16 SCIENCE 
mm good condition, in order that it may 
give accurate and trustworthy results, and 
to check measurements previously made. 
In most kinds of testing, not half the total 
cost of the work is due to the time re- 
quired to make the actual observations and 
ealeulations. But that is an ievitable 
condition, which never can be otherwise. 
For, if the work is not thoroughly reliable, 
its value has disappeared. 
One of the interesting phases of this 
testing work is the uniformity which 
in some cases it maintains throughout 
the country in the output of different 
companies and the service rendered by 
different agencies. Before the bureau 
began its photometric testing, the stand- 
ard of candle power varied from ten to 
twenty per cent. between different com- 
panies. The 16 candle-power standard 
lamps of different manufacturers varied 
from 14.5 to 17 candles. A 20 candle- 
power gas lamp on the average gave less 
light than a 20 candle-power electric lamp, 
for the unit in the gas industry was based 
on a different standard and was smaller. 
Now the unit of candle-power is the same 
for gas and electric light, and every manu- 
facturer and every lighting company 1s 
on the same basis, for all get their stand- 
ards, directly or indirectly, from the 
bureau. 
Often tests are made to settle disputes, 
either concerning the accuracy of instru- 
ments or concerning the performance of a 
machine sold under guarantee. The confi- 
dence that has frequently been expressed 
in the justness and impartiality of the 
bureau’s decisions, when thus acting as a 
court of appeal, has been gratifying to the 
officers of the bureau. 
a 
5. COOPERATION WITH ENGINEERING SO- 
CIETIES 
The bureau cooperates with many engi- 
neering societies and foreign laboratories 
[N.S. Von. XXXV. No. 888 
in the work of standardizing and unifying 
practise, defining terms and improving 
nomenclature, working out uniform speci- 
fications and methods of tests, ete. In this 
work the division of Hlectricity, Magnet- 
ism and Photometry comes especially into 
contact with the American Institute of 
Electrical Engineers, the Illuminating 
Engineering Society, the Society for the 
Testing of Materials, the American Com- 
mittee of the International Electrotech- 
nical Commission and the International 
Committee on Electrical Units and Stand- 
ards. The bureau is represented on the 
council or committees of all of these bod- 
ies, and each year many subjects arise that 
come within the field of the bureau’s activ- 
ities, and in the handling of which its repre- 
sentatives can cooperate. Reference was 
made above to the new tables of resistance 
for annealed copper wire. Heretofore, the 
English, German and American tables have 
all been different, not only for resistivity, 
but also for temperature coefficient, and 
two different densities were in_ use. 
Through the efforts of two of the above- 
mentioned bodies and the Bureau of 
Standards acting together in the negotia- 
tions with foreign laboratories and scien- 
tifie societies, we are assured in the near 
future of international uniformity in all 
these quantities. Much has been accom- 
plished also in securing international uni- 
formity in electrical units, a common 
photometric unit in England, France and 
America, in comparing and standardizing 
measurements of electrical and magnetic 
quantities between national laboratories, 
ete. 
The preparation of standard specifica- 
tions for various kinds of materials is an 
important work, in which the bureau co- 
operates with the engineering societies and 
with the departments of the government. 
