210 rosa: regulation of natural monopolies 



in testing is required, and it is a great advantage to the industries 

 to have uniform and rehable instruments, standards and methods. 



The same may be said respecting the measurement of hght and 

 illumination. The candlepower of a gas flame depends upon 

 the quality of the gas, the kind of burner used, the height of the 

 barometer, the amount of moisture in the atmosphere, and the 

 degree of purity of the air in which it burns; hence, if the quality 

 of the gas is to be determined (in part) by the candlepower given, 

 it is necessary that the test be made under very definite condi- 

 tions. The Bureau has done considerable work on flame stand- 

 ards employed in gas testing, but much remains to be done in this 

 respect. Photometric standards are supplied by the Bureau for 

 use in testing electric lamps of various kinds and colors, and gas 

 standards are calibrated and certified. Thus, uniformity of 

 value in light measurement is secured for the whole country, and 

 indeed by means of international comparisons made by the Bureau 

 for the whole world, the international candle being the name of 

 the unit of light universally employed in this country. Calibra- 

 tions are also made of photometers and auxiliary apparatus. 

 Similar uniformity, together with a much higher degree of pre- 

 cision, have been attained in electrical measurements. Electrical 

 energy is sold by the kilowatt hour or the kilowatt year (or a com- 

 bination of the two) and a large amount of testing is done by the 

 companies and commissions to insure accurate measurement of 

 the energy delivered. Here again uniformity and accuracy are 

 promoted by having a national laboratory for calibrating and 

 certifying standards and instruments, and settling such disputes 

 as may arise from disagreeing measurements. A large amount of 

 work has been done by the Bureau to secure and maintain accur- 

 ate standards and instruments, but much remains to be done, 

 particularly with reference to the specifications of instruments and 

 apparatus and the improvement of methods of measurement and 

 testing. 



In addition to its work on instruments and standards, the 

 Bureau has carried out other investigations which have a bearing 

 on the work of the public service commissions. One of these is 

 concerned with the specifications of illuminating gas, and the 

 methods of testing to be employed in controlling its quality. 



