Hercules was a Dutch steam paddle tugboat. She was also the first vessel to effectively use a compound steam engine. In about 1890, a discussion about the invention of the compound steam engine made that Fijenoord brought up the blueprints of Hercules. These proved that Gerhard Moritz Roentgen had invented the compound steam engine.
Construction
Context
In late 1815 the Dutch navy officer Gerhard Moritz Roentgen had arrived in England on board a ship of the line that was destined to the Dutch East Indies. This ship was in such a bad state that it did not get further than Portsmouth. It all led to Roentgen getting multiple assignments to study the British shipbuilding and iron industry. Roentgen became an expert in these fields, and in early 1824 Roentgen and others founded the Nederlandsche Stoomboot Maatschappij (NSM).
In April 1824 Roentgen sent in a report about the use of steam power on warships. He proposed that the government should promote or execute three projects. One of these was the construction of tugboats to tow warships on rivers, into sea, and even into the English Channel. Two others were about converting an existing warship to steam power, and about constructing a new steam powered warship. These latter projects would fail.
In 1825 the Dutch government offered the NSM a loan if it would build a tugboat for use on the rivers and at sea. The loan was 200,000 guilders at 3% to be repaid in 12 years. Meanwhile, the NSM expanded its capital in order to realize four projects. One of these was again: A tugboat for service on the rivers and close to sea.
Problematic construction
By 31 August 1825 the tug was under construction. Hercules was launched in June 1827 in Boom, south of Antwerp. In Boom F. de Center built a steamboat that was bought by NSM. Therefore, this shipyard might also be a candidate to have built Hercules. NSM's big shipyard Fijenoord was founded only in 1827. Lack of funding caused that by 1828 Hercules was still not ready.
The overview that had Boom as construction site for Hercules, also shows that the steamboat Agrippina had been launched for the „Preußisch-Rheinische Dampfschiffahrtsgesellschaft“ (PRDG) in Cologne (later Köln-Düsseldorfer) in March 1827, and that it was of the same size, i.e. 300 ton. Furthermore, NSM had designed both, but would herself build the machines for Hercules, while Taylor & Martineau built those for Agrippina. When Agrippina proved unsuitable for the PRDG, Roentgen decided to place the steam engine (but not the boilers) of the failed Agrippina in Hercules.
Invention of the compound steam engine
The engine of Agrippina was a high pressure steam engine. Its two high pressure cylinders had a diameter of 21 inch and a 5 feet stroke. In a first plan Roentgen wanted to add two low pressure cylinders, but this was found to be too expensive. Roentgen then got the idea to add a single large low pressure cylinder. The low-pressure cylinder would re-use the steam of the high-pressure cylinders, which would otherwise escape into the atmosphere. The low-pressure cylinder came from the failed ocean liner Atlas. Its diameter was 4 feet 6 inch. In March 1829 a shaft for the low-pressure cylinder was to be made from a shaft taken from James Watt.
This combination of high- and low-pressure cylinders was not new. It had been invented and was in use as a Woolf Engine. The essential difference with Roentgen's compound steam engine was that Roentgen used a receiver, which received the steam used by the high pressure cylinders while the intake of the low-pressure cylinder was still closed. This is the essential difference between a Woolf Engine and a compound steam engine.
The Dutch Professor Harry Lintsen (1949+) made a reconstruction of how the compound steam could be invented in the then backwards Netherlands. He noted that Fijenoord / NSM's repair ship was led by N.O. Harvey (1801-1861). Harvey's uncle H. Harvey owned a machine factory and foundry in Hayle, Cornwall. At this factory, Arthur Woolf worked on perfecting the Woolf Engine. Furthermore, an aunt of Harvey Jr., Jane Harvey, married Richard Trevithick, who visited Fijenoord in 1828. It is known that Roentgen and N.O. Harvey made all kinds of plans to use Woolf engines on ships. The result was a 'Dutch' invention of the compound steam engine.
(Re)launch
On 26 June 1829 Roentgen gave a general order to hasten the work on Hercules as much as possible, so that she could be launched again. A second launch seems strange, but Fijenoord indeed had a patent slip, which had e.g. pulled the German steamboat Concordia out of the water for repairs in 1827.