The Washington herald. [volume] (Washington, D.C.) 1906-1939, 1921-10-29
FINDS LAWS OF HEAT LOSS
IN AIR-COOLED ENGINES.

The fins which are cast on the
cylinder OF an air-CoOled gas engine,
whether the latter be a motorcycle
engine. lawn mower engine, or ava
ton engine. are there for the pur-
pose Of increasing greatly the nat
ural surface over that which would
otherwise be exposed by the cylinder
to the air blast that cools the en-
CINE" d. r. Harper. 3rd, physicist OF
the Bureau Of Standards. told the
Philosophical Society at its meeting
at the Cosmos Club Saturday night in
telling OF work done at the bureau
jointly with W. B. Brown. obvious
ly, the effectiveness OF these fins
depend upon several factors. the
width. the thickness. the velocity o.
air blowing past them. etc. 1t is
very desirable TO obtain definite re-
lations between all these things and
the effectiveness OF the FIN.
Now, by making a half dozen
simplifying assumptions, there Is no
trouble in getting such a msthemat-
ical relation and fortunately, il is
not only very easy to derive but also
very easy TO use Thus, the design
ing engineer has at hand a Conven-
lent formula to aid his work, pro-
vided that il is not seriously in
error on account Of the fact that the
simplifying assumptions on which Il
is based are too divergent from the
conditions which nature gives US
in reality. That is where the msthe-
matics of this communication come
into play. II is a careful investiGa-
ton OF the differences between
some quite exact formulas which are
very complicated and the less exact
but simple formula, TO which refer
ence has just been made"
He showed that these differences
are rather small so that Tor much
/ preliminary computation OF FIN d.
mansions in air-cOOled cylinder de-
sign, the engineer can use the sim
| pie formula without making any
corrections TO IL. when he does
want somewhat greater exactness
he can still use the simple formula
as basis and apply 20 IL corrections
read directly from tables or charts
which DR.. Harper has made.
NEW CHEMICAL TEST
DETECTS WATERED MILK.
| A new test that will tell with
great accuracy the amount Of
water that has been added to milk
has been perfected and recon.
mended as a standard test for food
chemists OF health departments and
other agencies, Julius Horvet, Of
ST. Paul. MINI, announced at the
annual meeting OF the American
Association Of Official Agricultural
Chemists at the Washington Hotel
| By utilizing the fact tina the ad-
dillon OF water 10 milk raises its
| freezing point, the chemists will be
able to detect additions as low a.
3 per cent
Certain types OF milk NAV con.
tain as high as 20 per cent or even
more actual added water without
| yielding positive Indications Of
adulteration by means OF any here
tofore applied method OF eNamina-
don" Mr.. HOrvet said IN explaining
the new cryoscopie test.
During the past year. collabors-
tors in all parts OF the country
have been making tests on milk
from different breeds OF COWS 10
determine the utility OF the frcez-
ing point method. The thermom-
oters used have to be extremely
accurate as 10 per cent water an
the milk changes the freezing pOin'
only fifteen-hundredths OF a de-
gree. The thermometers are stand
ardized by determining their reading
when placed in freezing distilled
water or solutions OF very pure
sugar.
| The town OF Butte. Mont, Is a
vast mining camp, combined with a
modern city. The Butte district
has produced more than 100000
900 worth Of metals; copper head
ing the list. This is the most pro
ductive metal-bearing area Of It's
size in the world.
4 In a study Of the smoke nuisance
at Salt Lake City an aeroplsne was
used to collect samples Of air Al
different levels
Gas that is practically incombus,
tible Is yielded by some Of the
wells drilled for nstVral gas IN
u Oklahoma.