890 



Popular Science Monthly 



Four four-mule teams are more efficient when pulling together than when separate where 



extensive transportation is necessary. The maximum traction effort required is less than 



four times the maximum for a single team 



Expensive Transportation 



IN many engineering projects, the cost 

 of transporting equipment and ma- 

 terials assumes a very high relative 

 value. 



In illustration, may be cited the case 

 of the hydro-electric development of 

 Big Creek in California. The site of 

 the works was to be located fifty-six 

 miles from the nearest railroad. It 

 was estimated that to do this work with 

 teams, the transportation cost would 

 have been about twenty 

 dollars per ton. So, the 

 contractors built a stand- 

 ard size railway. 



But they could not con- 

 struct a railway in order to 

 supply materials for 

 transmission line, 

 which is two hun- 

 dred and forty-one 

 miles long. Teams 

 had to be employed. 



A little con- 

 sideration will 

 make clear why 

 it is better to 

 unite four four- 

 mule teams in- 

 to one than to 

 use them sep- 

 arately . A 



The test-car is used for detecting faulty railway scales 



loaded wagon must ordinarily be hauled 

 by a team able to overcome the maxi- 

 mum difhculties. A string of four 

 wagons would hardly all of them have 

 their individual maximum difficulties at 

 the same moment. In other words the 

 maximum traction effort required for the 

 string is probably less than four times 

 the maximum effort required for a single 

 wagon. 



A Traveling Laboratory for Testing 

 Railway Scales 



ONE of the interesting phases of the 

 United States Bureau of Standards* 

 work is the testing of railway-track 

 scales by means of traveling test-cars 

 which make their way over the great 

 railway systems of the country. 



Two test-cars are now engaged in this 

 work. Each test - car carries ninety 

 thousand pounds of standard weights, 

 eight of ten thousand pounds each 



and four of two 

 thousand, five 

 hundred 

 pounds each. 

 The car carries 

 also a small 

 truck driven by 

 an electric mo- 

 tor on which 

 the weights can 

 be placed so as 

 to be rolled on 

 to the trucks of 

 the scale to be 

 tested. 



At the for- 

 ward end of the 

 car there is a 

 crane which 

 can be ex tend - 

 ed through 

 the end doors, and which carries an 

 electric hoist for raising the truck and 

 placing it on the track. The work of 

 the first test-car demonstrated that 

 seventy per cent of the number of 

 freight scales tested showed an error 

 of at least two hundred pounds in 

 weighing a freight car of one hundred 

 thousand pounds. This proves that the 

 test-car was needed. 



