What Was the Source of Nutter's Arithmetic Book?

I became quite interested to understand where the arithmetic examples in Jacob Nutter's notebook came from.  There were many references to variations of something called the "Rule of Threes" written in very formal language.  In addition there were many numbered arithmetic problems including multiplication, division currency conversions, and weights and measures.

There was one clue in the body of the text that eventually allowed me to track down the original source of this material.  Here is a clip from Nutter's journal with that clue:

It reads "See more of this in my yong algebraist Companion".  This seemed to be a clear reference to a text book.  Upon research on the internet I found, that yes, indeed, there was a "Young Algebraist Companion" by a Daniel Fenning, who was apparently well known for writing text books in the mid-18th century in England.  Further research showed that one of his other books was called the "British Youth's Instructor.  I was able to find a copy of one page of this book from a college libary collection that was shown on line.  Here is the page from that book:

Next I searched through the Nutter notebook and found this:

The exact same problems!!  I found the source!  Since then, I found a complete copy of Fenning's book on the internet through Google.  Here is a copy of the cover page:

Here is another comparison between the two books.

 So, now I know where the arithmetic problems originated from.  But how did the text get into the Prison?  According to Charles Herbert's detailed journal of his time spent at Mill Prison, The Reverend Robert Heath, one of the Commissioners assigned by the British government to look after the prisoner's welfare, would periodically bring to the prisoners various books donated by the local population who were sympathetic to the American cause.  It is likely that Fenning's book was donated to the prisoners and circulated about the prison for self improvement.  In 1778 the prisoner conditions began to improve and they were allowed pen and paper along with books and many began self studies to keep their minds occupied and perhaps Jacob Nutter had an opportunity to hand copy the original text.

My research also indicates that Richard Dale, one of the American officers a Mill Prison at the same time as Nutter, and later first Lieutenant of the Bonhomme Richard, also maintained a math notebook at Mill Prison which is now with his other papers at the Library of Congress.  Someday, if I have a chance to go to Washington again, I would like to look at his notebook to see if there is any similarity to Nutter's.