The Menlo Festival asked me to attend their latest winter series concert, a pairing of Brahms and Dvorak. So I slipped it into my Daily Journal schedule and reviewed it.
And then SFCV sent me off to hear some Schubert songs with the piano accompaniment arranged for string quartet. That was rather different.
Also on the program was Britten's Second Quartet, a work for which I needed to do a little study, so I checked the score from the library. And therein I found something unannotated which I couldn't explain: all over the chaconne movement were brackets covering phrases of two or three notes. They looked like the mark put on a note for a mandatory downbow stroke, but those are only on single notes, and as such these wouldn't make musical sense. (Also, I later noticed some on pizzicato notes, so no: not bowing.) They could be ties, indicating notes should be played together as a flowing phrase, but ties are rounded: these were square. So they must mean something else.
B. didn't know. The retired professional cellist who gives the pre-concert talks didn't know. So I asked the quartet at the post-concert Q&A. Three of them didn't know either, which is really disconcerting considering they'd just given a professional performance of the piece. They hadn't found out what the composer was telling them?
But the first violinist knew. They're rhythmic instructions specific to a chaconne. A chaconne is in 3/2, a slow triple time, with the emphasis normally on the second beat. These brackets appear on pairs of beats to indicate when the emphasis should be on the other beat. OK, that makes sense, and I see crescendo markings and accents that confirm this.