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Samuel Washington McCallie.

A preliminary report on the roads and road-building materials of Georgia online

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A steam-roller, which is a kind of locomotive mounted on broad
wheels, is fre-
quently made Fig. 23
much heavier
than horse-roll-
ers. They often
have a weight
of twenty tons ;
but the average
is usually from
ten to fifteen
tons. It has

been found by champion Horse Road-roller.

e xper ience,

that, if a roller is too heavy, it has a tendency to crush the stones-
into powder, in the process of consolidating, and to thus injure
the wearing quality of the road. Furthermore, the heavy rollers
are objectionable, on account of the strain on bridges and culverts.
The lesser the weight of the roller, the greater will be the num-
ber of times required to pass over a road, in order to consolidate it.
However, it is claimed by most road engineers, that the work is
more durable and satisfactory, when done by the lighter rollers.
For this reason, many road-constructors advocate the use of the
horse-roller, in preference to the steam-roller. Prof. Shaler, in
discussing the merits of road-rollers, says: ^ "The advantage of



American Highways, p. 202.



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:84 TOOLS AND MACHINES

the modern instrument (steam-roller) in all except the purchase
price is very great, and the cost of compressing a given amount of
stone by it is so much less than that incurred by the use of the
ancient instrument (horse-roller) that the price should, in most
cases, not be reckoned." It is quite probable, that this statement
is true, when applied to the Common-wealth of Massachusetts,
where highway improvement has reached an advanced stage.
However, through the South, where the majority of our highways
are common earth-roads, it is quite likely, that the horse-roller
will, for some time to come, answer all practical purposes.

There is a great variety of
^^s 24 both horse- and steam-rollers

on the market, all of which
will do satisfactory work,
when properly managed.

Rock-Crushers. — Prob-
ably the most important of
all modern additions to the
list of road-making machin-
ery is the rock-crusher. This
A steam Road-roUer. machine has, in the last few

years, so lessened the cost of
preparing stones for macadamized roads, that this class of high-
ways has been brought within the reach of many rural districts.
There is quite a number of different makes of rock-crushers now
on the market, the most of which are constructed on the plan of
the original Blake stone-crusher,* thus described by Gen. Q. A.
Gillmore : ^ MM **is a frame of cast-iron in one piece, which
supports the other parts. It consists of two parallel cheeks, shaded
dark in the drawing, connected together by the posts AA. B
represents a fly-wheel, working on a shaft, having its bearings at
D, and formed into a crank between the bearings. It carries a
pulley C, which receives a belt from a steam-engine. F is a rod
-or pitman, connecting the crank with the toggles GO. The end

I 2

Sec fig. 25, Roads, Streets and Pavements, by Q. A. Gillmore, p. 9a.



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TOOLS AND MACHINES



85-



of the frame A, on the right of the figure, supports a fixed jaw H,.
against which the stone is crushed. J is a movable jaw pivoted
at K. L is a spring of India rubber, which being compressed at
each forward movement of the jaw J, aids its return. Every rev-
olution of the crank causes the pitman F to rise and fall, and the
movable jaw to advance a short distance toward the fixed jaw and
return, so that a stone, dropped in between the jaws J and K, will
be broken at the next succeeding bite. The fragment will then
fall lower down

and be broken Fig. 25

again and again
at each succeed-
ing revolution,
until it passes
out at the bot-
tom of the open-
ing between the
jaws. The jaws
may be set, so
as to deliver any
desired size of
stone by suit-
ably adjusting

the wedge N, The Blake Patent Stone-breaker,

inserted against

the toggle-block O. The majority of crushers are supplied with a
revolving screen, which sorts the stones into different sizes as they
pass from the crusher, and drops them into bins, from which they
can be easily loaded into wagons. Stone crushers are divided into
two classes, namely, the stationary and the portable crusher. The
latter can be easily moved from place to place, and is most suit-
able for general purposes. Especially is this true, where stone
can be had at a number of places along the roadway."

Mr. Isaac B. Potter, in his work entitled **Macadam Roads'', gives
the following excellent advice on the selection of a rock-crusher: — *•

Page 48.



