168 



SCIENCE. 



[N. S. Vol. XXI. Xo. .327 



vacuum tubes and other phenomena in con- 

 nection with the passage of electricity 

 through gases at reduced pressure ; and 

 the investigation of questions connected 

 with the polariscopic analysis of sugar and 

 the testing of polariscopes. 



The latter subject is of special impor- 

 tance on account of the use of polariscopes 

 in determining the duty on sugar imported 

 into the United States. The bureau has 

 undertaken, at the request of the Treasury 

 Department, to supervise the work of polari- 

 scopic analysis of sugar in all the custom- 

 houses of the country. Sugar is the chief 

 source of revenue among articles imported, 

 the duties .collected by the government 

 amounting to over $60,000,000 per annum. 

 The duty on each importation is deter- 

 mined by the angle through which a beam 

 of polarized light is rotated when passed 

 through a solution of a sample of sugar, 

 the percentage of pure sugar being shown 

 by a specially prepared table when the 

 angle of rotation has been determined. 

 For some years a difference has existed be- 

 tween the experts of the government and 

 those employed by the sugar interests as to 

 the effect of temperature upon the indica- 

 tions of the polariscope, and although the 

 difference is only a fraction of one per 

 cent., it amounts to a large sum when ap- 

 plied to the hundreds of millions of dol- 

 lars paid in duty during the last few years. 

 The question is being contested in the 

 courts and in the meantime the bureau is 

 making some careful investigations on the 

 subject in the interest of the government. 



Another line of the bureau's work not 

 yet fully established is the testing of gas 

 and water meters, pressure gauges and 

 manometers for high and low pressures, 

 engine indicators and the determination of 

 the strengths of materials including cem- 

 ents and other building materials. This 

 will probably develop into a very impor- 

 tant branch of our work, in which we can 



be of much service to scientific and tech- 

 nical laboratories, as well as to the govern- 

 ment and the public. 



The oiiicial testing of scales, measures 

 of length and volume, gas, water and elec- 

 tricity meters and other instruments by 

 which the commodities purchased by the 

 people are measured is not done in this 

 country as thoroughly as it ought to be. 

 In very few cities do the sealers of weights 

 and measures go about systematically test- 

 ing the instruments employed for measur- 

 ing merchandise. England surpasses us in 

 looking after the interests of the people in 

 this particular. One of the functions of 

 the bureau is to educate the public to the 

 importance of this work. A step in this 

 direction is the national convention of 

 sealers of weights and measures to meet 

 next month in Washington in response to 

 a call issued by the bureau of standards. 



The various lines of testing and research 

 which have so far been mentioned, namely, 

 weights and measures, heat and thermom- 

 etry, light and optical instruments, and en- 

 gineering instruments, are included in the 

 first division of the work of the bureau of 

 standards. The second division includes 

 electricity and photometry. In the early 

 days of its development electricity was es- 

 sentially a qualitative science; its modern 

 history has seen it become distinctly quan- 

 titative, and its wonderful development has 

 been largely, if not mainly, due to the use 

 of measuring instruments in studying and 

 applying it. The three fundamental units 

 of measure are the ohm, the unit of resist- 

 ance ; the ampere, the unit of current -. and 

 the volt, the unit of electromotive force. 

 These are so related by Ohm's law that 

 when two are defined the third becomes 

 fixed and can be determined by the use of 

 the other two. These units are not arbi- 

 trarily chosen, but are determined by ex- 

 perimental investigation. Their magni- 

 tudes depend upon the fundamental units 



