44 EXPERLMENT STATlOxN. [Jan. 



become clogged with the roots of elm trees. This clogging pre- 

 vented the water from flowing through the tile, and caused a 

 dam, as it were, resulting in the water flowing back into the 

 conduit and flooding the steam pipes. A stream of cold water 

 flooding steam pipes is not conducive to the best results, since it 

 causes condensation and a decrease in the temperature of the 

 steam. It is necessary, of course, to leave the joints of Akron 

 tile open when used for the purpose of draining the conduit 

 trench of a central heating and distributing plant, since these 

 pipes must take off the water from the trench and prevent it 

 from coming into contact with the steam pipes in the conduit. 

 As long as the joints remain open it is with great difficulty that 

 the roots of trees, etc., are kept from growing in the tile, and 

 sooner or later it is made ineffective. Tree roots will penetrate 

 tile protected with carefully cemented joints, and become a nui- 

 sance, as is shown by the following letter. In the city of New- 

 ark, IST. J,, the Shade Tree Commission has been requested by 

 the department of sewers and drainage to omit the planting of 

 Carolina poplars on streets since the roots of these trees proved 

 to be a nuisance to drains, and the Shade Tree Commission has 

 decided to plant trees which are less of a nuisance in this respect- 

 on the streets of Newark in the future. At my request Mr. 

 Carl B. Bannwart, secretary of the Shade Tree Commission, 

 jSTewark. secured this statement from Edward S. Rankin, engi- 

 neer of sewers and drainage of the city of Xewark : — 



Rejilying' to yoiu* letter of tlie 20th inst., we find that the roots go 

 through Ihe joints of tile pipe even when carefully cemented, and 

 the trouble seems to be increasing. In 1909 we had 15 stoppages 

 caused by roots; for the first eleven months of 1910, 23, of which 5 

 occurred in the month of November. These stoji images were all in 

 house connections, and in addition to these we have also had a number 

 of cases in our main pipe sewers. The roots after penetrating the 

 pipe seem to spread out and practically fill the whole pipe. I have 

 no way of knowing how long a time it takes for these roots to grow. 

 To the best of my knowledge we have had no trouble with any of our 

 brick sewers. The trouble seems to have been caused in all cases by 

 pojilar trees. 



There recently came to our attention, through Mr. C. X. 

 Minott, field superintendent on the gypsy and brown-tail moth 

 work, a notable case where the small root from a pear tree had 



