U.S. DEPARTMENT OF AGRICULTURE.

FORESTRY DIVISION.

Bulletin No. (i.

TIMBEE THYSICS

PiVRT I.

PRELIMINARY REPORT. "" ,

1. NEED OF THE INVESTIGATION.

2. SCOPE AND HISTORICAL DEVELOPMENT OF THE SCIENCE OF

"TIMBER PHYSICS."

3. ORGANIZATION AND METHODS OF THE TIMBER EXAMINATIONS

IN THE DIVISION OF FORESTRY.

C<)MPILKI> l!V

B. E. FERNOAY,

CHIEF OF FORESTRY DIVISION.

PUBLISHED BY AUTHORITY oF llli: SECRETARY OK AGRICULTURE.

WASHINGTON:

GOVERNMENT PRINTING OFFICE,
1892,

CONTENTS,

Page.

Need of thk ixvesticatk >x 1

Prevailing ij^iiorniirc oftho siil).jeit 1

Conseiiucnt waste of valiiiiblti iiiati'i'ial 1; -'

PreHeut ciigiiieering tables nuieliable, based on European woods and on few and small test pieces 2, 3

Eelatiou of the iiivestigatio)i to forestry ^

Comprehensiveness of proposed investigation - 3

Letters from engineers, scientific societies, and others, expressing interest in the investigations and urging

their eontinnanee 4-16

Scope and historicai. development of the science of " Timber Physics " 17-28

American work in timber physics ^ 26-28

OlUJANIZATION AND METHODS OF THE TIMUEK EXAMINATIONS IN DIVISION OF FORESTRY 29-57

Work at the test laboratory 31

Examination into tlie jihysieal properties of test material 42

Instructions for the collection of test pieces ior timber investigation 51

Records :

Forms for collectors 5*4

Sample records of lests 55, 56

Records of physical examinations 57

CukSSLFIED INDEX '

ILLUSTRATIONS AND PLATES.

Figures 1-4. Method of sawing test sticks 31

5. Standardizing tests with calibrating springs 33

-. Curve of cross-bending test 36

6. Relation between cross-breaking strength and modulus of elasticity 39

7. Relation Ijetweon compressive strength and specific gravity 39

S. Variation of compressive strength and sjiecitic gravity for varying percentage of moisture 41

9. Relation between cross-breaking strength and percentage of moisture 41

10. Apparatus for determining specific gravity 44

— . Method of splitting disks for physical examinations 53

— . Curves of cross-breaking tests 55, 56

11. Diagram representing results of physical examinations 57

Plate 1. Floor plan of test laboratory at St. Louis.

II. Plan of large beam-testing machine.

III. Plan of small beam-testing machine.

IV. Plan of universal (Richie " Harvard") testing machine.
V. Illustration of tension and shearing tests.

VI. Plan of column-testing machine.

II

LETTER OF TRANSMITFAL.

U. S, Department op AraiicuLTURE,

Division op Forestry,

Wasliiiifjtov, ]>. ('.., Fcbruaitf I, 18<J2.

Sir : I biive the honor herewith to submit for publication the first of a series of bulletins which

are to record the results of an extensive investigation into the nature of our important woods,

especially their mechanical and technical properties, and the dependence of these upon structure

and physical condition and upon the conditions under which the wood was grown.

The present bulletin is entirely preliminary in its nature. Its object is to serve as a basis for

tlie work whicli is to follow and is partly begun. It discusses the need, object, and scope of the

investigation, gives references to the work which has preceded the present investigations, and

explains the methods pursued in these latter, including the forms of record and illustrations of the

machinery in use.

Eespectfully,

B. E. Fernow,

Chief of Forestry Division.

Hon. J. M. EusK,

Secretary.

m

TIMBER PHYSICS.

NEED OF THE INVESTIGATION.

INTRODUCTORY.

Scientific research is satisfied with its results without any reference to their practical applica-
tion. Increase of knowledge is its selfsufQcient aim. Whether this may in the end bruig us an
increase of power to control nature's forces or to utilize them to better advantage is not the concern
of science, and yet all increase of this power has come directly or indirectly from such scientific
research. Ackuowledguient of ignorance, then, from a scientific point of view, is suificieiit to
establish the need of an investigation. From a practical and economic point of view, however, it
would still remain necessary to point out whether and why the need is a pressing one and what
direct benefits uiay be expected from such an iuvestigation.

It will be admitted by all who have to handle wood in building, engineering, and manufacturing,
that our knowledge regarding the i^roperties of our various timbers is jiot very satisfactory, and
that while attempts more or less systematic have been made to determine these properties, and
knowledge gained from experience exists among those wlio have handled certain classes of woods
for certain purposes, there does not exist much reliable pul)lished information for general use.

It is also a well-known fact that from this ignorance of the value of our varied timber wealth,
and its special adaptation to particular uses, large quantities of valuable material have been wasted.
Everybody is famihar with the waste of our fine black walnut timber for fence rails, posts, and
fiLrewood. Until twelve or fifteen years ago many million feet of hemlock were left to rot in the
woods, after the bark had been taken for tanning purposes, or this timber was not cut at all
because its value for building purposes was not understood or was underrated.

In Alabama, along the Louisville and Nashville Eailroad, a few years ago a large amount of
chestnut oak was felled for the tan bark alone, the wood of the trees being allowed to rot, because
railroad people did not know its value for railroad ties. The Division of Forestry, by a little
circular, called their attention to the superiority of this timber for tie purposes, and now the wood
is utilized, and thus for this region alone a saving of from $40,000 to $50,000 annually was eU'ected,
or more than three to four times as much as the annual ai)propriations for the Division of Forestry.

Even now many thousand cords of this valuable wood are lost there and in other regions when
the bark is taken for tanning purposes, while the wood itself, which contains as much and more
tannic acid per cord than the bark, is left unused, because it can not be profitably transported in
its original form. Presently a new wealth will be developed for the tanners, where it was not
looked for.

Our railroad system requires annually 80,000,000 ties, costing the railroad companies about
$.30,000,000. Their life in the average may be computed at six and one-half years. There are
means of doubling their life easily by using only the more durabhi kinds, ])aying proper attention
to the handling of the ties and by impregnation with fungus-resisting materials or by other proc-
esses. Such increase of durability may bo obtained by an expenditure of, say, $20,000,000, by
which an annual saving of more than $."),000,000 would be effected, or 2.5 per cent on the additional
outlay. These figures are extremely conservative and the advantage might readily be dcmbled.
We could multiply such examples of wasteful practice in every direction, arising at least in part
from lack of knowledge.

17244— No. 6 1 1

rt would be impossible to estimate the direct and indirect losses \Yhich the country suffers from
our ignorance as to the true values and strength of our building timbers. Such losses occur by
using kinds unsuited for given purposes, or by emi)loying either more or else less timber than
necessary. Engineers and architects are fully aware of this defi(;iency in our knowledge, which
approaches "a state of ignorance" remarkable to contemplate when it is considered that timber
has always been a foremost building material.

To make good this assertion a resumd of some hundred letters received by the Department from
leading engineers, scientific societies, and others is appended to this report, which, while strongly
i;ivorin<^ the thorough investigation of our timbers, are of interest also as showing the multiplicity
of directions in which the work would be of benetit.

Not only are our engineers' tables, giving values of strength, uncertain, uureliable for practical
use, i)ascd n\mu European timbers, etc., but probably not one in a hundred engineers or architects,
who specifies timber for work, is capable of determining whether a given stick of timber is or is not
capable of doing the duty it is designed to do. Even if he recognizes the species of timber, which
he rarely can do with accuiracy, he would fail to recognize any relation between the appearance or
structure of the material and its expected or desired quality. And if he be better informed than
the majority it will be only through dearly-bought experience. Empiricism in this branch of
engineering still reigns supreme.

It is only six years ago that Prof. Lanza showed that tests made on small specimens, and on
which our tables for engineers' use are based, may give results more than twice as high as those
made on full-sized sticks; and although a factor of safety of 4 may have been applied in the speci-
fication, when it is found that material may have actually a strength .50 per cent less than that
<>iven in the tables, we may often strain our material, without knowing it, to its full capacity and
feel safe in so doing.

The following statement, which occurs in one of the letters referred to, may serve as an illus-
tration. Mr. D. H. Burnham, engineer of construction for the World's Columbian Exposition,
writes :

When I was apijointed ougiucer of coustniction, Woilil's Columbian Exposition, August 1, I found it necessary to
make changes in most of the biiililings because I (lid not dare to use as high u-iit stress in timber as was used by my
predecessor, aUliougli he claimed to be perfectly safe in his strains, and brought forward authorities— Trautwine and
others — to ]ir<)ve his statements.

Inquiries from woodworkers in all branches show that the same lack of reliable knowledge exists
with regard to the adaptation of woods to technical purposes. Especially are the ideas as to the
relation of properties to structure, physical condition, h)cality of growth, etc., entii-ely at variance
and lacking a sound basis derived from accurate observation and research. It would then appear
that from a practical point of view the need for an investigation exists, the more so since our forest
resources begin more decidedly to show the signs of lavish wastefulness, and proper economy
would dictate a more careful employment of our wood materials.

Lastly, since we are beginning to plant forests and since forestry does not concern itself with
the production of wood simply, but is to produce wood of given quality, we need this knowledge
in order to proceed intelligently in the selection of plant material with reference to local ily and
in order to be able to control in a measure the quahty of the product.

It is of interest to inquire why our ignorance exists and has prevailed so long, and to lind out
what is necessary in order to remove it.

There is one important factor of difference between other materials of construction and timber.
It is the factor of life. Life means variety, change, variability. Each individual differs from every
other in its development, and each part of the individual differs from its other parts in structure,
and hence in qualities. Each living tree of the same species, therefore, converted into building
material offers a different problem as to its properties, especially its strength, and each stick taken
from a ditlerent part of the tree shows different quality.

This endless variability it is that has kept us in ignorance as to the capabilities of oiu- timbers.
While, by experience, we have learned that these differences exist, and even learned to find some
relations between physical appearances, anatomical structure, and mechanical properties, the enor-
mity of the enterprise has battled investigators ami deterred them from carrying on, in a systematic

3

and comprelieiisivo, manner, such tests and examinations as wonld Inrnisli its not only witli relia1>1(>
data as to the range of capacity of our timbers, but also as to tlio exact relation of their pro|ierties
to their structure and physical condition.

In order to establish fully for any one species the possibilities of its adaption to our use, it is
necessary to test a very large number of specimens. lu order to formulate laws of relation between
physical condition, anatomical structure, and mechanical properties, each test specimen must be
earefully examined. In order to establish laws of relation betweeu the i)liysical and mechanical
ipialities and the conditions under whicli the spe<'imfn has grown, it is necessary to perform the
testing and the examination on a large number of specimens of known origin.

Almost all the investigations made in this line are deticient in one or more or all ot these points.
Xot only have there been few tests made on a sutlicient quantity of material to allow generaliza-
tion, but rarely Lave there been suHicient data furnished regarding the nature and origin of the
test specimens to enable us to form a judgmeut.

Whatever laws of interrelation betweeu physical structure and mechanical properties have
been established or indicated, we owe almost entirely to European investigators on European tim-
bers. Our engineers' tables are mainly made up from European sources, and while tlie extensive
tables of the Tenth Census, prepared by Prof. C. E. Sharpies, give us an indiciation as to the rela-
tive values our of many species, they can hardly claim to I'urnish data for iiractical application; in
fact the author himself distinctly disclaims this. Anyhow, no attempt lias been made to find out
the causes of variation in properties or even to give data from which argument might proceed or
a relation between properties and structure might be inferred.

It is to supply this absolute gaji in our knowledge — which causes tliousands and millions of
dollars of waste auuually — that the Forestry Division has entered upon a comprehensive and
systematic investigation which has become known under the name of "the Government timber

tests."

This investigation, the most comi)rehensive of the kind ever undertaken anywhere, in this
country or in Europe, differs from all former attempts in similar direction in this, that it starts
out Avith the fullest recognition of three fiicts:

(1) That in order to establish reliable data as to mechanical properties of our timbers, it is
necessary to make a very large number of tests, by which the range as well as average capabili-
ties of the species is determined.

(2) That in order to enable us to make the most eHicient practical application of the data thus
obtained it is necessary to know the physical and structural conditions of the test material and
bring these into relation with the best results.

(3) That in order further to deduce laws of relation between mechanical properties and the
physical and structural conditions, as well as the conditions under which the material was pro-
duced, it is necessary to work on material the history of which is thoroughly known.

Brieily, then, to solve the problems before us, it is necessary to make our tests on a large num-
ber of specimens of known origin and kiu)wn physical condition. Whih^ the tests in themselves
appeal at once and lirst to the engineer, inasmuch as, by their great number, they will furnish more
reliable data regarding the capabilities of the various timbers, the chief value and most important
feature of the work lie in the attempt to relate the mechanical properties to the structure of the
material and to the conditions under which it was produced.

We are not only concerned to know that a stick of this si)(!cies of tree will bear a given load,
but we want to be able to tell why this stick of the species will bear so much and why the other
stick of the same species will bear only half as much; why the timb.n- grown in this locality ia
found generally superior to that of the same species grown in another locality, etc.

When we have established such knowledge, then it will be possible for an engineer not only
to specify his timbers intelligently, but also to ins])ect them and to know whether or not they come
up to his spcciticatious. To be sure, we are not now quite without some knowledge regarding
these matters, although few users of wood seem aware of it. But not only is this knowledge
scanty, it is not quite certain or capable of general application, and the results and deductions
of one investigator may often be louiul contradicted by another or by the same authority after

further iuvcstigation. We know that there are differences in quality, at least for some timbers, in
sticks from diiiereut parts of the tree: not only the heartwood differs from the sapwood, but also
tbebuttlogfrom thetop log. .,.• ^- • e

While some experiments would lead us to believe that specific weight is a fair expression of
the strength of timber of the same species, yet it would be hazavdoas to rely upon this factor
without regard to other physical conditions and structural features of the timber.

Such "rino-.porous" woods as the oaks and ash show the greatest strength and elasticity when
their annual rings are wide, while the slow-gro%vii mountain oak seems to excel in stiffness. From
conifers, on the other hand, according to Hartig, the slow-grown timbers seem to exhibit superior
quality hence those fi-om rich soils are not desirable. This again has appeared doubtful, or at
least true only within unknown limits, from Bauschiuger's experiments, who showed that tensile
strength in pines was independent of the total width of the annual ring, but dependent on the ratio
between the spring wood and summer wood.

That wet soil produces brittle, dry or fresh soil tough timber, is believed but needs proof. Con-
trary to general opinion, the time of felling seems to be without influence on the strength of pines.
The degree of seasoning, on the other hand, seems to increase the strength, although it would
still have to be found out whether the manner and rapidity of seasoning may not change this
result. Toughness or capacity for bending without rupture, on the contrary, is claimed to be
inversely proportionate to seasoning.

Carriage-makers claimed " that the white oak when grown in the South loses its peculiar tough-
ness by which it excels in the North." We have shown by actual tests that this is not the case,
and claim the exact opposite from physiological reasons.

ABSTRACTS OF LETTERS.

The following abstracts of letters from engineers, scientific societies, and others, regarding
the timber studies and tests instituted in the Division of Forestry, received by the Department of
Agriculture, are given in this connection as showing the interest manifested in the subject under
consideration. The high professional standing of the writers, together with their strong expres-
sions regarding the importance and value of the investigation and the diversity of interests
involved in this work, form the best argument that could be given for the need of the investigation.
For ease in following the arguments adduced, the letters have been grouped under general head-
ings in italics expressive of the main ideas therein contained.

(IJ The information now available regarding the value, properties, and adaptations of our tini-
hers is scanty in amount and unreliable in character.

O. Chanute, consulting engineer, president Am. Soc. C. E., Chicago, 111.:

As a civil engineer of some forty years of practice I have become aware how little is really known concerning the
conditions under which the best results can be secured from commercially useful timbers, and I am glad that your
Department has begun its investigations with the southern pines and o.ak8, which must hereafter largely be drawn
upon to supply the place of similar woods now being exhausted in the North. The value of such investigations
depends so largely upon the competency of the men who are intrusted with them that it was undoubtedly wise for
Congress to start with a small appropriation, so that something might be known of the probable results before
expending any considerable sums. From my personal knowledge, however, of the thoroughness of Mr. B. E. Feruo w,
and Prof. J. B. Johnson, of St. Louis, I am convinced they will accomplish valuable results, and I hope you wiU
recommend sufficient appropriation by Congress to enable us to know within a year what practical results are to
be expected from the investigation. I, for one, shall be very glad to place at the disposal of your Department,
without charge, any information which I have thus far gathered, and I think that the experience gained by those
who have handled certain classes of woods, for certain purposes, will be also fieely at youi disposal.

M. H. Rogers, chief engineer, Denver and Eio Grande Eailway Company, Denver, Colo.

When the fact is considered that the information published on this subject at present, even in our most advanced
works ou engineering, is very meager and unsatisfactory, more especially since such tests as have been made are
with reference to the superior specimens of the different species of woods and that a great many of our native timbers
are omitted altogether, but little further argiunent is needed to show the advisaliility of such investigations by
the Department. Since the work will be conducted by experts under the directiou of the Government, the results
will bo most satisfactory and becouio an invaluable standard for engineers and others in the construction of all
works wherein wood forms an important part.

J. D. Hawks, chief engineer, Michigan Central Eailroad Company, Detroit, Mich. :

I have been engaged for twenty years on various railroads in the United States and Canada, and during that
time have found a great lack of reliable iulormation about timber. Questions are continually arising as to the
lastiniT qualities and the strength of dift'erent timbers. I know from the numerous inquiries from railroad ollicera
that others are bothered by this lack of precise information. • • » It is a very expensive matter for us to bo com-
pelled to learn the facts as to strength and lasting qualities of all these timbers by experience. If the Government
would undertake these tests for the people it would be a very great assistance, not only to the railroads, but to other
users of timber, as well as those who have timber to sell.

L. L. Randolph, engineer of tests, Baltimore and Ohio Railroad Company, Baltimore, Md. :

The information which exists upon this subject is extremely meager, being made up from the incomplete work
of a number of different investigators, who have been hampered by lack of means from going into the subject as
deeply as they wished and the importance of the subject demamds. We are using in many cases more timber than
should be used, on account of a lack of knowledge of its strength and other properties, and in some cases are ruuning
risks which should not be taken, relying on incomplete investigations. The investigations made by the Board
appointed to test iron and steel have been so very valuable to the engineers of the country that it has sho\Tn all the
very great necessity for similar work on timber.

H. S. Jacoby, professor of graphics and bridge engineering, Cornell University, Ithaca, N. Y. :

I was interested quite recently in a brief description, in one of the engineering papers, of the series of tests
which your Department has inaugurated relative to the strength of American timbers. In my class work in struc-
tural detaUs 1 am constantly reminded of the very meager knowledge concerning the strength of even a few species
of woods that is now available in the designing of wooden structures. Such investigations made with special care,
ou an extensive plan, are essential to economy in design.

J. C. Bland, Am. Soc. C. E., consulting engineer, Colorado Springs, Colo. :

I beg to s.ay that the value to the engineering public, the railways, and the public at large will in my judgment
be incalculable. Your intention to extend the tests to full-sized pieces as used in bridge construction is partic-
ularly admirable, such results being meager at present, as indeed are even reliable tests on small-sized speci-
men pieces ; also your purpose of determining the influence of continued services on pieces of bridge constructi(m of
known length of service, will, when carried out, put us in possession of highly valuable data now confined to the
very few who have had opportunity to make such observations. It is not hard to see how this point affects the
safety of the traveling public. In this part of the country we are compelled to use Oregon Fir for our best
wooden bridges and trestles, the native pine being deiicient in transverse strength, as well as short-lived, and cou-
cernin" neither timber do we know much in a scientific way. Oak as a rule behaves badly in this climate; hence
your purpose to determine "how far do climatic and soil conditions influence quality" is auother point from which
I expect valuable information. I can not state forcibly enough the very great value which I think such work as
you intend undertaking will have.

James Dunn, chief engineer, Atchison, Topeka and Santa F6 Railroad Company, Topeka, Kans. :
The knowledge of the physical properties of American timber is very limited, particularly as refers to timber of the
same variety growing in different localities and under different conditions, and the result of the tests wiU be of very
great value to engineers, architects, and builders.

F. C. Osborn, chief engineer. King Iron Bridge and Manufacturing Company, Cleveland, Ohio :
I wish to urge upon you the importance of this investigation both in regard to consumers of timber and to engi-
neering profession as well. * " * The data that are at present at hand in regardtostreugth of American timbers
in various positions, are very meager, and the large amount of timber used in connection with structures of impor-
tance makes it very desirable that some satisfactory results should be arrived at in regard to the strength of the same.

F. W. Skinner, Am. Soc. C. E., New York City:
There is a great scarcity of such data available for engineers, and as a bridge engineer I heartily appreciate its
value and hope that it will be fuUy supported.

ThePhcenix Bridge Company, engineers andbuilders of bridges, viaducts, etc., Phcenixville, Pa.:

We hope that these investigations may be continued until we have complete data in regard to the timbers used in
construction. At present this information is very meager and the investigation \iudortaken by the Departnuuit of
Agriculture will be watched with great interest. In the line of bridge construction the information secured by tLcso
tests will be particularly valuable.

^2) Tlie results of European tests, which form the prtnoipal basis of our engineers' tables, are
inapplicable to timber grown here.

G. Linden thai, chief engineei', North River Bridge Company, New York City:
There has not been so far an elaborate and continuous investigation of American timbers such as is now pursued
by the Forestry Division, and the meageruess of data relating to the subject has been repeatedly the cause of great
vexation and enibarrassmenttoengineers. » • » The absence of authentic and reliable knowledge of the physicaJ
properties of American timbers has been the cause of great losses, by reason of incorrect application and design,
mistaken judgmentin the preservationof such timbers, and of theirstrengthanddurability. • • • The informa-
tion engineers possess from similar tests in Europe naturally can not be applied to the timbers growu in this country,
and we ought not to be behind in this respect the information of the "Old Country."

Thomas Bglestou, professor of metallurgy. School of Mines, Columbia College, New York:

As a member of the committees of all the engineering societies of the United States, and at one time chairman
of the committees of the American societies of mining, civil, and mechanical engineers in charge of this subject, I
ur"cd at great length the consideration of this subject by a commission to be appointed by the United States
Government. It is one of the most important subjects connected with engineering, and I congratulate you on
having undertaken a wovlc whose results must be of such very great importance to the engineering profession in
all p.arts of the world. I am also glad to see by the circular that you intend to do some work on the botanical side
of the suliject. During the time tliat I was worlving witli the United States test commission, the extraordinary fact
was lirought out tliat at tliat time all tlie formuhe used in engineering for testing the strength of woods were
based on the tests of a snia,)] column of Dantzic Oak of a variety whicli does not grow iu tlie United States, and
that tliese tests were altogether valueless. By stating the botanical name of the wood and the conditions under
which it grew, these tests will become permanently valuable in the profession.

Thomas M. Cleeman, past president Engineers Club, Philadelphia, Pa. :

When the Engli.sh formula of Mr. Ilodgkinson, their gre.atcst authority, was shown by Mr. Smith's exper-
iments on large pillars to give results double what should be given, as stated in Trantwine's Pocket Book,
engineers felt a longing for full, .accurate and modern experiments, on large sizes, that they might not be in any
doubt as regards the strength of their work. The only method that will secure the information required is for the
Government to seek it in the manner jiroposed. It is just such work that will keej) it more in touch with the mass
of the people.

G. Bonscaren, consulting engineer, Cincinnati, Ohio:
As one especially interested iu the results of these investigations, I may be pardoned for expressing my apprecia-
tion of the same and the anxiety which I feel to .see them carried out to the end and without any curtailment of the
programme, which is admirably conceived. Timber is used as structural material iu the United States to a much
larger extent than in any other country, but American engineers and architects are still dependent in a large
degree for a knowledge of its strength on experiments made by European investigators. These experiments do not
generally agree, for the reason that they were made on timbers growing under different conditions of climate and
soil, often cut from trees of diflerent varieties and age, and treated in a different manner by the several experimenters.
This simple statement of facts should suffice to show the great and urgent need of the work inaugurated by you,
the results of which shall form a true scientific basis for a most important branch of the engineering art.

(3) Experiments made on small and selected specimens give unreliable data for use in the case of
large timbers.

William H. Burr, vice-president Company of Constructing Engineers, New York:
It is true that a considerable number of examinations and tests have heretofore been made under the auspices of
the Government, but almost or quite entirely on small and specially prepared specimens, quite different in character
from the pieces of the s.ame material used in engiueering practice and in the entire field of structural operations.
There are at pre.sent few results of investigations made under conditions which fit them to serve practical pur-
poses. • » « Permit me to say, therefore, that I trust you will encourage, in every legitimate and proper manner,
this physical and mechiinical investigation of the different varieties of American timber; and I can confidently assure
you that the engineering and building portioE. of the public will be served in a most efficient and valuable m.auner
thereby.

John C. Trautwine, jr., C. E., Philadelphia, Pa. :
I beg to express my appreciation of the value of such experiments, and especially the importance of having them
conducted on the most liberal scale. It is especially desirable that the tests should be made upon full-sized pieces, so
as to approximate as nearly .is possible to the conditions of actual service. Anything short of this would keep these
experiments down to the level of testa made in the past and rob them of their crowning advant.ago.

Louis DfcCoppet Berg, architect, Trinity biiildiii^, >rc\v York:

I beg to Bay that I deem these tests of the utmost imiiortniicc to iirchiteets and engineers. You will remembir
that up to within a few years ago we were using constants for the strength of timber, which were proven by Prof.
Lanza's limited tests on full-sizod timbers to be utterly beyond the strength of the beams. Tlicso eonstauts were
derived from tests on small specimens, niade by Hatfield and others, and, if it had not been for tlie large factor of
safety used, many accidents would liave hajipenod. A series of tests such as yoii propose will give us an intimate
knowledges of the action of our Auiprican timbers in large sizes when under strain, and will not only enable us to cal-
culate more accurately and safely the strength of our buildings, but will prove a great economy to all builders in
allowing us to use smaller factors of safety, which can safely be done where the actual strength and behavior of the
timber are accurately known.

Kudolph Hering, M. Am. Soc. C. E., M. Inst. C. E., M. Can. Soc. C. E., New York City:

We need much more information regarding the qualities of timber for constructive purposes, and private enter-
pvise can not give us results as extensive or impartial as can be obtained through the aid of the fiovernment. It
is true that we possess a great deal of information on the subject already, and for the most common cases in prac-
tice we are tolerably satisfied with the existing information as to tensile, compressive, and transverse strength of
test pieces of the common timbers of our country. But we are lacking reliable iufVuiuation regarding such rpiali-
ties in large beams as actually used in structures. We are not always safe in applying the results of small test pieces
to largo beams. We have likewise very imperfect knowledge concerning the durability of all the varieties of Amer-
ican timbers with reference to the conditions of growth, climate, moisture and temperature. I should consider that
in this direction particularly the benefits arising to the country from increased knowledge on the subject would be
very large.

E. L. CortheU, C. E., Chicago, 111., and Broadway, New York:

In my profession as a civil engineer I have, with others of my profession, filt the necessity of much more
extensive and thorough tests of timber than have ever yet been made, at least in our country. The rules that h.ave
been given us in the books for the use of timber have been found to he, in many cases, unreliable, for the reason
mainly that the experiments and tests have been made on small specimens instead of full-sized sticks. I have
recently had my attention called to this while making an examination of the Massachusetts Institute of Technology,
where tests are now being made on full sizes of timber with results v.arying in almost every instance from
accepted formulie. I therefore desire to express my interest in the work which you have undertaken, which, as I
understand it, is an elaborate investigation of the physical properties of our timbers. This investigation, as I
understand it, relates to the conditions of gTowth as well as to the uses of the timber. This is a work in which
the entire country must necess.arily be interested, for the works which we, as engineers, are building for commerce
are for the use of the public, and it is of the greatest importance that, when we use timber in bridges, buildings,
and other works, we use it properly and within safe limits of strain. Our General Government should not hesi-
tate a moment in giving your Department all the funds it requires to make and to continue to make the most thorough
investigations and tests of American timbers.

