112 STATE BOAED OF AGRICULTURE. 



increased to 1 in 24 tlie same Aveigbt "will only draw one-half the former load, 

 and if we increase the inclination still more, say to 1 in 10, the weight, as you 

 see, Vv'ill draw only one-quarter of the first load. 



In round numbers, on a slope of 1 in 44, or 120 feet to the mile, a horse can 

 draw only three-fourths as much as he can on a level ; on a slope of 1 in 24, or 

 320 feet to the mile, he can draw only half as much ; and on a slope of 1 in 10, 

 or 528 feet to the mile, only one-quarter as much. This ratio will vary some- 

 what with the natural condition of the road bed. As the effect of a nick in a 

 razor that is already in a bad condition is scarcely noticed, so on a road that is 

 already very l^ad a slight increase in the draught is not so perceptible as on a 

 good road, nor is it so large a proportion of the former draught. 



The loss of power on inclinations is even greater than these considerations 

 show, from the fact that the anatomical construction of a horse does not jiermit 

 him to apply his powers Avith the same advantage as on a level. A horse on a 

 level is as strong as five men ; yet on a steep side hill he is less strong than 

 three, — for three men, carrying eacli 100 pounds, Avill ascend faster than a horse 

 carrying 300 pounds.* 



Inclinations being always thus injurious, are particularly so where a single 

 steep slojie occurs on a long line of road that is comparatively level. It is in 

 such a case very important to avoid or lessen this slope, since the load carried 

 over the whole road can not be in excess of what can be conveyed up this slope. 

 Thus, if a long slope of 1 in 24 occurs on a level road, a horse can take over it 

 only one-half of his full load, and consequently his load over the entire stretch 

 of level road must be reduced accordingly. This evil is sometimes partially 

 remedied by adding extra horses at the foot of the slope, or more commonly by 

 severely exerting the horses for a few minutes, then allowing them an opportu- 

 nity to rest by blocking or otherwise holding the wheel. Both these methods 

 are jooor economy, and occasion a great waste of time to every vehicle that passes 

 over them ; and in nine cases out of ten, were this waste of time for a single 

 year actually employed in improving the road, the expense of passing over the 

 slope might be entirely obviated, or at least greatly lessened. 



Expenm of Grades. 



You saw by the exjjeriment that a slope of 1 in 24 was not very steep, and yet 

 that the motive power was double that required on a level. If such is the case, 

 our load must be decreased one-half, and consequently two trips will be required 

 to carry what could have been conveyed in one, had there been an absence of 

 grades. Should we assume as before a certain number of teams passing each 

 day over a certain length of road, and on account of grades only carrying half 

 loads, the cost per mile will be the same as before, viz., $400, provided we 

 assume the same amount of travel. Since a poor road surface, though level, 

 costs us in time $400 per mile each year, Avhile if hilly it costs an additional 

 S400, making in all $800 for each mile of road, we can well afford to spend some 

 little time in devising methods for permanent road improvement. 



Different Kinds of Roads. 



There are various methods of forming a surface for roads; but of these 

 methods there are probably only three that merit any particular attention from 

 the American public. The three kinds of road that I wish to call your atten- 

 tion to, as peculiarly adapted to our country, are the plank road, gravel road, 



* GiUespie, Roads and Railroads. 