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.86 TOOLS AND MACHINES

" Certain prominent facts should control the purchaser, to en-
able him to obtain such a machine, and to operate it in such a
manner, as will tend to the production of good work at a minimum
price. It is generally understood, that, from the nature of the
work required, a stone-crusher in its working parts exerts prodig-
ious powers ; but the fact is too often forgotten, that all machinery
is perishable, and that an overworked crusher, like an overworked
man, is likely to break down in the midst of an important task.

Fig. 26



Champion Rock-crusher with Elevator and Screen Attached.

All reputable manufacturers supply machines, in which the parts
subjected to the greatest strain and wear are of hardened and tem-
pered steel, and such machines, if fairly treated, will give good re-
sults and good satisfaction to the buyer. To obtain the best results
from any crusher, it should be regularly and constantly '* fed", while
in operation, and have its wearing parts renewed, whenever they
break or show signs of excessive wear ; and it should, moreover,
be run by power somewhat in excess of that actually required,
^his matter of power is an important one, and one, in which



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TOOLS AND MACHINES



87



apparent cheapness is the poorest economy. If, for example, an
engine of eight horse-power is just sufficient to run a crusher of a
given capacity, the work will be done and the crusher operated
with varying speed and with a jerky motion ; while an engine of
twelve horse-power will do the work with an ease and uniformity
of motion, which always proves the existence of reserve power,
saves the machinery, and renders more satisfactory results. When
we consider, in addition to these facts, that the smaller engine
costs about $500, and the larger one, only about $140 more (price-
list), the extra expense should offer no barrier to the purchase of
the larger engine.

"In the selection of a stone-crusher and engine for use in an or-
dinary country town, a machine capable of producing from two to
twenty tons of broken stone per hour will generally answer ; and to
run such a machine, it is best to select an engine of ample size and to
consult the manufacturers, before making the purchase. Roughly,
it may be estimated, that such a machine will cost from $700 to
$1,200; and the cost of an engine, to run it, will vary from $500
to $1,000, according to the make and quality. These figures are
intended to serve as a mere approximation."

The following tables, from Potter's *' Macadam Roads",' give
the regular published information, concerning some of the leading
stone-crushers : —





The Gates


Crusher (Chicago, III.)




Size


Weight-
Pounds


Capacity-
Tons per Hour


Horse-Power
Required


Price




I

2

3

4

5

6

8


3,100
5.500
7,800
13,500
20,000
27,000
36,000
89,000


2 to 4

4 to 8

6 to 12

10 to 20

15 to 30

25 to 40

30 to 60

100 to 150


4
8
12 to 15
20 to 30
30 to 40
40 to 50
50 to 60
125 to 150


1 400

600
800
1,200
1,900
2,500
3,500
7,000



' Page 55-



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1 14 *'/ i* -'. 4^-. -'v: ;. i*. 5^ 00c

2 ;2 ' :7 25 " •' 32.000

3 xo •• 25 *• ;5 * :€.ooo

4 '1 • 2\ " 12 ■• :^>x

5 7 •• 20 • 9 - - :-,ooo



Thf '.<•-•». /I^*T Lrui'^'r K'rKM"': V-*-'*. /-



Drinng
R«««nK Appro«ma-.e Approxi- p^.^ j,,,,^

^'" Capacitv fr<»iuctof j-tnc.-. mate spe*d i>iai«teT IW«-

Stor* per Hcr:r Weijfht and Face



^


7


bv


i^


in.


10


to


15


ton*


5


000


I^O


rev.


XX''


bj


S"


10


4


9


•*


*5


**


12


**


18


* *


8


000


160


**


44


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S


12



TiRKS. — There has been much discussion throughout the United
States in the last few years, on the 'question of wagon-tires ; and
in some States, notably Xew York and Michigan, laws have been
enacted bearing upon this question. Many of the European coun-
tries have laws fixing the minimum width of wagon-tires : and it
seems now to be only a question of time, when such a law will be^
come universal in this countr\'. The numerous experimcntss
which have been carried on in the last few years, thoroughly



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TOOLS AND MACHINES 89

•demonstrate the great advantage of wide tires over narrow tires.
Several of these experiments taken from Circular No. 31, U. S.
Department of Road Inquiry, are here given : —