R. D. McCreary, engineer, "Western New York and Penn. Railroad Company, Buffalo. N. Y. :
The data until recently relied upon by engineers in proportioning wooden structures were based in the main
upon comparatively crude experiments with small and imperfect specimens of the various kinds of timber, and
not upon the sizes nor the varying conditions of timber used in practice, and resulted in largo factors of safety
to cover known and unknown defects in the material used. A larger knowledge of the value of timber under the
practical conditions of construction is much needed, and in my judgment your investigations and tests should be
continued until this end is fully attained.

John R. Freeman, engineer department of inspections, adjustments, and surveys, Boston, Mass. :
For many years engineers have been using data derived wholly from extremely small specimens of selected
woods, and the few tests which have already been made on large-sized sticks would indicate that the large sizes of
timber, such as are commonly used in engineering structures of importance, will withstand scarcely half so great a
breaking strain as our old data would indicate. I most earnestly hope that at the coming session of Congress such
more liberal appropriations will bo earnestly sought as will enable the work to he pushed vigorously forward.

Henry B. Seaman, C. B., 10 "West Twenty-iunth street. New York City:

Constructors are in the greatest need of a series of tests of this kind, and the results will be invaluable to .all
who have occasion to u.se wooden structures, and to trust property or life to their safety. The engineering profession
has for years used data obtained from small specimen tests, trusting to a judicious factor of safety to cover the
deficiencies of experiment. More recent tests on large specimens, however, indicate that our former results were of
little value, and in many cases have led to the use of timber strained dangerously near the breaking limit. That
we m.ay at last obtain definite and authoritative knowledge upon this subject is a source of congratulation, and
the progress of the experiments will be watched with the greatest interest.

J. B. Davis, assistant professor, civil engineering. University of Michigan, Ann Arbor, Mich.:
I hope now to see results from tests of commercial shapes and sizes, bought iu the open market, substituted in

onr text-books and works of reference for those derived from plaything sticks (splinters really) chosen from the

choicest spot in the best piece to be found.

8

(4) A better Tcnowledge of the physical properties of woods will result in greater economy in the
use of material, and less forest waste.

G. H. Thomson, engineer of bridges, New York Central Railroad, Am. See. C. E., M. I. C. E. :

The value of timber, viewed commercially alone, possibly may be well known, but the structural properties,
durability, and suitability for the various purposes, etc., are not fully ascertained, so that consumers of large quan-
tities of timber can not always construct timber work with ultimate economy, not knowing all the premises which
should govern a conclusion involving large expenditures in timber. A better knowledge of the physical properties of
woods would result In greater economy and lesu forest waste, a desideratum worthy of national consideration.
E. D. Meier, C. E., and president of Heine Safety Boiler Company, St. Louis, Mo.:
Having frequently been at a loss to determine just what strains timbers of various kinds may be safely called
upon to bear, and having in ftict been several times obliged to make hasty and crude tests of my own, I take the
liberty to write you in hopes that you may find means to continue the very thorough tests you have begun. There
are few thinn-s of so general value to all classes of the community, both those who build structures and those who
live or travel over them, as a thorough knowledge of the timber which enters into their construction. We have,
through the efforts of the War Department, a tolerably thorough knowledge of structural materials, composed mainly
of steel or iron. But there are, and always will be, a large number of structures in which the engineer and the
builder are obliged to rely mainly on timber. Tliere are in this country some excellent examples of large timber
spans in bridges which have stood the test of a century's travel, but in examining them we are struck very forcibly
by the fact that an immense saving in material might have been ellcctod had their builders been able to obtain a
complete and accurate knowledge of the physical properties of the timbers they were obliged to use.

Edward Bates, engineer, Chicago, Minneapolis and St. Paul Railway Company, Chicago, lU.:
Having in my charge something over 100 miles of wooden bridges, besides wooden buildings of all classes, I am
competent to express an opinion that these tests will be extremely useful to engineers and others engaged in timber
construction, and would like, as far as I can, to emphasize my opinion as to their importance. I venture to add the sug-
gestion that io make the work complete all of the information obtainable regarding the different processes for the
preservation of timber should be added. The qiiestion of using our timber supply to the best advantage and pre-
serving it to the country is so important that 1 nuike no apology for tliis letter.

J. J. R. Croes, Am. Soc. C. E., M. Inst.-C. E., New York City:

While I had a general idea regarding the work being done in this direction by your Department, I was
not aware that so thorough and systematic an examination of the pro]icrties of timber h.id been undertaken, and I
am greatly impressed with the value of these investigations to all who are interested in knowing the relative value
for structural purposes of tlu> different kinds of timber in the United States. I beg leave to urge the necessity,
from an economic point of view, of having sufficient appropriations made by Congress to enable the work to be
carried to completion on the scale on which it has been begun.

L. L. Buck, C. E., 18 Broadway, New York:

It seems to be eminently a proper function of our Government to pursue the investigation exhaustively, as
proposed. The cost will not be excessive compared to the value gained by authoritative information thus laid
before the people. Moreover, such information will in time repay the expense of obtaining it, by removing an
important cause of destruction, to wit, that of cutting large quantities which, after being culled over, net but a
small portion of high-class material; while a far greater portion might have been found good if cut at the proper
time and age.

Benjamin Douglas, bridge engineer Michigan Central Railroad, Detroit, Mich. :
A knowledge of the results of such tests will be of great value to engineers and builders, and particularly
those made with large pieces— those showing the relation existing between the strength of large and small pieces cut
from the same tree, and the influence of continued service. A thorough knowledge of the properties of timber would
lead to considerable economy in its use, and this -will be of constantly increasing importance in the future as tim-
ber grows more scarce.

J. E. Watkins, curator, section of transportation and engineering, Smithsonian Institution,
Washington, D. C. :

To me, in common with other civil engineers of America, the need for an exact knowledge of the physical
properties of American timber is apparent. • • • i earnestly trust that sufficient appropriation will be ob-
tained from the next Congress to insure a continuation of the good work already begun. A more complete knowl-
edge of the subject will grow in economic value as our American iorests are depleted. Had this matter been taken
up fifty years ago millions of feet of timber which have been wasted might have been saved.

H. I. Miller, Supt. Pittsburg, Cincinnati, Chicago and St. Louis Railway Co., LouisvUle, Ky. :
Our useful timbers are being rapidly depleted, and if scientific research will assist in a better knowledge of their
uses it will unquestionably prolong the time during which we will have these timbers in thia country.

LewisKiiigman,Am. Soc.C.E., chief assistant engineer Atchison, Topeka and Santa F6 Railroad:

I consider this a very important work, and believe that the time and money expended will be appreciated,
and that it will result in the economical U8e of an immense amount of timber which is now recklessly used and de-
stroyed.

Alfied P. Boiler, C. B., New York City:

I sincerely trust that the work will continue on the broad scale laid out, that the intelligent and economical
use of timber may be spread broadcast among the people.

E. Montfort, chief engineer Louisville and Nashville Railroad Company, Louisville, Ky. :
Our information as to strength and other properties of timber is by no means complete. A full knowledge of the

properties of the difl'erent timbers will insure their more intelligent aud economic use, and will be benelicial not only

to railroads, but to all industries engaged in the use of timber.

(5) The proposed investigation will he of special interest to engineers, railroad companies, and all
engaged in building operations.

G. B. Nicholson, chief engineer Cin., New Orleans and Tex. Pac. Railway Co., Cincinnati, Ohio:

The present knowledge of the properties of timber amounts to a state of ignorance, and the cost of investigation
has precluded individuals from undertaking it. I speak in behalf of the civil engineers, but 1 might add that a
perfect knowledge of our timbers will be of benefit to the country at large, as civil engineers take an important part
in the planning and building of works on which vast sums are annually expended by the peoiJle. I respectfully ask
that your estimates to Congress will call for an appropriation large enough to prosecute vigorously this eminently
useful work.

J. J. McVean, chief engineer Saginaw Valley and St. Louis Railroad, Grand Rapids, Mich. :
These tests and examinations will be of inestimable value to engineers, architects, and builders, as well as to
the public generally, and if properly carried out and continued for a sufficient length of time to insure accurate
results, they will be a great saving to consumers of timber as well as a source of profit to owners of timber land.
Robert Fletcher, Am. Soc. C. E., prof, civil engineering, Dartmouth College, Hanover, N. H.:
I have the honor to urge upon your attention the value and importance of the investigation now being made
through the Forestry Division on the physical properties of American timbers. As a member of the engineering pro-
fession, I beg to emphasize the necessity of a far better knowledge than we now possess concerning the strength,
durability, and adaptation to structural and other purposes of available sorts of timber, and also of the various
conditions affecting their useful properties. The knowledge desired by the engineering profession is only to be had
satisfactorily from tests of full-sized specimens under conditions of actual practice. Such tests are generally
beyond the means and facilities possessed by individuals or firms, especially, in view of the time and expert atten-
tion which they demand.

William P. Shinn, C. E., late president Am. Soc. C. E., Pittsburg, Pa. :

I think it of very great and growing importance to the people at large that this investigation of the proper-
ties of our native woods should be made general, systematic, and thorough. To the engineering profession espe-
pially its results will be of incalculable advantage.

George W. Gooley, C. E. : Am. Soc. C. E., Minneapolis, Minn.:

The importance of a comprehensive system of tests on all timber entering into the various details of construc-
tion cau not be overestimated, and the engiueering profession should cooperate with the Department in every way
necessary to obtain full and accurate data on this most important subject. When it is considered that the safety
of millions of lives aud vast amounts of property depend upon the stability of timber structures, it api)ears that it
is of the utmost importance that the absolute strength of all material entering into such construction should be accu-
rately determined.

Engineering News, D. McN. Staufi'er aud A. M.Wellington, editors, NewYorkCity:
As the editors of a journal prominently identified with the advancement of engiueering interests in the United
States, we can not too much commend the good work inaugurated by your Department in commeuciug an elaborate
and complete scientific investigation into the properties of American timber. But as these experiments, to be really
useful, must be on a scale and occupy time that puts them out of the reach of individuals, we sincerely trust that the
wisdom of our legislators will ably second your own efforts to continue them to a proper end. » » • The informa-
tion gained by a complete and scientific investigation of all American timber will be of inestimable value to engineers
and all concerned in the production or use of timber. This information will not only be essential to the safe and
economical use of timber in construction, but it will undoubtedly vastly broaden the available supply of useful ma-
terial for general or specific purposes.

W. Kiersted, Am. Soc. C. E., consulting engineer, Kansas City, Mo.:

I beg leave to say that I am in full sympathy with the work, and trust the necessary measures may be taken to
carry it through to completion. The scale on which it is proposed to make the tests can not but be fiuitful in valu-
172.i4— No. G 2

10

able results of a kind that are in groat demand by those interested in structural work -where timber lo used. Doubt-
less every ci-^1 engineer wUl rejoice that these scientific investigations are being made on so extensive a scale and
under Government auspices, as it should be.

Charles M. Heald, manager Chicago and Western Mich. Eailway, etc., Grand Eapids, Mich. :
As a manager of railway properties, I consider such information of almost incalculable beueiit in aiding our
engineering dep'artment to obtain a more accurate knowledge of the relative strength of material entering into the con-
strliction of bridges, and for this reason, if for nothing else, I should favor an appropriation by the Government to
assist you in carrying out to the fullest extent the tests you are now engaged in making, and hope you will be suc-
cessfui in securing sufficient aid to enable yon to proceed with the work and carry it to a satisfactory conclusion. I
shall be glad to assist in this matter by carrying, upon application from you, free of expense, upon the lines under
my charge, any timber which you may desire to secure in om- territory for test purposes.

Arthur Beardsley, C. E., professor of eTigiiieering, Swarthmore College, Swarthmore, Pa.:
The value of the information to be obtained from these tests is so inestimably great to all engaged in the work
of construction, whether as architects, engineers, or builders, in any of the many arts and trades employing timber,
that one wonders that they have not been undert.aken on so comprehensive a scale long before this ; and it is to be
hoped that you may meet witli every encouragement in the work, until we shall have, through this means, such a
thorouo-h knowledge of all of these properties of our American woods as will enable those who use them in the va-
rious arts and trades to do so with the greatest economy and certainty as to the results.

S. Whinery, C. E., Cincinnati, Ohio. :

I desire to call your attention to the great importance of a proper series of tests of American timber, such as
have been inaugurated in the Forestry division of your Department. While some investigations have been made in
this line, they have not been conducted in a thorough and systematic manner and under the same conditions, and con-
sequently are neither complete nor comparable. I do not think your Department could render a greater service
to the engineers, architects, builders, and all others interested in the use of timber, than to carry out the scheme
proposed lor a complete series of tests of all American timber used in industrial .and engineering work, and I hope
that Congress may make the necessary appropriations to enable you to proceed with the same.

Joseph Wood, general manager Pennsylvania Company; E. B. Taylor, general sixperintendent
of Tranisportation Pennsylvania Lines, West Pittsburg; A. B. Starr, superintendent Pennsylvania
Company; J. Becker, chief engineer Illinois and St. Louis Eailway Company, Pittsburg, Pa.:

We, the undersigned, members of the American Society of Civil Engineers, beg leave to urge upon you the
necessity and importance of continuing the investigation of the physical properties of American timbers as related
to their conditions of growth and the uses to which they are put. Such investigations would be of the greatest
v.alue, not only to engineers, architects, and builders, but to Jill users of timber and to the public generally. We
understand that the work has been started with but limited appropriations, but we trust that you will see your w.iy
clear to arrange for its prosecution with greater energy, to the end that some final results may be reached at as
early a date as possible. From the character of the work a certain time must elapse before getting such results,
but unless carried on without interruption a great deal of what is already achieved will be lost, besides putting off
the day wlien this v.aluable information will be disseminated.

Engineers' Club, of Philadelphia, Howard Murphy, secretary, Philadelphia, Pa. :

At the last meeting of the Engineers' Club, of Philadelphia, it was ordered that the secretary be requested to
express to you its appreciation of the great importance of the extensive tests of timber recently undertaken bj' your
Department, and the hope that such appropriations may be granted as will enable the work to be carried out upon
the grand scale projected, and thus insure for it the desired degree of usefulness.

E. C. Morris, chief eug'r Nashville, Chattanooga and St. Louis Eailway Co., Nashville, Tenn.:
These examinations will prove of inestimable value to engineers, architects, builders, railroads, lumber manu-
facturers and dealers, and to the public generally. There is certainly a great demand for such scientific investiga-
tions. During the practice of my profession, I have often felt the necessity and importance of the information these
examinations and tests will supply. Hence I beg to urge upon you the necessity and importance of this work.

L. L. Eandolph, engineer of tests, Baltimore and Ohio Eailroad Company, Baltimore, Md. :
This information would be extremely valuable to the engineers of the country, and would in the end save the
people at large much money. As you are aware, investigations of this characterhave to be paid for, and it frequently
happens that engineers in different parts of the country simply duplicate each other's tests, with the result that the
infornnition gained costs four or live times as much as it should. Of course this increases the cost of the building
or whatever work is being done, and this again comes out of the pockets of the people at large.

D. C. Humphreys, prof, apphed mathematics, Washington and Lee University, Lexington, Va. :

I am glad to see that your Department has commenced \Yhat I hope will bo a complete, elaborate, and exhaustive
test of tlie ]iliysic.al properties of American timbers. Such an investigation is very much needed and the resulting
knowledge will be of incalculable value to engineers in designing structures in wood.

11

S. W. Robinson, professor of meclmiiical engineering, Ohio State University, Columbus, Ohio:
1 consider the testing, as outlined, to be of liighest importance to engineers, builders, furniture manufacturers,
otd/., and would urge such aid as can be given it.

H. G. Kelley, resident engineer St. Louis Southwestern Eailway Company, Texarkana, Tex. :

I desire to express my deep interest in this work. The value of it will be incalculable, not only to the railroads
but to the building interests of the country. The jtiofessional knowledge of the qualitii^s of the different timbers
in the various parts of the country is now almost a purely professional experience, which, at best, is a very uncertain
factor for the engineer and btiilder. I shall take great pli'asure in furui.shiiig all the assistance I can to such agents
or experts as may be sent out by the Department, and will, at all times, consider it a pleasure to give such infor-
mation, either personally or by mail.

C. H. Benzenbcrg, city engineer, Milwaukee, Wis.:

These examinations will prove of inestimable value to all engineers, builders, architects, manufacturers, and the
public in general, and thelal)ors of your Department in this direction will certainly be most heartily appreciated by
all those interested in the same. The great expense incident to a thorough set of tests extending over a number jf
years has prohibited most engineers or manufacturers, or even railroad companies, from entering into the subject to
any great extent, and hence it is most gratifying to know that the Government has commenced this work, which
will be of the greatest importance to all concerned.

AmoryCoffin, chief engineer Phoenix Iron Works, Phoenix-ville, Pa. :

Referring to the investigation of the physical properties of American timbers, recently begun in the Forestry
Division of the Department of Agriculture, I beg to express to you my high appreciation of the value of the results
sought to be obtained. I heartily trust that you will urge upon the proper authorities the importance of this work,
in order that the information desired may at an early date be available for the use of the engineers, architects, build-
ers, and general public of our country.

H. W. King, secretary King Iron Bridge and Manufacturing Company, Cleveland, Ohio:

I trust, as tbis investigation would be of great value to engineers and builders and the public generally, that
yon will succeed in securing the necessary appropriation from Congress for this purpose. Pn fact I do not see how
you can have any trouble in getting it, when the information is so necessary to every one.

J. H. Hinton, lumber dealer, Lumberton, Miss.:

The tests of timber, as carried on by Professor Johnson, of St. Louis, we think a very important work, and one
that is bound to result in much good to the liuilding trades, as well as to railroad interests. I trust you will use
your influence to secure a liberal apiiropriation.

D. H. Burnham, engineer of construction, World's Columbian Exposition, Chicago, lU.:
Such an investigation as this will be of the greatest value to the engineers and architects, and the value will

be increased in proportion to the rapidity with which the work is done and the results are published. We need
such investigations and need them now. Professor Lanza's tables, published recently, show that the old stress
used for timber was much too high, but we need additional and still more extended investigations. When I was
appointed engineer of construction. World's Columbian Exposition, August 1, I found it necessary to make changes
in most of the buildings because I did not dare to use as high unit stress in timber as was used by my predecessor,
although he claimed to be perfectly safe in his .strains aud brought forward authorities— Trautwine and others—
to prove his statements. I earnestly hope that Congress will make a liberal appropriation for this purpose, and
that speedily.

J. T. Fanning, M. A. S. C. E., consulting engineer, Minneapolis, Minn.:

Permit me respectfully to urge upon your Department the importance of continuing the elaborate investigations
and experimental determinations of the properties of American timbers, as already inaugurated in the Forestry
Division, under your direction. The experience of designers of architectural and engineering structures teaches
that the results will prove of inestimable value.

George H. Pegram, M. Am. See. C. E., civil and mechanical engineer, St. Louis, Mo.:
I do not know of any work of more importance to engineers than the timber investigations and tests, now
being conducted by the Government. As the timber is cut off and the selection becomes more and more restricted,
a more thorough knowledge becomes almost inijx'rative.

C. M. Bolton, chief engineer Kichuiond and Danville Railroad Company, Atlanta, Ga.:
Inlbrmation to be derived from these tests will be exceedingly valualilc, especially to civil engineers and rail-
roads. I will be very glad if you will have my name put on your list for the reports of tests that will be from time
to time issued.

E. B. Codwise, M. Am. Soc. C. E.; C. E., Bangston, N. Y.:

The results of this investigation will prove of great value to all engineers, architects, and others engaged in the
erection and care of timber structures. ► • • J would urge upon you the great importance of the work, aud
trust that you may obtain the uecessiiry appropriations for its speedy completion.

12

Samuel M. Gray, consiilting engineer, Providence, R. I.:

The gcueral practical value of the results of these tests to all eagineers and mechanics using timber for con-
struction of different works can not be overestimated.

OberUn Sn.itL, Am. Soc. 0. E.; Am. Soc. MecW. E.; Am. I. M. E.; Bridgeton, ^. J.:
I think I only a<.ree with the great majority of practical engineers in beUeving that this is a subject of vast
importance ti the industries of the country, as knowledge obtained in such a systematic and thorough manner ,s of
nfinSy more value, as well as very much cheaper, than can be the results of haphazard expernnents by md.vuluals^
i ho, e UaTthe Congressional committee in charge of the matter may be brought to see of how great -"-au--
are expei^e^ts of this kind, and that they should be made in the most thorough manner possible that their results
m^y settle once for all man^ puzzling questions that afflict the engineer a« well as the manufacturer, merchant,
and user of all kinds of timber in every form.

B T. Morse, civil engineer and arcMtect, inspector of buildings, Cleveland, Ohio:
Such investigations, examinations, and tests as are proposed to be made by the Forestry Division o.' th.
Department of Agriculture will be, in my judgment, of great value to architects, engineers, builders, and the
public generally.

A. Fteley, cliief engineer aqueduct commission ; vice-president Am. Soc. C. E., New York City ,
The engineering and other building professions are very mu,;h in need of the tests of timber, and an appro-
priation to that end would, in my judgment, be useful and timely.

W. L. Cowles, chief engineer Youngstown Bridge Company, Youugstown, Ohio:
There can be no doubt that this work wiU be of the greatest practical benefit to all parties engaged in occupa-
tions which involve the use of timber, and it is very important that our knowledge of the properties of different
timbers should be as thorough as possible. We trust that increased appropriations may be secured to engage In
this work.

H. V. Hincliley, ofUce engineer, Atchison, Topeka and Santa Fe Eailroad Co., Topeka, Kans.:
If these tests are carried on as suggested, they can not fail to bo of vast benefit to the engineering profession, to
the bridge and building fraternity, and to railroads especially. I heartily recommend the tests for your hearty
cooperation.

J. A. L. WaddeU, constructing bridge engineer, Kansas City, Mo. :

I indorse most heartily the action taken by the Department of Agriculture in this matter. The results of the
proposed tests, in my opinion, would be of incalculable value to the members of the engineering profession, as well
as to many others.

C6J The worJc is of greatest practical benefit andits importance can not be overestimated.

John MacLeod, constructing engineer, Am. Soc. C. E., Louisville, Ky. :

As an engineer in active practice of general constructive work, and representing a large clientage whose
interests will be greatly affected by the investigations and tests being made by the General Government as to the
physical properties of American timbers, I beg to be allowed to express my appreciation of the gre.at value of this
work to all who have to do with timber in any of its multifarious forms, of the admirable organization and methods
for carrying on the investigations, and of the ability and special qualifications of the gentlemen selected for the
work which is a guaranty that it will be exhaustive and the results reliable. Scientific investigations and tests
of American timber are a national need, second only in importance to similar tests of iron and steel, and there is a
growing want in every department of construction of the information that these investig.ations will develop, and
nothing should be allowed to retard the work.

Thomas Eodd, chief engineer Pennsylvania lines west of Pittsburg, Pittsburg, Pa. .

Such investigations would be of the greatest value not only to engineers, architects, and builders, but to all
users of timber and to the public generally. I understand that the work has been started with but limited
appropriations, but I trust that you will see your way clear to arrange for its prosecution with greater energy, to
the end that some final rcsxilts may be reached at as early a day as possible. From the character of the work a certain
leun-tli of time must elapse before getting such results, but unless carried on without interruption a great deal of
what is already achieved will be lost, besides putting off the day when this valuable information wiU be disseminated.

P. C. Eicketts, professor mechanics, Eensselaer Poly. Inst.; M. Am. Soc. C. E., Troy, N. Y.:

I write to express my opinion as to the very great value of this work to the people generally. Such experiments
necessarily can not be carried on by private individuals, and the results obtained far exceed in value any outlay
that might be necessary in making the determinations. I hope that the work will be pushed forward to a rapid
completion.

E. H. Thtirston, director Schools of Mech. Eng. and Mech. Arts, Cornell TJniver,sity:

This work is regarded, I am sure, by all engaged either in scientific or commercial work, in which the nature,
properties, and constructive values of our timber trees are a matter of consequence, as one of the most important and

13

directly useful schemes of scientific investigation ever yet nndertaken, and all will be very ninch gratified that so
extensive and satisfactory .1 work has been undertaken by such competent authorities. Its value to the whole country
is likely to prove vastly more than commensurate with its cost and with the time expended upon it. This is not an
individual opinion only, but is that of competent judges throughout the world, as is witnessed by the still earlier
action of the probably best organized forestry department in the world, that of the Prussian Government. No other
I'ountry has even approximately the number and variety of timber trees possessed by the United States ; and in no
other part of the world is the complete study of their useful qualities so inniortant. The rapid extinction of pine
tinil)er in the older sections formerly possessing large areas of pine lands, the imperative necessity of finding suitable
substitutes, and the even more imperative necessity of finding pronii)tly a way to inaugurate the replacement of
this lost forest, as a matter of s.anitation and climatic regulation, and of making this substitution by cultivating the
best timber trees, are facts which sufficiently well indicate the vital importance of the work already undertaken by
your Department.

C. J. H. Woodbury, vice-president Boston Manufacturers' Mutual Fire Insurance Company :

By way of introduction, I would say that, although an officer of an insurance company, we confine our business
entirely to underwriting upon manufacturing property, and mj' duties largely pertain to the numerous questions of
engineering involved in these matters. The only method of floor construction found feasible in our mills has been
to construct such floors of very heavy timber, because iron is not so well suited for that, as its anvil-like rigidity
causes the machinery to hammer itself to destructive results. The use of timber in mill work has been largely based
upon precedent, and but very little has been done outside of my own work on the matter of properly organizing and
formulating such results and methods. I do not know how I can call your attention to the importance of a careful
investigation upon the physical properties and strength of timber for mill work in other ways than to say that, by
the method of slow-burning construction in vogue in this country, mills are built at a cost of 75 cents for every square
foot of llnor, while the corresponding method of building mills in use in England involves a cost of about .$1.50 per
square foot of floor. The fire hazard of the American mill is also much less, such mills being insured at a cost of about
one-fifth of 1 per cent; whereas the cost of insuring the corresponding English mill largely exceeds this.

J. W. Andrews, assistant chief engineer Oniaba, Kansas Central and Galveston Eailroad Co. :
Learning that your Department has begun a series of tests of American timber, I beg to tender my wishes for a
full and elaborate investigation into the physic^al properties of our woods and their uses. With railroad men the
economic value of such tests will be incalculable, because of the great ignorance on this subject, which often leads to
serious results, not only in railroad bridges, but in large buildings. Many serious accidents and much loss of hum.-iii
life might be averted if engineers and mechanics knew precisely the value, in strength and durability, of the various
woods in structural uses.

George F. Swain, professor of civil engineering, Mass. Institute of Teclinology, Boston, Mass. :
I desire to express in the strongest terms my appreciation of tlie work which yon have inaugurated, and to bear my
testimony to the great value which the results will have for all persons interested in building or having to do with
the use of timber. I think that you and your De})artment are to be congratulated upon having been the first to enter
upon a work of great importance, and I sincerely trust that nothing may interfere with its successful prosecution.

A. G. Compton, professor applied matliematics, College of the City of New York, New York :
My attention has been called to the investigation into the properties of American timbers now being conducted
by the Department of Agriculture, and I write to express to you my sense of the great value which such a work may
have if conducted in a thoroughly scientific spirit. I hope the undertaking will receive hearty support.

