Waterbury evening Democrat., 1894-09-29

Decayed Stone Docs Not Cement and Is
 Poor Material For Read Metal.
 Practical information for tho guid- ance of all interested in the good roads movement is embodied in an important report of tho United States geological survey on the geology of the common roads of the United States, prepared by Geologist Y. $. Shaler. Tho report out lines the history of American roads, discusses the geological relations of common roads and the geological cOndi- ton of road materials and reviews tho sources of supply of road stones
 With the invention of macadam," says Professor Shaler, "a new path in road construction was opened Tho peculiar advantage arising from his dis covery is that roads can be constructed at relatively small expense as com pared with pavemcnts made of blocks. and tho work can bc done in many re- gions where suitable paving blocks can not be obtained. If mass of broken stones is allowed to lie with the frag- ments resting on each other, no evident trace of concentration takes place, but if the materials be repeatedly traverscd by heavy wheels or q roller of great weight then as soon as it is wet the cementa- tion sets in
 'This fixing of the bits of stone to- gether has been attributed to the inter lacing of their rough surfaces when they arc driven together. The effect, how ever, is due mainly to tho fact that the friction of bit on bit produces by the grinding action n sufficient amount of powdered rock to form the required ce- mcnt. The binding strength of tho ce- nent exists i'll some measure with all the species of stone.
 "No decaycd stone retains the capac- ity of concentration when powdered, though i'll some few cases where material is charged with iron oxides it may un- dcrgo a certain binding, and no ordinary fliuty gravUlS free from iron oxides can be made to form q firm rOadbcd- Pcb- blCS, even though they cannot be made to cement ill their natural state, will do so when broken into bits Thus tho macadam invention can bc applied in threo ways-brcaking stone which is taken from the QUar-y. using stone bro ken by natural processes and which Is not dCcayCd. and by rcbrcaking pebbles which in their natural state cannot be 4-+*aNaS NS O%+-NN -A-N NN+-aN+AAAAAC, H-cS eSscs.
 Tho volcanic rocks. the dykCstones and largo crystalline masses and the SUI 1 peri.cial lav:'s ay, the l,,St fitted for road making, aaI If these the material ! known aS laS@lt k much the best. Tho | lavaS which hlv" cooled in Assures arc stronger than thus. found on the earth E i surface.
 1 ''AlmUst a$ important as the character of tho road surface Is tho grade, and Cx- l pcriencc shows that, except under pc
 culiar conditions. it is very unprofitablc
 to build roads having five feet of fall ill each 100 feet Of length
 l In general, the repurt concludes: The ] greater l'art of the United States is
 characterized by great seasonal varia-
 tions and those climatic features which
 most affect tho conditions of carriage
 roads. ThUrC is prcvailinGly an altcrna- 1 ton of heavy rainfall and protracted 1 drought. During rain periods the roads
 arc subjected to n deep penetration of
 water and serious washings. In the dry
 season the upper surface becomes DOW 1 dcry. and thesc conditions make high grade roads peculiarly necessary and
 make their maintenance costly. -