January 6, 1905.] 



SCIENCE. 



9 



be lighted by the energy which now runs to 

 waste at Niagara. In St. Louis we look to 

 the slopes and canyons of the Rockies for 

 our supply of sweet, wholesome water — we 

 may yet look to the same regions for the 

 energy to drive our cars and run our mills. 



COMBUSTION ENGINES. 



The clumsy steam-engine, with its waste- 

 ful furnace, its huge boiler and chimney, 

 is doomed. It has done great woi'k in 

 producing available energy and in wasting 

 still more. It has played a most important 

 part in modern civilization, and it deserves 

 well at our hands, but nothing can stay 

 the decree of progress. Sentence will soon 

 be pronounced, but the day of execution 

 has not been set. I never expect to see 

 the day when steam power plants will cease 

 to exist, but my children will see such a 

 day. 



Think for a moment of the present com- 

 plicated, indirect method of procedure for 

 converting the energy stored in coal into 

 mechanical energy in a moving piston or 

 a revolving shaft. Coal and air are fed 

 into a furnace where combustion converts 

 them into great volumes of a mixture of 

 hot gases. The greater part of the heat 

 and all the volume of these gases escape 

 through the chimney ; a small part of the 

 heat only is drawn off by the steel shell 

 and tubes of a boiler and transmitted to a 

 body of water, which is thereby trans- 

 formed into steam. The steady generation 

 of steam against high pressure, added to 

 its expansion as the pressure is reduced, 

 enables it, when conducted to a cylinder, to 

 drive a piston or revolve a shaft, thereby 

 producing mechanical power. The clumsi- 

 ness of the operation is equalled only by its 

 wastefulness, which varies from 88 per 

 cent, to 95 per cent. 



The problem to-day is : What is the most 

 direct and most economical road from coal 

 to moving machinery? Engineers are at- 



tacking this problem on all sides, and at- 

 tacking it successfully — gas-engines, and 

 combustion-engines of various sorts bear 

 witness. The future prime-mover will burn 

 (not explode) its fuel in the working 

 cylinder, and the piston will be driven, 

 tirst by the products of combustion as their 

 volume increases, and secondly by their ex- 

 pansion against a diminishing resistance. 

 I predict great things of the Diesel motor. 

 Originally it was designed to burn 

 powdered coal mixed with hot compressed 

 air ; but crude petroleum was found to be 

 preferable. So long as oil flows abund- 

 antly from wells, oil will generally be used, 

 l)ut powdered fuel, native or prepared, will 

 doubtless prevail ultimately. The economy 

 and directness of the combustion motor 

 can not be excelled, and when a few years 

 of study and experiment have been applied 

 to the work of simplifying the mechanism 

 (it was a century from James Watt to a 

 triple-expansion Corliss), we may expect 

 it to come into general use for all great 

 centra] ])ower stations. 



The vitality of the steam-engine is due 

 to-day to the mechanical perfection of its 

 design. Its simplicity is marvelous. It 

 is started and stopped with the greatest 

 ease and it almost takes care of itself. The 

 invention of the steam turbine has prob- 

 ably given to the furnace and steam-boiler 

 another lease of life. The wonderful 

 adaptability of the turbine for electric gen- 

 erators is something which was not an- 

 ticipated. 



Will not some one design and construct 

 a combustion engine which shall consume 

 continuously oil and compressed air, thus 

 maintaining a high pressure in a gas chest 

 and driving a turbine with the products of 

 the combustion used expansively as is now 

 done with steam? The proposition is an 

 attractive one, both for the lecture room 

 and for the engineering laboratory. It is 

 sufficient now to call attention to its pos- 



