22 
TRANSACTIONS OF THE TEXAS ACADEMY OF SCIENCE. 
minds to improve only a portion of the width of recorded road for a long 
time to come. For main roads intersecting at the county seat or other 
important points, I would suggest 18 feet as a desirable width for the 
track, and in byways 10 or 12 feet. 
A road that has given excellent results is built as follows: Width 30 
feet, centre 6 inches higher than the sides; an 8-inch bottom layer of rock 
broken to pass through a 2^-ineh ring, and 12 inches of “ metal” to clear 
a 1-J-inch ring. The whole rolled in two layers with a slight binder, which 
last should preferably not be clayey , but acts better if it is as hard as the road 
material itself. Soft binders are apt to become lubricators in wet weather 
and tend to make the stones move upon each other. If the rock be broken 
by hand, it is in better shape than if broken by a crusher, but the process 
does not form a sufficient proportion of chips and screenings to compact 
the metal readily under the roller. It has been suggested that convicts 
might break the stone at suitable points along the line of work, and it 
certainly seems practical justice that those who have worked the State an 
injury in one w r ay, should be made to repair it in another. 
In North Carolina the State lets convicts to the counties, and our own 
recent local laws contemplate the employment of county convicts in this 
work, and indeed many counties have done so in the past. 
The specification given above is too expensive for any district where 
rock is not immediately available, and gravel will generally have to take 
its place, and the width must be reduced. In the coast counties shell 
makes an excellent road surface, and mixed with sand forms a sort of 
concrete, as may be seen to advantage in Corpus Christi, where the streets 
lhade of this material are very good. There are rumors of the possibility 
of burning black land to a sort of adobe clinker, and this is being ex¬ 
perimented upon by the Texas Midland Railroad for ballast. That such 
a material will make a wearing surface or stand rolling is very much to 
be doubted. 
Telford roads are out of the question for the country generally. They 
are expensive, and unless the foundation stones are thorougly laid and 
well spawled, they become energetic puddlers of the mud, shifting on 
one another, and forming lumps and holes, and further destroying the 
wearing surface of the road by the upward suppuration of the mud. 
San Antonio furnishes many examples of this action. Herschell agrees 
with Telford, and says that Macadam’s idea of small broken stones as a 
foundation has been proved to be all wrong. I think he must have 
formed this opinion by observing exceptionall} 7 bad examples. 
The earth or sub-grade having been established, it is ready for the 
“ metal.” In very bad black land bottoms I would change the practice 
somewhat, and suggest a track 18 feet wide having a bottom layer of 6 
inches of coarse sand and a surface of 10 inches of broken rock or gravel. 
