Google Ngram Viewer. Awesome.
The frequency of the word "dementia" spiked in the period 1870-1885. It then rose gradually to 1920 and fell until 1962 or so. Since then it has skyrocketed.
"Hepatitis" was used (Upper case "H", searches are case sensitive at the moment) around 1818, but then it disappeared until 1940. I wonder what it meant in 1818; it wouldn't be the modern meaning of the word.
"Schizophrenia" does not appear at all before 1910.
Slide rule starts rising in 1880, spikes in 1940, and then fall smoothly to plateau around 1990.
The usage patterns of the "n-word" is remarkable -- there are peaks in 1860 (the war to preserve slavery), around 1940 (black Americans in the armed forces), 1970 (civil rights), and the late 90s (the meaning and usage of the n-word changes?).
Imagine how a teacher could use this.