Evening star. [volume] (Washington, D.C.) 1854-1972, 1904-06-18

Director New Bureau Of Standards.
They are placed in a whirling machine of
known speed and all whose mercury COL
umns do not return to the normal at that
speed are rejected, because too difficult for
the average human arm to handle One
common error in these devices Is a too
rapid dropping of the mercury after being
taken out of the patients mouth and be-
fore being read. These are called retreat
ers," and are denied certificates.
Standard thermometers are now being
supplied for the convenience of manufac-
turers. promoters, for measuring the
very high temperature of hot furnaces are
also being standardized. In the hardening
of steel the instruments are very valuable,
also in the burning of porcelains and china
ware. Much money will be saved to these
Industries by giving their promoters great
er accuracy. Armor plate, for example,
depends for its uniformity and hardness
upon the eXactness Of the promoters read
ing The bureau also tests thermometers
filled with alcohol, taluene, ether and PEN
tame, and which used for measuring
very low temperatures, down to 400 degrees
below o. F., which is colder than liquid air.
Special apparatus Is devised for these ex-
treme tests. The promoters are placed in
electric furnaces made of porcelain tubes
wound over with spirals of platinum foil,
which, when charged with a strong cur
rent, can maintain temperature as high as
5000 degrees F. in the tubes For the ex-
tremely cold tests the bureau is equipped
with a complete liquid air plant.
New Standard Candle Power.
In your house you perhaps have mean
descent electric lamps said to be sixteen
candle power. Hitherto there has been no
standard of candle power IN this country.
In one room of the institution 1 was
shown the nations first standard of illu-
mination. 1t is already testing electric
burners for both manufacturers and pur
cha sers. and yet only a few years ago our
navy had to send to Germany for this work.
An instrument throws simultaneously upon
two parts of a screen the light from both
the standard burner and that being tested.
The brighter lamp is moved away until the
two parts of the screen are equally illumf-
mated. and graduated scale, measuring the
distance from the screen, indicates the
candle power. The observers who make
these tests rely entirely upon their acute
ness of color perception. The screens vary
for different tests, some being of white
plaster of paris, others of white paper and
still others of ground glass.
Electric and Gas Meters.
The meters which measure the electric
supply of houses are also standardized here.
Through a standard instrument for meas
uring current the electricity Is first passed
and then fed to the meters being tested. At
the standard meter is stationed man with
telescope, who watches the minutest
keeps the current constant All sorts of
meters used in the electrical sciences and
industries are tested with as great and
oftener greater exactness.
Water meters come in for their share of
the testing. A large water tank rests upon
very delicate weighing scales Water run
ming through the meter under test falls into
the tank and its actual volume calcula ted
from its weight. is compared with the vol
ume indicated by the meter. Gas meters
are similarly verified. They fed in turn
by a miniature of our city gas tanks. An
amount of air. which serves for the test,
pa sses out of the tank, which measures it
precisely before 1t is regulated by the indi-
ator of the meter Pressure and tempera-
ture are taken into account ana the test is
very technical.
One of the most interesting instruments
in the bureau is dividing engine" re-
Gently imported from Geneva. 1t will grad
uate a measuring rule with microscopic
lines as near together as one-hve-thou-
sandlh of an inch. This will be used in the
manufacture of all sorts of precise scales
and for comparing those submitted to the
bureau The ruling is done by arm
bearing diamond point, and which moves
al right angles to the bar being ruled. The
latter is moved with precisely equal jerks
along a carriage driven by endless
screw.
The bureau standardizes and verifes the
most complicated optical and engineering
instruments. 1t tests the strengths of ma
tries. and even the heat value of fuels
In it will be conducted much original and
scientific research. 1t will save millions of
dollars year to the trade and Industries
and will give scientific work greater accu-
racy. Its tests will not be generally COM
pulsory, but it will be sought by sellers as
we'll as buyers.
JOHN ELFRETH WATKINS