An introduction to the skill of musick in two books : the first, the grounds and rules of musick, according to the gam-ut, and other principles thereof, the second, instructions & lessons for the bass-viol, and instruments & lessons for the treble-violin / by John Playford ; to which is added, The art of descant, or composing musick in parts, by Dr. Tho. Campion ; with annotations thereon, by Mr. Chr. Simpson.