66 ILLINOIS ACADEMY OF SCIENCE. 



with mechanical stokers and best types of boilers only 15 per cent 

 is used. Similarly, the ordinary steam engine utilizes only 5 per 

 cent of the steam energy. The use of producer gas and gas 

 engines has been shown to yield one brake horsepower hour with 

 only 37 per cent of the fuel required under water-tube boilers. 

 Large gas-engine installations have been made recently at Gary, 

 Indiana, and the improvement is being slowly introduced into 

 other large plants. 



Another serious loss in the country is seen in coke ovens of 

 the beehive type, which waste enormous quantities of volatile by- 

 products. Modern retort ovens would save $50,000,000 annually. 



Use of coal for domestic heating and lighting purposes is even 

 more wasteful. Thus ordinary electric light utilizes only i per 

 cent or less of the energy in coal. It is stated that 8 per cent, 

 or 20,000,000 tons, of the coal used in making light, heat, and 

 power goes up the chimney. Locomotives, of course, waste a 

 much larger percentage. 



It is obvious that the development of central plants for light, 

 heat, and power is very desirable, for it will give smokeless com- 

 bustion of low-grade coals, with the highest possible efficiency. 

 Where possible, such stations should be located in the coal fields 

 and the energy should be transmitted as electricity and coal gas. 

 It is understood that long-distance transmission from the anthra- 

 cite region to New York City is under consideration, and that 

 the plan is also considered for Chicago. 



Water Power and Solar Engines^. The unnecessary use of coal 

 where other forms of energy are available is, of course, deplor- 

 able. Attention has been called so emphatically to the enormous 

 waste of water power that we may confidently look forward to 

 the utilization of its full energy, to the limit of economical trans- 

 mission. 



The solar engine has been so far perfected, I understand, that 

 an installation at Stanford University has operated economically 

 in comparison with coal-fed boilers for a long period of testing. 

 The apparatus comprises a large box covered with glass, and 

 partitioned so that water circulates through it slowly, and if 

 heated by the sun. All interior surfaces are black so as to assist 

 absorption. The water becomes remarkably hot and is then 

 vaporized slightly below atmospheric pressure for use in a steam 

 turbine. The hot water is stored in buried reservoirs and operates 

 the engine night or day. 



It is not impossible that the use of solar engines of this simple 



