Note: SS THETIS, 1857, A Daring Experiment
Early steam navigation was restricted to river, coastal and short sea passages. Many improvements were required before ocean travel became viable for steamships, due to the low efficiency of their engines. The iron-screw steamship Thetis, built on the River Clyde in 1857, represented a daring stage in the process of engine improvement. Her compound engine used steam at the phenomenally high pressure for the day of 115 psi, not reached again until another quarter of a century had passed. Though the experiment was a failure, it showed the way, with better materials and engines, to future developments.