The ten topics I originally chose were crime, love, money, face words, “chillin’ like Sherlock” (my strangely-named topic for words like pipe, sat, fire, smoke, silence, and bachelor), male descriptive words, detective words, investigation, sailing, and death. The following graphs show how some of these topics relate and, in exceptional cases, reveal interesting correlations with historical events that took place at the time when the stories in which they appear were printed, which I found really intriguing to delve into and analyze.
These topics seemed similar enough. Ironically, however, trends appeared somewhat sporadic throughout, though there was a strong correlation roughly from 1909 to late 1911, with a significant peak in early 1911. This correlates most strongly with the release of The Red Circle (http://sherlockian.net/), though I couldn’t find any historical relevance.
These topics, clearly connected through the crime of murder, showed a close trend in March 1922, the time of release of Thor Bridge (http://www.sherlockian.net/). In this story, the crime is, of course, murder (http://en.wikipedia.org/wiki/The_Problem_of_Thor_Bridge#Plot_summary). No related historical events were found.
Yet again, these topics seemed to make sense together, but trends were very sporadic. There was, however, a directly correlated peak in March 1923, the time of release for The Creeping Man (http://www.sherlockian.net/), which makes perfect sense for obvious reasons. No direct historical relation was found.
Figuring sailing and money were both tied to trade, I decided to look for trends between these two topics. Interestingly enough, “sailing” peaked in March 1904, then dipped in April 1904, at which time “money” spiked. In April 1904, the Entente cordiale was signed (http://www.branchcollective.org/), which established peace between France and England, likely opening up trade between the two, which makes sense with the spike in money-related words. The cause of decline in sailing-related words at this time, however, still remains unclear (or possibly unrelated).
Figuring these words might be related through the written portrayal of how people respond to the people they love (with regard to facial expressions, at least), I thought it might be worth comparing the trends between the two. Sure enough, they peaked together in March 1922 and January 1924. March 1922 was the time of release for Thor Bridge (http://sherlockian.net/), which seems to be sort of a fluke in terms of trying to explain the relation to the prominence of these topics. January 1924, however, was when The Sussex Vampire was released (http://sherlockian.net/). This story, featuring a child as the culprit (http://sherlockian.net/), in conjunction with the obvious implications in its name, seems to fit the bill for a story that would predictably feature frequent mention of the topics of love and things having to do with the face. I was not, however, able to find any direct historical relation to the prominence of either topic.