W. G. Curtis, general manager Southern Pacific Company, San Francisco, Cal. :
Our attention has been called to the comprehensive timber tests recently inaugurated in the Forestry Division of
the Department of Agriculture. Without doubt such tests will be of great benefit to the scientific world, as well as
to tlie public generally, and we think it important that the investigations be vigorously prosecuted and carried to
final conclusions at an early date.

William B. Jenkins, receiver New Orleans and Northwestern Eailway Co., Natchez, Miss.:
Such a work will be invaluable to the engineers, architects, builders, railroad companies, lumber manufacturers
and dealers, and to the public generally. But few tests have been made of Southern timbers, whilst the Southern
States are full of the most valuable and durable kinds of wood, all suitable for building purposes. Tests of these
timbers, giving weights and strength, will fill a w.int long felt. In many instances an engineer has to refer to an
English authority for information in regard to building timbers. Railroad classifications are based upon such infor-
mation as can be obtained only by approximation. Consequently this work, when completed, will be in great
demand.

John J. Ganahl, president Ganahl Ijumbcr Company, St. Louis, Mo.:

We consider it of very great importance for the Government to make the necessary appropriations for obtaining
the required tests by scientific investigations, to ascertain the strength and durability of the ditferent kinds and
qualities of our forest products. We trust that you will use every opportunity for obtaining the necessary funtb to
make the desired tests, to enable us to give the inforniation wanted to our customers in order to guide them to use
the proper kind of lumber in the construction of the difierent classes of buildings.

14

E. E. Kelley, sec. Texas and Louisiana Lumber Manufacturers' Association, Beaumont, Tex. :

Thp members of this association are taking a deep interest in the tests of American timbers now beiii;; made under
the, supervision of the Department over which you so ably preside, and trust to see them prosecuted to an early com-
pletion. They feel that great advancement has been made in recent years in determining the relative value of tim-
bers, but they are also cognizant of the fact that much remains to be done, and they hope for advantageous results
fiom tlie investigations now being made by the Forestry Division of your Department. If you will indicate how this
association may be of service in promoting the investigations it will readily extend you all the assistance in its power.
Coleman Sellers, Am. Inst. C. E., consulting engineer, Philadelphia, Pa. :

I apprehend that Congress has not fully appreciated the importance of this work, which bears upon so mauy
industries in the United States and is of such vital importance. I have had occasion to seek for information in this
direction lately, and have met with so much difficulty in finding what I wanted that I sincerely hope that the work
will go on, and that publications will be made from time to time by you that will give users of wood the fullest in-
formation in regard to the resources of our country in this direction.

W. W. Coe, chief engineer Norfolk and Western Eailroad Company, Eoanoke, Va. :

I note with great pleasure that this work has been commenced, and believe that an investigation of this matter
will be very useful and instructive. Personally I shall be glad to aid in any way in my power in furtherance of such
investicatiou, and will take pleasure in recommending to our company that they aflord means for obtaining and trans-
porting specimens, should it be desired by the Department.

M. G. Howe, receiver Houston, Bast and West Texas Eailway Company, Houston, Tex.:
;Having had many years' experience in the use of timber in the construction and operation of railroads, I fully
appreciate the importance of the proposed work, both to the railroad interests and to the general public, and feel that
I can not urge too strongly the necessity of continuing this work in a practical way.

L. M. Haupt, A. M., C. E., University of Pennsylvania, Philadelphia, Pa. :
The work will be of inestimable value to the country in furnishing correct data to engineers and architects, and
I trust that Congress will exercise a wise liberality in this matter of so great utility by making a liberal appropria-
tion for its contiuuance.

C. Palmer, engineer Chicago and Northwestern Eailway Co., Am. Soc. C. E., Escambia, Mich. :
In view of the extensive use of timber in important Btructures, no reasonable expense should be spared to make
the tests exhaustive and reliable.

fTJ Such a work must be carried on by the Government, because it is too difficult and expensive to
be undertalcen by private parties.

Eobert Moore, chief engineer St. Louis Merchants' Bridge Terminal Eailway, St. Louis, Mo. :

Allow me to express my sense of the great value to engineers and all users of timber of the investigation now in
progress under your direction, and my strong wish that nothing may interrupt it until fully completed. It is a work
of a kind which can not be done by any private individual or corporation, and when once done in the manner in which
it has now been begun will be done for all time.

Theo. Cooper, C. B., mechanical engineer, 35 Broadway, New York, N. Y. :

The study and investigation of the characteristics, properties, and capabilities of the great variety of timber of
our country is a most desirable work. It would not be possible to have such investigations, requiring many years of
careful observations, work, and record, undertaken by private means or through the personal action of isolated inves-
tigators. The benefits of such rese-arches would be immediately felt by the whole people, equally by the laborer and
the capitalist. As the benefit would be for no one class, but for the whole people, it is, in my opinion, a proper field
for governmental action.

George S. Lacey, vice-president and general manager Keystone Lumber and Improvement
Company, Bogue Chitto, Miss. :

I can not too highly recommend to your favorable consideration this scheme, believing that it is a step in the right
direction. The Southern Lumberman's Association (of which I have the honor of being vice-president) have contrib-
uted $500 to aid in furthering the same object, but this whole matter is one that can be reached only by such action
and expenditure of money as the General Government could afford. The diversity of our forest products is so
immense that no one jiarty or persons engaged in but bne line can attempt to intelligently enter on this field with
any idea of its investigations being comparatively of any good.

J. P. Frizell, chief engineer board of public works, Austin, Tex.:

Wliile much legislation has lately been enacted and great expenditures have been authorized for objects the pro-
priety of which is the subject of fierce and bitter contention, there Ciin be no question in any well-informed mind as
to the propriety of liberal expenditures for such objects as this; to procure information for the people which, from
the nature of the case, they can not procui'e for themselves.

15

W. S. Pope, president Detroit Bridge and Iron Works, Detroit, Mich.:

It is plain that such invcsti},':itious can ho thoronglily and auth(nitativcly made only by the Oonpral novornniPiit,
:iiiil as every citizen is more or loss interested, it seoms an eminently proper branch ol' novcin nlal wuik.

Horace Andrews, city engineer, Albany, N. Y. :
I can urge the utility of such tests with gioat couHdence, and can see no way in wliich a complete series of tests
can be made without Government aid. Data as to the strength of mot.ils are more easily obtained by private enter-
jirise and necessity, but no exhaustive experiments on the strength of American timber cau be expeclod from private
sources.

Cliaiincey Ives, chief engineer Cumberland Valley Eailroad, Chambersburg, Pa.:
Tlio tests should be made of full-sized pieces as used in bridges and buildings, and this can only he done by tlie
(iovcrnment, as no private individual or individuals could afford the expense. The result of such investigations would
be of the greatest advantage to all classes of citizens, as well as to engineers, architoits, railway companies, etc.
Charles M. Jervis, president and engineer Berlin Iron Bridge Company, East Berlin, Conn.:
The field is so large that no private party cau furnish the means to conduct the investigation in regard to the
l>hysical properties of American timber, and as it is of the greatest importance to engineers and architects th.it the
work he continued, we request that you will urge upon Congress the advisability ot making an extra appropriation
for this piiri)ose.

M. L. Holman, Am. Soc. C. E.; Am. Soc. M. E., etc., St. Louis, Mo.:

A complete investigation should be made and the results formulated for the use of architects and engineers. As
this work cau be carried on by the United States Government only, I have the honor to request that you will endeavor
to have the investigation continued and the results published.

^VilIiam Cain, professor of engineering and mathematics, University of Korth CaroUna, Chapel
HQl, N. C:

I regard these tests as the most valuable to the engineer that could be undertaken at this time. Tests on iron and
steel are counted by the thousand; but very few satisfactory tests have been made on timber, nor probably wUl be,
until the Government steps in and makes an exhaustive investigation.

(8) Public money could hardly he expended for a better object, or for one so likely to secure
vahiable results.

Walter Katte, chief engineer New York Central and Hudson Eiver Eailroad Company, New
York; Am. Soc. C. E., M. I. C. E., Great Britain; M. West'n Soc. C. E.:

I think there can be but one opinion in regard to the very great importance of such investigations as are con-
templated, and of their immense benefit and usefulness to all parties, and especially to those engaged in the use of
timber for manufacturing and constructive purposes. Personally, I would be very glad indeed to see these labors
completed at the earliest possible date, in order that the valuable information derived from them may be furnished
for use at the earliest possible time. I can hardly conceive of an expenditure of public money for a better object, or
for one so likely to return the most valuable results, in which such a largo proportion of the citizens of this country
are directly and financially interested.

C. C. Martin, chief engineer ajid superintendent New York and Brooklyn Bridge, Brooklyn,
N. Y.:

Tests have been made, from time to time, which possess some value, but nothing to compare with the complete
series that Mr. Fernow proposes. In my judgment, no better use could be made of money than in ascertaining the
))hysical qualities of American timbers. The building and engineering industries would be immensely benefitted
tliereby. The plan laid out is an excellent one.

James Christie, Am. Soc. C. E.; Am. Soc. Mech'l Engrs.; A. A. A. S., Pencoyd, Pa.:
The growing scarcity and increased cost of our timbers render it important that their use should be governed
by a more accurate knowledge of their physical properties than that which has been heretofore possessed. Increased
knowledge of the subject will tend to prevent much misapplication and waste of valuable materi.al. If Congress
can be prevailed upon for liber.al aid, I am sure its action wUl be fully appreciated and it will be a crowning act for
the present honored atlministraticm.

C. L. Strobel, chief engineer Keystone Bridge Company of Pittsburg, Pa., Chicago, HI. :
The determination of the strength and other qualities of timber, with reference to its use in constructions, is
preiiminently a Government work, .md I think that the meaas at the disposal of the Government can not be put to a
more useful purpose. Private enterjjrise is not interested to any great degree in doing such work, as the public will
receive the principal benefit, in greater security to life and limb and in greater economy. Such tests as have been
made are incomplete, and the proportions adopted by different engineers vary widely. Considerable discussion and
dilierence of ojiiuiou has only recently l)eeu evolved in connection with the unit strains to be allowed for the wood
constructions of the World's Fair buildings. While many engineers, in the ligiil of future investigation, will prob-
ably be found to err on the safe side, no doubt others will be shovvu to have erred in the other direction.

16

W. F. Allen, secretary, American Eailway Association, 24 Park Place, New York City:

I have the honor to inform you that at a meeting of the American Railway Association, held at the Hotel Bruns-
wick in this city on Wednesday, October 14, 1891, the following preamble and resolutions were unanimously
agreed to:

Whereas, the American Railway Association, representing 166 railroad companies, operating about 125,000 miles
of railroad, feels a deep interest in the "timber tests" now being conducted by the Department of Agriculture:
Therefore,

Resolved, That in the opinion of this association this work is one which earnestly recommends itself to the
favorable consideration of CongresR.

Resolved, That the secretary be directed to furnish a copy of this resolution to the Hon. Jeremiah Rusk, Secretary
of Agriculture.

(9) Expressing admiration of the organization and method of the investigation as planned hy
the Division of Forestry, and urging ample appropriations by Congress for prosecuting the proposed
investigation to a proper completion.

Charles B. Dudley, chemist, Pennsylvania Railroad Company, Altodna, Pa. :
I should like to say that I most heartily approve of making these tests, and also of the plan which has been out-
lined and is being carried out in actually doing the work. There is very great need of careful accurate study of the
value of our woods, and no one appreciates this necessity more than those who constantly use our native woods in
construction. I sincerely hope that Congress will be so liberal in its provisions for this work that it will go on as
speedily as possible. I have the pleasure of Mr. Fernow's acquaintance, and regard him as in every way competent
to carry on such a system of tests as has been inaugurated. If I can assist in auy way in securing the necessary
funds to bring about the result desired, I hope you wiU not fail to command me.

C. N. Brown, professor of civil engineering, Ohio State University, Columbus, Ohio:

These tests will be of inestimable value to all engineers, and I hope that they may be carried out according to
the plans of the Department. I hope that you may be able to prevail upon Congress to make such appropriations as
will permit the work being pushed with vigor.

J. B. White, president Southern Lumber Manufacturers' Association, Grandin, Mo. :

The Southern Lumber Manufacturers' Association is composed of the largest manufacturers of lumber in nine of
the Southern States, and they recently donated $500 to aid Professor .Johnson in purchasing a machine to make experi-
mental tests of Southern woods. The work will be of inestimable advantage to the Southern States especially,
as their financial resources must largely come from the forests which occupy such a large proportion of their domain.
If Congress can be prevailed upon to increase the annual expenditure for this purpose, it will result greatly to the
prosperity of the lumber States South. I wish to urge upon you the necessity and importance of this work.

C. B. Davis, hydraulic and sanitary engineer, Chicago, 111. :

I desire to urge the great importance of this work, of its vigorous prosecution, and of the necessity and desira-
bility of a liberal appropriation being made at the earliest date possible.

J. W. Schaub, engineer Detroit Bridge and Iron Works, Detroit, Mich. :

The company with which I am connected is engaged in the designing and building of bridges and similar engi-
neering structures, in which timber is used to a considerable extent, and we are thus brought to appreciate the desira-
bility of a more extended knowledge of the various properties thereof. * * * As every citizen is more or less
directly interested, it seems an eminently proper branch of governmental work. I heartily recommend, therefore,
liberal appropriations for the purpose.

W. Howard White, consulting and executive engineer, 74 Wall street. New York :
I trust that the work already done on the testing of United States timber as to physical properties will be con-
tinued by appropriations from the next Congress. I am myself engaged upon a set of tables intended to facilitate the
correct proportioning of the various parts of wooden buildings. At the base of the calculations upon which these
tables are made lies the correct factor of strength to be used; and the satisfactory use of such tables depends there-
fore upon the satisfactory determination of this factor.

P. H. Griffin, president New York Car Wheel Works, Buffalo, N. Y. :

My attention has been brought to the proposed Government timber tests, and being impressed with the impor-
tance and value of the work, I trust Congress will see fit to make the necessary appropriations to carry it out. I
deem the result one of great benefit to the public.

George E. Mann, city engineer, Bufialo, N. Y. :
Being aware that the limited appropriation for the investigation of American timbers delays the obtaining
prompt and valuable results, I write to urge the recommendation for a larger appropriation and such as the impor-
tance of the work demands.

SCOPE AND HISTORICAL DEVELOPMENT OP THE SCIENCE OF "TIMBER PHYSICS.'

Whenever Imiiiaii knowledge in :uiy i);ii-ticulai- direction has j^rown to such an exteril and
complexity as to make it desirable for greatei- eonvenieiu'i^ and better comprehension to group it,
correlate its parts, and organize tlieni into a, systematic whole, we may dignily sucii knowledge by
a eollective name as a new seienee or branch of science. The need of such organization is espe-
cially felt when a more systematic progress in accumulating lu'w know ledge is contemplated. In
devising, therefore, the plans for a systematic and compiehensi\(^ examination of our woods it has
appeared desirable to establish a system nnder which is to be organized all the knowh'dge we have
or may acquire of the nature and behavior of wood.

To this new branch of natural science T i)ropose to give the name of " timber physics," a term
which I have used tirst in my Iteport for 1.S87, when, in devising a systematic i)hui of forestry science,
the absence of a collective name for this class of knowledge became apparent.

"^Tiile forest bioh)gy contemplates tlie forest and its components in their liviii;/ condition, we
comprise in timber physics all phenomena exhibited in the iJead material of forest production.

The practical applic'ation of timber or wood for human use, its technology, is based upon the
knowledge of timber physics, and under this term we comprise not only the anatomy, the chemical
composition, the physical and mechanical properties of wood, but also its diseases and defects,
and a knowledge of the influences and conditions which deteriTiine structure, physical, chemical,
mechanical, or technical ])roperties and defects. This comprehensive science, conceived under the
name here chosen, although developed more or less in some of its parts, has never yet been digni-
fied by a special name, nor has a systematic arrangement of its parts been attempted before. It
comprises various groups of knowledge derived from other sections of science, which are neither
in themselves nor in their relations to each other fully developed.

While i)lant physiology, biology, chemistry, aiuitomy, and especially xylotomy, or riie science
of wood structure, are more or less developed and contribute toward Imilding uj) this new branch
of science, but little knowledge exists in regard to the interrelation between the i)roperties of
wood on one side and the moditications in its comjiosition and structure on the oth(!r. Even the
relation of the proi)erties of various woods, as couii)ared with eacli other, ami their distinct specitic
peculiarities is but little explored and established. Less knowledge still exists as to the relation
of the conditions which surround the living tree to the properties which are exhibited in its wood
as a result of its life functions. 8upiiositions and conjectures more or less plausible i)reponder-
ate over positive knowledge derived from exact observation and from the results of ex))eriments.
Still less complete is our knowledge in regard to the relation of properties and the methods and
means used for shai)ing or working the wood.

The close interrelation of all branches of natural siaenee is now so well recognized that 1 need
not remind my readers that hard and fast lines can not be diawn. whereby each Held of incpiiry is
confined and limited; tlnnc must necessarily b(^ an oveilapping from one to the other. Any system,
therefoie, of dividing a larger ficdd of ini|niry into i)arts is only a matter of convenience; its
divisions and correlations must be to some extent arbitrary ami varied, according to the point of
view ti'om which we jiroceed to divide and correlate

There are two delinite and separate directions in which this branch of natural science neeils
to be devehiped, and the knowledge comprised in it jnay be divideil accordingly. On one. side it

17244— Xo. i; — .•; ''

18

dra'srs its suhstanre largely from the more compreheiisive fields of botany, uiokfiilar physie.s, and
chemistry, and on the other side it rests npoii investigations of the wood material from the point
of view of mechanics or djniamics. In the first direction we are led to deal with the wood material
as it is, its nature or appearance and condition; in the second direction we consider tlie wood
mateiial in relation to external mechanical forces, its behavior under stress.

The first part is largely descriptive, concerned in examining gross and nunute structures, phys-
ical and chemical condrtions and properties, and ultimately- attempting to explain these by refer-
ring to causes and conditions ^hich produce them. This is a field for investigation and research
by the plant physiologist in the laboratory in connection with studies of environment in the forest.
The second part, which relies for its development mainly upon experiment by the engineer, deals
with the properties which are a natural consequence of the structure, physical condition, and chem-
ical composition of the wood as exhibited under the application of external mechanical forces.
It comprises, therefore, those studies which contenudate the wood substance, with special refer-
ence to the uses of man, and forms ultimately the basis for the mechanical technology of wood or
the methods of its use in the arts.

The correlation of the results of these two directions of study as cause and effect is the highest
aim and ultimate goal, the philosophy of the science of timber physics. Timber physics, in
short, is to furnish all necessary knowledge of the i-ational application of wood in the arts, and at
the same time, by retrospection, such knowledge will enable us to produce in our forest growth
qiralities of given character.

Conceived in this manner it becomes tlie pivotal science of the art of forestry, around which
the practice both of the consumer and producer of forest growth moves.

The first part of oar science would require a study into gross and minute anatomy, the struc-
ture of the wood, form, dimensions, distribution, and arrangement of its cell elements and of groups
of structural parts, not only in order to distinguish the different woods, but also to furnish the
basis for an explanation of their physical and mechanical i)roperties. We next would class here
all investigations into the physical nature or properties of the wood material, which necessarily
also involves an investigation into the change of these properties under varying conditions and
influences. A third chapter would occupy itself with the chemical composition and jjroperties of
woods and their changes in the natural process of life, wliicli ju'edicate the fuel value and dura-
bility as well as the use of the wood in chemical technology.

Although, philosophically speaking, it would hardly seem admissible to distinguish between
physical and mechanical properties or to speak of " mechanical " forces, for the sake of convenience
and practical purposes it is desirable to make the distinction and to classify all phenomena and
changes of nonliving bodies, or bodies without reference to life functions, into chemical, physical,
and jnechanical phenomena and changes. As chemical phenomena or changes, and therefore also
conditions or properties, we class, then, those which have reference to atomic structure; as phys-
ical phenomena, changes and properties, those which refer to and depend on molecular airange-
ment; and as mechanical (molar) changes and properties those wluch concern the masses of bodies,
as exhibited undei-the influence of external forces, without altering their jdiysical or chemical con-
stitution.

There is no doubt that this division is somewhat forced, since not only most or all mechanical
(as here conceived) changes are accompanied or preceded by certain alterations of the interior
molecular arrangement of the mass, Init also many i)hysical phenomena or properties, like density,
weight, shrinkage, having reference to the mass, might be classed as mechanical; yet, if we con-
ceive that physical phenomena are always concerned with the "quantity of matter in molecu-
laf arrangement" and with the changes produced by interior forces, while the latter are concerned
rather with the " position of matter in molecular arrangement " and witli changes under applica-
tion of exterior forces, the distinction assumes a practical value.

Our conception of these distinctions will be aided if we refer to the physical laboratory as fur-
nishing the evidence of physical phenomena, and to the mechanical laboratory as furnishing evi-
dence of mechanical ijhenomena.

These latter, then, form the subject of our second i)r dyinuiiic jiart of timber physics, which
concerns itself to ascertain maiidy l)y experiment, called tests, under application of the laws of

19

elasticity, tlie stnMi<rtli of tlu' material aiitl other i)roi>erti('s wliicli are. exliibited as reaetions to
the. intlucncc ot api)lie(l stresses, and those which need consideration in the inccliaiiical use of the
material in the various arts.

Ilaviuji^ investiii'ated the iiiatcrial in its imriiial coinlil ion, uc would necessarily come toacon-
sideriition of sucii ])hysieal and chemical conditions of the material as are abnormal and known as
disease, decay, or defects.

Finally, havinj;' deterniiiied the properties and their chanj;cs as exhibited iu material produced
iiuder chausiuj;- conditions or ditt'ering in physical and sliiutural respects, it would remain the
erowninji' success and yoal of this science to relate mechanical and physical properties with ana-
tomical and physiolojiical dcvelojiment of the wood snl)stance.

The subject-matter (•onii)rised in this I)ranch of apidied natural science, then, may bo brouj;hfc
into the followins-- sehcmatie view:

TIIWBER PHYSICS OR THE SCIENCE OF WOOD.
I. — Wood STRt'CTCHE on XYLOTO.MY.

(a) Exterior Jorm.

Here, wonlil t)(> doscril)ocI the form (lovolojiineut of timbor in thd standing troo, ditforentiatod into root
system, root collar, bole or trunk crown, branches, twigs; relative amounts of material furnished by each,
(ft) Inlirior stnictiir<tl apjimrancc; <lifferentiation and arrangement of groups of structur;il elements.

Here would be described the gross structural features of the wooil, the distril>ution and siz<> of medul-
lary rays, vessels, fibro-vascular liuiulles, as exhioited to the naked eye or under the magnifying glass on
tangential, radial, and transverse sections; the apjiearance of the annual rings, their size, regularity, dif-
ferentiation into summer and spring wo(h1, and all <listiuguislilng features due to the arrangement and
proportion of the tissues composing the wood.

(c) Minute anatomy or hixtolony; diifereutiation and arrangement of structural elements.

Here the revelations of the microscope are recorded, especi.ally the form, dimensions, and structure of
the different kinds of cells, their ariangenient, proportion, and relative importance iu the resulting tissues.

(d) Compuratire classification of woods, ai'.cordiug to siructurul features.
(«) Laics of wood firotrtli- with reference to structural results.

Discussion of the factors that inlluenee thi> formation of wood in the standing tree.
(/) Ahnormal formations.

Burls, bird's-eye, curly, wavy, and other structural abnormities .and their causes.
II. — Physical properties, i. e., properties l)ased on molecular (physical) constitution.
(a) Exterior appearance.

Such properties .as can 1)6 observeil through the unaidral senses, as color, gloss, grain, texture, smell,
resonance,
(ft) Material condition.

Such properties or changes as are <leteruiined by measurements, as density or Aveight, water c-ontents
and their distribution, volume and its changes by shrinkage and swelling,
(c) Classification of woods according to pln/sico-tcchnical )i7-operties, i. c, such physical projierties as determine their
application in the arts.
III. — Chemical PROPERTIES, i. e., projierties based on atoniii; (chemical) constitution.
(a) General chemical analysia of irond ((|nalitati\T ;ind i|uantitatlve).

Here would be discussed tlie eliemical constitution of tlitferent woods mui! ditfereut p.'irts of trees and
its changes due to pliyslologica! |>rocesses, age, conditions of growth, eti'.
(ft) f'arholiydralcs of the wood.

Here would be more specially discus.sed eeilulo.se and ligiiin. emli tiii niaticms, organic <!ontents and their
changes, and such pro])erties as predicate the fuel value of woods, its ni.iiiiil'.ietiire into charcoal, its food
value, pulping (|ualities, etc.

(c) Extractire mnleriah.

A knowledge of these underlies the appli<'atiou of wnod in Ibc uianufactuie i>!' tan extracts, resin, and
turpentine, t.ar, gas, alcohol, acids, vanillin, <'tc.

(d) Antiseptic materials.

A knowledge of those chemical ])roperties which i)redicate durability and nridiTlie ]U'ocesses of increasing
the same.

(e) Mineral constituents.

A knowledge of these in ])articular will establish the relation of wood growth to ndneral constituents of
the soil and also serve as b.asis for certain technical uses (potash).

20

IV.-Mechax.cal properties. ;. ..■ properties based on elastic, coudilions exhibited by the aggregate masB under
inllucuce of exterior (moehiiuical) forces.
(a) rorm changes wilhontdeslnicUon of cohcxion, coi.m.only called chisticity, llexil.iUty, toughuess.
\l>) Farm changes "nth des,n,cUon of cohesion, co.um.mly .■ailed strcugth (tensile, compressive, torsioual, shearing),

eleavability, hardness,
v.— Technical PROPERTIES, j. c., properties in conibination.

Here would be considered the woods with reference to their technical use. tl,c.r applicatn.n n, I l,e a.ts,
which is invariably based npou a, c.nnbination of several physical or mechanical properties.

VI.— Diseases ^vxD FAULTS. , j. ■ i „ i;,i ,,..

Herewonld be treated the changes in structure ami properties irom the normal to ab.mnna] co,„l,l,u„s,

duo to influences acting upon the tree during its life or upon the tiiuber durmg its use.
V/ 1.— Relation of properties to each other. , • i , ■ ,

Here would be discussed the e.m.iection which may be established between st rueture, physical, ehemieal
and mechanical properties, and also between these ami the conditions of growth und..r which the material
was produced. The philosophy of the entire preceding knovvledge would here be brought together.

To contribute toward this impoit:uit braiu'h of Immau knowledge, and to help in the bnilding
of its foundation, the work, undertaken by th.> Division of Forestry, described in this bulletin,
was designed by the writer; and, in order to build with a knowledge of what has been done before
on this structure, a brief review of the progress in the development of timber physics seemed
advisable. In this I have followetl largely the excellent resume by Dr. W. F. Exuer m Lorey's
Handbuch der Forstwissenschaft.

HISTORICAL.

The first important and exhan-stivc work was that of Parent, publisli.d in tlie Menioires de
I'Academie des Sciences in the years 1707 and 1708, being "investigations into the strength of oak
and lir." The idea of elasticity, so important in the application of timbers, was not even known to
him. A work memorable in tliis tirst period of scientilic cttorts in this direction was produced by
MUSCHENBROBCK in 1762 (Introductio ad p'.iil(Uo;)hia:n iiaturalcm), discussing especially the
differences of strength in the different parts of the same tree. Although not a sufficient number of
satisfactory experiments were conducted to prove his deductions fully, they were remarkably clear
and in the main correct. The celebrated naturalist, BuffoN (Oeuvres, Vol. x), occupied himself in
a comprehensive manner with a determination of the mechanical properties of oak wood. In 1780
apiic.ired the often-cited work of Duhamel DuMoncbau, Traite de la Conservation ct de la
Force, which contains a number of references to tlie properties of timber.

