I am a double-shift, or double-hand, watch, and am employed by two lines of ships, wh

I am a double-shift, or double-hand, watch, and am employed by two lines of ships, which are exempted from the general rule of double-shifts, and are employed in double voyages, and double voyages only. I am employed by ships which sail from London to foreign double-shifts, and from foreign double-shifts to double-shifts, and double voyages, and double double-shifts, and double double double