116 SMITHSONIAN CONTRIBUTIONS TO KNOWLEDGE VOL. 27 



The engine, which is clearly shown in the dimensional drawing, Plate 26B, is 

 of the plain slide-valve type, using a piston valve and solid piston, without pack- 

 ing rings. The cylinder Is formed of a piece of steel tubing 35mm. outside di- 

 ameter, with flanges 47 nun. in diameter and 2.25mm. thick brazed to each end, 

 to which the cylinder heads are attached by small machine screws. Inside this 

 cylinder is a thin cast-iron bushing in order to obtain a better rubbing surface 

 for the piston. The cross head is a small piece of aluminum bronze, running on 

 round guides that also serve as cylinder braces. There are also four hollow 

 braces, 5 mm. in diameter, running from the back cylinder head to a corru- 

 gated steel bed-plate, that stands vertically and reaches from one side rod of 

 the frame of the hull to the other, and to which are bolted the bearings of the 

 main shaft. The connecting rod has the cross-section of a four- rayed star and 

 drives a crank in the center of the shaft. The following are some of the princi- 

 pal dimensions of the engine : 



millimetres. 



Inside diameter of cylinder 33 



Stroke of piston 70 



Length of cylinder inside 88 



Length of piston 11 



Clearance at each end 0.5 



Diameter of piston rod 5 



Length of cross-head 17.5 



Diameter of guides 4.5 



Distance from center to center of guides 26 



Length of guides 110 



Length of wrist-pin bearing 8.5 



Length of connecting rod 150 



Ratio of connecting rod to stroke 2 1/7 to 1 



Length of crank-pin 10 



Diameter of main shaft 8 



Length of main bearings 25 



Distance from center of cylinder to center of valve stem.. 35 



Length of valve 72 



Width of ports 2 



Outside lap of valve 4 



Inside lap of valve 3 



Lead of valve 



Travel of valve 13 



Cut-off from beginning of stroke 57 



Exhaust opens End of stroke 



Exhaust closes on return stroke 4S 



Diameter of valve stem 4.5 



Diameter of eccentric 36 



Width of eccentric 4 



Width of crank-arm 4 



The weights were nearly as follows; 



grammes 



Engine 464 



Pump and pump shafts 231 



Gasoline tank and valves 178 



Burners 360 



Boilers, frames holding boilers, and mica covers over boilers 651 



Separator, sleani gauge and pipe for engine 540 



Exhaust pipe 143 



Smoke stack 342 



In all, 2909 grammes, or 6.4 pounds. 