These three authors are abnost the only ones who occupied tliemselves with the determination
of density and strength in the different parts of the same tree and of tlie inrtuence of soil conditions
on these properties. The contradictions in their views and deductions, however, left these
important questions undecided. < )nly the authors of later periods gave any tliought to tlie study
of elaisticity. Among these were Oibard (Traite Aiialytique de la R'^sistance des Solides, 1798),
who experimented on oak columns, and Perronnet (Memoires sur les pieux et les pilotis, 1782).
The latter found that a contiiuums even load increases the depth of detlection, which he argues
could not be the case without a change in elasticity, by losing part of its energy. At the end oi'
the last and the beginning of this century a immber of recognized men of science lia\e determined
by experiment, for a large number of timbers of tlifterent kinds and locality, the density, tlie
strength, and the coefacient of elasticity. :N"otable among these are Bblidor (Architecture
hydrauUque, 1782), Rondelet (Art de batir), Barlow (Essay on the strength of timber, 1817),
Ebb ELS, and Tredgold in various works.

Charles Dnnx published in the Journal de ri5c:)le Polytechni(iue, Vol. 10, 1815, an exten-
sive work on the mgiihanical properties of wood (Experiences sur la tlexibilite, la force, et rclasticit6
des bois). He investigated the nature of the elastic curve, the position of the neutral plane (fibre
inrnriable), and he corrected the formulas which express the relations of the size of test pieces and
the applied loads to the resulting d eflections.

Bevan occupied himself especially with the determination of the modulus of elasticity, derived
from experiments in torsion. (Philosophical Transactions, 1829.)

8AVART utilized tone vibrations of wooden plates in order to determine the differences of
elasticity and the position of its axes. Tliese plates were cut from a piece of beech, in various

21

(liit'i'tioiis. lie supposed tlirci' axes, one lyaiullo.l to tlu' (ihi-rs, tlic second in tli(^ direi'fion oC the
radius, tlie tliiid tangential to the annual iin,i;-. He (bund tliat if tlie resistance against cross
bending in the direction to the tangent is taken as unity, the resistance in the direction of the
radius is 2.25, that in the direction of th(i fiber is 10. (Menioires de l'Aca(h''niie des Sciences, 1830.)
The same question was discussed by Wiieatstone in the Philosophical Transactions, in 1833.
He says:

^\^l(!n a plate is cut out so that tlie fibers run parallel to one of the siile faces the axes of the j,'reatest aud
smallest elasticity are rectauRular to each other ami parallel to the sides. If the plate has the shape of a rectangle,
the sides of which are inversely pro]iortional to the scjuares of their resistance to ben<Iins. both kinds of vibrations
parallel to the sides, although these may vary in length, become synchronous, and its consistency furnishes a
resulting figure with lines parallel to the diagonal.

Llcnce, by tiuding experimentally the relative length that these sides should have, the relation
of the coeHicients of elasticity in two directions perpendicular to each other may be found.

I'ONCELET, in his Mecaniiiue Industiiel,18:>9, enters into a very detailed discussion on the elas-
ticity of timbers and especially ou exiierimeuts into the lesistancc^ to torsional forces. He derived
from the experiments of Minard, Desormes, and Ardent the conclusion that for the first load the
elongations are ])roportional to the straifiing forces, and he calculates from these elongations the
coeflicieuts of elasticity.

According to Eaton Hodgkinson (Combes, Exploitation des Mines), a shortetiing by 0.0027 of
the original letigth of a rectatigular (tiot bent) prism alters the elasticity considerably.

Hacien (Poggendorfs Aniialeti, Vol. LViii, p. 12."j) has itivestigated the elasticity of several
kinds of timber by crossbending of sticks, which were cut in the one case in the direction of the
fiber, and ifi the other case perpendicularly to the same, and did not find atiy great dilference
betweefi the heart and sap wood; but he lecognized that the coefficient of elasticity decreases con-
siderably when the wood contains much water.

In tlie year 1845 two Italian physicists, Paccinotti atid Pbki (II Cifuento, Vol. in), ])ublished
a very precise and detailed investigatiofi into the elasticity of titnbers, in which the various
methods for the determitiatiofi of the coefficient of elasticity were coini)ared and their value
examined. They operated according to the three methods of tension, flexion, atid torsioti, with
cubic blocks of 27 to 30 millimeters side. Iti the experiments witli flexion they employed dif-
ferent methods of fastening or support. They measured the elastic as well as the ])ermaiiefit
elongations, the augles of torsion, the ordinates corresponding to the different points of the stick
during its deflection with ati increasing load. In the second part of their work, Paccinotti and
Peri cofuiiare the numerical results of their experifnents with the figures which were calculated
by the ktiown formulas, aud attempt to find a relation between the density and the coeiUcient of
elasticity for the timbers experituented ujiou.

They arrived at the following conclusions:

(1) The elasticity allows in th<^ <litferent parts of the wood cliangcs in diiuiiusioii, which are in iiroportiou not
only to tlie first load but also to those whi<-li comi^ near that load wliich produces rupl-nre, provided care is taken to
ditferentiate from the elastic changes those permanent ones which are due to the softness of the material or to the
continuity of the load.

(2) The curves of dellection wliich tlio sticks assume when fastened securely at one <iiil dili'cr uiiiler otherwise
e()iial conditions from those wlii<-li the same sticks fm-m when botli ends are supported ; this must be ascribed to the
reai-tion of the liber in the two opposite branches foriiK^d in the latter method of sujipori . The same theory, however,
may servo for the ]>nrpose of depriving the two kiiiils of curves, jirovided tliat in tlie iiitc-gial ion of the respective dif-
ferential cijiiations care is taken to projicrly determine the sonstant (the value of wliich depends on the degree of
the iuvarialillily of tlie fastening or insertion of the stic-ks (^xl>erillleuted upon).

(3) The ditt'ercnccs whicli ajipear in tlu^ deteriiiiiiatiou of the coeflicieut of elasticity disappear almost entirely,

if by this expression is understood tlic iiuoticiit ''j^,^.. i" which K denotes the common term for tlic (■oefUcieut of

elasticity and O the specific gravity.

(4) The coefficient of elasticity Ei, although there are some differences in the various species of wood, is in gen-
eral ciiual to 2,000 for the stiuaro millimeter of transverse cut.

(.')) The coefficient of elasticity can be determined not only by tension but also by flexion and torsion, but with
these ditferent methods dill'erent values are founil, and to reduce these to thesame value it will be necessary in each
case to deteriuiue a constant coellicii^nt dcpeiidiMit ii|ion thi^ metliod of operation.

(ti) The easiest metliod for the dctcriiuiiatioii of the coeflii^ieiit of elasticity is that in which Mie stick is sup-
ported at both ends and is loaded at equal distance from the two points of siipiiort (center).

r. -i of Paecinorri and Peri aj*f as exact as it was p«->ssil>lf ro make them without

the ap,.^. .... .. . me katheiometer. These authors, however, also negleitf-.l to e»jasi<ler the part

of the tree fii:>m which the experimental yiieces were taken an»l the degree of seasooing at the time
o; at. It is fci: - is not t" - " - ' the tree and changes

cc_- :y with the a: -" "L thi< i> --^ -nch small .sticks as

the authors used: so that the result of these experiments are not entirely capaWe of comparison or
gener'

E. - the results of investigations obtained in this field up to the middle of our century,
we find that great projrress was made in the methods and the exactness <>f the reasoning, but the
results were often contradic* — - ' Tmsatisfiictory. Keco^mizing this, two French .scientists, one
a forester, the other a te. . -". <:HEVA:rDiEK and Weetheth. undertook a far-reaching
inTestigation- The timlwrs tor experiment were taken from a Lx-ality of the Western Vosges
Hoontaias. France, the l<x--al con<iitions of which were thoroughly known t<» the experimenters.
In a forest comx'rising ab«>nt lO.WM) acres sufficiently numerous variations of site and kinds of
trniber were found. The same exa«rtitude was u.-*ed in the - repa-
ration of the test pieces as in the experiments them.-ielve;-. ; . - . r iis of

satis&«tt«y quality were at their disposal Chevandier and Wertheim published their work, the
fruit of m - 1 l»een e ' mh a de, ' i never before

attained. U- . - - - , . entitleii ■ -« sur la ^ . .ue du bois.

Tke foDowing questions were to be determined by the authors :

(1 _-'---;

chaai^- -- ,, '- — *^

i2i Do the me^-hani. i' !.rnT,..rTie8 of tlie wood vary —

(s) with th« . t. <r„ acconiiQg to the poettioa in the tre« in reistioB to the p^xnts of the eompads ;

( h ) wtth tht .^-j _ . • ■ . inaistmc ;

(e) with the position in the tree in relatiaa to the distance irtxa the axis to the circi(BleieBC« at the same

height:
{i) with the poiHtioa in the tree aeeordin^ to the height from the groond'
(3) In "" " a do the Dietfha.nical prop^rrie? ' -tajid in the direction ..i riirr ni^er aku-i lu tnc tiirec-

ti«n p^T^E'- ■ _e sajme respe^tiTely at varyxD _: , -''imihe ;^i.timdf

;■ trews exert ?

: mnnal rings ( rate of 2r'»»H!V tfe^* <'it'*«»tt<». »Bd tfc»» ««Q '«»!iditions show J
(6 ijctwcTrn tile several meihaiii '

(7 > cau be considered proper to .- iml what i-on-

cloKoaA Tesoit tiieretrooi Sue the praetiee i

The results of the "r:; -ats of these two - ng to ti: " ' - ' " '^hich we

employ t-ven tiMiay. T. :s tirst review th^ ..ese iuvr-- . -. ._ ^ we have

here given, re«i>rdnig in a table the results of exjieriments by their preileeessors. and in eighteen
additional" ' ' -':e resnlts of their own work. Here for the first time we find a rather fiill
re<rord of - .- nnd nature of the test material Regard is taken of th»* moLsturt- per cent

in fiooT sta.g»-> ag: fresh, partly tlried. well sea.soneii. and kiln -dry. These authors also

T^-r.-.] larger I _ ■.^, :>> 'J6 feet in length). They also employe«l the metho«l by sound vibrations
-rminetheroetficient of elasticity, and finally correlateil theirresults with a \iew to answering

T . with<xit doubt, must be considered the fathers of the new science of Timber

Phyaes, and while their eonclnsions may not be acirepted as having settled ail the questions,
b*- ' ' '■ ' .' ilata of record. •■ :tetl out the nxnl along which we

ij. -.it. Yet it has re ., y untraveled Until our time.

TwelTe years after Chevandier & Wertheim's publicati^jn there appeared in Germany the most
eompr ' ■- ~ -t in thi* line of inv^ - . - . .- fullest dist-u.-^sion of all the

tn<jw. : ta<rts regarding w<j.». ution. by Dr. H. yr.EDLXSGEii.

Ij«)fess<jr of forestry and Oberforster at Mohenbeim. Wiirtemberg. The means for his long-
, ..nririxK.^ exj)^^"' '-^^- and accumulation of data were furnished by the direction of the Forest
mv at If I an<l the Minister of Finuufe of his State. The first fruit of his studies
1 the standard work eutitleil The Technical Properties of Timber, for
i .- -_ lechnolotcL^t.s. and ilunulacturers.

23

Foo" Ihe meelraiiical furcvftei'tjes yf"-!!'' _■■ • i ...-i^ ,..j,...i . , ^^^

W*srtibeiiiii, Wt "srilli p-e-at as^iilnny In • a

iiiiiiiT«-saiI tj'ea.tise <»u tibe ^ 'rf

tithe Taaicnus tdmbei's, im tJbe I -^jK... ,...,.... :^...; ^.*„,. ,...jk„ ;...,• ..... ,„..., ,.....,.. ,.^. . ■•d

aud exi>laiiitid frc»iij tib* aaatKUDT. Besid'es. be tu'eatied njicmi jrii'sim.'Ooiica-, ]us:i*ii. t3-ai ■ >r,

<-.ajiaifiTy few i. ' ^ ■ v,

liajHiuess. cle.j -._.:.- - ;___.- _ — _ - ^ — _, -—-:-. — - :, -_-- , ''-

^■>t^Tnv-ji,1 <ioi!iD.p(>$iti(aii., ioiA xaH'ue. naXmr^ dmc^tioMf^ mud iamMs «<f itimlber. Tliiis tym
' ■ ■ '■ ' "'- ^r mciire i~ ■ ' ,. , . ^ . ^^

i>ead- A- _ _ ■• rs

j»mi:>ili5l»eid aaiofc, at ieasS m. G^rmaia, aa* Jtiaj^ed imoire or less oe XifurdiLD.ger's "w^oalk, mcme ibamgaa^r
^iiuiiiititaifciT'e^T id - " ' '

Of tbes* pn: .^iiLg, iic*t of emeyt-ik^jia'die c+r eatk'eily •ciMiiipQlaikiinr itaitiu'e^ aire

m-*)irtibj of iDemtaom :

Tables #f tiie BesnJlt.s of a s«tK;s of Expetimesnts coi Biitisih Col'— ' ^ ■ ^ '^;«r WoodR,
prejiaired Ijt Feancis Fgwke. vas j^ublisilied im 1S67 aftiei' a long stsries < : - ■ •ti ra.tb«r

cmde piiiK-iples. IMs «(i!).c«iiaoiiis "woi-t iias dcKoe Etitle serviee for stiwiMie.

Im tiw same reaa- ,{1^7) a r-eTised ediitaom 'of JP^etee BaieijO'W^s Sifct'eaiglJli c«t' M.a.t.t i i^> . -j igiiiaiDj-
in 1&17) "was ]:>ub]isli<ed im LcmdoiD, irhic-lj iiafioii'ds mtamT oJdeii- exf imjDeiiiitrt. besides tihfc aiQitihar''s
«-wB. amd is a book foM of solid. iha|;My g, and : u.

Caelt. Jekst, prcrffessorat tibe Iii^j. ..... ^c-.dkQoloj;'.,..... ^._.. .-..^ . . j.t T'ienmaL, -eairried -iini liis

■work m|«cai a eompi'eilwaisaTe plam ait ihe fspemse ctif itibe HimiraTiam C^OT'tirmmefriit. OhIt a paal <rf
t3»e ■«rork "K'a> -" . Het•^ * .in

as opposed irt^' J .. .■: - — .. ™g s-creD^:.- ^ : : . . ■.. _ _ .__.:. ; ...->iJe

sQieajrtih flif ibemsiodi cm n-nmfiaji-snTi timbea's, tube MsitaiT" of 'wMda ver-e toQcrwii as iiegairds !I<icai]xt;j' ciif
Tired: . ^ . . - ' ■ ' ' _■>.

., . r-dhamieail j)irof»eirtaes '«rf timliei- groTm in

Boltemia -were made hy Cael MrROiLASCHKiK :at !tib« amsifcaiBoe erf' tlbe FcKPest Exj^riiinemt STAtion at
"^ From t' • ■ '"■ ■. - . ^ ■ -,-,, ^ ^^ M'iT" ' _ ' "^ - ' ^ «n

'• . - --resfcii <_*■ - - - . .ledin'.ttd, bui ,r,a.

AiJtei' tMs tiiii»e tfee jp>eink«djt-.al Mtieraitniire ctf tlbe dajr dcaataiins a great iiiaiiij -essiiys :mt& mi&ipe i«r
less Talmaible records of expeiinaeiits.

As of sptitda] iiuflnenc-e tiik>ii tbe deTeiojMoeait 'otf tOnis laraiirt "f ■a«ieni>w- t^o sfndites of greatieir
erticmt, botih appealing im tibe Teai' 18s>3. reqmi-e imeaitioiru M- ■ ■ ^rf tl>eExianinat)i>ii

of Stqss Biiiidiig limbers, by L.TETMAJEE, professor at tbe ^-■..^•- . .i >..i..,..i .rv-..-,.-^

Suod ImvesngaTaons iiit«.» tbe Ela.s,la.dty and I^emsity of SjaTioe ai>d I , . J.

Bacschts GEE, professes ol' T- L amies and Grapl

Im tbe fii-st-iaeiiitioned a*,. i^ ;„. ..„.jor if)roposes a i„ ... .. _ .:.l:s aibbemliifiiL of

^Jetenmimim^ tlie ^■qimaJlity"" «(lf tmnteer fcxr l^naMins puirpioses iby tibe **'wi«rikrai^ <5a|ia<-ity -of

aJiove aea leTel j, .age, aiiii4 apjpearaDieie tif libe ^wmnA, was gwen.

Bam- ' - ' - ■ - ----- " ■ - _ - - .,.,.

oi-alorin:- ■ ^ . - • ■ in

1SS7, VciL m, piTopcised maamly tio fiawi omt tlte Miifliaiem«e icttf tlbe sWie aaad onf tftw tmnaie of fieffiLng

• - . ■ ■■ -■ _-■■' '■ - ,-■,--- . , — -. T-- - - — ...-ut

, , ... _ ■ . - .re

giK^^ima mwka- sdmaiian- wmdalaoms <Dt' sitie, ipea'tetinly beaitiiiij' amd t. _ , ai

. - - . - = -■ - .re = fi2

siq. iin. cross- sectiom ) and 'were T*!Stie(i ioi' tn^ijon, tieiusK>n, t-i ■ - .te

sti<-k<'>f eaieib ti-ee, specdaJDv pi'epared for tbc pturpose, am invt .-.. ._ - . .. of

tliemti(liamir.al lelasTwaty amd st3"emgtb)amd t.l>e j'ilbjsi<sJ idemsin ies, in order
tc» iitaidei- tlie resiits &&m <»ti*er eii>eiriiQemts ocmajiairable-

24

Bauscliins'er tbiiiid that wintci-felled wood of these couifers was lT) per eeut stionger than the
summer felled, if they are both used immediately after felliug, but that this difference passes away
with seasoning. Heclaims a direct proportion between strength and density (or weight of the dry
liber), which he ventures to formulate thus:

Crushing strength per cubic inch = 6.35 D - 0.635, where D denotes density of wood with 15 per
cent moisture, calculated upon the dry wood. He considers crushing tests, using test pieces 6
inches high, as the most satisfactory for tiudjer.

Altogether the work of Bauschinger ranks as one of the best and most caretiil researches in
this direction, and has to some extent served as a basis for the work now proposed on American
timbers. Further illustrations of the results of Bauschinger's work will be found further on in this

bulletin.

Although not undertaken for the ]iuri)osc of determining any relation of mechanical and phys-
ical properties of timbers, we may here mention, on ac.'ount of careful methods, the tests performed
by David Kirkaldy, of Loudon, commented upon in an interesting publication entitled Illustra-
tions of David Kirkaldy's System of Mechanical Testing, by Wm. G. Kirkaldy, 1891.

It is interesting and gratifying to note liere that almost simultanecmsly, but without knowledge
of the fact, both the Governrae"nts of Prussia, and of the United States in the present proposed tim-
ber investigations conceived the necessity of more careful, painstaking, and comprehensive work in
timber physics than has been attempted before.

With the careful and circumsi)ect manner which chanuterizes all tlic (loverument work of
Prussia, before engaging fully ui)on the main work, a ])reliminary investigation into methods was
determined upon in 1884, when a special conimission was charged by the Minister for Agricultuie,
Public Lands and Forests to determine upon a working jilan.

The results of this preliminary investigation, in which three pine trees were most carefully
investigated, were published in 1889 as. a report by M. Kudeloft', first assistant of the Eoyal Tech-
cal Exi>eriment Station, at Berlin. IJi)ou the basis of this investigation a plan for the executiou
of the principal work has been elaborated. Although this preliminary work was not known to the
writer when devising similar work for Ameri<-au timbers, it appears that in the main the working
plans resemble each other closely with the one exception, namely, that the need of i)ractically
applicable results has here been kept in the foreground. We have not spent time to arrive at sat
isfactory methods befoi'c proceeding to the main work, but expect to improve the methods as the
work i)roceeds, meanwhile accunuilating valuable and useful data.

In regard to the mechanical properties which adapt wood to building, construction, and engi-
neering purposes generally, there exists since (Ihevandier and Wertheim a considerable, rich, and
varied mass of results of experimentation. We hare, hoirerct; hardhj Jhiinil vioir thun the meth-
ods of investigation and a few examphs to illustrate them. To satisfy scientife inquin/ more fully
will require a considerable amount of mental and peeiiniari/ effort, ahieh should be si/stenuitiealli/ ear-
ned on after a well-dinested plan like thai now inaugurated in the Forestry JUrision, and not be
dependent on aevidental opportunity.

The knowledge of other groups of properties is in some respects still further removed fi-om
the goal that it is desirable to reach. The least has bec'n done with regard to the scientific develop-
ment of technology. While Habtig, at Dresden, has taught how to test wood- working machines
with reference to their effectiveness, nobody yet has tried to determine quantitatively the working
(pialities of wood in such a manner that the expenditure of energy necessary in t heir working could
be determined beforehand; nobody has yet discussed the connection of these degrees of quality
with the mechaiucal and physical properties and with the structure and chenustry of wood.

Carl KARMAi!sii,the celebrated technologist, who raised descriptive technology to tlic rank
of a science, laid the foundation for the discussion <if all technical jiroijerties which stand in rela-
tion to the working and use of wood in the industries in his celebrated stantlard work, Han(ll)uch
der mechanischeu Technologie (Handbook of Mechanical Technology), 1st ed., 1837; 5tli ed.,
187."); last edition, enlarged by II. Fisher in 188S. In this work elasti<'ity and even strength are
considered of less moment than density, hardness, deavability, change of volume, which are of so
much account in shaping and in keeping in shape wood structures. The main merit of his work
lies in the comprehensive representation of all the reliable old and new data and in bringing to-

25

getlier till' experiences wliich had aceiiiiiiilaleil in rin^ nieeiiaiiicai, iihysical, and ciieniieal treatment
of woods and in re.siard to 1 heir iJioperlies. 1 lis tollowers, E(ii5i;i; T Uovkk, (lichibneh dec veiyleicli-
endeii mechauischen Teehnoh)j;ie, 1878), Franz StObchkn-Kiuciiner (Karniarseh-llecrens tech-
nisehes Woerterhneh), (hird edition, lSS(i, and Prof. A. Ledkiuir (Die Vera Hx-itunu- des llol/.es aiif
ineelianiseheni Wege, 1.S.S1), could use alieadythe \vorl< of the foresters and Ixitanists, Niirdlinyer,
Dr. Julius Wiesuer, Dr. R. Hartig, Theodor Hartij^, etc. A good eouipihitory woik ou the pro[i-
ertiesof wood, unieli used and cited in teclniiealcirch's, is IttnoLPii (jOTTGki'heu's I'hysisehe und
cheniische IJescliatlenheit der llaunniterialien (IMiysical and Ciieinieal ti>ualities of Building 31ate-
rials), third edition, IJerlin, ISSO.

An entirely modern idea of the part which the properties of wood play in technological regard
is presented by Ledebur, who separates them into " working proi)erties" ( Arbeitseigeuschalten ) and
"technological })ropertics" ((rewerl)seigenschaften).

In addition to those, authors who developed timber physics in the mechanical direction, a num-
ber of botanists must be mentioned who made a specialty of tlie study of wood in its anatomy,
physiology, and histology, with the use of the microscope.

Dr. JuLirs VViesnkk, of Vienna, gave a new form to this branch of investigations and placed
it on a scientific basis. His main works in this field are, Einleituug in die technisclie Microscojjie
(Introduction into Technical Microscopy), Vienna, 1807, and Die KohstolVe des PHanzcnreiclis
(The raw materials of the Vegetable Kingdom), Leiijzig, JS7.'J. In the latter work for tlie first time
in an extensive manner were given the characteristics for the discrjmiinition of the different kinds
of wood, their phy~sical jiroperties and their use, and numy current misconceptions were shown up
and permanently removed.

Dr. J. MoELLER, distinguished by his excellent "(Jontributions to the Comparative Anatomy
of Wood,'' and by other studies, published in 1883 his vei'y valuable monogra])h, Die Kohstott'e di^s
Tischler-nnd Drechsler-Gewerbes, 1 Theil, das Ilolz (Kaw Materials of the Cari)enters' an<l Turners'
Industry, part I, Wood), in which were discussed in an ai)t manner botanical as well as technical
points.

The following botanists also furnished various contributions : Boehni, R. and Th. llartig, I loenel,
Reinke, Rossmann, linger, Sanio, Schacht, Weiss, Willkomin, and many others.

Nordlinger, too, enriched the literature, after the appearance of his iimin work, with sjjccial
studies, e. (/., Der Holzring als Gruudlage des Baumkorpers (The Annual King as basis of tlie body
of the tree), Stuttgart, 1872. R. Haktig investigated green and dry weight, etc., the water con-
tents and the shrinkage of pine timber (Berlin, 187-4), and published in 18.S.") the excellent mono-
graph Das Holz der deutschen Conifereu (The Wood of the German Conifers). J. Sachs pub-
lished his investigation into the Porositiit des Holzes (Porosity ()f Wood), Wiirzburg. 1877, etc.

In an api^endix will be found in addition a list of works which serve the needs of the practice
immediately and the popularization of tlie science, containing many valuable data, besides refer-
ences to articles bearing on the sciences of tindjer physics.

I!y far the greater part of the work has been done by Gernnin investigators, although valuable
sporadic additions have been made by Fren(;h, English, and American workers.

Of Knglish publications which tr(!at broadly on the subject in connection with other mailcis
Professoi' Uankink"s .Manuals of CMxil Engineering, of ^Vpplied .Mechanics, and ol -Machinery and
Millwork and Trkd(K)Ld's Cari)entry are ])erhai)S best known.

One of the newest and best publications on the general subject of testing is that of W. C.
Unwin, The Testing of Materials of Construction, London, 1888, which besides a general di.scnis-
sion on the pro])erties of inatei-ial and of methods and nia<hinery for testing, devotes fourteen
l)ages to timber especially, in wliicli Bauschinger's and Professor Lanza's experiments are discussed
at lengtli.

In addition there may be mentioned, besides the references made in the foregoing historical
account, Tnos. LAbLETT's Timber and Timber Trees, London, 187;"). Tests on large beams were
made by Lystee, engineer in chief of Mersey Docks and Harbor Board, recin-di'd in Engineering,
London, volume 10, 1S7."», and by McCi.ii;E, Ct.ark, a7i(I <!raiiam; references to these are fouiul
in Burr's Elasticity and Resistance of the Materials of Kngineering.
17241— No. (i 1

20

AMERICAN WORK.

While it may be possible to work out the general laws of relation lietweeu physieal aud
mechauical properties on material of European origin, for practical jiurposes we can uot rely upon
any other data thau those ascertained from American timbers, and so far as dependence of qiuil-
ity on conditions of growth are concerned this truth is just as jiatent. Although in the United
States probably more timber has been and is being used than in any other country, but little work
has been done in the domain of timber jjhysics.

Among the earliest American experiments falling in the domain of timber physics, may be
cited those of Marcus Bull, to determine "the comparative (luantities of heat evolved in the
combustion of the principal varieties of wood and coal used in the United States for fuel," nuide in
the years 182;5 to 1.S25 and published in 1826. Here the experiments of La\oisier, Crawford and
Daltou, aud Count Rumford on similar lines are discussed and followed by an able series of exper-
iments and discussion on American woods and coals.

The only comprehensive work in timber physics ever undertaken on ^Vmericau timl)ers is that
of Mr. T. P. Shabples, in connection with the Tenth Census, and published in 1SM4, vol. ix
on the Forests of North America. Comprehensiveness, however, has been sought rather in
trying to bring under examination all the aborescent species thau in furnishing fuller data of i)rac-
tical applicability on those from which the bulk of our useful material is derived. "The results
obtained," the author says, "are highly suggestive; they must not, however, be considered con-
clusive, but rather valuable as indicating what lines of research should be followed in a more
thorough study of this subject."

Not less than 412 species were examined in over 1,200 specimens. The results are given in
live tables, besides four comparative tables of range, relative values, averages, etc. The specimens
were taken "in most cases from the butt-cut and tree from sap and knots;" the locality and soil
from which the tree came are given in most cases, and in some its diameter aud layers of heart and
sapwood; determinations were made of specific gravity, mineral ash per cent, and fi-om these data
fuel values were calculated.

