What you see above is a video of Quire Cleveland performing a song called Sherburne, sung to music written by the 18th century American composer Daniel Read. This music first appeared in The American Singing Book (New Haven, CT, 1785), a hymnal published and sold by Read himself.  In that publication, the song is shown with “Words by unknown.” However, according to some modern sources, the words are attributed to Nahum Tate, having first appeared in 1700 in a supplement to the New Version of the Psalms of David (1696), authored by Nahum Tate and Nicholas Brady and published in England. 
I first heard Sherburne sung by The Boston Camerata as part of the album Sing We Noel: Christmas Music from England & Early America (Joel Cohen, director) recorded in 1978. I found the sound of the music to be unique and hauntingly beautiful. It came to mind recently when I heard music that seemed to have a similar unique sound. I’ve since learned that Sherburne is part of a body of early American music that’s sometimes referred to as Sacred Harp music. There are a number of YouTube videos that provide additional information and various performances of this music. Here are links to some of the videos that have contributed to my understanding of this music:
Sacred Harp Singing
The Sacred Harp of Hoboken
“Soar Away” (Sacred Harp 455) Cades Cove Primitive Baptist Church
Coming Again, White Hill AME Zion Church, Rock Hill, SC
Quire Cleveland sings Shiloh by Williams Billings
Anonymous 4 sings Bethleham by William Billings
 Rhoades, Mark D. Anthology of The American Hymn-Tune Repertory. Retrieved from https://people.bethel.edu/~rhomar/index.htm.
 ibid. Retrieved from https://people.bethel.edu/~rhomar/TunePages/Sherburne.html.
 See Wikipedia article While shepherds watched their flocks.