Like many of the landscape draughtmen of his day, Pars was chiefly dependent for his livelihood on aristocratic patronage and on the demand for careful records of antiquarian and topographical subjects. This watercolour documents a site he saw on a tour through Switzerland in 1770 with his patron Henry Temple, second Viscount Palmerston. Pars brings to the best of his work a degree of expressiveness which is unusual for works of topography at this date. Here, by boldly raising the arch of the stone bridge against the sky, he has produced a very daring composition, and he has coloured it very vividly in strong greens and yellows. Palmerston has inscribed the word 'marvellous' on the mount.