GLOSSARY. 291 



Gearing, a series of cog-wheels -working togetlier. 



Governor, a self-regulator of a steam-engine, so constructed tliat 

 centrifugal force throws up weights AV'hen the engine runs too fast, and 

 partly closes the admission pipe of steam ; and, dropping again when it 

 runs too slow, opens the steam pipe. 



Gravitation, the attraction between bodies in mass, as distinguished 

 from cohesion hetvrcen the particles ; the force which causes bodies to fall 

 by the attraction of the earth. 



Guard, one of the fingers in the cutting apparatus of a mowing or 

 reaping machine, for protecting the knives from injury from external ob- 

 jects. Open Guard has an opening above the knives, to prevent clog- 



oi'la- 



Hat-tedder, a machine for spreading and turning hay. 



Header, a reaping machine which cuts the heads of the grain and 

 leaves most of the straw standing. 



Head-land, the strip or border of nnplowed land left at the ends of 

 the furrows. 



Hound, the forward portion of a wagon, to which the tongue is at- 

 tached. 



Hydraulic Kam, see Ham. 



Hydraulics, the science of loater in motion, or the laws of motion 

 and force as applied to running water, and to machinery driven by it. 



Hydrodynamics, the laws of motion and force, as applied to liquids, 

 both in motion and at rest, and embracing Hydraulics and Hydrostatics. 



Inclined plane, a plane or surface deviating more or less from a 

 level. 



Inertia, the property or force of matter by which it retains its state 

 of motion or rest, requiring force to start a body at rest or to stop one 

 in motion. 



Jack, an engine or machine for raising heavy weights. 



Jack-screw, a strong iron screw for raising timbers, buildings, etc. 



Journal, the portion of a shaft or axle which revolves on a support. 



Kerf, the opening or slit made by the passage of a saw. 



Key, a wedge of wood or metal driven into a mortise or opening, to 

 secure two parts together. 



Knee-joint, or Toggle-joint, a contrivance for exerting power or 

 pressure, by straightening a double bar with a joint like that of the knee. 



Land, a term applied to the oblong portion of a field around which 

 the team passes in plowing, the field being usually divided into several 

 lands for this purpose. The term is also applied to the side of a plow 

 opposite the mould board, and a plow is said to run to land when it takes 

 too wide a furrow-slice. 



Land-side, the side of that portion of a plow which runs m the 

 soil, opposite the mould-board, and next the unplowed portion of ground. 



Lantern wheel, a pinion made of two small wheels connected by 

 parallel rods which form the teeth. 



