February 14, 1S90. 



SCIENCE. 



103: 



which, in the case of the single-rope tramways, would be 

 impracticable. Again: a precipitous rise in the ground 

 presents no insuperable difficulties, since the curves can usually 



The cost of both construction and maintenance is greatly 

 increased for single-rope tramways by the use of spans longer 

 than too feet, or the occurrence of very steep grades. Even if 



BLBICHERT WIRE-ROPE TRAMWAY AT GRANITE, MONTANA. 



be laid out so as to bring the inclination of the carrying-cables 

 within the proper limits. 



The other objection is obviated by the arrangement that 

 when the car reaches either terminal, or any switch or turn-out 



only one such span, or one such grade, is present in a whole 

 line, it becomes necessary to make the entire double length of 

 moving rope strong enough for the special strain due to tha 

 one spot, over which, in its endless travel, every part of the rope 



INTERIOR OF LOADING TERMINAL OP BLEICHERT WIRE-ROPE TRAMWAY AT GRANITE, MONTANA. 



on the line, it can be automatically disconnected, and run off 

 to any point required for loading and discharging. This system 

 also permits the introduction at any point on the line of mov- 

 able or temporary switches or terminals, without the erection 

 of special structures for their support. 



must pass; and this increase in the size of the rope affects the 

 dimensions of the supports, sheaves, and other fixtures through- 

 out the line, thus requiring a general increase of cost, nearly 

 as great as if all the spans were equally long or all the grades' 

 equally heavy. The wear of the rope is also increased by reasoit- 



