The chronometer watch on the left is signed John Arnold and Son. It is a precision watch and embodies several of Arnold's inventions which he devised for use in marine chronometers. The watch movement on the right is by Jean Antoine Lepine of Paris, France. Lepine was the first to replace the continuous top plate of the watch movement by a series of bars; an arrangement which helped him to make his watches very thin and paved the way for the modern thin watch.
© Science Museum / Science & Society Picture Library