JANUARY 5, 1912] 
multiplied by six as standing for the work 
of the bureau as a whole. 
2. SCIENTIFIC INVESTIGATIONS 
The scientific researches which have been 
carried out in the electrical division, the 
results of which are contained in more than 
100 papers published in the Bulletin of 
the bureau, may be grouped under the fol- 
lowing five heads. 
(a) Theory of Electrical Measurements 
and of Absolute Instruments——One of 
the first things that demanded atten- 
tion when the bureau was established 
was the fixing and maintaining of the 
standards for electrical measurements, and 
the choice and development of meth- 
ods of measurement. This has involved a 
thorough study of the theory of electrical 
measurements, and of the theory of the 
absolute instruments which are employed 
in the various kinds of absolute electrical 
measurements. Such studies naturally led 
to new methods and to the improvement of 
existing methods, and to a better knowl- 
edge of the theory of electrical measure- 
ments and of electrical instruments. The 
Bulletin contains twenty-seven papers 
under this head, including such subjects 
as the calculation of self and mutual in- 
ductance of the various kinds of coils used 
im the absolute instruments employed in 
the measurement of resistance and current 
in C.G.S. units, and in many other kinds of 
measuring instruments; the theory of dif- 
ferent kinds of electrodynamometers, and 
of a new method for the absolute measure- 
ment of resistance; theory of coupled cir- 
cuits and other problems in wireless teleg- 
raphy, and the preparation of a complete 
list of formule for use in calculating in- 
ductances of almost every kind of electric 
eircuit. 
(b) Methods of Electrical Measure- 
ment.—In the work of electrical testing 
SCIENCE 9 
and research much attention was given to 
improving methods of measurement, and 
the Bulletin contains thirty-three papers 
on this subject, including the absolute 
measurement of inductance and of capac- 
ity, the measurement of inductance in 
terms of capacity by means of alternating 
currents, wattmeter methods of measuring 
power, the influence of wave form upon 
electrical instruments and upon hysteresis 
losses in iron, the measurement of energy 
losses in dielectrics, and in iron, a stand- 
ard method of demagnetizing iron in meas- 
urements of magnetic induction, methods 
of testing transformer iron, measurement 
of the ratio of transformation and of 
phase relations in current and potential 
transformers, quantitative measurements 
in radio-telegraphic circuits and experi- 
ments with high frequency circuits and 
various papers on methods of measure- 
ment in photometry. 
(c) Haperimental Researches wpon Con- 
crete Electrical Standards.—The results of 
absolute electrical measurements are pre- 
served by means of concrete electrical 
standards, and the practical units of elec- 
trical measurements as defined and agreed 
to by international electrical congresses 
are expressed in terms of concrete electrical 
standards, and not in terms of the C.G:S. 
system. The accuracy attainable in abso- 
lute measurements and the definiteness of 
legal values are both limited by the con- 
staney and reproducibility of the concrete 
standards by means of which they are ex- 
pressed and preserved. The principal 
conerete standards are (1) the mercury 
column, the resistance of which defines the 
international ohm, and the wire standards 
to which values are assigned in terms of 
the mercury ohms; (2) the silver voltam- 
eter which defines the international ampere ; 
and (3) the Weston normal cell, the concrete 
standard employed for the measurement of 
