Why did ACD choose 221B?

WRITTEN BY TOM CAMPBELL, SHS
​February 21, 2022

Loyal readers know that Arthur Conan Doyle chose the number 221b to be the Baker Street address of Sherlock Holmes and Dr. John H. Watson, and the starting point of many of ACD's stories. But as a life long Sherlockian, I just can't accept that the notion that ACD's selection of this address was completely random. Why did he specifically choose the number 221b?

​So in January 2022, I attempted to answer this question with a paper entitled "THE BAKER STREET SECRET", which suggested that ACD arrived at the number 221 by multiplying two prime numbers together. The first prime number was 13, which was the number of letters in the name "Dr. John H. Watson", and the second prime number was 17, which was the number of letters in the name "Sherrinford Holmes". This theory was debunked by William Treacy, of THE STRANGER'S ROOM Facebook page. You can read this theory on this website.

Although I was initially disappointed when my first theory was invalidated, it turned out to be a stroke of good luck for me. If William Treacy had not debunked my first theory, I might never have discovered the real reason why ACD chose the number 221b. As I am sure many of you who are reading this will recall, Sherlock Holmes himself remarks to Watson in a STUDY IN SCARLET that "It is a capital mistake to theorize before you have all the evidence." So taking Sherlock's own advice, I put forth this new theory by presenting the following evidence. ​

THE EVIDENCE

According to Wikipedia, ACD was brought up Catholic, but late in his life, he abandoned Catholicism and became a spiritualist and mystic. In the spring of 1922 Conan Doyle visited Houdini in his New York City home, whereupon the magician set out to demonstrate his "Slate Writing Trick". He had ACD write several words on a piece of paper, and then conceal them from everyone. The words ACD wrote were "mene, mene, tekel, parsin" from the Book of Daniel found in the Holy Bible. He then used his "Slate Writing Trick" to write out the same exact words that ACD had written. After the trick was over, Houdini tried to convince ACD that it was just a trick, but ACD refused to believe him, thinking that Houdini had authentic spiritual powers. 

Using "mene, mene, tekel, parsin" for Houdini's trick demonstrated that ACD knew the Book of Daniel pretty well, probably due to his Catholic upbringing. Those words came out of Chapter 5, dealing specifically with the hand writing on the wall.  However, a little earlier in the book, there is a story of Daniel being ordered to interpret King Nebuchadnezzar's first dream, when his own mystics and sorcerers could not. Daniel prays to the God of Isreal for help, and in a vision, God tells Daniel what he needs to know. In return, Daniel prays a prayer of thanks to God for giving him the interpretation he needs. 

At the time of his upbringing, ACD would have used the Challoner-Rheims Bible, which was used by English Speaking Catholics from 1752 to 1941. One of the verses in Daniel's prayer of thanks, taken directly from the Challoner-Rheims Bible is as follows:

And he changeth times and ages
taketh away kingdoms, and establisheth them: 

giveth wisdom to the wise,
and knowledge to them that have understanding:

This is a two-part verse, where the  second part describes how God "giveth wisdom to the wise, and knowledge to them that have understanding." It is based on the assumption that information does not become knowledge until it is understood by the person who receives it. Furthermore, it is viewed as wisdom by the wise, rather than the foolish.

When ACD created Sherlock Holmes, he equipped the great detective with the unique ability to understand how to create knowledge from information, and the wisdom to know where and when to use it. And as we all know, Sherlock Holmes demonstrates this unique ability many times throughout the Canon.

​I believe that ACD felt so strongly that this verse described the unique abilities of Sherlock Holmes, that he used this biblical notation for this verse as the famous Baker Street address.  In case you have not yet figured it out, the second part of this verse in standard Bible notation is:

​Daniel 2:21b

A message to all who read this theory

I did quite a bit of research trying to verify the information used for this paper, including the possibility that others may have already come to this same conclusion. I teach Sunday school in my church, and have taught lessons from the Book of Daniel many times. So while I came up with this theory on my own, I hope you will let me know if this theory has already been presented, and I will happily share credit with them.

- Tom Campbell, Author