Just one more day to go, it is the second to last day in A2Z challenge. I really enjoyed this competition and I regret not participating before. I enjoyed writing for my theme of the month. For this day it is the letter “Y”. So, I will tell you the story of the invention that made our lives more secure than ever. The “Yale Locks” story.
We know Yale locks, we know locks in general. Can you imagine your life without locks? Locks
today vary from the traditional pin tumbler locks to the modern digital security locks. But how did people secure themselves and their stuff before the invention of locks? Actually, the first lock is not the “Yale Lock” as we may think.
Locks have been around since man first decided to keep his belongings to himself, around 4,000 years according to evidence of the oldest lock, found in the ruins of an ancient Egyptian palace. The first Egyptian lock comprised a wooden bolt securing a door, with a slot with several holes on its upper surface. A device attached to the door contained wooden pins which would drop into the holes and secure the bolt. The key, also wooden, was a large toothbrush–shaped affair, whose ‘bristles’ were actually pegs that matched the holes and pins in the lock. To open the door, it would be inserted into the keyhole located below the pins and lifted, raising the pins and allowing the bolt to be slid out.
This lock also (or the oldest discovered version of it) was found in the Khorsabad palace ruins near Nineveh, Iraq. But before locks, what was actually used? We can say that the only way was to use wooden blocks on the doors, like the ones we see in movies about ancient people.
The first serious attempt to improve the security of the lock was made in 1778 in England. Robert Barron patented a double-acting tumbler lock. The tumbler (or lever) falls into a slot in the bolt which will yield only if the tumbler is lifted out of the slot to exactly the right height. As its description suggests, the Barron Lock had two such levers, each of which had to be lifted to a different height before the bolt could be withdrawn.
Joseph Bramah patented the safety lock in 1784. Bramah’s lock was considered unpickable. The inventor went on to create a Hydrostatic Machine, a beer-pump, the four-cock, a quill-sharpener, a working planer, and more. So convinced was he that his lock was inviolable, Bramah put up £200 reward (about £250,000 in today’s money) for anyone who could pick it. It was more than 50 years before the reward was claimed, by an American locksmith.
Barron’s device was developed further in 1818 by Jeremiah Chubb, who incorporated into the lock a spring which would catch and hold any lever that had been raised too high by a lock picker. Not only did this add an extra level of security, it showed when the lock had been tampered with.
In I857, James Sargent invented the world’s first successful key-changeable combination lock. His lock became popular with safe manufacturers and the United States Treasury Department. In 1873, Sargent patented a time lock mechanism that became the prototype of those being used in contemporary bank vaults.
But, what we aim for is a little before Sargent invention. The mid–nineteenth century saw huge activity in
lock development, based mostly on Bramah’s cylinder lock or Barron and Chubb’s lever locks. In 1848 in the US, Linus Yale, and later his son, also Linus, patented and improved the Yale compact cylinder lock, based loosely on the earliest pin–tumbler Egyptian model. Even now, the Yale lock is one of the most commonly used domestic locks.
The pin-tumbler design is based on a main barrel which is drilled so it has 5-6 cylinder slots that are set close together in a line. A metal pin, or “tumbler,” fits closely to the walls of each of the slots. A second metal pin, or “driver,” sits above the tumbler and is pushed down on the tumbler by a very small coil spring, which is permanently compressed as it sits inside the lock’s enclosed case.
The best illustration of the lock function I found on Wikipedia:
In spite of some extraordinary innovations in lock engineering, it remains the case that most locks in use today are based on the Bramah, lever, Yale and combination models. Keys have developed too, and some now open a lock using magnets, not serrations. Master keys are not magic, but careful arrangements of wards, so a master key can be shaped to avoid the wards in all the locks it masters. Alternatively, two keyholes, or two sets of levers, or two concentric cylinders (in Yale locks) are used.
If you want to take a better look of the history of locks, you can visit the “Lock Museum of America“. They have a very wonderful collection of both ancient and modern locks.