MIAINAGE OF HOLLAND. 301 



parallel motion, air-pump, nor vacuum. The agri- 

 cultural engines of 1813 l and the South American 

 engines of 1816 2 had neither cylinder cover nor any 

 other part of the Watt engine, yet they successfully 

 competed with it in power, economy, and usefulness. 



This design reveals a stumbling-block that superficial 

 people fall over. The boiler in the boat was surrounded 

 by brick flues, while a life-long claim of Trevithick's is 

 that before his tubular boiler with internal fire, there 

 could not be a successful steamboat, because brick flues 

 were dangerous in sea-going vessels, but in an iron 

 boat in smooth water it answered its purpose without in 

 any respect falsifying Trevithick's former claims or plans. 



The chain pumping machine was in an iron barge, 

 the 36-inch diameter pump fixed just outside the 

 bow, its lower end a foot in the water ; its height of 

 8 or 9 feet enabled the water from the pump-head to 

 flow through launders over the banks of the lakes to be 

 drained. Some of the directors came to Hayle to see it 

 work, and were well pleased at the constant stream of 

 water rushing from the foaming pump-head into the 

 launders. The large size of the rag-wheel gave the 

 rapidly revolving chain and balls a great speed. In 

 passing through the pump each ball forced upwards the 

 water above it, and drew up after it the following 

 water ; before any ball had passed out at the top of the 

 pump the following ball had entered its bottom. The 

 directors having desired the writer to take the engine 

 to Holland and set it to work with the least possible 

 delay, adjourned for refreshment before starting for 

 London. In those few minutes differences arose, result- 

 ing in the engine remaining for months in the barge, 

 and then going to the scrap heap. 



1 Sec vol. ii., p. 37. - !Stv vl. ii., p. 208. 



