PARK AND CEMETERY. 
228 
SUBTERRANEAN IRRIGATION OF STREET TREES 
AT DRESDEN. GERMANY. 
Of the large cities, Washington, perhaps, pos- 
sesses the best street tree plantations in the United 
States. Many of the cities of the south and of 
Connecticut and Western Massachusetts are deserv- 
edly famed for their avenues of street trees. But in 
the large cities numerous agencies concomitant with 
urbanlife threaten, with ever increasing power, to 
destroy the street trees cultivated in the usual man- 
ner. Soil surcharged with gas and electricity, at- 
mospheric gases and their residue, smoke and over- 
head telegraph wires are agents baneful to thrifty 
vegetable life. To be successful in the culture of 
street trees in the larger cities of America it is 
necessary to adopt decidedly artificial means of 
maintenance. In opening a discussion of the street 
tree problem we present an adapted translation of 
an article dealing with a detail of the subject. The 
following is taken from Moeller' s Dculsehe Gaertner 
Zettiuig, Vol. XV., p. 406, and is by M. Degen- 
hard, City Garden Director. 
The editor of this publication desired a descrip- 
tion which would be a revision to date of the com- 
prehensive essay on subterranean irrigation which 
appeared in a former number of this periodical. 
They informed me that the first treatise was fre- 
quently reprinted and is now found in many cities 
of the magistracies which is very adulatory for our 
Dresdenian arrangement. 
Below I shall describe this simple and suitable 
m.ethod without confining myself to the original 
description which I have not at hand and choose 
not to trouble to obtain and which I later gave to 
a garden Journal desiring it. I wish it would bene- 
fit the well being of street trees, the people and 
beasts, particularly the carriage horses suffering 
from heat. 
I was still a novice in my position of city gar- 
den ;r when the question presented itself as to 
which is the best, most efficient method of water- 
ing trees. After speaking of drain pipes to the 
commissioner, afterwards mayor. Dr. Stuebel, he 
made observations as to this method of tree water- 
ing and found a short section in front of the theatre 
at Hanover watered in this way. The pipes were 
merely butted. Soon thereafter I had an oppor- 
tunity to visit my colleagues at Hanover and found 
the condition as explained to me but the arrange- 
ment was so primitive that I could not forego 
adopting real improvements on it. There was too 
great a loss of water through the joints of the 
loosely laid pipes which were short and easily dis- 
joi nted. 
The distribution of the water was, however, de- 
ceptive, particularly for great distances and espe- 
cially in porous soils. I therefore ordered longer 
pipes, now' 60 cm., with collars made out of clay 
and which allow of their being conveniently slipped 
over the pipes. 
To prevent the escape of water betw'een two 
distant trees the pipe-i are entirely sealed but only 
partially sealed in other sections, according to the 
requirements of the trees and the character of the 
soil. 
Certainly I experimented with a section pre- 
vious to filling in the e.xcavation so that the sealing 
could be thickened or lessened thereby obtaining 
the most perfect and equal distribution, in other 
words, that at the filling points the openings would 
be closed more than in the middle and less toward 
the ends furthest from the filling points. In time 
the e.xperienced workmen knew how to fix the 
pipes to conduct the water for the purpose of pro- 
curing a proper seepage throughout the length of 
the pipe, also when more or fewer trees are to be 
connected by one clay pipe through different soils. 
We connect from four to ten trees according to the 
distance of the spacing, /. e., from five to 10 m. 
and the sort of tree, its thrift and the porosity or 
imperviousness of the soil. 
Figure i indicates a double branch leading to 
each tree. The ends may be advantageously pro- 
vided with curved pipes obtaining thereby an al- 
most encircled watering which allows the estab- 
lishing of a gutter shaped basin around such trees 
which must unfortunately be planted closer than 
w'e should like to have them. 
The end of the pipe is cl^^sed by placing over it 
a stone or potsherd in a manner to enable sufficient 
water to escape without inequalizing the pressure 
of the w'ater. 
The watering of trees has been adopted in 
Dresden since 1877, or really since 1876, and of the 
30,000 street trees 9,737 will be watered this year. 
To date, i. e , during the past twenty-four years 
there has been but a single instance of a so-called 
root knot which has stopped a conductor. A sec- 
ond instance occurred by an employe forcing a 
pliable root into the crevice at a joint of ihe pipe, 
which resulted in the matting of a root inside the 
pipe. 
Watering is now done without undue conspic- 
uousness or interrupting traffic. 
More recently we provided several water cocks 
so as not to be dependent upon the fire hydrants 
and fire department which the taxation provided. 
The fire hydrants were expensive and inconvenient 
because they are located in the streets and only a 
fireman is allowed to turn on the water fre m them. 
Though w'c employed hose bridges over which 
many horses refuse to pass, traffic and our work 
