The earliest locks are found on Egyptian tombs, and the Greeks and Romans made locks with bolts, keys and wards. Merchants and travellers used padlocks to protect their belongings in unfamiliar or hostile territories. Combination locks were invented to eliminate the need for keys – all the owner needed to do was to remember the password or combination to open the lock, and he did not need to worry about the key being stolen.
This is a Victorian combination lock, with five wheels, each having 6 letters, giving a total of 7,776 possible permutations. As the wheels are rotated, a slot in each one aligns with an internal bar, and when the correct combination is lined up, the central barrel can be removed, opening the lock. Antique locks of this sort are quite collectable.
Quite when combination locks were invented is not known, but they must have been used by the early 1600s, as the lines in Beaumont and Fletcher’s play A Noble Gentleman, from about 1613, have :-
A cap-case for your linen and your plate,
With a strange lock that opens with A.M.E.N. (Act V).
In 1622, Thomas Carew wrote some verses to prefix Thomas May’s 1620 play The Heir, which include the lines : -
As doth a lock, That goes with letters;
For, till every one be known
The lock's as fast, as if you had found none.
Perhaps the most famous example of a combination lock in modern times is the cryptex featured in Dan Brown’s 2003 book The Da Vinci Code. Supposedly invented by Leonardo, the cryptex is a cylinder that can only be opened by aligning the lettered wheels to the correct password. As an additional security device, the cryptex contains a glass vial of vinegar that will shatter, destroying the parchment inside, if an attempt is made to force open the cryptex. ‘Cryptex’ is a neologism, coined by Brown, combining elements from ‘cryptology’ and ‘codex’.