The specimens tested were "carefully seasoned." P\>r transverse strain they were made 4
centimeters (1.57 inches) scpiare, and a few of double these dimensions, with 1 meter (3.28 feet) span.

One table illustrates "the relation between the specitic gravity and the transverse strength of
the wood of species, upon which a suflicieut number of tests has been made to render such a com-
parison valuable." This table seems to show that in perfect specimens weight and strength
stand in close relation. A few tanning determinations on the bark of a few species are also given.

The object of the work as stated, namely, to be suggestive of a more thorough study of the
subject, has certainly been fully and creditably attained. Of compilatory works, for use in prac-
tice aud for refercnice, the following, published in the United States, may be cited :

De VoLSON Wood: Kesistauce of Materials (1871), containing rather scanty references to
the work of Chevandier aud Wertheim.

li. G. Hatfield: Theory of Transverse Strain (1877),which, besides other references, contains
also twenty-three tables of the author's own tests on white i)ine, Georgia i)ine, hemlock, spruce,
white ash, and black locust, on sticks 1 by 1 inch by l.C feet in length.

William H. Bure: The Elasticity and Kesistanceof Materials of Engineering, third edition,
1890, a comprehensive work, in which many references are made to the work of various American
experiuienters.

Gaetano Lanza, in Applied Mechanics, 1885, lays especial stress on the fact that tests on
small select pieces give too high values, and quotes the following experiments on long pieces. He
refers to the work of Capt. T. J. IiODMAX, U. S. Army, published in Ordnance Manual, who used
test pieces 25 by 5i| inches and 5 feet length without giviug any reference to density or other facts
concerning the wood ; and to Col. Laidley's U. S. Navy tests (Ex. Doc. 12, Forty-seventh Cougi-ess,
first session, 1881), who conducted a series of exi)eriments on Pacific shipe timbers, "white and
yellow pine," 12 feet long and 4 to 5 by 11 to 12 inches scpiare, giving also account ol' density and
average width of rings.

Lastly, the iiuthor's own experiments, made at the Watertown Arsenal for the Boston Mauu-
factun-rs' Mutual Fire Insurance <;'ouii)auy, on tlie columnar strength of "yellow i)ine" aiul wliite
oak, 12 feet long and C to 10 indies thick, are brought in sujiport of tlie claim that such tests show-
less tlian half the unit strenglh of those on small pieces; data as to density, moisture, or life his-
tory of the specimens are everywhere la(-king.

R. H. Thurston, Materials of Engineering, 1882, contains, perhajjs, more than any other
American work on tlie subject, devoling. in Chapters ii and in. 117 jiages to timber and its
strength, and in thecliai)ter on I'^uel several pages to wood and ciiarcoal and the products of
distillation. It also gives a description of some twenty five kinds of American and of a few
foreign timber trees, witli a (lescri[)tion of tlie structure and their wood in general; directions for
felling and seasoning; discusses briclly shrinkage, eiiaractei'istics of good timber, tiie inliucncc of
soil and climate on trees and their wood, and of the various forms of d(^eay of timber, methods of
preservation and adai)tation of various woods for vai'ious uses, nuu-h in the same maniuT as Kan-
kiue's Manual of Civil Engineering, from which many conclusions are adopted. The author refers,
besides foreign authorities, to the following American investigations:

Gr. H. Corliss (uni)ublished?) is quoted as claiming thiit proi)ci' seasoning of hickory wood
increases its strength by 15 per cent.

R. G. Hatfield is credited with sonic of the best exiieriinents on siieariiig strength, published
in the American House Carpenter.

Prof. G. Lanza's experiments are largely reproduced, also Trautwinc's on shearing, and some
of the author's own work on California Sjiriice, Oregon I'iiie. and others, esjiecially in torsion,
with a specially constructed machine, an interesting plate of strain diagrams accompanying the
discussion.

In connection with the discussion on the influence of iirolonged stress by the author, there is
quoted as one of the older investigators Herman Haux)t, whose results on yellow lu'ne were ]nih-
lislied in 1871 (Bridge Construction).

Experiments at the Stevens Institute of Technology are related, with thi^ important conchisiou
that a load of 60 per cent of the ultimate strength will break a stick it left loaded (one small test
piece having been left, loaded fifteen months with this result).

Ill addition the following list of references to American work in timlx^r ])liysic,s is here inserted,
with a regret that it has iiotbeen i)ossiblt! to include all the stray nol(^s which maybe in existence
but were not accessible. Those able to add further notes are invited to aid in making tiiis refer-
ence list complete.

Abbott, Arthur V. TListinj; macliiucs, their history, coustruction, aud use. Witli illustrations of machines, includ-
ing that at Watcrtowu Arsenal. Van Xostrand's Magazine, vol. 30, 1883, ]>p. 204, 325, 382, 477.
Day, Frank M., University of Pennsylvania. The microscopic examination of timber with regard to its 8treu),th.

Read before American Philosophical Society, 1883.
Estrada, E. D. Kxperiinents on the strength aud oth(!r properties of Cuban woods. Investigations carried uu in

the laboratory of the Stevens Institute. Van Nostrand's Magazine, vol. 2i), 1883, \>\<. 417, 141.

Flint, . Report of tests of Xicanigua woods. .lourual of Fraulcliu Institute, Octidirr, 1887, pp. 289-31.").

Goodale. Prof. George L., Harvard rniversity. Physiohigical Hotany, 188."i. chapters 1, 2, 3, .">, 8, 11. and 12.
Ihlseng, Magnus C, Ph. D". On the iiindiiliis of elasticity in sonic AmcricuTi woods, deterniiiiid by viliration. \ai)

Nostrand's Magazine, IS), 1S78.
— . On aniodc of measuring the velocity of sounds iu woods. Head licfore the National Academy of Science,

1877; published in ,\nieriiMU .lournal of Science and Arts, vol. 17, lS7i(.
Johnson, Thomas II. I)n the strength of columns. Paper read at annual rorivi'ution of American Society of Civil

Engineers, 188.5. Transactions of the Society, vol. 15.
Kidder, F. E. Experiments at Maine .State Collegi'ou Iransversi; strength of southern ;nHl \\ liile jiine. VauNostrand'a

Miigazine, vol. 22, 1879.

. Experiments with yellow and white pine. Van Nostrand's Magazine, vol. 23, 1880.

. Experiments cm the strength aud stitfness of small spruce beams. Van Nostrand's Magazine, vol. 24, 1880.

. Influence of time im bending strength and elasticity. Journal of Franklin Fnslitute, 1882. Proceedings

Institute of Civil Engineering, vol.71.
L.anza, Gaetauo, professor Massachusetts Institute of Tiu'hnology. .Viblri'ss bclore American Society of Mechuuiual

Engineers, describing the .")l),00()-i)ound testing miicbiuc at Watcrtown Arsenal and tests of strength of large

spruce beams. Journal i>l' l.'ranUliM lusti(u^(^, ISSIJ.

28

. Report to Boston Manufacturers' Mntual Fire Insiirauee Company of tests made with Watertown machine

on columns of pine, whitewood, and oak of dimensions nsed in cotton and woolen mills. See summary and
tables of same in Burr's Elasticity and resistence of the materials of engineering, p. 480.

Macdonald, Charles. Xecessity of government aid in making tests of materials for structural purposes. Paper read
before the American Institute of Mining Engineers. Van Xostrand's Magazine, vol. 27, 1882, p. 177.

Norton, Prof. W. A., Yale College. Results of experiments on the set of bars of wood, iron, and steel after a trans-
verse set. Experiments discussed in two papers read before the National Academy of Sciences, 1874 and 1875.
Published in Van Nostiand's Magazine, vol. 17, 1887, p. 531.

. Description of machine used is given in proceedings of the A. A. A. S. eighteenth meeting, 1869.

Parker, Lieut. Col. F. H., U. S. Ortlnance Department. Report of tests of American woods by the testing machine,
United States Arsenal, Watertown, under supervision of Prof. C. S. Sargent, for the Census Report, 1880. Senate
Ex. Doc. No. .5, Forty-eighth Congress, first session, 1882-'83.

. Report of experiments on the adhesion of nails, spikes, and screws in various woods, as made at Watertown

Arsenal. Senate Ex. Doc. No. 35, Forty-ninth Congress, first session, 1883-'84, and in report on tests of metals
and other materials for industrial purposes at Watertown Arsenal, 1888-'89.

. Also in report on tests of iron, steel, and other materials for industrial jiurposes, at Watertown Arsenal,

1886-'87, pp. 188, 189.

Report on cubic corapre.ssion of various woods, as shown by tests at Watertown Arsenal, 1885-'86, in repf)rt

on tests of metals, etc., for industrial purposes.
Philbrick, Prof. Iowa University. New practical forniulas for the resistance of solid and built beams, girders, etc.,

with problems and designs. Van Nostrand's Magazine, vol. 35, 1886.
Pike, Prof. W. A- Tests of white pine, made in the testing laboratory of the University of Minnesota. Van Nos-
trand's Magazine, vol. 34. 188.5. p. 472.
Rothrock, Prof. J. T., University of Pennsylvania. Some microscopic distinctions between good and bad timber of

the same species. Read before American Philosophic ."society.
Smith, 0. Shaler, c. K. Summary of results of 1,200 tests of fuU-size yellow pine columns. See W. H. Burr's

Elasticity and Resistance of the Materials of Engineering, pp. 48.5-490.
Thurston, Prof. R. H., Cornell University. The torsional resistance of materials. .Journal of Franklin Institute, vol.

&5, 1873.

. Experiments on torsion. Van Nostrand's Magazine, July, 1873.

. Experiments on the strength, elasticity, ductility, etc., of materials, as shown by a new testing machine.

Van Nostrand's Magazine, v<d. 10, 1874.
. The relation of ultimate resistance to tension and torsion. Proceedings of lustitnte of Civil Engineers, vol.

7, 1878.
. The strength of American timber. Experiments at Stevens Institute. Paper before A. A. A. S., 1879.

Journal of Franklin Institute, vol. 78. 1879.
. Effect of prolonged stress upon the strength and elasticity of pine timber. .Toumal of Franklin Institute,

vol. 80, 1880.
. Influence of time on bending strength and elasticity. Proceedings A. A. .\. S., 1881. Proceedings Institute

of Civil Engineers, vol. 71.
Watertown Arsenal. Summary of results of tests of timber at. in Ex. Doc. No. 1, Forty-seventh Congress, second

session. See Burr's Elasticity and Resistance of Materials of Engineering, pp. 486 and .535.
Wellington, A.M., c. E. Experiments on impregnated timber. Railroad Gazette, 1880.

CONCLUSION.

WTiile it may appear from this brief review of investigations and publications that our
knowledge of timber physics is not qnit<» barren, yet we are only at the outstart of exact inve.sti-
gatiou, and especially for our American timbers even the first practically aiiplicablc reliable data
are lacking, not to sjteak of laws of interrelation between phy.sical and meclianical ]iroperties or
conditions ot growth. We find then here altogether a wide field for scientific investigation,
promising results of highest practical value.

ORGANIZATION AND METHODS OF THE TIMHI'R liXAMlNATIONS IN THE DIVISION

OF FORESTRY.

The (imlior examinations recently be.iinn under tiie direction of the Division ol' Foicsiry have
for their object to determine more precisely than has ever been done the mechanical, physical, and
chemical properties of the most important American timbers and the relation of these iiropcrdcs
to each other. IJesides more reliable data rejiarding the properties of onr princi])al timbers, tlicrc
i.s to be gained from this investifiatiou a means of determinins' (piality by the examination of
physical appearance and structure, aud of establishing- an interrelation between (|nality and
conditions of growth.

To define the objects of the work more in detail, some of tlic (pu'stioiis which it is expected
ultimately to solve may be formulated as follows: What are the essential working properties of
onr various woods and by what circnmstances are they inthwiiccd ? Ibtw does age, rapidity of
growth, time of felling, and aftertreatnient change (iiuility in (liU'crciit tindx'rs? In what relation
does structure stand to (juality? How far is weight a <Titciion «il' sticngth.' What macroscoi)ic
or microscopic aids can he devised for deternuning (piality from |)hysical examination:' What
difference is there in wood of different parts of the tree? IIow far do climatic and soil ((inditions
influence quality? In what respect does tapping for turpentine afl'ect (piaiiiy of pine timber.'

There are four departments necessary to carry on the work as at present organized, namely:

(1) The collecting department.

(2) The department of mechanical tests.

(3) The de])artment of physical and microscopic, examination of the test material.
(-1) The department of compilation and final discussion of results.

The region of botanical distribution of any one species that is to be investigated is divith'd
into as many stations as there seem to be widely different climatic or geological ditVerences in its
hal)itat. In each station are selected as many sites as there seem widely different soils, elevations,
exposures, or other striking conditions occupied by the sjjecies. An expert collector describes
carefully the conditions of station and site, under instructions and on blanks ap])ended to this
rc^jort. From each site five mature trees of anyone s])ecies are chosen, four of which areavei-age
representatives of the general growth, the fifth, or "check" tree, the? best de\('loi)e(l that can he
f(mud. The trees are felled and cut into logs of merchantable size, and from the butt end of each
log a disk 6 inches in height is sawed. Logs and disks are marked with numbers to indicate
luimber of tree and nnml)er of log or disk, and tlu^ir north and south sides are marked ; their lieiglil
in the tree from the ground is noted in the iccord. The disks are also weiglied immediately, then
wrapjx'd in oiled paper and |>ackinu pajiei', and sent by mail or ex])ress to the labr»ratory, to serve
the ])ur]ioseof (jhysical and structural examination. .Some disks of tlie limhwood and of younger
trees are also collected for otiier physical and [)hysi(dogical investigations, and to serve with flu-
disks of the older trees in studying the rate of growth and other problems. The arduous work of
collecting has been done hitherto chieliy by Dr. Charles Mohr, of Mobile, Ala., and has been con-
fined so far mainly to the (•ollecfion of i)ines and oaks from Alabama, of which during the year one
hundred aiul forty-nine trees were collected, luadditmn. twenty-two trees of white pine lidni
^^'isconsin were collected.

29

30

The logs are shipped to the test hiboratory at St. Louis, iu charge of Prof. J. B. Johnson, and are
there sawed and prepared for testing, carefully marked, and tested for strength, as described fur-
ther on. Up to the time of writing some twenty-six hundred tests have lieen made.

The fact that tests on large pieces give different values from those obtained from small pieces
being fully estabhshed, a number of large sticks of each species and site will be tested full length in
order to establish a ratio between the values ol)tained from the different sizes. Part of the material
is tested green, another part when seasoned by various methods. Finally, tests which are to
determine other working qualities of the various timbers, such as adapt them to various uses, are
contemplated.

I consider it my duty to state here that through the energy and devoteil interest of Professor
Johnson alone has it been possible to carry this work into execution, since he provided by personal
and private endeavor the entire outfit of the test laboratory, and with much financial risk organized
the testing work.

The disks cut from each log and correspondingly marked are examined at the botanical labora-
tory of the University of Michigan, at Ann Arbor, by Mr. Filibert Koth, who has prepared himself
for this work, requiring great care and painstaking, by several years' preparatory studies. An
endless amount of weighings, measurings, countings, computings, nucroscopic examinations, and
drawings is required here, and recording of the observed facts in such a manner that they can be
handled. Chemical investigations have also been begun in the Division of Chemistry of the Depart-
ment of Agriculture, the tannic contents of the woods, their distribution through the tree and their
relation to the conditions of growth forming tlie first series of these investigations.

It is evident that in these investigations, carried on by competent observers, besides the main
object of the work, much new and valuable knowledge unscmght ibr nnist come to light if the
investigations are carried on systematically and in the comprehensive i)lan laid out. Since every
stick and every disk is marked in such a manner that its absolute position in the tree and almost
the absolute position of the tree itself or at least its general condition and surroundings are known
and recorded, this collection will be one of the most valuable working collections ever made, allow-
ing later investigators to verify or extend tlie studies.

Although the work as now organized has been carried on for hardly a year, the niunber of
definite problems which present themselves and are destined to be solved by it is quite astonish-
ing. Besides the general examining and testing species by species, tliere become, therefore, neces-
sary special series of investigations. For instance, the inlluence of seasoning on the strength of
timber will form such a special series presently to be undertaken. The influence on the quality
of the wood of tapjang the Southern longleaf ])ine for turpentine is a series on which we are now^
engaged, and a brief resume of the most important results of which has been i)ublished.

The influence of the length of service upon construction members will form another series as
material can be obtained. Altogether there is o])ened up an almost endless field of useful work,
the richest mine of unexplored knowledge, the importance of which can hardly be overestimated,
for after all, though we in the United States are slow to realize it, wood is our most important ma-
terial of construction, and increased knowledge regarding it must aftect, directly or indirectly, Q\ory
conceivable interest.

By and by it is expected that the number of tests necessary may be reduced considerably,
when for each species the relation of the diflerent exhibitions of strength can be suflnciently estab-
lished, and perhaps a test for compression alone fiu-uish sufficient data to compute the strength iu
other directions.

31

WORK AT THE TEST LABORATORY AT ST. LOUIS, MO.

(Wriltcii liy rrof. .1. I!. Jdii.vsuX.)
SAWIMG, STOKING, AND SEASONING.

On arrival ulilic lo^s in St. Louis tlu'val■(^ sent to a> .sawmill and cut iiitu sticks, as sIkiwh in
Figs. 1 to 4.

In all cases the arraiiucnicnts shown in Fius. 1 and L.' arc used, cxcc])t when a detailed stiulvol"
the tiuil)er in all parts of the cross section ot the loi;- is intended. A few of the most iicrfect logs
of each species are cut up into small sticks, as shown in I'igs. .3 and 4. The logs tested foi' deter-
mining the effects of extracting the turpentine from the Southern jiitch i)ines were all cut into small
.sticks.

In all cases a " .small stick" is nominally 4 inches .square, but when dressed down for testing
maybe as small as 3i inches s(iuare. The "large sticks" vary from (I by ll' to S by k; inches in
cross-section.

All logs vary from lli to 18 feet in length. They all have a north and south diametral line,
together with the number of the tree and of the log plaiidy ni;nked on their larger or lower ends.

The stenciled lines for sawing are adjusted to this north and .south line, as shown in the figures.

•>5

Each space is then branded by deep dies with three numbers, as for instance thus: "2, which signi-

4

fles that this stick was number 4, in log 2, of tree 25. A facsimile of the stenciling is recorded in
the log book, and the sticks there numbered to corres]>ond with the numbering on the logs. After
sawing each stick can be identitied and its exact origin dc^termincd. These three numbers, then,
become the identification marks for all .specimens cut from this stick, and they accompanx the
results of tests in all the rec(U'ds.

The methods of sawing .shown in Figs. 2 and 4 are called ''boxing the heart;" that is, all the
heart portion is thrown into one small stick, which in practice may be thrown away or put into a
lower grade without serions loss. In imi)()rtant bridge, lloor, or roof tindiers, the heart should
always be either excluded or "boxed" in this way, since its ])resence leads to checking :ind impairs
the strength of the stick.

After .sawing, the tiinbers are stored in the laboratory until they are tested. The "green
tests" are made usually within two montlis after sawing, whilethe "dry tests" are n)ade at various
subsequent times. One end {(iO inches) of each small stick is tested green, and the other end
reserved and tested after seasoning. The seasoning is luistened in some cases by means of the
drying box shown on Plate i. Thetem])eratureof the inllowing air in this drying box is kept at about
100° F., with, suitable precaution against checking of the wood, and the air is exhausted by means
of a fan. The air is, therc^ibre, .somewhat rarefied' in the box. The temperature is at all times
under control. It operates when the fan is running, and this is only dui'ing working hours.

32

THE LABORATORY.

The testing laboratory is the basement story of the gymnasium building of Washington Uni-
versity. Its dimensions are 71 by 46 feet, with one corner partitioned off, as shown on the floor
plan, Plate i. The net area used for laboratory purposes is 2,500 square feet. All the apparatus
suspended from the ceiling, as shafting, steam pipes, exhaust tan, etc., is shown in dotted lines.

The apparatus pertinent to the timber tests consists of a 1,000,000-pound columu-testing
machine; one 100,000-pound beam-testing machine, one 1()(»,00(> pound universal testing machine,
of Riehle's "Harvard" pattern; one small portable beam machine, one 6-horse power Brayton coal-
oil engine, one 4-horse power steam engine, one planer and one lathe, for ironwork; one planer,
one band saw, and one cutting-off saw, for shaping and dressing wood specimens; suitable scales,
drying ovens, etc., for the moisture and specific gravity tests; the drying box with its steam coils
and exhaust fan, and all the necessary appliances, benches, tools, desks, etc., including a Thatcher's
slide rule for making the computations. The timber is stored in various parts of the room not
otherwise utilized. Ultimately a warehouse will have to be obtained for storing the broken speci-
mens.

The cross-hn'filiufj texts.

Large /x'rtwi.s.— The large beams are tested on the large beam-testing mac^hine shown on Plate ii.
The base of this machine consists of two long-leaf ])ine sticks {Pinm p<(hintris), 6 inches by 18
inches by 24 feet long, with a steel plate three-fourths of an inch Ity is indios by 20 feet long, all
bolted up as one beam. The power is applied by hydraulic pressure upon a plunger below, to the
crosshead of which are attached the two side screws, on which the u])])er crosshead is moved by
sleeve mits and spur gearing. The beam to be tested rests on pivots at the ends, placed on top
of the base beam, and the upper crosshead is moved down liy means of the gearing until the central
pivot attached to it comes in contact with the beam, or rather witli the distribution blocks placed
on the beam at this point. The test then begins, the power originating in a d.mble-plnnger pump,
operated by hand or by steam power in another part of the rt)om.

To prevent the pivots or "knife-edges " from crushing into the timber, it is necessary to make
the contact at both ends and center, first upon a cast-iron plate, then through longer Avooden
blocks to the timber. The center block is curved somewhat on the lower side, to allow for a con-
siderable deflection in the beam when nearing its maxinuim load.

In the tests of all beams, both large and small, the load is put on at the same uniform rate, so as
to eliminate the time effect, which is very great in timlier tests. The load on the small beams is
increased at such a rate as to produce an increase in the deflection of one-eighth inch per minute
without any pause until rupture occurs. This causes rupture in from ten to fifteen minutes time.
The load is rend off wh(ni it reaches certain even amounts, and an observer notes the corresponding
deflection without stopping the test. The time required for the large lieam tests is about the same,
the deflection rate being greater when the total deflection is expected to be greater, as is the case
with 4 by 8 inch sticks 12 feet long. The deflections of the large beams are observed upon a paper
scale, graduated to inches and tenths, glued to a i)iece of mirror, which is tacked to one side of the
stick at the center. A fine tliread is stretched, by means of a rubber band, over nails driven into
the side of the stick above the end supports on the line of the neutral axis. This string or thread
is moved about an inch away from the surface of the timlier, and all parallax, or error of reading
from an oblique position of the eye, is avoided l)y keei)ing the eye where the thread and its image
in the mirror coincide and form one and the same Une. The readings are taken to inches and
hnndredths by estimating the tenths of the graduation spaces on the scale.

The loads are weighed on the large universal testing machine in another part of the room.
This is done by having both machines connected up to the same pump, blocking the weighing
machine so that the load on its plunger is transmitted to the scales and weighing beam, and then
pumping into both machines. The plungers are of exactly the same diameter; they have similar
leather cu]) i>a(kiiig, and hence the error -of this method is simply the difl'erence in the friction of
the two plungers in their packing rings. To test the accuracy of this method, and to (h'termine
the error, if any, at any time, a nest of calibrating springs, sliown on Plate ii, was made and tested
first on the limery machine at the United States Arsenal, at Watertown, Mass. The loads were

33

found which conospomlod (<• f;ivrii dptlfclions, <.r in othor wonls the stress diafrram of these
springs up to a. o(l,(l(M)-p()inid load, which corrospoiids to a litth- more tliaii (uie inch dastic dctloctioii.
By repeating- this test ou the l()(»,0(H>-pouiiil universal or weighing machine, and then on the huge
beam machine, nnd i)h«tting the. stress diagianis ohtaiiied froiii each, not only can tliese rnacliincs
he compared with eacli other, but botii can l)e coini)ared or calii)rated with tiic Emery machine at
the Watertown Arsenal.

In Fig. 5 the three curves corresponding to tlu> three m;i<-liincs are given. They are so nearly
coincident that it is shown that not only is the universal l(H>,()(M)-poiind Kiehle machine correctly
graduated, but that the method used of weighing the loads ou the beam machine by means of the
universal machine results in no appreciable error. This test can be api>lie(l at any time, and proof

Uellectiuu in iuclles.

Kk;. 5. — .Sl.iniilardizing tests with oaliliiatiii;; spiinj^s.

readings have been made at frequent intervals. The beam machine is greatly simplified by thus
dispensing with all attached weighing apparatus, which would be greatly in the way in the
handling of lai'ge l)cams sometimes weighing over 1,()(M) ])oun(ls.

tSmoll hcama. — The small beams which are nominally I inches scjuare and (in inches long
between supports are tested on the small beam-testing machine, shown on Plate iii. This machine
was designed originally for testing cast i ion beams, the load at one eml or one-half the load at
the center being weighed on a i)air of ordinary i)latform scales. The deflections are read oil' to

17244— No. « .'5

34

thousamltlis of an inch upon a micrometer screw held in the top iron crossbeam. By this means
a rigid connection is obtained, through parts not under stress, from the end supports to the center
bearings. The movement of the center witli reference to the ends is therefore obtained, regardless
of the absolute movements of the parts. The load is put on by the hand wheel and power screw,
and the weighing beam kept in balance by putting on overweights and moving the poise. Three
men are required to make this test. One moves the power screw, wliich has one-fourth inch pitch,
so as to make one revolution every two minutes, and he continues this uniform motion till rup-
ture occurs. Another keeps the scales balanced and calls off the even hundreds of pounds.
Another keeps the micrometer screw in contact with the head of the power screw, reads it for cer-
tain even hundred-pound loads called off, and records the time of each such reading to the nearest
minute, the load, and the corresponding reading of the micrometer screw. Here also the end and
center bearings are protected by iron plates large enough to prevent any appreciable distortion
from lateral compression.

After rupture occurs the stick is bored for samples from which to obtain the moisture tests,
and the uninjured ends sawed off and used for the remaining tests, as described below.

The moisture text.

The borings are taken from two holes, L'O inches from each end, and at about one third the
width of the stick, from cither side. Tliese borings are first weighed on a delicate balance then
placed in a drying oven, at a temi^eraturc of 212° F. until tliey have reached a nearly constant
weight, when they are reweighed. The dry weight is taken as the basis on which to compute
the ^percentage of moisture. Thus, if the original weight is twice the final weight, then there
was as much water as woody fiber in the stick, or one lialf or 50 per cent of the original weight
was water. But when computed on the basis of the dry weight there would be 100 per cent of
water. The advantage of computing the percentage on the dry weight is that it furnishes a con-
stant basis of comparison, whereas if computed ou the actual or wet weight the basis on which the
percentage would be computed would vary with every change in the amount of moisture.

The upccific grarity.

The specific gravity is found by taking one of the end pieces, usually i by 4 by 8 inches,
measuring carefully its lateral dimensions by calipering them at tlie middle i)oiuts of the sides
at the central section, measuring the length in a similar manner, and taking the product of these
three dimensions as the volume. From the total volume and the actual total weight, the weight
per unit volume or per cubic foot is found, and from this the specific gravity, which is the weight
per cubic foot divided by the weight of a cubic foot of distilled water. It must be understood
that all the small {i by 4 inch) beams are planed up true and rectangular b.-fore testing and
that all the crosscuts are made by a power saw so adjusted as to cut truly at right angles to the
sides. The volume can therefore be very accurately computed from the dimensions as above
described.

