in 



SCIEN 



[Entered at the Posi-Offlce of New York, N.Y., as Second-Class Matter.] 



A WEEKLY NEWSPAPER OF ALL THE ARTS AND SCIENCES. 



Sevknth Year. 

 Vol. XIV. No. 346. 



NEW YORK, September 20, li 



Single Copies, Ten Cents. 

 ^3.50 Per Year, in Advance. 



THE JONSON BALANCED COMPOUND ENGINE. 



The illustrations show a new type of balanced compound high- 

 speed steam-engine now being introduced to the notice of steam- 

 users by the Jonson Foundry and Machine Company of this city. 

 In this engine there are two steam-cylinders, placed side by side. 



cylinder having the full area of the piston above the trunk. In the 

 engine here illustrated the diameter of the steam-cylinder is twelve 

 and a half inches, and the diameter of the trunk is eight and five- 

 eighths inches, the stroke being ten inches ; so that the engine has 

 two high-pressure cylinders, each about eight inches in diameter. 

 In the operation of the engine, steam is admitted to the high- 



the jonson balanced compound engine. 



the connecting-rods working in trunks, and the cranks being set at 

 an angle of a hundred and eighty degrees with each other. All 

 the working parts are enclosed as shown. 



It will be seen that the arrangement forms a pair of half-trunk 

 engines, the high-pressure cylinder being the annular space be- 

 tween the trunk and the steam-cylinder, and the low-pressure 



pressure cylinder for the upward stroke of the piston, and, being 

 exhausted into the low-pressure cylinder, actuates the piston on 

 the return stroke. For small engines, the valves of the high and 

 the low pressure cylinders form one casting, and the steam from 

 the high-pressure cylinder is exhausted through ports in the valve 

 to the low-pressure cylinder. When an automatic cut-off is fitted, 



