The Cipher in Thomas Newell’s Diary

Last month I went to a one-day display of interesting Revolutionary documents from the Boston Public Library’s Archives & Special Collections department.

Among the items I saw for the first time was the diary of Thomas Newell (1749–1827), nephew and either protégé or employee of merchant and selectman Timothy Newell.

I’d read the text of that diary as published by the Massachusetts Historical Society and even quoted it for crucial details in The Road to Concord, but I didn’t know that the document still survived at the B.P.L.

Even more eye-catching, the archivists had opened it to a page about the lead-up to the Boston Tea Party, and one entry contains two lines of mysterious writing. Here’s a clip from the digitized version.

On 2 Dec 1773, Capt. James Bruce arrived in Boston harbor with the second shipment of East India Company tea. Thomas Newell did or saw something that evening. And the next day he joined two dozen other men in patrolling the docks to ensure no tea was landed.

I spoke to the archivists about the writing. Was it a cipher? An attempt to write in Hebrew? I put this diary on my list of things to investigate.

Now I can’t take all the credit for what I found because none other than the statesman Edward Everett worked out the cipher in the mid-1800s. He didn’t explain it, but he translated what Newell had written, and those translations are in the published transcript. That let me reverse-engineer the method.

As I suspected, Newell used a type of pigpen cipher, in which letters are written into tic-tac-toe grids and the boundaries of each cell stand in for the letter within. Newell’s cipher treats I and J as the same letter, and U and V as the same letter. So the grids are:

No dots over a symbol mean the letter is in the left-hand grid, one dot the middle grid, and two dots the right-hand grid. Thus, a square (all four boundaries) with no dot is an E, with one dot an O, and with two dots a Y.

That system let me decipher Newell’s secret lines. Or, rather, it let me confirm what Everett deciphered about a century and a half ago.

TOMORROW: So what did Thomas Newell write?