No. 5. 



TABLE EXHIBITING THE COMPARATIVE LENGTHS, COST, ETC., OF THE 

 DIFFERENT ROUTES, WITH EXPLANATORY REMARKS. 



BY CAPTAIN A. A. HTTMrHIlEYS, COKrS lOPOQRAPniCAL ENGINEERS. 



The distances and estimates of cost of the route of the thirty-fifth parallel, given in the 

 following table, are not those contained in Captain Whipple's revised report. The line from 

 the Big Sandy river to the Colorado river, adopted by Captain Whipple, is 54 miles in length. 

 It is nearly an air line, has never been passed over, and was not noted during the examination 

 in the field as probably affording a practicable route, but was deemed practicable after a study 

 in the oflice of the field notes. For these reasons, it can only be considered a line which future 

 examinations may show to be practicable ; and not one to be adopted, and the cost of a railroad 

 along it elaborately estimated. Upon this principle, the reports upon the other routes have 

 been revised. The corrected distance along the route examined between these two points is 160 

 miles, which is the length used in the following table. The shortest probable railroad route, 

 from the Mojave river to the Tah-ee-chay-pah pass, is 73 miles in length. The measured 

 distance through the Tah-ee-chay-pah pass is 42 miles. There are parts of the line where the 

 reduction of length shown in Captain Whipple's report may be considered problematical. 



However elaborate the field operations of an exploration of this character may be, the extent 

 of ground passed over in a day is so great, that even detailed maps like those of Captain Whip- 

 ple, though prepared with great care, must represent the ground less broken than it really is. 

 Had, however, the location of the railroad line been made in the field, and notes taken, or rough 

 computations made upon the spot of the excavation, embankments, &c., required, or had the 

 portions of the line been assimilated at the time to lines of road already built, with which the engi- 

 neer was personally familiar, the liability to error in the estimate of cost would have been less 

 than by the method followed on the route of the thirty-fifth parallel. The location of th 

 railroad line of that route was made on the maps in the ofiice ; it follows the actual line of 

 survey for less than half the distance^ in many places deviating widely from it, and in occasional 

 cut-offs (one of which is over 50 miles in length) lying over ground that was not examined. 

 The chances of error in the estimates of cost by this method are greater than by the other, and 

 any computations of excavation and embankment are rendered liable to serious inaccuracies. 



Captain Whipple's estimated cost of the first T06 miles is probably $5,000 per mile too small. 



The estimated cost on the cut-off from the Big Sandy to the Colorado, where there is a descent 

 of 3,400 feet in less than 40 miles, if the line be found practicable, will probably be doubled ; 

 but until the line has been examined, the route should be estimated along Bill Williams' fork. 

 In the estimate contained in the following table, one-third of the distance to the mouth of that 



