There is a debate concerning whether this word should be transcribed as "Sor" or "Sir." An observation I wanted to make is that every lower case "i" in the Lusk letter is accompanied by an i-dot. Since there is no i-dot in this word, that would suggest it should be transcribed as "Sor" (unless one wishes to make this word the lone exception).
I've never seen it transcribed as anything but "Sor," and wasn't aware that there was a debate.
I have seen it discussed on another thread. I think the argument for 'Sir' is that the writer was in the habit of adding a superfluous up-stroke at the end of some words. If that is factored in the word looks like 'Sir' with an undotted 'i'.