The tension test.

The tension test piece is cut from one end of the broken beam. It is 16 inches long, 2i inches
wide, and IJ inches thick. Its thickness at the center is reduced by cutting out with a band saw
circular segments, leaving a breaking section of some 2^ inches by three-eighths inch. This
specimen is then placed between the plane wedge-shaped steel grips, and pulled, the same as a
bar of iron, in the Universal Machine, shown on Plate iv. This simple method has been found
very satisfactory in practice, and is fuUy illustrated on Plate V. For this test care is taken to cut
the specimen as nearly parallel to the grain of the wood as possible, so that its failure will occur in a
condition of jjure tension.

The endwise compression test.

Most of these tests are made on sticks 4 inches square by 8 inches long, the ends having been
cut perfectly true and at right angles to the sides. They are tested in the Universal Machine,
the compression continuing until the stick has been visibly crushed and has passed its maxinuim
load. The crushing usually manifests itself over a plane section, by crushing down, or bending

35

over all the fibers at this section, which may b(^ citlicr a riglit or an oblicine section. The section
of failure, however, is seldom al the very end. The slij;litcst siairce of weakness may determine
its position, as a very small knot for e\am[)!c, for knots are a source of wmkness in compression
as well as in tension.

Some tests are made on colniiins t(l inches lon.^ by I inches s(|nareon ihe larfe beam machine
but these usually fail tiie same as the short bh)cks, and not liy bcndiiijif sidewise.

Compression across the urn in.

Si)eeimens 4 inches square and 6 inches long are tested in compression across the grain. An
arbitrary limit of distortion, namely .3 ])er cent of the height, has been chosen as a reasonable
maximum allowable distortion in practice. This limit is indicated in the test l)y the ringing of an
electric bell, and the load then on the specimen is called the com])ressive strengtii across the grain.
The same limit has also been found to be very near the maximum load in lateral compression,
which is also determined.

The shearing tests.

Since timber fails by shearing, or splitting, oft ener liian any other way this test becomes a
very important one. The six'cimeu is taken 2 inches s(iuare and S inches long, and rectangular
holes mortised 1 iucli from each end, and at right angles to each other, as shown on Plate V.
The specimen is then i)ulled, in the Universal Machine, by means of snita])le stiirups ami keys,
as shown in the plate. The ends are kept from spreading or splitting by iiutting on small
clamps with just enough initial stress in them to hold them in place. After one end shears
out two auxiliary hoops or stirrups are used to connect the key wiiich slieared out to a pin put
through the hole at the center of the specimen as shown. The other end is then slieared, and two
results are obtained on i^lanes at right angles to each other. In this way the shearing strength is
determined on two planes at right angles to each other.

Tests of full-sized column!:.

No set of experimental tests of timber would be complete without numerous tests on full-
sized columns. This requires a machine of not less than l,(MM),(l(M» pounds capacity, cajiable of
crushing to failure columns from 12 to 14 inches square and at least 30 feet long. Such a machine
has been built exjiressly for this work, and is shown on Plate VI. It is capable of exerting a com-
pressive force of l,(MMt,()00 pounds on a length of -'{(i feet or less. The sides or tension members of
this machine are made of four long-leaf yellow pine sticks {Pinus palustris), trom Georgia, each 8 by
12 inches and 45 feet long. The power is applied by the same hydraulic pum]> which operates
both the large beam machine and the l(Mt,0()0-pound universal machine. The loads are weiglu'd
on this latter machine the same as for the beam tests. The plunger in the column machine
has Just ten times the area of that in the weighing machine, and hence the loads in the column
tests are just ten times those indicated on the weighing beam, with a sliglit correction for the
friction differential, which has not yet been deterniined. The tail block is of cast iron, resting in
a spherical socket, which is carried on a car, and which can be held by struts resting in slots
in the timber. The outer ends of these struts !<re kept from sineading by means of tiebars, as
shown, and the whole cond)ination can be moved forward or back so as to make the distance between
face i)lates any even number of feet from two to thirty-six. The spherical socket in the tail
block will i)ioduce an accurate adjustment of the end bearings at the beginning of the test, but
after the load is on it is tliought that this joint will remain rigid, the same as a solid block, esiiec-
ially if precautions arc^ taken to increase the frictional resistanc<' between these bearing surfaces.
This spherical socket is provided to eliminate the effects of unequal shrinkage in the side tind)ers,
or any uneipialcom])ressioniu the bearing sockets, and not toserv(>as a nmnd-end bearing for the
column. When long columns are tested a part of their weight will be supported by means of lines
^nd pulleys, so as to make the test correspond to a vertical load in actual i)ractice.

36

Significance of results.

From the cross-breaking tests are obtained the cross-breaking- inodnhis of rupture, the
modulus of elasticity, or measure of the stiifuess, and tlie clastic resilience, or measure of the
toughness.

The loads and their corresponding deflections are plotted as rectinigiilar ((uirdinates, and the
modulus of elasticity and the elastic resilience are obtained from a study of this strain diagram.

The following is an example of the record made for every beam test. This is a record of a
test made on a 4 by 8 inch stick of long- leaf pine, 12 feet long, which was ])laced on supi)orts 140
inches apart.

(16
Mark /3

(1
Length, 140.0 inches.
Height, 8.04 inches.
Breadth, 4.02 inches.

CROSS-BREAKING TKST.

I Strength of Extreme Fiber,

3 Wl
where/= ,^ = 10,910 pouuils per si|U;ire inch.

Modulus of Elasticity ^ 2,070,000 pduuds per s(iuar6 inch.
Total Kesiliencc ^= 35,440 inch-pounds.
Resilience, per cub. in. = 7.83 inch-pounds
Total Elastic Resilience = 8,650 inch-pounds.
Elastic Resilience, per cubic inch = 1.91 iu(li-))ouuds.

[Number of animal rings per inch = 14.]

A
27

iigust
1801.

Load.

Beflection

/(. 7rt.

1 58

1,000

0.17

59

2,000

0.34

59

3, 000

0.50

2 00

4,000

0. BO

00

5,000

0.82

01

6,000

0. 9(1

02

7,000

1. i;i

02

8, 000

1.27

03

9, 000

1.40

03

10, 000

1.65

04

11,000

1.03

05

12, 000

2.27

07

13,000

2.85

09

13.500

3.85

Scale
reading.

11.02
11.19
11. 3.')
11.51
11.07
11.81
11.98
12. 12
12.3]
12.50
12.78
13.12
13.70
14.70

Remarks.

Top end.

Maximmn load.

15000

B

A

r

n

•

____

" '

■on

/

/

^

^"

^y

/

>

y^

y

y

r/'

/^

/

'I

•

y

f°

^

4

c

y

0

/

•

^j'

•

1'

/

sooo

s

m^

/

/

/

•

/

/

/

A

r

,,'

a

/y

_<-

n

/

■Deflection 1 in inches. K

E 4

;^7

The obseivod data arc given in the cohiinns headed "Time," "Load," and "Scale Reading."
These results are recorded on this slieet in ink as they are observed. Tlie icsult in the " l)et1(!C-
tiou" coliunn is coniimted from tlie scale reading, [t is placed next to the column of " Loads" for
convenience in i)]otting the strain diagram, which is done ou the ruled .sciuares at the bottom of
each sheet. These i)lotted results fall in all cases ou a true curve, similar to the one shown on )). 36.
The total area of this curve, 0. D. JJ., properly evaluated by the scales used, represents the total
mtniber of foot pounds or inch-iiounds of work doue upon the stick before rui)ture occurred. This
is called the Total Vronn-birakiixj licniUence of the stick, and when dixided by the volume of the
stick in cubic inches it gives approximately the total cross- breaking resilience of the stick in inch-
pounds ]>er cubic inch of timber.

A better criterion of toughness, or resistance to shock, is some delinite portion of this strain
diagram area, as 0 P K, for example. This amount of resilience or sprmg can be used over and
over again, and is a true measure of the toughness of the timber as a working (|uality. To locate
the point P, the following arbitrary rule has been followed:

Draw a tangent to the curve at the origin, as 0 A. Lay off A C=hB A, and draw 0 G.
Draw m n parallel to 0 C and tangent to the curve. Take the point of tangency as the point /',
and draw P K. The area 0 P K is then called the Relatii-c Elantic KeaUicnvc*

There is no " elastic limit" in timber as there is in rolled metals. In this respect it is like cast
iron. The point P is the point where the rate of deflection is 50 per cent more than it is at first,
and usually falls on that jiart of the curve where it begins to change rapidly into a horizontal
directi(m or where the deflection liegins to increase rapidly. The areas of these curves are meas-
ured with a planimeter and reduced to inch-pounds. Thus, if 1 inch vertically represents .'>,()()()
pounds, and 1 inch horizontally represents 1 inch deflection, then 1 square inch represents ."),0(M»x
1=5,000 inch pounds. If the area 0 I' K is 1.73 squaic inches, then the corresponding resilience
is 8,<)50 inch-pounds. This means that a weight of 100 pounds, falling St;.5 inches, or 1,000 pounds
falling 8.G5 inches, would have strained the beam up to the point P or it would have deflected it
l.(!(i inches, and the beam would have been then resisting with a force of 10,000 pounds, since /'
falls on the 10,000-pound line. If this result — !S,(i.")0 iucli-i)ounds — be divided by the number of
cubic inches in the stick between end l)earings, the result is the true Relatire Resilience in Cross-
hrcal-infi in inch-pounds per cubic inch. This result is independent of the dimensions of the test
specimen, and is therefore a true measure of the (puility of timber which is usually known as
toughness. It depends, as toughness in the usual understanding does, on both the strength and
the deflection; in fact, it is very nearly the half-product of the strength developed and the deflec-
tion produced at this particidar point P. It is i>robably the nearest ipuintitative measure of the
tonghness that can l>e arrived at.

The strength of the extreme fibre is computed by the ordinary formula —

where / = stress on extreme fibre in pounds per square inch,

W = load at center in itounds,

I = length of beam in inches,

h =: breadth of beam in inches,

/( = height of beam in in<-hes.
At the time of flnal rupture this formula by no means represents the actual facts. It assumes
that the neutral plane remains at the center of the beam till rujiture occurs, which is far from
correct. In green timber, where the crushing strength is greatly retluced by the presence of the
saj), the crushing resistance is only about one-third as much as the resistance to tension, so that
the stick invariabl.N' begins to fail on the compiession side. This causes the neutral |ilane or plane
of no stress to be htwered, and at the time of final rujiture this ])lane may be from one-fourth to
one-sixth the depth from the bottom side of the beam. The value of /<-om])uted by this formida
from a cross-breaking test, therefore, will always be intermediate between the crushing strength

'Tliis term h;is been roiued to <l(^finl■ tliis ]>;irlii'iilar ]niiti(>ii (if tlic ivsilieinH- wliirli will Ik- used t'cji i'iiiii|i:iriii)f
tlie relative elasticity or tougliuess of UiUerout limlnrs.

38

and tlK- streugth iu tciisinu. Tims tlic cinsliiii,i; strength of a givcu stitk was fonnd to be 5,820
pouuds per square iiicli, while the tensile strength was 15,780 pounds ; the cross-breaking strength
was found by this test to be 10,900 pounds.

The modulus of elasticity is computed from tlie formula—

WP^ _ WP _W P . . . . (2)

^ - IS J) I~4l)h¥~ D' 4b ¥
where E = modulus of elasticity,

and ^^ ' '' ''' '^^^ '' "^ "' ^^^' '^''^
J) = deflection of beam.

I = moment of inertia of the cross-section = -^ b ¥ for rectangular sections.

To find this modulus, a tangent line is drawn to the strain diagram at its origin, as 0 A, and
the coordinates of any point on this line used as the W and D from which to compute E.

The modulus is thus seen to vary directly as the load and inversely as tlie deflection, hence it
is a true measure of the stiffness of the material. It is the most constant and reliable property of
all kinds of engineering materials,* and is a necessary means of computing all deflections or dis-
tortions under loads.

In using the modulus of elasticity of timber for coiiipiiting deflections, it must l)e remembered
tliat in this case the time ettcct is very great (it is nearly zero in metals) and tliat this factor can
only be used to com])ute the deflection for temporary loads. The deflection of floor or loof timbers,
for instance, under constant loads is a very difierent matter, as it increases with time.

Relation between strength and stiffness.

In Fig. 6 is shown the relation loiind by Professor Uauschingert between the modulus of
elasticity (stiffness) and tlie cross-breaking strength, from tests on pine, larch, and fir timber.
Althougli the results show a wide range, there is evidently a general relation between these two
quantities, as indicated by the straiglit line ilrawn through llie plotted points. The algebraic
expression of the law shown by this line, rendered into pounds per square inch, is, in round
numbers —

Cross-breaking strength — 0.0045 Modulus of Elasticity + 4.">0. (3)

If it should be found that there is such a law for all kinds of timber, then there may be derived
an equation of this form, but with different constants, for each species.

Relation between sfrenfith ami n-cight.

In Fig. 7 is shown the relation between the crushing strength and the specific gTavity, when
both are reduced to the standard percentage of moisture, which was taken at 15 per cent.

These results are also taken from Professor Bauschinger's jmblished records of tests on Pine,
Larch, and Fir timbers, and they conclusively show that the greater the weight the greater the
strength of the timber. The law here is a well-defined one, so far as these timbers are concerned.
When rendered into English units (pounds per sq. in.), the equation of this line is:

Crushing strength = 13S0(» specific gravity — 900. (4)

when the timber contains but 15 per cent of moisture. This equation would also vary m its
constants for each species of timber.

* Tlie wide raufe of values of tlie modulus of ehistieity of tlie various metals, found in iiublislied records of
tests, must be explained by erroueous metliods of testiug.

t See PI. II, vol. 16, of Professor Bauschinger's Reports of Tests made at Government Testing Laboratory at Munich.

.'U)

800

o

o ,.

^

600

o

o

c

o

o

o^^
o^^ o

^(5

o

o

i.

400

^

o
o o

0
o o

o

'r,

o

-^

> o

1

200

1

o

1

■-11

ISO.OOO

(.'ross-breakiiij: stivii^th iu iituiosplu-ros.
Fig. G.— Relation between cross-breaking strengtli and modulus of elasticity or stifVness lor Pine, Larch, Spruce, and

Fir timber. (After Bauschinger.)

[Cros.s-broakiiig strength = 0,0045 niiidulu.s ol' elasticity + 450.]

Speeific

Fig. 7.-

giavity (n-dneed to 15 ]ier(M-ii1 iiiuisliire).
-Relation between compres.sive slrenj;ll

timber. (After UauscUinger).

and s].erilic gravily or w.-i;,'lil lor I'iuc, l..ii<-li, S|ii
Coniiiiessive Htrengtli ^ i:{,«00 siie.ifH- gravity — 900.]

and l"ir

40
Relation between the comprenxire strewjth idkI the percentaye of moisture.

In Fig. 8 are plotted .some very careful te.sts by I'rofes.sor Bauschiuger to show the relation
between the percentage of moisture and the crushing strength.

There is no question but the crushing and the shearing strength are both greatly reduced by
moisture. The crushing test also gives a very fair indication of the strength of the timber in all
other ways. In this instance four sticks were taken and sections tested flj'st green, or having an
average of .37 per cent of inoisture when computed on the wet weight, or 59 per cent of moisture
when computed on the dry weight, as is the practice in the tests made by this Department. The
sticks were then dried until there was an avei-age of 14.« per cent moisture on the wet weight, or
17 per cent of tlie dry weiglit. The remaining portions of the sticks weic further seasoned until
there remained but 8.2 per cent moisture computed on the wet weight, or II per cent moisture on
the dry weight, and then tested. This is a smaller percentage of moisture than outdoor lumber
ever reaches, as the ordinary humidity of the external aii' will usually maintaiii at least 10 per
cent of nxjisture in all kinds of timber.

When these three groups of results are ])lotted, and tlic most probable cnr\e drawn through
them, there is seen to be a remarkable increase in the crusliing strengtii wlien the percentage of
moisture falls below fifteen or twenty. The variation in strengtii abo\e tliat limit is very small.
Professor Bauschinger has published a great many such curves, all showing the same general law.
This curve illustrates tlie necessity foi- Hnding the percentage of moisture for every test of strength
made.

Professor Bauschiuger Inis published very few tests showing the relations between the cross-
breaking strength and the moisture, but Fig. 9 is a reproduction of such results as he has given.

When the percentage of moisture sinks as low as 10 there appears a wide variation of strength,
not satisfactorily explained. There would seem to l)e a law of dependence, however, but less
marked than in the case of comi)ressive strcMigth.

Relation between xpeeijie f/rorlti/ and moi^sture.

In Fig. 8 the '• specific-gravity" curve sliows the relation between the s]>ecific gravity and the
percentage of moisture. At first the specific gravity diminishes rapidly as tlie percentage of
moisture is reduced, but when this has been reduced to 15 ])er cent the specific gravity changes
very little for any further reduction in moisture. This shows that the shrinkage is insignificant
until the timber becomes nearly dry, when it swells and shrinks almost directly with the
percentage of moisture, so that the weight of a unit volume, which is a measure of the specific
gravity, remains nearly constant. This curve is also only one of a great many similar ones given
by Professor Bauschinger.

41

800

o.ao

\

D ^

^

600

\

a

■'^'^ D

\

w o.co

\

D ^

.i

a

\ °

«1

\ ^

400

^K

0.40

'fi.

i'^'

o

O

0

200

10 20 30 4 0

Percentage of moisture (ecmiputetl on the wet weight) .

l''l<i. 8. — Variation iifi'diiiprnssivo streufictli :iiicl nf specific gravity for varying purcoiitagi's of luoistiiro. Ri^siilts <iii

Scotcli I'im^ timber. (After Baiiscliiuger. )

Percentage of muisture (coniputeci 111! llif Wi-t wci-hl).
■'lO. !t.— Relation l.itwciii < losK-Iircukinjj str.iiKtli ami iier.enta>;e of moisture for Pine, Lardi, Spruce, ami Vw lim-

licrs. (After Hausehiiiger).
17244— No. U 0

42

EXAMINATION INTO THE PHYSICAL PROPERTIES OF TEST MATERIAL.

(Written by Filibekt Koth.)

The physical' examination consists in ascertaining the specific weight of the dried material,
and incidentally the progress and amonnt of shrinkage due to seasoning; the counting and
measuring of the annual rings, and noting other microscopic appearances in the growth; the
microscopic investigation into the relation of spring and summer wood from ring to ring; the
frequency and size of medullary rays; the number of cells and thickness of their walls; and, in
short, the consideration of any and all elements which may elucidate the structure and may have
influence upon the properties of the test piece. The rate of growth and other l)iological facts
which may lead to the finding of relation between physical appearance, conditions of growth, and
mechanical properties, are also studied incidentally.

CONDITION OF THE MATERIAL ON AKKIVAL.

The specimens sent by mail, and in double wrapper, oiled paper inside, have arrived in all
cases in very good condition. The journey from Alabama to Michigan occupies from two to four
days, and only in exce])tional cases arc the wrajipers worn. To determine the effect of the wrap-
per as a preventive against evaporation, several pieces were allowed to remain in their original
wrapper, and were thus weighed from time to thne.

The following figures refer to a half disk of Pinun palustris, consisting almost entirely of
sajjwood.

Date.

Oct. 24....
Oct. 20 ... .

Oct. 30

Oct. SI ... .
Nov. 2....

Loss (2.2 per cent)
Dec. 12

Loss (17.2 per cent)

Weight of

l)i(H'f!

including

1,607

1,600

1,572

1.572

1,568

39
1,330

Kemarks

ler rubbed oft' at one corner.
I'hiced on a ahelf 10 feet from a steani-licitinK coil.
AftiT weighing to-dav a ilanip cloth w a.s placid over the piece.

Cloth remaineil, but was not renioi-stencd ; it therefore became dry and wan removed.
The piece felt moist and was covered with inuld.

During the same time a piece of the same disk and weighing 823 grams at first, was left
without a wrapper in an unheated room and lost 298 grams or 3G.1 per cent. These figures
show that the wrapi)er alone reduces the evaporation to a minimum, which may well be left out of
consideration, and also that if this wrapper is reinforced by dampened cloth, a precaution always
observed during the time of working up the specimens, the evaporation ceases entirely.

SHAPING AND MAKKTNG OF THE MATERIAL.

The obiectof this work being in part the di.scovery of the differences that exist in the wood, not
only in trees of different s))ecies or of the same species from various localities, but even in the wood
of the same tree and from the same cross section, a careful marking of each piece is necessary.
The disks are si)lit, first h\U> a north and south i)iece, and each of these into smaller pieces of vari-
able size. Ill one tree all pieces were made but ;! cm. thick radially, in another 4 cm., in still others
5 cm., while in some trees, especially wide-ringed oaks, tlie pieces were left still larger. In the
conifers the outer or first piece was made to contain only sapwood. Desirable as it appeared to
have each piece contain a certain number of rings, and thus to represent a fixed period of growth,
it proved impracticable, at least in the very narrow-ringed disks of the pines, where sometimes the
width of a ring is less than 5 mm. (0.2 inch).

Some of the disks were split to a wedge shape from center to periphery, so that each smaller
piece not only reitresents a certain period of growth in ([uality, but also in quantity, thus simplify-
ing the calculations for the entire piece or disk. Other pieces were left in their prismatic form.

43

wlicii to cjilciiUitc till' iivi-iafic (Ifiisilv nf tlic (.■iitirc piece llie <leii.sit.v of eaeli smaller |iR'ce is

iimltiplied l).v the mean di.staiiceor this smaller piece Inim the center, ami the sii f the pHMluets

divided l)y tlie sum of the distances. For it would not he sufficieut to add the (hMisities of tlio
several pieces, and divide this sum by the number of ]»ieces. in which ease the central (prismatic)
pieces would inordiinitely iiitiuence the result.

For instiuice, a giveu pri.sm gave for the four sections from periithery to center the following
values :

Section.

Density.

Mean dis

tance from

center.

Product.

a
b
c
d

Total....

0.60
0.50
0.40
0.30

14

10
6
■J

8.40
5.00
2.40
0.60

1.80 1 32 16.40

The density from simple adtlition woidd be -Lf^ = .4.5, while the method as used will give

13.iJl — 51
3 2 — •'"^•

Each iJiece is marked, first by the nninber of the tree, in Arabic; sec(md, by the nnnd)er of

the disk, in Eoman numbers; ami if sjilit into small jiieces, each smaller piece by a letter of the

alphabet, tlie piece at the periphery in all cases bearing the letter «. Besides the uuniber and

letters mentioned, each ])ieee bears either the letter X. or S., to indicate its orientation on the north or

south side of the tree. To illustrate: "> — vir X. a., means that the piect; bearing the label belongs

to tree 5 and disk vii, comes ftom the north side of the tree, and is the peripheral part of this di.sk

piece. From the collector's notes the exact position of this jiiece in the tre<- can readily be a.scer-

tained.

The entire prisms sent by freight are left in the original form, unle-ss used for .sjiecial imr-

poses, and are stored in a dry room for future use.

"WEIGHING AND JTKASURING.

The weighing is done on an ajiothecary's balance, readily sensitive to 0.1 gram with a load of
more than 200 grams. Dealing with pieces of 200 to 1,000 grains in weight, the accuracy of weigh-
ing is always within 1 gram.

The measuring is done by immersion in an instrument illustrated in the following design.
V is a vessel of iron, <Sf represents one of two iron standards attached to the vessel and ])i()-
jecting above its top; B is a metal bar fastened to the cii]) -1, which serves as guard to the cup
and i)revents it going down further at one time than another by coming to rest on the standards S.
The cu]) A dips down one-.sixteenth to onti-eighth of an inch below the edge of tlie knee-like sjiout.
In working, the cup is lifted out by tlie handle which the bar />' forms, water is |)Oured into the
vessel until it overflows through the spout, tlieu the cup is set down, replacing tlie nioliile and
fickle natural water level by a constant artiticial one. Now the instrument is set, the )ian /'
is])laced under the spout, the cup is lifted out and held over the vessel, so that the drijijiiiigs fall
ba<-k into the latter, the i>iece of wood to be measured is put into the vessel and the ciiji re])laced,
and pressed down until the bar /.* i-ests on the standards iV. This is done gently to pre\-eiit the
water from ri.sing aboxc tlie rim of the vessel. This latter |irccaution is suj)erfliious where tlic cup
fits closely, as it does in one of the instruments thus far u.sed. The jian with water is then weighed,
the pan itself being tared by a bag of shot. The water is poured out, the pan wiped dry, and
the process begins anew. To work well it takes two persons, one to weigh and record. The
water pan is a .seamless tin pan, holding about l,o(>0 cc. of water and weighing only 1)4 grams.
The temperature as well as density of the water are ascertained, the latter, of cour.se, omitted
when distilled watei- is used. To maintain the water at the .same temperature it reiiuires frei|uent
changing.

In constructing the apparatu.s, care should be had that t Ik- point X is higher than lliejioint
M; if this is not the <Mse, some air. slightly comiiressed by a closely fitting cui>, .suddenly finds an

44

outlet, and carries .some, water aloiij;- with it. The accuracy of this instrument is very consitlei'al)lc
and easily tested ; its management is simple, its construction easy. Previously two ways had
been tried. In one case a similar vessel about 15 cm. diameter had been used, having a graduated
glass tube on the outside communicating with the vessel. The readings, made with a magnitier,
were facilitated by a tioat. A rise of 1 mm. requiring about 17 cub. cm. would have to distinguish
one-seventeenth of a millimeter. Without further discussing the ditticulties of this nu'thod, it may
be stated that it proved by no means satisfactory. The second way was to allow the water to flow
over a broad, short and steep spout with a clean, sharp edge, and then to weigh the water, as is
done at present. This gave much better results than the method just described, but it is a slow
method ; the water recjuires too long to arrange its level, and any slight sh< tck or disturbance readily
vitiates the experiment.

\pparatus for ili'tiTiiiiiiiiiK speiilic gravity.

DISCUSSION OF VARIOITS METHODS TO ASCERTAIN VOLUME.

Having described the mode of doing, the application of the method of measurement by im-
mersion for jiorous bodies like wood requires some consideration. The fact that it has been, and
is to-day, extensively emidoyed by the best of experimenters is certainly a recommendation, but
can not serve as an argument for its accuracy, and it appeared necessary, therefore, to resort
to spcM'.ial exi)eriments. Before describing these experiments and their results, a consideration of
the objections and their justiflcation from a general standpoint may not prove amiss. The objec-
tion of inaccuracy of the apparatus ceases at once with an instrument whose accuracy can be
demonstrated any monu^nt, and expressed in grams or i)arts of such, ^ot so with the more com-
mon objection that " wood soaks up water while the measuring is going on." This statement
generally appears to express two more or less clear notions, one implying a swelling of the wood
oil imbibing water, and thus a change of dimensions during the process of the expcnnient; tlu^
other a. soaking of water into the cell cavities anah)gous to the rushing of water into the capillary
tubes of plaster of Paris, and thus a decrease of w-ater in the vessel and a consequent inaccura(\\'
of the experiment. The correctness of the tirst of these two notions, experiment alone coidd es-
tablish ; that of the second necessitates a consideration of general wood structure. A i)iece of pine
wood, for instance, resists the passage of water in a radial direction even when under considerable
pressure, less so in a tangential direction, and, of course, very much less longitudinally. In a
radial direction it is a process of soaking from cell to cell, often, in split wood commonly through
the tliick cell walls of the summer Avood, anil even the tnedullary rays, owing to the small radial

45

dimension of their elements seem not to improve the eoiiduetivity to any grent extent. This is
quite (iiflfereut in a taiiRcntial tlireetion where every ek-meiit possesses dolli'd pits. But llirsc ])ils

are .yiuuded by iricmhranes, and any one who lias watched a thin section licsidy cut IV a drv

stick with its man.y jiersistent air bubbles, appreciates why water (h)es not [lass readily throu;;li
wood across the grain. lu a longitudinal direction, tlic lumina, or pores are open. Ileie each
lumen acts as a capillary tube, and once moist is as eaj^er to take up water as a capillar\- tube df
the same dimensions in plaster of Paris. In pine wood the greatest length of these tubes is about
6-7mm. Assuming that the cells are cut in such a man ner t hat t lie average length of the tube exposed
by the section is one- half of the total length, or .!-.") nmi., also that the capillary attraction is such
that it equals a pressure of one half atmosphere, then the aii- contained in each cell will be reduced
to three-fourths of its original volume, allowing one-fourth of the tube to be tilled with watci-. In
the case assxmied then, water would till the tubes for about '{-l ram., and if these tubes occnjiy
three-fourths of the entire cross section (the other one-fourth being tube, or cell wall) the water at
each cross section crowded into the wood, amounts to a sheet less than 1 mm. thick and ■{ of the
cross section in extent. Actually tliis maximum is probably never attained.

