268 Description of Mr. Rider's 



lower concentric part of the outside cylinder, at which place the 

 power is obtained, and they are close in the recesses of the inside 

 cylinder when passing the upper concentric part. 



Fig. 1, r.r.r.r. is an oblong flanched box, which has a cover 

 screwed to its flanch ; through the cover are screws with guard 

 rivets XD, which press down the hemp packing k, by means of the 

 plate 1, keeping the piece of brass o close to the inside cylinder 

 2.2.2.2. 



The ends of the piece of brass o come close to the inside of the 

 revolving flanches, and a packing is completely formed between 

 the outside of the upper concentric part (in the eccentric CC.) and 

 the inside of the revolving flanches 5.5.5.5. 



Fig. 2, yy, are sections of rings kept close to the outside of the 

 revolving flanches 5.5.5.5. by spiral springs placed in the thick 

 part of the cover eeee. 



The engine is placed between the boiler and condenser, the 

 boiler producing, and the condenser destroying, steam. It has on 

 the boiler-side a pressure of steam, and on the condenser-side 

 nearly a vacuum, the steam-gauge standing at six inches of mer- 

 cury more than the pressure of the atmosphere, and the vacuum- 

 gauge standing at 26 inches less. This gives a power of 16 

 pounds on the square-inch. 



The course of the steam gives a velocity of 600 feet per minute 

 of a revolving motion, to the extremity of the sliding valves, and 

 forces round the inside cylinder 2.2.2.2. and the shaft 1. Fig. 1. 

 - > — > show the course of the steam from the boiler to the 

 condenser, according as the engine is connected to them. 



The engine can be made so that the motion may be reversed at 

 pleasure. The air-pump and under work belonging to the engine, 

 which are not shewn in the plate, may be made on the common 

 construction. 



[To the Editor of the Quarterly Journal of Science.] 



Fort Breda, 27 th August, 1S23. 

 Sir, 



In addition to Mr. Rider's letter explanatory of the advantages 



