THE GENESEE FAP.MER. 



'^uiitljs' itjwitnrat. 



:^ 



Fig. £. 



Fig. 3. 



cU 



(^ 



CENTER OF GRAVITY. . 



TnE following article on the Center of Gravity we take from an excellent paper in the Transactions 

 of the New York State Agricultural Society, on Agricultural Dynamics, by J. J. Thomas. It will 

 prove both interesting and instructiye to our youthful readers. 



The center of gravity is that point in every hard substance or body, on every side of 

 which the different parts exactly balance each other. If the body be a globe or round 

 ball, the center of gravity will be exactly at the center of the globe ; if it be a rod of 

 equal size, it will be at the middle of the rod. If a stone or any other substance rest on 

 a point directly under the center of gravity, it will remain balanced on this point ; but if 

 the point be not under the center of gravity, the stone will fall towards the heaviest side. 



Every farmer who erects a wall or building ; every teamster who drives a heavy load, 

 or even he who only carries a heavy weight upon his shoulder, may learn something 

 useful by understanding the laws of gravity. 



If any body, of whatever shape, be suspended by a hook or loop at its top, it will 

 necessarily hang so that the center of gravity shall be directly under the hook. In this 

 way, this point in any substance, no matter how irregular its shape 

 may be, is ascertained. Suppose, for instance, we have the irregular 

 plate or board shown in the annexed iigure, (fig. 1,) first hang it by 

 the hook a, and the center of gravity will be somewhere in the 

 dotted line a h. Then hang it by the hook c, and it will be some- 

 where in the line c d. Now the point e, where they cross each 

 other, is the only point in both, consequently this is the center 

 sought. If the mass or body, instead of being flat like a board, be 

 shapeless like a stone or lump of chalk, holes bored from different suspending points 

 directly downwards, will all cross each other exactly at the center of gravity. 



An imaginary line from the center of gravity perpendicularly downwards, to where 

 the body rests, is called the line of direction. 



Now, in any solid body whatever, whether it be a wall, a stack of grain, or a loaded 

 wagon, the line of direction must fall within the base or part resting upon the ground, 

 or it will immediately be thrown over by its own weight. A heavily and evenly loaded 

 wagon on a level road will be perfectly safe, because the 

 line of direction falls equally between the wheels, as 

 shown in fig. 2, by the dotted line, c being the center. 

 But if it pass a steep side-hill road, throwing the line of 

 direction outside the wheels, as in fig. 3, it must be in- 

 stantly overlurned. If, however, instead of the high load 

 represented in the figure, it be some very heavy material, 

 as brick or sand, so as not to be higher than the dark 

 part of the figure, the center of gravity will be much lower down, or at 5, and thus the 

 line felling within the wheels, the load will be safe from danger, unless the upper wheel 

 pass over a stone, or the lower wheel sink into a rut. The center of gi-avity of a large 

 load may be nearly ascertained by measuring with a rod ; and it may sometimes happen 

 that by measuring the sideling slope of a road, all of which may be done in a few 

 minutes, a teamster may save himself from a comfortless upsetting and perhaps heavy 

 loss. Again, a load may be temporarily placed so much towards one side, while passing 

 a sideling road, as to throw the line of direction considerably more up hill than usu il, 



^ 



3 