*' Onondaga County, New York, furnishes an interesting illus-
tration of the value of wide tires as road-rollers. The Solvay Pro-
cess Company, of Geddis, in that county, was accustomed to haul-
ing heavy loads of stone, for four and a half miles from the quarry.
To test the wide-tire theory, they built several wagons having 4-
inch tires on the front wheels and 6-inch tires on the rear wheels,
and with the rear axles longer than the others, so that the track of
the rear wheels would just lap outside of those made by the others.
The result of the use of these wagons was to produce a hard,
smooth, compact surface ; and the road, having been filled, so as
to raise the middle, or "crown" it, is thoroughly drained at the
surface, and always fit for use with the heaviest loads. Loads of
8 tons are frequently hauled over them, and instead of tending to
cut up the road, serve to roll it harder and harder. The superin-
tendent reports, too, that the improved condition of the road has
reduced the cost of hauling the stone from 80 cents per ton to 60
cents, or 25 per cent.

" It has also been proven by experiments upon a number of occa-
sions, that the use of wide tires considerably reduces the amount
of power required to move loaded wagons. One of these tests was
made by the officers of the U. S. Department of Agriculture at the
Atlanta Exposition in 1895. Two wagons, both weighing alike
with their loads, were drawn over a wet piece of clay road, one
wagon having 2-inch tires, the other, with 4-inch tires and with
the rear wheels farther apart, than the front wheels, so as not to
run in the same track. It was found by the use of the tract-
ometer, an instrument made to register the power exerted, that
twice as much pull was required to haul the 2 -inch tired wagon as
was required for the other. That part of the road traversed by the
narrow-tired wagon was cut and rutted to a depth of several inches,
while the tires of the other wagon had rolled the road into a
-smooth and hard surface.



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90



TOOLS AND MACHINES



"The Missouri Agricultural Experiment Station made a series
of tests, extending from January, 1896, to September, 1897, in
order to thoroughly and scientifically ascertain the value of wide
tires as compared with narrow ones. They were made with two
wagons, one with 6-inch tires, the other with standard i J^-inch
tires, both wagons of the same weight, and each loaded with 2,000
pounds. It was found that the same power needed to draw the
narrow-tired wagon, with its 2,000-pound load, on a gravel road,
would have pulled a load of 2,482 pounds'on the wide-tired wagon •
The same power, required to draw the 2,000-pound load, on narrow
tires, over dirt and gravel roads, when these were dry and hard,
was found suflScient to draw a 2,530-pound load on the wide-tired
wagon under the same conditions ; and it was shown, that, when
these roads were deep with mud, but partly dried at the surface
by a few hours' sun, the same power, required to draw the 2,000-
pound load over them, on the narrow tires, would pull a load of
3,200 pounds on the wide tires. Director Waters, of the Station^
states, that the conditions, under which the narrow tires offer an
advantage over the wide ones, are 'unusual, and of short duration, *■
and that, 'through a majority of days in the year, and at times,,
when the dirt roads are most used, and when their use is most im-
perative, the broad-tired wagon will pull materially lighter than
the narrow- tired wagons.' He states, that *a large number of tests
on meadows, pastures, stubble land, com ground, and plowed
ground, in every condition, from dry, hard and firm to very wet
and soft, show, without a single exception, a large difference in
draft in favor of the broad tires. This difference ranged from 17
to 120 per cent' As a result of all experiments conducted, he
says : *It appears, that six inches is the best width of tire, for a
combination farm and road wagon, and that both axles should be
the same length, so that the front and hind wheels will run in the
same track.'

" Experiments made at the Agricultural Experiment Station in
Utah have demonstrated, that a i J^-inch tired wagon drew about
40 per cent, heavier, than one with 3-inch tires, and weighings



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TOOLS AND MACHINES



91



with its load, the same as the other. At the Ohio State Univer-
sity, it was shown, that a wagon with 3-inch tires and loaded with
4,480 pounds, could easily be hauled by two horses over an ordi-
nary dirt road in good condition and with a hard surface ; while,
with a narrow tire, half as much was a full load for a double team."
In view of these various experiments, all of which demonstrate
conclusively the special merits of the wide tire, there should no
longer be any doubt, as to which kind of tire to adopt for common
earth-roads.



