180 
PARK AND CEMETERY. 
make some experiments along these lines, 
as it is thought that the cost of trans- 
portation will not make this material pro- 
hibitive. 
If the construction of the oiled maca- 
dam road in some of our national parks 
should be found satisfactory, the item of 
cost of sprinkling saved thereby should not 
be overlooked, as in some instances the 
cost of this item is considerable, and I 
call attention to the estimate for the nec- 
essary equipment for road sprinkling in 
the report of the acting superintendent of 
the Yosemite National Park for 1908, 
which is about $18,000 for approximately 
10 miles of road. 
There are very little data available cov- 
ering actual cost of an oiled macadam road, 
but that which I am able to find would 
appear to fix a maximum cost for the ad- 
dition of oil over an ordinary macadam 
road of about 14 cents per square yard. 
At this figure the first cost of applying 
011 to a 16-foot road for a stretch of ap- 
proximately 10 miles would be about 
$13,000, or a saving of about $5,000 be- 
tween the first cost of the oiled macadam 
road and the purchase price of the neces- 
sary equipment for sprinkling the same 
road. 
Quoting from an article on oiled ma- 
cadam road construction and maintenance, 
found in the transactions of the American 
Society of Civil Engineers for March, 
1911, Mr. Ross, who has charge of the 
roads for Newton, Mass., says : 
“Asphaltoilene was used in 1907 on two 
roadways in Newton, a surface of 16,822 
square yards being treated at the manu- 
facturer’s contract price, 6 cents per square 
yard. At present these roads are in very 
good condition. 
It will be noted that this statement was 
made after the road had been in use about 
four years. Quoting further from the same 
article : 
“Several macadam-surfaced streets hav- 
ing varying grades up to a maximum of 9 
per cent and subjected to heavy horse- 
drawn and auto traffic were submitted to 
the liquid asphalt treatment. The method 
was as follows : A quantity of sand was 
heated to a temperature of 200° F., dumped 
in a pile, leveled, and asphalt was poured 
over the hot sand in the proportion of one 
gallon of asphalt to each cubic foot of 
sand, and then the whole mass was turned 
with shovels, or mixed in a concrete mixer 
(the latter being preferable on account of 
the cost). This work was done at the pit. 
The mixture was teamed to the work and 
spread on the roadway to a depth of one- 
fourth of an inch, being raked even with 
14-tooth wooden rakes. Rolling was not 
considered necessary and the street was 
kept open at all times. The cost of this 
treatment was about 3 cents per square 
yard. It has the advantage of leveling and 
building up the surface of the road, each 
new application providing a new wearing 
surface. This work has remained in per- 
fect condition without further expense 
since the summer of 1909.” 
There has been considerable of this class 
of work done in Spokane, Wash., but at 
this location it cannot be said to have 
proven entirely satisfactory, but I attribute 
this more to the fault of construction than 
to the principle involved. 
Along the lines set forth in this paper 
the following conclusions are drawn : 
(1) That there should be located in each 
one of our national parks, where the rev- 
enues and appropriations would warrant it, 
an assistant engineer to act under the direc- 
tion of and in conjunction with the super- 
intendent of the park, all reports including 
plans and specifications to be submitted by 
the superintendent to a central office to be 
in charge of a man having technical 
knowledge of such matters, this office to 
be equipped to prepare proper plans and 
specifications for the various classes of 
construction work, which will arise in the 
parks. 
(2) The adoption of standard plans and 
specifications, in so far as possible, for 
the various classes of construction. 
(3) Careful surveys and estimates for 
future extensions of the work, in accord- 
ance with a general road and trail plan 
previously adopted. 
(4) The carrying on of experiments with 
oil and tar macadam roads and a general 
discussion among the superintendents of 
this subject, especially as to dust pre- 
ventatives. 
INJURY TO PLANTS BY SMOKE 
Address by E. Engleman, Gardener, Middle Division, Pennsylvania Lines, 
at Nashville Convention of Railway Gardening Association, 
It is my object to explain to you as well 
as I can the injury caused by smoke to 
growing plants, trees and shrubs. We 
must have some idea of smoke in order to 
better understand its action on vegetation. 
The following gases occur in smoke from 
coal, viz., carbon dioxides, 13 6/10 per 
cent. ; dioxygen 3 per cent. ; carbon mi- 
oxide 1 per cent, and the various com- 
pounds of nitrogen, as nitrogen sulphide, 
nitrogen oxide, etc., 82 per cent. 
Carbon dioxide in the quantity found in 
smoke is beneficial to plant life as the 
leaves of the plants will assimilate carbon 
dioxide and give off oxygen. The quanti- 
ties of dioxygen and carbon monoxide 
are so small as to be negligible in their 
effect on vegetation, but the various com- 
pounds of nitrogen which compose 82 per 
cent of the volume of smoke are very 
injurious to plant life. The nitrogenous 
compounds of sulphur enter the stomata 
of the leaves and attack the membrane of 
the cells. The chlorophyll granules lose 
their shape and become colorless and form 
a homogenous mass, thus preventing the 
leaves from performing their natural func- 
tion of digestion, the absence of which 
causes an emaciated condition of the tree 
or shrub. The bleaching of the chloro- 
phyll granules cause the leaf to assume a 
yellowish color and finally fall to the 
ground, through lack of nourishment. 
The number and activities of the soil 
bacteria are greatly reduced because of the 
sulphuric acid, a part of the smoke. The 
nitrifying bacteria especially are very sensi- 
tive to an acid soil, and soil exposed to 
long action becomes sterile. The physical 
properties of smoke are small particles of 
carbon, together with a sticky tarry matter 
which settles and sticks to everything it 
comes in contact with. The visible smoke 
or particles of carbon are very injurious to 
plant life. The soot settles on the leaf 
and hinders the intake and assimilation of 
carbon dioxide on the minute pores or 
stomata. This carbon dioxide is converted 
in the plant into starches, sugars and other 
carbohydrates. Thus plant life is inter- 
fered with, growth is impossible and death 
often results. It is almost impossible to 
maintain a healthy plant life in a smoky 
atmosphere. 
Besides the chemical and physical injury 
to plants, smoke proves injurious because 
of the lessened amount of light which 
reaches the leaves. The energy of the 
sunlight is required by the green leaf for 
the conversion of carbon dioxide into 
carbo-hydrates, and when as much as 40 
per cent, of this energy is cut off by the 
smoke cloud the effective growth of the 
plant must be very considerably checked. 
The different trees and shrubs possess 
varying powers of resistance in their bark 
and leaves which renders them more or 
less susceptible to injury from smoke, and 
I offer from my observation of many 
years the following list of ornamental de- 
cidious trees in the order of their resist- 
ance, Ailanthus, Platanus orientalis, Pla- 
tanus occidentalis, Cerasus serotina, (Wild 
Cherry), Salisburia adiantifolia, Acerplata- 
noides, Populus, Quercus' rubra, Palustris, 
Sassafras officinalis, Pyrus, Aesculus hippo- 
castanum, Ulmus campestris, Fraxinus, 
Salix, Robinia, Tilia, Betula, Fagus and 
Prunus. 
From my observation a few examples 
will explain the resistance of fruit trees 
to smoke. The plum seems to be the least 
resistant, while cherries are better growers 
in smoky atmospheres. Grafted cherries 
are more sensitive than wild, and sweet 
cherries resist less than the sour. The ap- 
ple does not hold out as well as the pear. 
