City roads and pavements suited to cities of moderate size. . HARD DL\BASE TRAP ROCK. ROCK FRAGMENTS BEFORE AND AFTER ABRASION natural size. HIGHWAY DIVISIOX, MAKYLAND GEOLOGICAL SURVEY. 148 TESTS OF ROCK FOR ROAD-MAKING. The following table shows the results of loo tests ofthe six kinds of rock most used in Massachusetts andNew York: KIND. Diabase trapLimestone. .Granite . .. . Gneiss Sandstone. Per cent OF Loss BY i Number oftests. 1 Max. Min. 35 24 10 4-30 7 5-9° 12 6-57 1-73 12 Mean. 3-52 ?>-(^?>
City roads and pavements suited to cities of moderate size. . HARD DL\BASE TRAP ROCK. ROCK FRAGMENTS BEFORE AND AFTER ABRASION natural size. HIGHWAY DIVISIOX, MAKYLAND GEOLOGICAL SURVEY. 148 TESTS OF ROCK FOR ROAD-MAKING. The following table shows the results of loo tests ofthe six kinds of rock most used in Massachusetts andNew York: KIND. Diabase trapLimestone. .Granite . .. . Gneiss Sandstone. Per cent OF Loss BY i Number oftests. 1 Max. Min. 35 24 10 4-30 7 5-9° 12 6-57 1-73 12 Mean. 3-52 ?>-(^?> (The last item includes Medina Sandstone at and Ulster Bluestone at ) Several local rocks are sometimes available of whichthere may have been no tests, but experience willusually enable a selection to be readily made of the onewhich will give the best results. The rock which willbind the most readily will probably be the least durable,and it may be more economical to make a long haul ofa good rock than to use one which is near at hand, butwhich will soon
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectstreets, bookyear1902