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CHAPTER VII



THE TOPOGRAPHY OF GEORGIA IN ITS RELATION
TO THE HIGHWAYS

The cost of building and maintaining highways depends, in a
great measure, upon the topography of the country, through which
they pass. If the country is level, little or no expense is incurred
in grading ; while, on the other hand, if the country is mountain-
ous, the chief cost of road-construction is chargeable to this account.
High mountains and precipitous ridges often become such obsta-
cles in the way of road-building, that no intercourse or traffic is
carried on, between the inhabitants of adjacent valleys, although
they may lie only a few miles apart. Frequently, swamps and
morasses also are, in like manner, difficult barriers to the way of
free communication between localities having a common interest.

In discussing the topographic features of Georgia with reference
to highway-construction, it is thought advisable to divide the State
into three divisions, namely, the Paleozoic area, the Crystalline
area and the Tertiary area. The last embraces both the Tertiary
and the Cretaceous deposits of the State. Each of these divisions
is named from the geological formation of its respective area,
which has given rise to certain well-marked topographic feat-
ures. The smallest of these divisions is the Paleozoic, lying in
the north-western part of the State. It comprises an area of about
3,500 square miles, and includes the greater part of ten counties,
all of which are well adapted to agricultural purposes. The rocks
of the Paleozoic area consist of limestone, shale and sandstone,
originally horizontal, but now compressed into gentle folds having
a northeast-and-southwest trend. In places, these folds have
been so closely pressed, that the strata have been broken and re-

(92)



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TOPOGRAPHY OF GEORGIA



93



lieved by huge faults, some of which show a total displacement of
several hundred feet. This characteristic structural geology of the
region explains, in a great measure, the striking topographical
features of the area. Its present configuration is due almost solely
to surface erosion ; but this, in turn, has been conditioned largely
by the original folding and faulting of the strata, together with the
relative position of the hard and soft rocks.

Dr. C. W. Hayes, of the U. S. Geological Survey, in describing
this area, divides it topographically into three divisions: (i)
plateaus; (2) sharp edges; (3) undulating or level valleys.

The plateaus are confined to the western part of the area, and
include Lookout and Pigeon mountains and a portion of Sand
mountain. These plateaus, which have nearly a level surface, are
elevated from 2,000 to 2,400 feet above the sea, and terminate in
precipitous escarpments rising a thousand feet or more above the
adjacent valleys. Owing to the steepness of these escarpments, it
is a very difficult matter to construct a road with easy grades,
from the valleys to the plateaus ; but, when the elevated areas are
once reached, the evenness of the surface reduces the cost of con-
struction to a minimum. As the plateaus are nowhere intersected
by streams, they form barriers, affecting, more or less, free inter-
communication between the adjacent valleys.

The second type of surface, which is confined to the eastern
part of the area, consists of a number of sharp parallel ridges, hav-
ing a northeast-and-southwest trend. The ridges are due to the
slow weathering of the upturned edges of hard sandstone, which,
in the plateau, lies almost horizontal. The smaller of the ridges
are frequently intersected by streams, along which cross-country
roads, of easy grade, can be constructed. The main thorough-
fares are located in the narrow valleys, where no serious obstruc-
tion is presented to road-construction.

The undulating-valley type of surface lies between the plateau
on the west, and the sharp ridges on the east. It consists of low,
wide, comparatively level valleys, drained by deep, sluggish



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94



TOPOGRAPHY OF GEORGIA



streams. The famous Chickamauga National Park is located in
one of these t>'pical valleys. Owing to the comparatively level
surface of the valleys, this division of the Paleozoic area presents
fewer difficulties to highway-construction, than either of the other
divisions. Cross-country roads can here be built with but little
cost ; as the intervening ridges are low and can be ascended on
easy grades.

In considering the Paleozoic area as a whole with reference to
highway-construction, it may be stated, that the topographic feat-
ures of the region ofiEer, as a rule, no very marked difficulties to
highway engineering, so long as the roads have a northeasterly and
southwesterly direction ; but, on the other hand, when they trav-
erse the country at right angles to this direction, the grading is
likely to be heavy. This is especially true, in crossing the main
parallel ridges.

The Crystalline Area. — The Crystalline area is divided
topographically into two distinct divisions : (i) the mountainous
region, (2) the plateau region. The former division comprises
several counties in the northern part of the State, east of the Pale-
ozoic area, which are very mountainous. Many of the higher
peaks reach an elevation of more than 4,000 feet above sea-level.
The valleys of this region are narrow, and the streams are gener-
ally quite rapid. The ridges have a general northeast-and-south-
west trend ; but there are also many cross-ridges, which give to
the surface of the section a very rugged and picturesque appear-
ance.

