The term 'some strings' refers to four different types of string instruments: celli, viols, violas, and cellos. Celli are a type of string instrument that is similar to a double bass, but slightly larger. Viols are a type of string instrument that is similar to a violin, but with a deeper sound. Violas are a type of string instrument that is similar to a violin, but slightly larger. Cellos are a type of string instrument that is similar to a double bass, but slightly smaller. All four of these instruments are commonly used in orchestras and other musical ensembles.