xiv Contents. 



PAOB. 



PRINCIPLES UNDERLYING THE DRAFT OP THE HORSE 492 



Direction of the line of draft, p. 492 ; Influence of weight on the 

 draft of the horse, p. 493; Influence of the distribution of 

 weight on the draft of a horse, 494 ; Influence of the strength 

 of the hock muscle on the draft of a horse, p. 494 ; Influence 

 of the width of the hock on the draft of the horse, p. 495 ; 

 Attachment of the traces to the hames at the shoulder, p. 496 ; 

 Two-horse evener, p. 49(5 ; Giving one horse tne advantage, p. 

 498 ; Three-horse equalizer, p. 499. 



THE TREAD POWER 499 



Working the horse in the tread power, p. 500. 



THE SWEEP POWEB 501 



STEAM ENGINES 002 



Principle of action in the steam engine, p. 502 ; Efficiency of the 

 steam engine, p. 503 ; Pressure of steam at different tempera- 

 tures, p. 504 ; Cry and wet steam, p. 504 ; Causes of water in 

 the cylinder of an engine, p. 505 ; Wetness of steam from the 

 boiler, p. 505 ; Wetness due to condensation in steam pipes and 

 valve chest, p. 506 ; Initial condensation, p. 506 ; Condensation 

 due to work during expansion, p. 507 ; Engine boilers, p. 508 ; 

 Construction of steam boilers, p. 509 ; Gage cocks, p. 510 ; Gage 

 glass, p. 510 ; Pressure gage, p. 511 ; Safety valve, p. 511 ; 

 Care of the boiler, p. 512 ; Firing, p. 513 ; Foaming, p. 513 ; 

 Low water in the boiler, p. 514 ; Soft plug, p. 514 ; Water sup- 

 ply, p. 515 ; Cross-head pump, p. 515 ; The Injector, p. 515 ; 

 Boiler Incrustation, p. 517 ; The engine, p. 518 ; Governor, 

 p. 521; Lubricator, p. 521; Fly wheel, p. 522. 



GASOLINE ENGINES 522 



Gasoline and steam engines contrasted, p. 523 ; Principal parts of 

 a gasoline engine, p. 523; The working cycle, p.. 523; Arrange- 

 ments to prevent over-heating, p. 524 : Types of gasoline en- 

 gines, p. 524 ; Cylinder, p. 525 ; Pumping mechanism, p. 525 ; 

 Governor, p. 526 ; Valve mechanism, p. 528 ; Igniting the 

 charge, p. 529 ; Lubrication, p. 529 ; Gasoline, p. 530 ; Size 

 of engine,-p. 530. 



WINDMILL 530 



Work to which the wind mill Is adapted, p. 531 ; Wind pressure, 

 p. 532 ; Relation of wind pressure to wind velocity, p. 532 ; 

 Ability of wind to do work, p. 533 ; Relation of diameter of 

 wheel to its efficiency, p. 533 ; Unsteadiness of wind velocity, 

 p. 534 ; Hlght of towers, p. 534 ; Observed amount of work 

 done by a windmill in pumping water, p. 51,5 ; Observed amount 

 of work done by a windmill In grinding feed, p. 536. 



