TELPHERAGE. 



277 



examples of much more than experimental work, namely, merely con- 

 veying material Ix'tween two points, o'encrally in a straig-ht line, 

 placed in some vacant lot or loft, and tluu'ii seemed to he a desire to 

 force the method of transportation according to certain preconceived 

 ideas, rather than to pay the necessary attention to its commercial 

 adaptation. 



Coihstru<'th»i. — On account of various advantages in regard to the 

 distribution of material — such as depositing at an elevation — most of 

 the telpherage plants thus far installed have l)een overhead. As engi- 

 neers, you will be most interested in hearing what has been accom- 

 plished. The descriptions are, therefore, contined to overhead work. 

 Under the head of construction, it may be stated that the track is made 



Fifi. ].— Supporting pole, double line. One of the simplest iiutliniis oi pole construction lor double 

 lines. Especially reconinicnded for long lines and wlici'c trees are available. 



of cabl(>, especially drawn, cither of standard wir(^ or lock coil type, 

 which latt(M- has a strength approximating it.") ])er cent that of the solid 

 bar, or else solid rail, either of Hat, girder, or ])\\\h type. 



The cal)le tracks are supported every 100 feet, provided it is con- 

 venient to ei-ect poles or structures. Wher(\ thei'e ar(>. deep ravines 

 or l)etween u[)])er stories of factories, the span is made to correspond 

 with the distance, and ctui be made of any reasonable length. In 

 addition to th(> track cable, upon which the telpher runs, thcM'e is also 

 what is known as the suspension cable. As is well known, it would 

 be impossible to prevent considerable sag in the track cable and then^- 

 fore the track cable is suspended from this suspension cable by means 