Eeturning to the experiments, the above conclusions were largely veritied, but not all.

To determine the behavior of wood as regards swelling, a jiiece of white pine was caiefidly
dressed, measured with a micrometer caliper of Darling, Browne and Sharpe, VJ inch, with vernier

accurate to one-fiftieth of a millimeter^ ^^^^ inch )

The width measured was 4.528 cm. The piece was then measured by immersion, wiped, and
measured with the caliper, which had been left set. The caliper still fitted at the particular place
which had been marked with pencil. The piece was then iiiiniersed for one minute; the caliper
still fitted so iierfectly that no ditlerence in friction on sliding it up and down coulil be obseived.
The same was true after an additional inunersion of two minutes and then one of live minutes.
The piece of wood was then left todry and was again measured forty-live minutes later. The width
had changeil from 4..")28 to 4..532 cm. during the titty minutes since the time of tirst immersion.

This simple experiment shows what might have been expected, that the imbibition by the cell-
walls, on which swelhng depends, is too slow a process ever to interfere in measurements.

To study the rush of water into the wood, numerous weighings on ditt'erent woods, including
pine, both hard and soft, white wood, and oak were made.

The agreement in their behavior is such that the following illustrations may serve the jiurpose
of showing the ettects. A piece of dressed white pine was weighed when dry, then it was meas-
ured by immersion, not to obtain the volume but to make the time of immersion that commonly
requisite to do the work. The results stand thus :

Grams.

Weight when ilry - *^--2

After first immersion - ^'■^■^

After second immersion 85.7

After tliird inmiirsion 86.2

After fourth immersion 8().;)

After fiftli immersion 86.(j

After sixth immersion 86.6

After seventh immersion 86.8

After eighth immersion 87.1

After ninth immersion 87.1

After each immersion the piece of wood w^as wiped with a damp cloth, a process whicli re-
moves the drippings, but also aids in iierfectly nioistening the wood. Of two |iieces of white w<iod
molding, one was given a coat of linseed oil, the other left uiioiled; the foHowing ligur<'s describe
their behavior :

WeiEht.

Dry ,

After iminiirsion ana wiping

Oiled piece.

112. 1

Xot riiled.

1 1 2. .I
11.-.. 2

46

A neatly dressed piece of white pine was measured with caliper and its dimensions in centi-
meters found to be as follows :

Width (one side)

Wirttli (other side)

Heijilit (one side)

Hei;;lit (otlier side)

Av<-rage lengtli

Average wid"tb

Average heiglit

Volume cm^

Volume by immersion

Ditierence cm

Ouo end.

4.528
4. 48U
4.538
4. .'J24
15. :i80
4. 405
4.527
312. 983
309. 700
3. 265

Middle.

4.520

4.476

4. rao

4.538

Other end.

4.504
4.464
4.524
4. 508

After 8 minutes of immersion :
Volume by immersion: 310.8, first trial.
Volume by immersion : 310.9, second trial.

The surface area of this piece is in round figures 318 cm^, of which 40 fall to the ends. If the
difference, 3.2G cm' of water, were evenly distributed over this area, the sheet of water soaked
or rushed in would be but 0.01 cm., or 0.1 iniii., or 0.001 inch thick.

Again, the end surface is 10 cm., the density of the piece about 0.10; setting the density of
wood substance at about 1..5(J, one fourth of this surface is cell-wall, the other throe fourths cell-
lumen. According to the calculations set forth above, the sheet of water drawn into the cut lumina
of the cells is less than 1 mm. thick. This when .spread over three-fourths of the 10 cm-, or 30
cm^, would account for nearly 3 cm^ of water.

In a third experiment, on apiece of fresh oak wood, the volume by immersion was found to be:

720 cubic centimeters First trial

729 cubic centimeters Second trial

730 cubic centimeters Third trial

730 cubic centimeters Fourth trial

730 cubic centimeters Fifth trial

These experiments show that the water in filling all crevices and pores does not proceed uni-
formly; that its progress depends on variable circumstances, of which the form and dimension of
the cavities and the existence of a film of air are probably the most important. Tliey also indicate
that, whether fresh or dry, the water adapts itself to the configuration of the wood, a cover sheet
is formed which adheres to the wood and is held tliere by a capillary attraction, but that the water
does not rush Into the wood in a manner analogous to that observed in inorganic porous bodies.
In every case the measurement of the caliper is greater than that found by immersion.

The ([uestioii now arises, is the measurement by immersion, with its variable factors, suffi-
ciently reliable or should the volume be determined by tlie caliper? To decide this question it is
necessary to examine the latter method itself. In doing so we may ask, is it more accurate, and
is it practicable? Turning back to the calijier measurements recorded above, we find that in a
soft, well-dressed piece of wood the dimensions varied veiy considerably. The height, for in.stance,
was on one side 4.524 at one end, 4.538 at the middle, and only 4.508 at the otlier end. Comparing
this with measurements made on machine-planed pieces of molding, etc., it was found that the
latter varied as much— in some cases even more. None were free of the wavy outline so charac-
teristic of machine i>laning. The end surface produced bj^ a saw-cut requires no mention, for every
one is familiar with its appearance. To be reliable, then, much more accurate work in dressing
would be requisite.

The practicability of this method is limited to pieces which can first be accurately dressed ; fresh
woods, checked pieces, etc., are thus excluded. The time requisite to determine the volume can
easily be estimated when we consider that fifteen measurements, each requiring the use of the
magnifier and the delicate adjustment of the micrometer instrument and nine arithmetical proc-
esses, were retjuisite to find the volume of one piece of wood.

From the above we see that the caliper measure is preferable only if the piece is dressed and
(pressed perfectly. As it is, the caliper measures the wood only at its projections, the water presses

47

too deep into tlu' ciiviMcs. Ilence tlie dinereiice, and (lie neeessary elioice between tliein. Both
ways fiiiiiish vaiial)Ie results, tliese deinMidiiij;- in tlie case of tlie eali])ei' on aeeuraey of dressing
and precision in the management of a delieate iustrunient, and involving the danger of tmi (1^111)11
cat ed computation. In the case of the measurement by iinmcMsion the variations depend <in the
nature, form, and size of the piece of wood, but the nietliod is relatively free from the danger ot'
error accompanying the use of delicate instruments, inaccuracy of reading, and complicated com-
putation.

DRYING.

A^GV marking the pieces are left to dry at ordinary temperature. Then they are placed in a
<lr.\' kiln and dried at 100° C.

The drying box used is a double-walled sheet-iron case, lined with asbestos paper and healed
with gasoline. The air enters below and has two outlets on top. The temperature is indicated by
a thermometer and maintained fairly constant.

The reason for clioosing thetemperatureatlOO'^C., or the boiling ])oint of water, is the fact that
experimenters generally have used this particular temperature, and for the sake of com])arableness
of results the continuance of this practice is desirable. To Judge from the experiments so far
made, this tenipiTature is taken somewhat too high. Prof. Baiischinger, of Mtinich, describes
similar experiments where the wood at this temperature lirst grew lighter and Anally increased
again in weight. The same thing has been observed in our work, but neither the cause nor the
nature of the process has as jet been determined. Moreover, the wood is brought too near the
burning point and danger from conflagration is great. Besides these two chief objections it may
be argued that wood in all ordinary uses is never subject to teui])eratures ninch above (!()' ('.

To determine the difference in liuniidity of wood dried at different tempi'raturcs, and to obtain
moistiu'e-coeflficients corresponding to the different temperatures, some experiments weic made un
the wood of the white i)ine and that of the longieaf pine. For one of these, i)ieces of sapwood,
split nearly as thin as matches, were used. Tliese were tied in loose bundles, weighed, then i)laced
in the oven to dry.

The following figures contain the priucii)al results:

Woiplit bi'fore plaoing in kiln

Dried .-it 60 to 62" C

Dried atun to 82° C

Dried at 100 to 105° C

V, palnstris.

7.1.5
(!8.4
67.5

ce.9

P. Strobnx.

Gram».

.■)5. 4
:);;. 3
:i2. 8

33.5

From these results the humidity expressed as percentage of dry wood dried at varying de-
grees is :

p. paliiutris.

P. Slrobus.

At ordinary temperature (.about 25° C)

Dried at abnutnnoc

Dried at about 80° C

Dried at about 100° C

Gramt.

Oravu.

8.1

2.4

.0

.U

Though this problem is by no means solved by these few experiments, it is clear that a lower
temperature than KH)'^ 0. would have served .just as well, and al.so that wood drieil at 80° ('. (a
much safer temperature) is nearly as dry as that dried at 100° C.

MOISTURE EXPERIMENTS.

In connection with these exi)criments in drying at different temperatures a .series of exjx'ri-
ments on the shavings of the sapwood of white pine and longieaf ])ine were made ; one to detei'inine
the amount of nioi.stnre which shavings of this kind aic caiialilc of taking nji, another to dctei'mine
the daily changes going on in the humidity of wood, I'^or the Ijrst of these, air dried >liavin^s of

48

sapTvood were suspended in a saturated atmosphere for three months. To prevent ftingonsgro-wth
a little carbolic acid was added to the water and the vessel hermetically closed and placed in a
dark room wlicre a very uniform temperature ])revails. At the end of three months the shavings
were taken out, weighed at once, and then left to dry. After a few days they were placed in a
kiln and dried at 100° C, and it was tV)nnd that for each 10(» cm' of dry wood substance there
had been absorbed in —

P. palustris -W cubic centiuictcrs of water.

P. 8trol)iis 4,5 cubic centimeters of water.

which represents tlie water capacity of the sii])woo(l of these two species.

The following ligures illustrate the daily changes of humidity in shavings of sapwood:

The weather was clear, and the temperature of the atmosphere rose each day to about 28° C.

(80° to 85° F.). The shavings were on a plate and in a clean, well- ventilated room.

Humidity in

shavings of—

P. palustris.

P. Strobus.

Per cent.
9.03
8.77
7.7a
8.W
8.50
8.37
7.18
7.31
7.57

Per cent.
8.51

8.23

7.52

7.66

8.23

8.23

6.95

6.95

7.38

July 11, 7 ,a. m

1 p. in

4:30 p. m. (temperature 84° ¥.)

9 p. m

.July 12. 8 a, m. (warm night)

10 a, m, (94° F.)

1 :25 p, m

3:25 p.m

8 p. m

After being dried, the pieces of wood are weighed and measured, in the same way as described
for the fresh wood, and from the data thus gathered the density, shrinkage, and moisture per cent
are derived in the usu:tl manner.

The formulae employed are :

/i\ -rw -i. e 4^^^^, ^ „,i Weight of fresh wood.

(1) Density of fresh wood==^^-=^5 — ^ .^

^ V oluine ot fresh wood.

/o\ Tw -w ^ 1 J Weight of dry wood.

(2) Density of dry wood==f^^i-5 n-,-^^^ -•,

^ ' V olume of dry wood.

(3) Shrinkage= ^^^"'^ volume-dry volume.

(4) Moisture in wood:

Fresh volume.

_ Fresh weight — dry weight.

Fresh weight.

In presenting these values they are always multiplied by 100, so that the density expresses
the weight of 100 cm.' of wood; thus the shrinkage and the amount of moistiu-e become the
shrinkage and moisture per cent.

SHRINKAGE EXPEEIMENTS.

To discover more fuUy the relations of weight, humidity, and shrinkage, as well as "checking"
or cracking of the wood, a number of seiiarate experiments were made. A number of the fresh
specimens ^ere weighed and measured at variable intervals until perfectly <lry. Some dry pieces
were placed in water and kept immersed niitil the maximum volume was attained. Without
describing more in detail the.se tests and tlieir resnlts, it may be mentioned that in the immersed
l)ieces studied the final maximum volume differed very little, in some cases not at all, from the
original volume of the wood when fresh; and also that in a piece of white pine only 1.5 cm. long
and weighing but 97 gs. when dry, it required a week before the swelling ceased.

To determine the skrinkage in different directiims a iinmber of measurements were made in
pieces of various sizes and shapes. In mo.st cases pins were driven into the wood to furnish n firm
metal point of contact for the caliper. A number of pieces of oak were cut in various ways to
study the effect of size, form, and relative position of the grain on checking.

Since the shrinkage of the entire piece is a result ;int change of form and dimensions of the
iadividual cells, :i study of the behavior of the cell elements tliemsehcs during slirinkage wa.s
undertaken. Portions of thin sections of the wood of J'. tStrohu.t and 1\ pohistri.s were magnified

49

5S0 diameters and .Irawn Arith tl.o camera lucida. The sections were then allowed to dry under
the cover glass, to avoid any waipix-. and were a-ain .Irawn, when dvy, with every part occupy-
mg as nearly the same iK)sitiou in the tiel.l as the shruulien condition would allow. One cell wus
exactly superposed and served as a starting point. ISo difficulty was experienced in drawin- the
dried section; the])ictnre agreed with the sectiou on removal ofcov.T -lass, and also after ad^linrr
glycerine to the dried se.-ti..n. Left in glycerine a few weeks, the original picture could besuper"^
posed (With the camera) almost but uot quite perfectly. Whether this liict is due to a ditterence
in swelling of wood in water and glycerine is not yet ascertained.

The results so far obtained from tiiis study are in perfect agreement with the general theory of
shrink-ng. Thick walls shrink more than thin walls. The change of form and dimension of lumiua,
on the other hand, was found to be variable; some lumina changing their dimensions very markedly'
others scarcely or not at all. Lumina with circular cross-section appear to have changed less
than those with a compressed, slit like cross-sectiou ; in general the change was more apparent in
the summer wood than iu the spring wood.

WOOD STRl-CTURE.

The most time-robbing, but also the most fascinating, part of the work consists in the study of
the wood as an important tissue of a living organism; a tissue where all favorable and unfavorable
changes experienced by the tree during its long lifetime find a permanent record.

GENERAIi APPEARANCE.

For this study all the specimens from one tree are brought together and arranged in the same
order in which they occurred in the tree. This furiushes a general view of the appearance of the
stem ; any striking jieiuiliarities, such as great eccentricity of growth, unusual color, abundance of
resin in any part of the stem, are seen at a glance and are noted down.

A table is prepared with separate columns, indicating —

(1) Height of the disk in the tree, (this being furnished by the collector's notes);

(2) Radius of the section;

(3) Number of rings from iieriphery to center ;

(4) Number of rings in the sap wood ;

(5) Width of the sap wood ; and

(6) Eemarks on color, grain, etc.

The results from each disk occupy two lines, one for the pieces from the north side and one
for those of the south side. The radius is measured correct to one-half millimeter (0.02 inch), and
the figures refer to the air-dry wood.

To count the rings the piece is smoothed with a sharp knife or plane, the cut being made
oblique, i. e., not quite across the gi-aiii nor yet longitudinal. Beginning at the periphery each ring
is marked with a dot of ink, and each tenth one with a line to distinguish it from the rest. After
counting, the rings are measiu-ed in groups of ten, twenty, thirty, rarely more, and the.se meas-
urements entered in separate subcolumus. In this way the rate of growth of the last ten, twenty,
or thirty years throughout the tree is found; also that of similar ])ei'iods previous to the last; in
short, a fairly complete history of the rate of growth of the tree, from the time wiieu it had reached
the height of the stump to the day when felled, is thus obtained. Not only do these rings furnish
informatiou concerning the growth in thickness, but, indicating the age of the tree when it had
grown to the heigiit from wliich the second, third, etc., disks were taken, the rate of growth in
height, as well as that of thickness, is determined, any unfavorable season of growth or any series
of such seasons are found faithfully recorded iu these rings, and the influence of such .seasons,
whatever their cause, both on the quantity and on the (piality or proi)erties of the wood, can thus
be ascertained.

In many cases, especially in the specimens from the longleaf pine, and from the limbs of all
pines, the study of tliese rings is somewhat difficult. Zones of a <!entimeter and more exist where the
width of the rings is sucli that the magnifier has to be used to distinguish them. In some cases
172-ti— No. t> 7

50

this difiSculty is increased by the fact that the last cells of one year's gro^vth differ from the first
cells of the next year's ring only in lorni and not in the thickness of their walls, and therefore
produce the same color eiiect. Such cases frequently occur in the wood of the upper half of the
disks from limbs (the limb sii]>i)()rted horizontally and in its natural ])ositi()n) and ol'ten the magnifier
has to be reinforced by the microscope to furnish the desired information. Fortius (lurpose the
wood is treated as in all microscopic work, being lirst soaked in water and then sectioned with a
sharp knife or razor and examined on the usual slide in water or glycerin.

The reason for beginning the counting of rings at the periphery is the same which suggested
the marking of all peripheral pieces by the letter a. It is convenient, almost essential, to have, for
instance, the thiity-fifth ring in Section II represent the same year's growth as the thirty-fifth ring
in Section X. The width of the sapwood, the number of annual rings comixising it, as well as the
clearness and uniformity of the line separating the sa])\vood from the lieartwood, are carefully
recorded. In the columns of "lemarks" any peculiarities which distinguish the i)articular ])iece of
wood, such as defects of any kind, the presence of knots, abundance of resin, nature of the grain,
etc., .are set down.

When finished, a variable number, commonly o to (J small pieces, fairly representing the wood
ot the tree, are split off, marked with the numbers of their respective disks, and set aside for the
microscopic study, which is to tell us of the cell itself, the very element of structure, and of its
share in all the proi^erties of wood.

The small pieces are soaked in water, cut with a sharp knife or razor, and examined in water,
glycerin, or chloriodide of zinc. The relative amount of the thick-walled, dark-colored bands of
summer wood, the resin ducts, the dimensions of the common tiacheids and their walls, l)oth in
spring and summer wood, the medullaiy rays, their distril)ution and tiieir elements, are the prin-
cipal subjects in dealing with coniferous woods; the ((uantitative distribution of tissues, or how
much space is occupied by the thick-walled bast, how much by vessels, how nnich by thin-walled,
pitted tracheids and i)arenchyma, and how much by the medullary rays; what is the relative value
of each as a strength-giving element; what is the space occupied by the lumina, what by the cell
walls in each of these tissues — these are among the imi)ortant points in the stuily of the oaks.

Continued sections from center to jieriphery, magnified '2'i diameters, are employed in finding
the relative amount of the summer wood; the limits of the entire ring and that of spring and sum-
mer wood are marked on paper with the aid of the camera, and tluas a panoranni of the entire
section is brought before the eye. The histology of the wood, the resin ducts, the tracheids and
medullary rays, their form and dimensions, are stuilied in tlnn sections "magnified 580 diameters
and men more. Any peculiarity in form or arrangement is drawn with the camera and thus graph-
ically recorded; the dimensions are measured in the manner described for the measurement of the
sununer wood, or with the ocular micrometer. In measuring cell walls, the entire distance between
two neighboring lumina is taken as a " double wall," the thickness of the wall of either of the two
cells being one-half of this. The advantage of this way of measuring is apparent, since the two
points to be marked are in all cases perfectly clear and no arbitrary positions involved. The length
of the cells is found in the usual way by separating the elements with Schidtze's solution (nitric
acid, chlorate of potassium). All results tabulated are averages of not less than ten, often of more
than one hundred measurements.

In the attempt to find the quantitative relations of the different tissues, as well as the density
of each tissue, various ways have been followed. In some cases drawings of magnified sections
were made on good, even paper, the different parts cut out, and the paper weighed. In other cases
numerous measurements and computations were resorted to. Though none of the results of these
attempts can be regarded as perfectly reliable, they have done much to point out the relative im-
portance of different constituents of the wood structure, and also the iiossibility and practicability,
and even the necessity, of this line of investigation.

51

INSTRUCTIONS AND BLANK FORMS, WITH ILLUSTRATIVE RECORDS.

INSTRUCTIONS FOli THE COLLECTION OF TEST PIECES OF PINES FOR TIMBER INVESTKiA'lIONS.

A. — Ob.tf.ct or WORK.

The collector shoiilil uiiilerstuiiil tliat the ultiiii;it(! object of tlie.se investigations i.s, if )>ossible, to e.stablish the
relation of qnalitv of timber to tlie romlit ions under which it is <;rown. To accomplish this object he is ex]>ecte<l to
fnrnish a very careful descriptioii of tlie con<litions uniler which the test trees have grown, from which test jiieces
are taken. Care in ascertaining these ami minuteness anil aecnracy of (le.scrii>tion are all-Important in assuring
properresults. It is also necessary to selec^t anil i)repare the test pieces exactly as described and to make the records
perfect as nearly as possilile, since the history of the material is of as much imjiortance as the determination in the
laboratory.

li. — I.OIAMTIKS loR foI.I.ia'TINi;.

As to the locality from which test trees are to be taken, a distinction is made into station and site.

By station is to be understood a section of country (or any places within that section) which is characterized
in a general w.-iy by similar climatic conditions and geological formation. "Station," then, refers to the general geo-
graphical situation. ■■Site" refers to the local conditions and surroundings within the station from which test trees
are selected.

For example, the drill- deposits of the (iulf Coast plain may be taken for one .station; the limestone country of
northern .\labama for a second. Hut a limestone formation in West Virginia, which dill'ers climatically, would
necessitate another station. Within the lirst station a ricli, moist hummock m.ay furnish one site, a sandy piece of
nplauil another, and a wet savannah a third. Within the second or third station a valley might furnish one site,
the top of a hill another, a difl'erent exjiosure may call for a third, a dril't-iriii]icil ledge w-itli deei)er soil may war-
rant the selection of amilhcr.

Choin: of statioim. — For each species a special selection of stat ions from whicli test jiieces are to he collected is
necessary. These will bo determined, in each case separately as to number and location, from this oilHie. It is pro-
posed to cover the field of geographical distribution of a given species in such a manner as to take in stations of
climatic difference and ditl'erent geological horizon, neglecting, however, forthe iiresent, stations from extreme limits
of distribution. Another factor which will determine choice is character of soil, as dependent upon geological forma-
tions. Stations which i)romise a variety of sites will be preferably chosiin.

CltDicr of xilc. — Such sites will be chosen at each station as are usually occupied by the .si>ecies at any one of tlio
stations. If unusual sites are founil occupied by the species at any one of the stations it will be determined by
special correspondence whether test pieces are to bo collected from it. The determination of the number of sites at
each station must be left to the judgment of the collector after inspection of the localities; but before determining
the number of sites the reasons for their soh'ction must be reported to this office. The sites are characterized and
sehclcd by diti'ereuces of elevation, exposure, soil conditions, and forest conditions. The ditterence of elevation
which may distinguish a site is provisionally .set at 500 feet; that is, witli elevation as the criterion for choice of
stations the dirt'erence must be at least .500 feet. Where ditl'erences of exposure occur a site should l>e chosen on each
of the exposures present, keeping as much as ])o.ssiVde at the same elevation and under other similar conditions. Soil
conditions may vary in a niunbcr of directions, in mineral composition, physical proi)erties, depth, and natnri^ of the
subsoil. For the present, only extreme ditlerences in depth or in moisture conditions (drainage) and decided dill'or-
ence in mineral composition will be considered in making selection of sites.

Forest conditions refer, in the first place, to mixed or pure forest, oi)en or close stand, and shoulil be chosen as
near as possible to the normal character prevailing in the region. If what, in the judgment of the collector, const i-
tules normal conditions are not found, the history of the forest and the points wherein it diH'ersfrom normal nnuli-
tionsmust be specially noted.

C. — ClIOICK oi' TRKES.

On each site five treivs are to be taken, one of which is to serve as "check tree." None of these trees are to bo
taken from the roadside or open Held, nor from the outskirts, but all from the interior of the forest. They are to be
representative average trees— neither the largest or best nor the snialhsl or worst, preferably old trees and such as
are not overtopped by neighbors.

The "check tree," however, shouhl be selected with special care and should rci)rc8ent llo- best developiMl I rco
that can be found, judged by relative height and diameter ibvelopment and iiertect crown.

The distance between the selected trees is to he not less than 100 feet or thereabout, yet care must be exercised
that all are found under precisely the sanu> conditions for which the site w.Ts chosen.

There are also to bo taken six young trees as described under H.

If to bo had within the .station, select two trees from 30 to GO years old or <dder, which are knoin, to have
grown up in the open, and two trees which are known to have grown up in the forest, but have been isolated for a
known time of 10 to 20 years.

52

D. — Procedure and oi-tfit.

The station deterniiiioil upon, the collector will proceed to examine it for the selection of sites. After having
selected the sites, he will at once communicate the selection, with description and .justiticatiou, to this office,
negotiate with the owners of the timber (which might be done conditionally during the iirst examination) for the
purchase or donation of test trees; and the latter arrangements completed, without waiting reply from this office,
he will at once proceed to collect test pieces on one of the sites, in regard to the selection of which he is not in
doubt.

To properly carry out the instructions, the following assistance and outfit may be required :

(1) Two men* with axe and saw; a boy also may be of use.

(2) Team, wagon, and log trucks for moving test pieces and logs to station.

(3) Frow or sharp hacking knife for splitting disks. Heavy mallet or medium sized "maul" to be used with
frow.

(4) A hand saw.

(5) Red chalk for marking. (A special marking hammer will be substituted.)

(6) Tai)e line and 2-foot rule or calipers.

(7) Tags (specially furnished).

(8) Tacks (12 ounce) to fasten tags.

(9) Wrapiuug 2>aper and twine.

(10) Franks for mailing test Jiieces (specially furnished).

(11) Shipping tags for logs.

(12) Scales, with weight power not less than ISO pounds.

(13) Barometer ibr ascertaining elevations.

(14) Comjiass to ascertain exposures.

(15) Spade and pick to ascertain soil conditions.

(16) Bags for shipping disks.

E. — JIetiiui> of making tkst riKCES.
((() Matiin liTcs.

(1) Before foiling the tree, blaze and mark the north side.

(2) Fell tree with the saw as near the ground as i)racticable, avoiding the ilare of (he butt and making the
usual kerf with the axe opposite to the saw, if possible, so as to avoid north and south side. If necessary square off
the butt end.

(3) Before cutting oti' the butt log mark the nortli siilc on the second, third, and further log lengths.

(1) Measure ott' aud cut logs of merchantal)le hugth and diameters beginning from Ihc butt, noting tlie length
and diameters in the record.

Should knots or otlier impertections, externally visible, occur within 8 inches of the log mark, make the cut
lower down or higher up to avoid the imperfection.

(.5) Continue measuring the full length of the tree and record its length. Note also distance from the ground
and position on the tree (whether to the north, south, west, east,) of one large sound limb. Mark its lower side
aud .'iaw it off close to the trunk and measure its length and record it; the limb to be utilized as described later.

If the tree after felling prove unsound at the butt, it will be i)ermissil)le to cut off as much or as little as noces-
sarv within the first log length. If sound timber is not found in the first log, the tree must be discarded. Only
sound timliir must be shipped. Any logs showing imjierfectious may be shortened. Be careful to note change in
position of ti^st pieces.

