DENVER & RIO GRANDE WESTERN ROUTE. 



189 



20 miles to the north. The term " wash " is applied in the West to 

 a stream or to the bed of a stream that is generally intermittent and 

 that carries so much material that it clogs its own channel and is 

 thus compelled to wander over a wide area. In some places where 

 these streams are crossed by the railroad they have cut deep chan- 

 nels that have nearly vertical sides. Ordinarily very little water 



the stream is at the stage at which 

 the measurement is made. 



Large rivers or even small streams 

 at their flood stage can not be meas- 

 ured by wading, on account not only 

 of the depth but of the swiftness of 

 the stream, which may make it almost 

 impossible to stand against the cur- 

 rent, so that it may be necessary to 

 work from a bridge or to span the 

 stream with a cable from which the 

 meter is suspended and held at the 

 proper depth in the water by means 



to the current-meter equipment it 

 always happens when the engineer is 

 suspended in midstream while it is 

 raining or while a wind is blowing 

 what the loyal Westerner mildly terms 

 " just a stif£ breeze." 



Discharge measurements are made 

 at different stages of the water. Per- 

 haps half a dozen will cover the range 

 between high and low water. These 

 measurements, when plotted on cross- 

 section paper, define a curve Icnown as 

 the " rating curve " for the station. 



FiocBB 49.— Method of measuring the flow of a river at a cable station. The view shows 

 the section of the river and the car, gage, and other apparatus. 



of lead weights. To swing a meter 

 weighted with 20 or 30 pounds of lead 

 for several hours in measuring a swift 

 river from a bridge is a form of exer- 

 cise that is a sure cure for insomnia. 

 If there is no bridge at the gaging sta- 

 tion, the stream must be spanned witli 

 a cable, and the engineer must worlr 

 from a car swung beneath it, as shown 

 in figure 49. In this car he pulls him- 

 self along the cable to the points 

 where measurements are to be made. 

 A cable-car measurement is an even 

 better cure for insomnia tlian a bridge 

 measurement. In passing, it may be 

 noted that if anything wrong happens 



From this curve the discharge for any 

 stage of water can be estimated, and 

 the engineer can calculate Avith suffi- 

 cient accuracy for most purposes the 

 daily flow from the gage readings fur- 

 nished by the local observer. 



If a river carried the same quantity 

 of water each year it would be neces- 

 sary only to maintain a gaging station 

 at a particular place for a year, but 

 as the flow varies widely from year 

 to year it is necessary to maintain the 

 stations for several years in order to 

 determine the flow not only for an 

 average year but for tlie wet and the 

 dry years. 



