16 



MASS. EXPERIMENT STATION BULLETIN 156. 



has been done to quite an extent in large cities, especially in the busi- 

 ness sections, the telephone corporations having adopted this system 

 to a much greater extent than the electric light companies. It is an 

 expensive system, however, and those who so strenuously advocate its 

 adoption do not always consider that in the end it is the patrons who 

 have to pay for it. 



Another method of preventing wire injuries is the erection of high 

 poles to bring the wires over the trees. This is sometimes done, espe- 

 cially where the trees are young or of a species that naturally grows 

 low, when a very high pole would be sufficient to clear them for many 

 years. The cable system may be used for telephone wires, and much 

 injury to trees prevented. Large cables are rather expensive to install, 



R 



□ \J 

 o 



Fig. 13. — Showing differeut methods of attaching wires lo 

 trees: «, wire attaclied to lagbolt, and tree iirotected from it 

 by wooden blocke; z, cross-section of same; b, wire loops 

 l)laced tightly around tree, causing girdling; ./", showing 

 attachment of trolley guy wires ; j, loose loop fastened witli 

 clamps and separated from tree by blocks; c, <-ross-8ection of 

 same; o, <'reosotcd oak blocks with groove .c to support 

 the wire. 



but what is termed the " ring construction " system may be used to 

 advantage in many instances, particularly in the suburbs. In this way 

 it is possible to run a line through avenues of fine trees in the countr}- 

 districts without necessitating pruning or disfiguration. 



Rights of way for poles on private property back of residences are 

 sometimes secured, and by this means the poles and wires may be re- 

 moved from the streets, much to the advantage of the trees. But such 

 rights are often difficult to secure, and are not always satisfactory 

 either to the public-service corporations or the owners of the property. 

 The former naturally do not care much for these rights of way unless 

 they are legal and permanent, and the owners in granting permanent 



