DOMESTIC MOTORS. 



331 



fore been given to the construction of such an apparatus, termed a 

 regenerator. This has taken various forms in different machines from 

 a number of simple perforated plates to nests of tubes. Practically it 

 has been found most economical to attempt to abstract only a part of 

 the heat, as to do more offers too great an obstruction to the passage 

 of the air, with the result of losing as much in power as is gained in 



heat. 



One of the earliest hot-air engines to obtain a recognized place as a 

 valuable aid to motive power was the well-known engine of Ericsson, 

 which has long been on the market, and has come into somewhat gen- 

 eral use. It is of the class using a fresh charge of air with each 

 stroke, the air being drawn into the cylinder, compressed, heated, and, 

 after doing its work, discharged. The engine is made both for pump- 

 ing and power, and is constructed in sizes up to four-horse. It is too 

 well known to require any description here. 



Fig. 9. 



Quite recently a new and much simpler engine designed for pump- 

 ing purposes has been perfected by Mr. Ericsson, and is now being 

 manufactured. It belongs to the class in which the same air is used 

 over and over again, being alternately heated and cooled. The cylin- 

 der is placed upright, and projects below a table, by which it is sup- 

 ported, into the fire-box placed beneath. This is an iron shell provided 

 with the ordinary grate and brick-lining at its lower end when the fuel 

 used is coal, and with three Bunsen burners when it is gas. The lat- 

 ter fuel is much the most desirable, as it is cleanly, no trouble, and 

 allows of starting and stopping quickly, and of always having the 

 heat under perfect control. The working parts of the engine are a pis- 



