The hound of the Baskervilles chapter 3

From the typescript, Holmes quickly discerns not only which newspaper the words were taken from, but also from which article, and in fact determines that the words were cut with nail scissors. He further deduces that the person who composed this letter was educated, but wished to pose as an uneducated man. He suspects the culprit worried that Sir Henry would either recognize his handwriting or soon enough encounter it. Finally, he notes that the letter's composer was in a hurry, likely because he feared an interruption.