Evening star. [volume] (Washington, D.C.) 1854-1972, 1891-08-21
SCIENCE AND ENGINEERING.
The Important Subject Of Goversment Tim
Der Treated I'm Several PapesA

SCIENCE AND ENGINEERING.
The Important subjees Of Gever.mcnt Tim
Der Treated I'm Several PapeEA
The section of mechanical science and en-
cheering met for the first time for the eonsid-
GRAFTON Of papers today, II having held no scs-
sion yesterday. Economy Produced by the
Use Of Water Injected as a Fine Spray Into Air
COMPRESSOR and Mote on the Efficiency Of
the Screw Propeller" were presented by James
e. Denton.
Professor Todd presented q paper on Tx
pcrimental Results Obtained With a New Form
Of Direct Action Propeller" and then the i'm
portant subject Of government timber tests was
taken up. Prof. B. 4. Fernow OF this city intro
duced the subject
He said there had been inaugurated in the
forestry division OF the Depar tmens of Agricul-
nations Of American tinbers. tho ultimate OBJ
leet of which is tho solution Of q biological
problem, namely, to establish the relation of
technical and physical qualities to each other
and to conditions Ut growth. In the pursuit of
TINS investigation, naturally, many questions OF
immediate practical va!ue in the ase OF wood
for engineering purposes will be solved.
Inc novelty IN this enterprise lies mainly In
It's coMprehenslveness and scope. A very large
number OF tests alone on material Of known
origin and condition and an y h.ustive examina-
ton Of the same will permit generalization and
the recognition Of laws OF interreiation.
The work requires the organization of four
distinct depaI Iments. FIRST the selec ton Of
teal material from rs many essentially different
climatic and soil conditions rs the species may
occupy, five fully matured and two young trees
being carefully rejected each site and cut
up for test material; secondly, the examination
OF the structure and physical condition OF the
test material requiring the minutess detail;
thirdly, the usual toa;ing with special care and,
lastly, the compilation and comparative discus
SION OF tic results of the tests in connection
with tho phyaical examination and the known
conditions OF growth
Besides more reliable data than hitherto nt-
talnabie OF the qualities of our principal tim
bers thore Ii to be gained from This irvestiga
SION knowledge OF conditions under which
desirable qualities can be produced by the
forest grower.
TESTS OF STRENGTH OF AMERICAN WOODS.
1.-The United States Tests of Strength of
American Wooda,. Made ut tho Washington
University Testing Laboratory, St Louis" was
the title Of Prof. J. i. Johnson's paper. He is
director Of the testing laboratory, and told
how the full-slyed logs received in 81. Louis
from tho collector OF the forestry division of
the United States Agricultural Department are
steneiled OF to sizes OF four inches by
four inches and upward. duly marked by
dies AID sawed. Inc test sticks are stacked
under shelter ut the university laboratory tc
await the tests. While still green one-half of
each stick is tested and the other half is nrti-
hcially dried in a cold-draft dry kiln specially
prepared for this purpose. From each log Is
cut one or more large sticks, up to eight
inches by sixteen inches in cross section.
These are tested only in crossbreaking
ON a machine operated by hydraulic power and
capable OF putting on and accurately weighing
load OF lOO, 600 pounds on beam of any
length up to twenty-four feet. The small
sticks. four inches by four inches in section
and sixty inches long, are tested first in cross-
breaking, then the specific gravity and the
percentage Of moisture determined. after which
the uninjured ends are sawed off and tested
III tension, compression and shearing along
the grain, and for compression across the grain.
From the strain diagram of the cross breaking
test the strength per square inch, the modulus
OF elasticity and the total cross-breaking resii-
ence In inch-pounds per cubic inch are OBJ
tanned. In the shsaring test two slotted holes
at right angles to each other are pulled out ON
each specimen. The tension tests are made on
similar sized sticks, some sixteen inches long,
which have been reduced at the center
to thickness of thrce-eiShths OF an inch
by cutting away the sides on circular curves.
The stick is then gripped the same az iron
specimens. Advantage has been taken Of all of
Prof. Bauschingers methods and results on
testing timber in planning and carrying out
these tests, but our appliances are all different
from his Every pertinent fact is made mat
ter of final record. The work will probably
progress at the rate Of about ! 900 tests OF all
kinds per month.
A preliminary study has boon made of the
variation of the strength of southern pine over
the cross section of the log or tree. the results
Of which are submitted. Also Prof. Bauschin-
gers mean curves, showing the relation of
crushing strength, cross breaking strength and
OF specific gravity to percentages Of moisture.
OTHER PAPERS READ.
Other papers read before the engineering
section were: On ''The Crushing Of Short Prisms
Of Homogeneous Material" by Charles L. Bou-
ton; on "A Method of Holding Samples of Wood
and Brick for Determination OF Tensile
Strength" by Prof. Denton, and on Expansion
of Steam CalOrimsters." by Prof. Thomas Gray;
Maximum Error Due to Nsglecting the Radia-
ton Correction Of o Barrus Calorimeter," by
d. T. Jacobus.
Prof. Gray also read a paper on "Tests of
Electric hallway Plants" describing the apa-
ratus and methods used in electric railway
tests In Terre Haute Ind He save details to
the total horse power used. the power lost,
variations and power required per car.
Prof. VIM. Kent Of New York presented a
paper on the Opportunity for the Chemical
Research at the Worlds Fair" He said that
tests made at the centennial had proved of great
service to the engineering profession in estab-
fishing the limits Of efficiency to be expected
in steam boilers Large expOstious afforded
unusual opportunities for mechanical tests be-
cause these. the best examples Of various
varieties OF appliances, were grouped
| together, making comparisons easy and ac-
| curate, the tests all being made under
practically uniform conditions. Prof.
Kent said he had brought 10 the attention
Of the worlds fair people the advisability of
| making tests Of fuels. furnaces. engines pumps,
DC, and hoped his suggestion would be adopted.
| He advocated the appointment OF a committee
to look after the matter.
Prof ID. $. Jacobus also read a paper show
ing the inferiOrity of carbolic acid as the
working fluid of refrigerating machines, the
ammonia process being much superior.
THE NOMINATING COMMITTEE.