilt Kinneil engine. But there are two reasons why Old Bess and Beelzebub are the same engine. First, Beelzebub's name came from its wild action during experiments. These experiments were done on the engine built in 1777. Second, Beelzebub is described as a 33-inch engine. Old Bess is also a 33-inch engine. Boulton & Watt never built another engine of this exact size.

See also

• Smethwick Engine – the oldest working Watt steam engine