Track 30

Track 30.

You will hear port of a lecture about the history of locks.

First you have some time to look at questions 1 to 10.

Now listen carefully and answer questions 1 to 10.

Good afternoon, ladies and gentlemen, and welcome back, as we continue our lecture series on currency, from ancient times to the modern day.

For today’s talk, we’re going to discuss a need that emerged from an age-old, negative side to human nature.

When wealth is portable particularly when it can be easily compressed into thousands of individual items of coinage, it inevitably becomes more attractive to a certain group of people.

Even in ancient times, the wealthy, people of status, traders and so on, realized that, to discourage thieves, their money would need to be either hidden or protected.

And to do that, they had a choice.

They could either keep their riches safe by keeping them in temples which were guarded twenty-four hours a day, or they could find a way to store their assets somewhere closer to home, where access was more convenient.

And so the ancient Egyptians came up with a locking device.

This was a mechanism similar to what is known today as a dead bolt that required the insertion of a key.

The key operated a series of pins, and allowed a long metal bolt to be withdrawn from its locking position, which in turn gave the owner access to their valuables.

How long ago did this happen?

We’re a little vague on this. but definitely at some point later than 4,000 BC.

Since the Egyptians wanted their locks to be very strong, these locks suffered from one notable problem, their size.

Some of the bigger examples we have found are over half a meter long, and weigh around 30 kilos.

The Romans later adapted these Egyptian locks to make them more functional and available for use in regular homes.

They took the Egyptians designs, made them smaller, and added their own inspired invention.

one that enabled them to create a more sophisticated locking system: steel springs.

One negative side-effect they did suffer from was that, by using a spring instead of a bolt, it was relatively easy for a particularly dedicated and powerful thief to damage or remove the lock using brute force.

However, the Roman locking mechanisms made it difficult to actually force the lock open, thanks to their precise construction.

For their time, it’s hard not to be impressed by such technology.

The examples we have talked about so far are key-based locks, but next I’d like to look at a variation on this, the combination lock.

The combination lock is the basis of many modern safes.

As we will see, the combination lock shares many features of those used by the Egyptians and Romans.

For the purposes of this explanation I’ll begin by looking at a combination padlock, which is easy to grasp.

One of the most important aspects of any locking system is protecting the lock itself.

In the case of the padlock, there’s a secure outer casing to protect the delicate lock mechanism inside.

This casing is usually constructed from a hard metal, such as brass.

Having this strong outer casing prevents a potential thief from simply breaking the padlock with a tool, such as a hammer.

The main move able part of the lock, the part which opens and closes, is a strong bar often made of reinforced or galvanized steel.

As you can see, the bar is curved, almost u-shaped, but much longer on one side.

At the end of this longer side is a metal spring, which is pushed down when the padlock is locked.

So how is a combination lock unlocked?

The metal bar has four pins on it, which prevent it from being opened.

However, each of the pins can be released by moving a combination dial.

These are circular and numbered from 0 - 9.

Move all the dials into the correct position, and the spring is released, forcing the lock to open.

Now that is a very simple combination lock.

The lock of a safe, on the other hand