11 



nient ; as the readiness and simplicity with which the lead can 

 be given to the slide valves, to correspond with the various speeds 

 and loads the engine may be put to, is a desideratum which 

 could not be obtained by eccentrics, without much labour and 

 time in loosening and resetting the eccentric wheels. 



14. Dr. Lardner''s Self-Re- 

 cording Steam Journal, con- 

 structed for the Steam Navi- 

 gation Committeeofthe British 

 Association. — The purpose of 

 this apparatus is to register by 

 mechanism those several vary- 

 ing effects connected with the 

 operation of the engines and 

 the performance of steam ves- 

 sels, on which their efficiency 

 depends. It will be attempted 

 by means of the present mecha- 

 nism to make and preserve 

 a constant record from five 

 minutes to five minutes, of 



1. — The pressure of steam be- 

 tween the slides and the steam 

 valve. 



2. — The pressure of steam in 

 the boiler. 

 3 — The state of the vacuum 

 in the condensor. 



4. The part of the stroke at which the steam is cut off when it works 



expansively. 

 5. — The quantity of water in the boilers. 

 6. — The saltness of the water in the boilers. 

 7. — The velocity of the paddle wheels. 

 8. — The draft of the vessel. 

 9. — The trim of the vessel. 

 10. — The rate of the vessel. 

 1 1 . — The course of the vessel. 