The underlying rocks are chiefly contorted mica-schists, gneisses
and slates, whose uneven weathering has had much to do with
shaping the topography of the region. Road-building in this
mountainous part of the State is both difficult and expensive ; and,
as a consequence, the highways are generally in bad condition for
traffic. The valley roads are sometimes in fair condition ; but
even these often have steep grades and are difficult to maintain,
on account of the frequent overflow of streams.

The plateau region of the Crystalline area embraces all that part



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TOPOGRAPHY OF GEORGIA



95



of the State, lying north of an irregular line, connecting Augusta,
Macon and Columbus, with the exception of the Paleozoic area
and the mountainous region of the Crystalline area, just described.
This portion of the State, known as the Piedmont plateau, is the
southern extension of a wide and fertile undulating plain travers-
ing the Carolinas and Virginia. It is the remnant of an old worn-
down mountain range, whose peaks and ridges once towered
several thousand feet above the present land surface, and probably
reached, in places, the height of perpetual snow. A few fragments
of this elevated region are still to be seen, as isolated peaks, widely
distributed over the plateau. Some of the most noted of these
lonely sentinels in Georgia are Kennesaw, Stone and Graves
mountains, which owe their elevations almost entirely to the
superior hardness of the rock, of which they are formed. The
Piedmont belt in Georgia has an elevation varying from 500 to
1,500 feet above sea-level. It slopes gradually to the southeast,
and is crossed by numerous streams flowing in winding valleys
from 100 to 250 feet below the surface of the upland plains.
When viewed from an elevated point, the plateau has all the
appearance of a level plain ; but in traversing it the seeming plain
is found to have an undulating or rolling surface. Low, broad
ridges, forming water-sheds between the main streams, are more
or less common, and often extend for many miles without a break
or interruption. Along such ridges and their adjacent valleys,
highway-construction is comparatively easJ^ The grade from the
valleys to the ridges is often considerable in a direct line ; but, by
a sinuous or zig-zag route, the elevation can generally be attained
by a comparatively small cost in grading. The underlying gran-
ites, gneisses and mica-schists of the Piedmont belt are generally
decomposed on the hills and ridges to considerable depths, so that
the actual cost of grading is reduced to a minimum. Material, of
good quality for macadamizing purposes, is abundant throughout
the entire area.

The Tertiary A^ea. — The Tertiary area, comprising all the
Coastal Plain, lies south of the Crystalline area, and embraces



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96



TOPOGRAPHY OF GEORGIA



more than half of the entire State. It is, generally speaking, a
comparatively level plain sloping generally to the south. Many
streams traversing this area are of large size. They have cut
broad, shallow valleys along their courses from 50 to 150 feet
below the surrounding country. Ravines and small gorges are
common along the shallow valleys, where tributaries join the
main stream. The adjacent uplands, in the immediate vicinity
of the valleys, are also often carved into rounded hills, which give
rise to distinct topographic features resembling very closely the
surface configuration of the more northern Crystalline area. The
valley and hill features of the region become less pronounced
toward the south, where the surface becomes remarkably leveL
There are a few localities even in the extreme southern part of
the State, and notably in the vicinity of Thomasville and Whig«
ham, where the surface is quite undulating and much broken.
Such areas, however, are of limited extent ; and they soon give
place to wide stretches of piney woods, which are occasionally
interrupted by cypress swamps, old sloughs, lime-sinks and lakes.
Low sandhills are of frequent occurrence in the Tertiary area; but
they are usually of limited extent and are confined mostly to the
vicinity of the coast or near the larger streams. These sand dunes
become conspicuous features of the landscape in the vicinity of
Butler, Albany and Bainbridge, where they form hills fifty feet or
more in height. Along the coast, they become quite prominent
in Camden, Glynn and Wayne counties. In the latter county,,
they are crossed by the Southern Railway near Pendarvis P. O.

T*he northern part of the Coastal Plain , where it comes in con-
tact with the Crystalline area, has an elevation of from 250 to-


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Online LibrarySamuel Washington McCallieA preliminary report on the roads and road-building materials of Georgia → online text (page 7 of 22)