82 
TRANSACTIONS OF THE TEXAS ACADEMY OF SCIENCE. 
macadamized road. Its co-efficient would be nearer 46 or 65 pounds 
than 200. However, this is true for only a small fraction of the year, and 
during this fraction the country does not need the roads for working its 
crops. 
Several attempts have been made to either verify or correct Morin’s 
results, as given above, but these results are still taken as a standard. In 
1893 the Studebaker Bros., of the great wagon industry, made a series of 
experiments with their wagons of different widths of tires. These tires 
were If, 3 and 4 inches wide, respectively. The result of their tests was 
that on a hard surface the width of tire had very little effect, if any; that 
on a soft surface they found the expected result that the advantage was 
with the wide tire. On a stone block pavement, the traction force varied 
with the vehicle, and varies from 30 to 65 pounds; from 60 to 100 for a 
gravel road, and from 240 to 325 pounds per ton on a muddy road. These 
results were obtained after the wagon had been started, and it was found 
that it required an extra expenditure of 125 to 200 pounds per ton to 
start the wagon. 
The United States government recently carried on a series of experi¬ 
ments at the Atlanta exposition for the purpose of finding the co-effi¬ 
cients for various surfac.es. These results are published in Bulletin Ho. 
20, under the title of “Traction Tests.” They were made under S. T. 
Heely, the assistant engineer of the road engineering department. The 
following deductions were made from this series of tests: (1) the force 
of traction varies universally as the diameter of the wheel; (2) the force 
of traction increases with the speed upon hard roads, but not in propor¬ 
tion to the velocity. It is probable that the word “universally” is a mis¬ 
print for the word “inversely;” otherwise, the statement is contrary to 
the facts established by former experimenters. 
The power of a horse, or the force a horse can exert continuously, in 
pulling a load on a level has been the subject of many investigations. If 
the horse is equivalent to the theoretical horse, as defined by James Watt 
when he introduced the term “horsepower,” he can exert a horizontal 
force of 150 pounds at the rate of 24 miles an hour. It is highly proba¬ 
bly that 100 pounds would be a liberal estimate for our Texas work 
horses. It is even questionable whether they exert this much tractive 
force. 
The advantages to a city obtained by improving the roads that feed it 
are easily seen. If the town is the market for wheat, cotton, etc., and its 
feeding roads are so improved that the same wheat and cotton can be 
hauled two or three times as far without further expense, it is manifest 
that the trade of said town can be increased four to nine times. Again, 
when one town knows that on account of bad roads it will be impossible 
for the farmer to take his produce elsewhere, it is probable that that 
