126 farmers' a?jd mechanics' joornal. 



Another course of experiments was made by Mr. Walker before 

 several gentlemen, well versed in mechanics, on a waggon-like 

 model, weighing about 156 lbs.; the fore-wheels four feet two 

 inches in diameter, and the hind-wheels five feet six inches, with 

 an obstruction placed against the two fore-wheels of 6 ]-4 inches. 



When the line of draught was perfectly horizontal, or even with 

 the top of the fore-wheels, it required to draw it over the obstruc- 

 tion a weight of 60 lbs. 



When the direction of the line of draught made an angle with 

 the horizon of seven degrees, by lowering the point of draught 

 six inches below the top of the wheel, the weight required was 

 48 lbs. 



When the end of the line of draught was lowered, till the direc- 

 tion of it was at an angle of 1 1 degrees with the horizon, it got 

 over the obstruction with 41 lbs. 



When the end was lowered to the centre of the wheel, and the 

 line of draught was at an angle of 15 degrees with the horizon, the 

 obstacle was surmounted with 33 1-2 lbs. 



When the end of the line of draught was lowered to 6 1-4 inches 

 below the centre or axle, so that the angle with the horizon was 

 17 degrees, it was drawn over with 30 1-2 lbs. 



When it was lowered to one foot and half an inch below the 

 centre of the wheel, so that the angle was 18 degrees, it was drawn 

 over with 29 lbs. 



When it was lowered to 18 3-4 inches below the centre, (being 

 only 6 1-4 inches above the road, and exactly level with the height 

 of the obstruction,) the angle 23 degrees, the weight necessary to 

 draw it over the obstruction was 27 lbs. 



These experiments, though made upon so much larger a scale 

 than the former, produced exactly a similar result. 



A third experiment with a common chaise, when drawn by a 

 splinter-bar as high as the top of the fore-wheels, proved that it 

 required 80 lbs. to put it in motion ; when drawn from the axle, 

 it required only 51 lbs. 



With another chaise, and the splinter-bar three-fourths of the 

 height of the wheel, the draught over an inch obstruction, requir- 

 ed 100 lbs. ; but when drawn from the axle, only 61 lbs. 



With another chaise, and the splinter-bar three-fourths of the 

 height of the fore-wheel, the draught over an inch obstacle, requir- 

 ed 1 19 lbs., but when drawn from the axle, only 93 lbs. So that 

 in both cases there was one-fourth in favor of the draught from the 

 axle. 



With the same chaise, drawn up a hill rising one foot in six, with 

 the splinter-bar one-fourth of the wheels' diameter from the top, 

 it required 168 lbs. to draw it up. But when drawn up the same 

 hill from the axle, it only required 129 lbs. ; there was, therefore, 

 the same advantage nearly in this mode of draught up-hill as on 

 level ground. [London Mcch. Mag, 