(6) Mark butt end of each log with a large N on north side. Saw off simarely from the bottom end of each log
a disk G inches long, and beyond the log measure cut oft' disks every 10 feet up to 2-iuch diameter. I'lace each disk on
its bottom cud, after having ascertained and marked the north and south line on top end. Split the disk with a sharp
hackini' knife and mallet along this line. Split from outside of the west half of the disk enough wood to leave a
prism 4 inches thick. Split from the east half two wedges with one plane in the south-north line and with their
wedge line through the heart of the disk; the outer arc to be about 4 inches. (See figures im opposite page.)

Mark each piece as split ort' on top side with number of the tree (.\rabie), the serial number (Roman) of the disk
in the tree beginning with No. 1 at butt log, and with a distinct N or S, the north or south position of the piece as
in the tree.

Write the same data on a card and tack it to the piece to which they belong. Whenever disk pieces are small
enougli for mailing leave them entire. Whenever they can not be shipped by mail leave disks entire, wrap in paper,
and shiji by express.

(7) Weigh each piece and record weight in notebook, using the same marks as api>ear on the pieces.

(8) Wrap each piece in two sheets of heavy wra]>ping paper aud tie securely.

(9) Mark on the newly cut bottom end of each log with a heavy pencil a north and south line, writing N on
the north aud S on the south side of the log, large and distinct. Also mark centrally with an Arabic number on
each log the number of the tree in the series, and with a distinct R(UMau uiiMiber the serial number of the log in the
tree, counting the butt log as first.

' Only men familiar with felling and cutting timber should be chosen.

53

Tack to th,. butt end of eaoli loj; mcurHy a car.! (.cntrally), »u which is written name of tree, species locality
from whi.h five IS taki'ii, (l,-uotf<l l.y Hit- lelt.T coriespondiutt to tliat used ill the notebook, uuiiiber of tree and sec-
tion. This card or tag is intended to insure a record of each I<>k in addition to the markiiiK already made.

(10) IJmb !(oo(?.— Having, as before noted, selected a limb, measur.'d and recorded its distance from the butt and
position on the trunk, and marked its lower side and sawed it off dose to the latter, now take a disk V, inches Ion"
from the butt end and otliers every 5 feet up to 2-inch diameter at the top. Number these consecutively with Roman
number, calling tlie butt disk No. 1. Note by letters L and V the lower and upper side.-as the limb appeared
on the tree, and place the (Arabic) number of tree fnun wliich the limb came on each. Enforce the record by cards
containing the same information, as done in case of other disk pieces.

Weigh, and wrap and mail in the same manner as the other pieces.

(11) Cluck (n«».— I'nmi the •• check tree," which is to be the very best to be fouu.l, oul v three disks or three logs
are to be secured, from the butt, middle, and toj. j.art of the tree. Absolutely clear timber, free from all knots and
blemishes, is to be chosen. The disk pieces are to be of the same size, and to be secured in the same manner as
those described before; the logs to be not necessarily more than li feet; less if not enough clear timber can he found.

Note the position of eacli piece in the tree by measuring from the butt cut to the butt end of the piece.

Prepare and mark all pieces in the same manner as those from other trees, adding, however, to each piece a X
mark to denote it as coming from the "check tree."

(12) Yoiiiin trees. — Select six trees from each site approximately of following sizes: Two, G-inch diameter, breast
high; two, 4-inch diameter, breast high; two, 2-ineh diameter, breast high. Mark north and south si.les and chop
or saw all close to the ground and cut each tree into following lengths: First stick, 2 feet long; second stick, i f(;et
long; the remaining cuts 4 feet long up to a top end diameter of about 1 Inch. Cut from tlie basal end of each log
a disk r> inches long. Mark and ticket butt end of each log :is in cast' of large trees. Mark a north and south line
on lop end of each disk, with N and S at extreniiti<>s to denote north and south sides; and also (iiket with same data
as given rui l;uge disk i)ieces. Weigh and wrap as before. Of these trees only the ilisk jiiei'es ;ire to be mailed.

F. — .Shipping tkst pieck.s.

• Shi)) all pieces witliout delay. To each log tack securely a shipping card (furnished), so as to cover llie marking
tag. The logs will go to .J. 15. Johnson, St. Louis, Mo. The disks and other pieces are to be mailed to F. Koth, Ann
Arbor, Mich., using franks securely pasted for mailing, unless, as noted before, they must be sent by express.

Mail at once to the above addresses notice of each shipment, .and a transcript of not(^s and full description to
this office, from wliich i-opies will be forwarded to th(^ recipi.'iits of the test pieces.

If free transportation is obtained from the r.tilroad c(uui>anios, special additional iiislriii'lions will he given
under this head.

O. — Kkcouds.

Careful and aci-urate records are most es.sential to secure the success of this work. A set of specially prepared
record sheets will be furnished, with instructions for their use. A transcript of the record must be .sent to this olliee
at the time of making sliipuwiit ; also such notes as may seem desirable to idiiijdete the record and to give additional
explanations in regard to the record and suggestions respecting the work of eolleetiug. Original records and notes
must be preserved, to avoid loss in tninsmission by mail.

54

POEM OF FIELD RECORD.

(Folder.)
Name of collector i (Charles Mobr.) Species; Pinua palustria.

Station (denoted by capital letter) : A.

State: Alabama. Comity! Escambia. Town: Wallace.

Longitude: 86^12'. Latitude: 31° 15'. Average altitude : 75 to 100 feet.

General configuration : Plain— hills— plateau— mountainous. General trend of valleys or hills

Climatic features : .Subtropical ; mean annual temperature, 65- ; mean annual rainfall, 62 inches.
SiTK (denoted by small letter) : a.

Aspect: Level— ravine— cove— bench— slope (angle approximately).

Exposure : Elevation (above average station altitude) : 125 feet.

Soil Conditions:

(1) Geological formation (if known): Southern stratified drift.

(2) Mineral composition: Clay— limestone — loam— marl— sandy loam— loamy sand— saud.

(3) Surface cover: Bare— grassy— mossy. Leaf cover: Abnndant— scanty— lacking.

(4) Depth of vegetable mold (humus) : _Al>sent-moderate— plenty— or give depth in inches.

(5) Grain, consistency, and admixtures: Very fine— fine— medium— coarsc—p o r o u s— 1 i gh t— 1 o o s e -

liiodirately loose — compact — binding— stones or rock, size of:

(6) Moisture con.litions: Wet— moist— liesh-dry —arid— well .Iraiued— liable to overfiow- swampy-

near stream or spring or other kind of water supply -

(7) Color: Ashy-gr.ay.

(8) Depth to subsoil (if known): Sballow. 3 to 1 inches to 1 foot-1 foot to 4 feet, deeji— over 4 feet, very

deep — shifting.

(9) Nature of subsoil (if ascertaiualile) : Ked, ferrugiuou.s sandy loam; moderately loose, or rather slightly

binding; always of scmie degree of dampness; of great depth.
Forest conditions: Mixed timber— pure— dense growth— moderately dense to open

A.ssociated species: None.

Proportions of these

Average heiglit : !tO feet.

Undergrowth: Scanty; in the original forest often none.
Conditions in the open: Eield— pasture— lawn-clearing (how long cleared): In natural clearings untouched
by fire, dense groves of second growth of the species.
Nature of soil cover (if any): Weeds— brush— sod.

(Inside of folder.)

St.viion: a. Sitk: a. Species: P. palustris. Tree No. 3.

Position of tree (if any special point notable not appearing in general description of site exceptional exposure to

light or dense position, etc., protected by buildings, note on back of sheet) : In rather dense position.
OiUGix of tree (if ascertainable) : Natural seedling, sprout from stump, artificial planting.

Di.vMBTER breast high: 16 inches. HEKiiiT (>¥ STUMP: 20 inches

Hfight to first limb : 53 feet. LENGTH OF felled tree : 110 ieet 4 inches. •

A(iE (annual rings on stump) : 183. Total height: 111 teet 8 inches.

No. of disk.

1
II

ni

IV

V

VI

VII

VIII

IX

X

Distance
from butt.

Peel.

0
13
19
32
47
57
67
77
87
97

Weight of
combined
disk pieces.

Pounds.
27
20
20
18
16
14
17
14

9i
6

Kemarks.

Crown touching those
of nearest trees to the
N. and NE. Open
toward SW.

No. of log.

I

II

III

IV

V

VI

VII

VIII

Distance
from hutt.

ri. In.

8 U

13 8

19 8

32 S

47 8

Length of
log.

Diameter,
t)iitt end.

Inches.
103
14i
14"
13J
1-4
114

»i

H

LiMBWooi):

Distance fbom butt:
Number of disks taken:

Position on trunk:

Total Length:

Note.— As much as possible make description by underscoring terms used above. Add other descriptive
terms if necessary.

55

SAMl'IJ-: KECORDS OF TESTS.
CUOSS BREAKING TEST.

(IIG.
Mark, •' 1. White piuo.

Li'iifith, (iO.O inclu's.
Hi'i>ilit, :!.7I iiiilics.
Kioadtli, ;i.l~> inches.

Strengtli of extreme fiber,

\vheie/=^-— - = ,-j,6G0 )).>iiii<ls per square inch.
Mc.ilnlns of ehistioity = 1.3L>n.(Mi(i immim.In per K.iiiaie inch

total rrsilienei. -= H, lilo ir>rh.i,.Mi.„ls. El. Kes.. .550.

KesilLi-Hce, per ciibw i[i(li = t.U iiieh-pouiuls. El. Ues 0 0-)

fXinnlifr :iriiiu:il riii^s piii- inch = 19.

July 18,
iSiU.

Loud.

Do flection.

Microiiietor.

litiiiiarkK.

A. 7».

i

4 24

i;oo

.042

0. 7r»7

25

.211
. 300

0. 920
1.005

26

1,000

V///

27

2, uuo

. 454

1. 109

^///y

28

2,200

.511

1.220

^///

2!)

2, 400

.505

1.310

////

31

2, 600

.000

1.405

///y

.■53
35

2,800
3, 000

.853
1.01.5

1. 50K
1. 730

/ / //

37

3,200

1.276

1.991

""

40

3,300

1.521

2. 230

Max^iuutiii li);ul.

X>ef lection, in, incJies

(3.

Mark, < 3.

Lonf;lp:if pine.

Leugth. 60.0 inches.
Height, 3. 50 inches.
Breadth, 3. 72 inches.

[Number anuuiil rings per inch

56

CROSS BREAKING TEST.

Strength of extreme fiber,

3 W I
where /^ ;—-—-; = 10,230 pounds per square inch.

Modulus of elasticity =1,700,000 pounds per square inch.

Total resilience =.5,110 inch-pounds, Kl. Res., 1,780.

Kesilieuce, per cubic inch =6..54 inch-pounds. El. Res., 2.28.

July

Load.

Deflec-

Micro-

20,1891.

tion.

meter.

h. m.

2 58

300

.042

0. 958

■J- 0

1,000

.208

1.124

1

l.BOO

.324

1.240

•y

2,000

.404

1.320

3

2,400

.4S1

1.307

4

2, 800

. .WS

1.474 '

5

3, 200

.040

1.556

8

3, 000

.721

I.B37

7

4,000

.815

1.731

8

4,400

.926

1. 842

9

4,800

1.0ff4

1.990

13

5,180

1.544

2.460

J>efIccttoTv in inclies.
FINAL RECORD OF TIMBER TESTS.

Mark.

Lons-leaf pino

3

3

1

Wliite pine :

IIG

1

3

Percent-
age of
moisture.

Cross bending tests.

I>imeD.sioDB

Time.

Length.

Height.

Breadth.

Min.

Inchea.

inches.

Jnclieg.

60.0

3.50

.3.72

15

00.0

3.74

3.75

10

Deflec-
tion.

Founds. \ Inches.
5, 180 1, 544

3,300

StriMigtli

per

square

inch.(/)

Voundt.
10. 230

5,6eo

Modulus
of elas-
city.(c)

Resilience

in inch-
pounds per
cub. inch. (r)

Pounds.
1. 760. 000

1, 320. 000

0.54

4.11

Mark.

Long-leaf pine

3

3

1

"White pine :

116

1

3

Crushing endwise.

Dimensions.

Height.

Inches.

i a. 1

I"

Cross

3.46
3.72

3.73
3.73

Sq. in.
1 12. 87

1 13.91

Crushing
load.

Pounds.

77, 71K)

Strength

per

square

inch.

Crushing across grain.

Dimensions.

HeigM- ^^^Zl.

Founds.
0, 040

3,480

Inches.
3.73

Inches.

( 3.47
I 3.93

3.72
3.93

Sg. in.
f 13.63

I 14.62

Cruahing
load.

Pounds.
10,400

5,200

Strength

per square

inch.

Founds.
760

360

Mark.

Long-leaf pine

3

3

1

"Wliite pine :

116

1

3

Tension teats.

Size of re-
duced sec-
tion.

Sq. i».

2. .38
.41

Area.

^q. in.
0.971

Breaking
load.

Pounds.
11,400

Strengtli

per square

inch.

Pounds.
11, 680

9,880

She.iring t^^ata.

Total

aliearing

area.

St/, in.

4.14
3.97

4. IC
4. 02

Breaking
load.

Founds.

2, 280
2,580

1.700
1,600

Shearing
strength.

551
650

409
398

57

RESULT OK I'HYSILAL EXAMINATION. (Sample.)

5."— ' — ^jv:

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Long-leaf IMnf. (/'. pulmlris), treeS.
LocaUiti : Walhwf, AlaliHiiia.
Site: ITplaixI lurest, *piite flense.
Soil: Saiitl.v.

Whitf. Pink (7". SIrobut), tree 116.
hueality : Marntlmn Cimiity Wisronsiii.
Site: Grown ill deiirti' iiii.\t'(I (»»re.Ht.
Soil: .Saiidv, willi nauil.v HuliHuil.

Legend.

/). Denotes density or speciiio gravity ol'tlie dry wood.

W. Denot«.s percentage of water in the frosli wood, related to its

weight.
S. Denotes percentage of shrinkage in liiin drying.
H.W. Denote.s width of ring (average) in niiliinielerM{2'> mm.— 1 inch).
/»'. W. Denotes percentage 4>f snnnner w iiod as relalcii tt> total wfioil.
Konian nnmbers refer to nnmlter of ilisli, platted in position of disk.

Height is given in feet from tlio gronnd : scale, 10 feet=^ 2 inches.
JCadins. north and south (dotted line), in inillinielers; scale, 10 mm. =:

0.1 inch.
Median lint? rei)re8en(a the pith.
l:i;:lil hand nnmWers relate to north side, lell-bund nninberH to south

side,
t Inter lines represent outlines of trees.

CLASSIFIHI) INDEX.

Arguments for PKOPOf.KD Timber Examinations:
Difficulties of the work, 2, 3, 11, ir>.
Deliiieneies in existing exaiiiinations, 3, 0. 7. 111.
Economy of material resulting, 1,7,8,9.
European investigation.s not sufficient, 2, 3, (i.
Forest waste reduced, 1, 2, 8, 13.
Gov(^rnment work uecessary, 'J. 10, 12. 14. 1."), 16, 28.
Iguorauoe of proiiertii's of timber prevailing, 1, 2, 4, .">.
lulbrmatiiin scanty and unreliable, 1.4.7.
Eoss and waste due to ignorance, cxamiiles !,,"),().
Saving liuancially, 1, 7, 13.
(Small teat speciuii'us give unsatisfactory results, 2,

6,7,11.

Uncertainty in s]iecitications, 2, 13, 1,5.

Definition.s :

Chemical properties, 18, 1!>.

Elastii'ity modulus, 38.

Mechanical properties, 18, lit, 20.

Physical properties, 18, 19.

Physico-technical properties, 19.

Resilience, 37.

Site, 51.

Station, 51.

Technical properties, 20.

Technological jiroperties, 25.

Timber physics, 17, 19.

Working properties, 25.
FORMl'LAS:

Coefficient of elasticity, 21 (Pai^ciuotti).
Cross-breaking st/ength related to modulus of elasti-
city, 38.
Crushing strengfli relatcil to specific gravity, 24,38.
Density, 48.

Modulus of elas(wity (Young's), 38.
Moisture, 48.
Shrinkage, 48.

Strength oi extreme fiber, 37.
Influences on Properties. (See Properties.)

INSTRU.MENTS. (SEE MACHINES De.SCKIBKD.)

Machines ano Instruments Mentioned and De-

sCRlliEl) (d):
Heam-ti^sting maebine. small, 32, 33, (d) jdali- ill;

large, 32 (d) )date 11.
Calibrating springs 32, (d) plate ii.
Ctdiimu-testing machine, 32,35 (d) plate VI.
Dry kiln, 31, 32 (d). .34, 47, l>late li.
Laboratory, 32, plate I.

Micrometer caliper (Darling, Urowii .V .■^biiipe), 45.
Slide rule (Thatcher's), 32.
Specilic gravity apparatus 43 HI), 44.

Machines and Instruments — Continued.

■ ITniversal Testing Mailiine (Kiehle's "Harvard"),
32, 34. 35, idates IV, V.
Methods:
Tisliny —

Be:inis of large size, 22, 25, 32.

Calibrating, 32.

Columns of large size, 27, 28 (Lanza), 27 (T. H.

Johnson).
Compression, 28. 34. 35 (Smith), 35.
Cross breaking, 32, 33.
Cubic blocks (P;icciuotti A Peri), 21.
Fuel value, 26 (Bull), 26 (Sharpies).
Moisture, 34, 47.
Prolonged stress, 27, 28.
Shearing, 35.

Shrinkage, 48. '

S})ecitic gravity, 34, 43.
Tanning values, 26, 30.
Tension, 34.
Time inflm'nce, 27, 28.
Tone vibration.s, 20, 21 (Savart), 22 (Chevandier),

27 (Ihlseng).
Torsion, 21, 27, 28 (Thurston).
Velocity of sound. 27 (Ihl.seug).
Wood-working machines, 24.
Working capacity (Tetmajer), 23.
Test malcrUil —

Collecting, 22, 23, 51, 62, 53.
Condition, 42.
Drying, 31, 47.
Measurement, 43, 44, 50.
Moisture dctermiiiatious, 34, 47.
Prejiariug and marking, 31, 34, 35, 42, 53.
Struitur:il examinalion, 49, .50.
Weighing, 43-46.
Names mentioned:

Abbott, A. V. (testing machines), 27.

Allen, W. F. (lettc^r), 16.

Antlrews, Horace (letter), 15.

Andrews, .1. W. (hitter), 13.

Harlow (strength of timber), 20, 23.

Bates, Edward (letter), 8.

Bauschinger (strength of pine timb.T), 4, 23, 24, 38,

40, 47.
Bcardsley, Arthur (letter), 10.
Uelidor (mechanical properties of wood), 20.
Benzenberg, C. 11. (h-ttcr), 11.
Berg, L. D. (letter), 17.
Bevau (experiments in torsion), 20.

I

II

Namks mentioned — Contiimod.
Bland, J. C. (Iftter), 5.
Boeliin (botanist), 25.
Boiler, A. P. (letter), 9.
Bolton, C. M. (letter), 11.
Bouscareu, G. (letter), 6.
Brown, C. N. (letter), Ifi.
Buck, L. L. (letter), S.
Buifou (jiroperties of oak wood), 20.
Bull, Mareus (fuel value of woods), 26.
Buruham, I). H. (letter), 2, 11.

Burr, William H. 6 (letter), 26 (elasticity of mate-
rials).
Cain, William (letter), 15.
Chanute, O. (letter), 4.
C'bevandier (test work), 22.

Christie, James (letter), 15. .

Clark (tests on large beams), 25.
Cleeman, T. M. (letter), 6.
Codwise, E. B. (letter), 11.
Coe, W. W. (letter), 14.
Coffin, Amery (letter), 11.
Compton, A. G. (letter), 13.
Cooley, George W. (letter), 9.
Cooper, Theodore (letter), 14.
Corliss, G. II. (seasoning affecting strength), 27.
Corthell, E. L. (letter), 7.
Cowles, W. L. (letter), 12.
Crawford (combustion tests), 26.
Croes, J. J. R. (letter), 8.
Dalton (combustion tests), 26.
Davis, C. B. (letter), 16.
Davis, J. B. (letter), 7.

Day, Y. M. (microscopic tests for strength), 27.
Duhamel Du Mouce.iu (projierties of timber), 20.
Dunu, .James (letter), 5.

Dupin, Charles (mechanical ])ro])er(ies of wooil).20.
Egleston, Thomas (letter), (>.
Engineering News (letter), 9.
Engineers' Club (letter), 10.
Estrada, E. D. (exjieriimMits on streugthj, 27.
Exner, W. F. (timber physics), 20.
Fanning, .T. T. (letter) 11.
Fletcher, Robert (letter), 9.
Flint (Nicaragua woods), 27.

Fowke, F. (tables of experiments on woods), 23.
Freeman, J. R. (letter), 7.
Frizell, J. P. (letter), 14.
Fteley, A. (letter), 12.
Gauahl, .1. J. (letter), 13.

Goodale, George L. (j)hysiologieal botany ), 27.
Gottgetreu, R. (properties of wood), 25.
Girard (elasticity of oak), 20.
Graham (tests on large beams), 25.
Gray, S. M. (letter), 12.
Grifliu, P. H. (letter"), 16.

Hartig, E. (testing wood-working machines), 24.
Hartig. Th. (botanist), 25.
Hartig, R. (qualities of conifers), 4, 24, 2.5.
Hagen (experiments), 21.

Hatfield, R. G. (transverse strain theory), 26, 27.
Haupt, Herman (prolonged stress), 27.
Haupt, L. M. (letter), 14.
Hawks, .1. D. (letter), 5.
Heald, C. M. (letter), 10.

Names mentioned — Continued.

Hering, R. (letter), 7.

Hinckley, H. V. (letter), 12.

Hinton, .1. H. (letter), 11.

Hodgkinson, E. (change of elasticity), 21.

Hoeuel (botanist), 25.

Holmau, M. L. (letter), 15.

Howe, M. G. (letter), 14.

Hoyer, E. (technology), 25.

Humphreys, D. C. (letter), 10.

Ihlseng, JI. C. (tests by sound), 27.

Ives, Chauncey (letter), 15.

Jacoby, H. S. (letter), 5.

Jenkins, W. B. (letter), 13.

Jenny, C. von (test work), 23.

Jervis, C. M. (letter), 15.

Johnson, J. B. (tests St. Louis Laboratory), 30, 31.

Johnson, T. H. (strength of columns), 27.

Katt<;, W. (letter), 15.

Karmarsch, C. (mechanical technology), 24.

Kelley, H. G. (letter), 11.

Kellcy, R. E. (letter), 14.

Kidder, F.E. (strength of j)iue timber), 27.

Kiersted, W. (letter), 9.

King, H. W. (letter), 11.

Kingman, L. (letter), 9.

Kirkaldy, D. (tests), 24.

Lacey, G. S. (letter), 14.

Laidley, Col. (tests, pine), 26.

I.,a8lett, T. (timb(!r and timber trees), 25.

Lanza, Prof, (tests), 2, 26, 27.

Lavoisier (combustion tests), 26.

Ledebur, A. (mechanical technology), 25.

Lindenthal, G. (letter), 6.

Lyster (tests, large beams), 25.

McClure (tests on large beams), 25.

McCreary, R. D. (letter). 7.

Macdonald, Charles (Governmcnl aid for te.st8),28.

M.acLeod. John (letter), 12.

Mac Vean, J. J. (letter), 9.

Miinn, G. E. (letter), 16.

Martin, C. C. (letter), 15.

Meier, E. D. (letter), 8.

Mikolaschek. Carl (mechanical i)n>iierties of tim-
ber), 23.

Miller, H. I. (letter), 8.

Moeller, .7. (wood anatomy), 25.

Mohr, Charles (collecting material), 29.

Montfort, R. (letter), 9.

Moore, Robert (letter), 14.

Morris, R. C. (letter), 10.

Morse, B.T. (letter), 12.

Musehenbroeck, (strength of dilierent i)arts of tree),
20.

Nickolson, G. B. (letter), 9.

Nordliuger, H. (technical properties of timber), 22, 25.

Norton, W. A. (experinu>nts on set), 28.

Osborne, F. C. (letter), 5.

Paccinotti, (elasticity coefficients determined), 21,
22.

Palmer, C. (letter), 14.

Parker, F. H. (tests at Watertowu, etc.), 28.

Parent, (strength of oak and liri, 20.

Pegr.am, G. H. (letter), 11.

Perronnet, (elasticity limit discovered), 20.

Ill

NaME8 JIENTIOXED— rmitinilril.

Peri, (cla.sti(it.v(ii<tlki<'iils(l.'t(Tiuinetl),21,22.
Phoenix Hiulge t'omi);iiiy (letter), 5.
Philbrick, Prof, (resistaucc formulas), 2S.
Pike, W. A. (tests of -nliitc piue), 28.
Poncelet, (elasticity coefficients), 21.
Pope, W. S. (letter), 15.
Randolph, L. L. (letter), 5.

Rankine, Prof, (manuals of (^nfjineerinjj;, etc.), 25.
Reinke (botanist), 25.
Kiekcts, P. C. (letter), 12.
Riolile (universal testing nuiehine), 32, 34, 35
Rc1)ins(m, 8. W. (letter), 11.
RoiUl, Thomas (letter), 12.
Roilman, T. J. (tests, ordnance), 26.
Kofjers, N. H. (letter), 5.

Roiidelet, (mechanical properties of tinilMT), 20.
Kossman (botanist), 25.

Roth, Filibert (physical exaniiuations of test ma-
terial), 30, 42.
Rothrock, J. T. (microscopic tests), 28.
Kudelofl', M. (report on timber investigations), 21.
Rnmford (combustion tests), 26.
Savart (elasticity determined by souud), 20.
Sachs, J. (porosity of wood), 25.
Sanio (botanist). 25.
Schaeht (botanist), 25.
Schaub, J. W. (letter), 16.
Seaman, II. B. (letter), 7.
Sellers, Coleman (letter), 14.
Shai-ples, S. P. (timber physics), 3, 26.
Shinn, W. B. (letter), 9.
Skinner, F. W. (letter), 5.
Smith, C. Shaler (tests of columns), 28.
Smith, Oberlin (letter), 12.
Strobel, C. L. (letter), 15.

Stubchen-Kirehner, F. (techuolo^jical (li(lioMary),25.
Swain, George F. (letter), 13.
Tetmajer, L. (properties of timber), 23.
Thatcher (coni]iutiug slide rub'), 32.
Tliomsou, G. H. (letter), 8.
Thurston, R. H. (letter), 12, 27, 28.
Trautwiue, J. C. Jr. (letter), 6.
Tredgold (carpentry), 25.
linger (botanist), 25.
tin win, W. C. (testing of materials), 25.
Waddell, J. A. L. (letter), 12.
Watkins, .1. E. (letter). 8.
Weiss (botanist), 25.

AVellington. A. M. (impregiutting timber), 28.
Werthcini(test work), 22.
Wheatstone (axes of resistance), 21.
Whinery, S. (letter), 10.
White, .1. B. (lett<'r), 16.
AVhite, W. H. (letter), 16.
Wiesuer, ,J. (technical microscopy), 25.
Willkonnn (botanist), 25.

Wood, I)e Volson (resistance of mat(Tials), 26.
Wood, Joseph (letter), 10.
Woodbury, C. J. H. (letter), 13.
Propertie.s ok Wood:
Classification, 18, 19, 20.
Cross-breaking strength, 30.
Crushing strc^ugth, 24, 34.
Density, 43, .50.

PuorKKTiEs OF WooD— Continued.

Durahilily, 1,23.

Klasticity, 20, 21, 22, 2.3, 26, 27, .36, :W.

Records, 36, 53, 57.

Relation to each otluT, 4, 20, 23. 21, 3H to 41.

Relation to other conditions, 3, 4, 20.

Annual rings, 4.

Axis of strain, 21.

Climate, 4, 5.

Continuous loail, 20.

Density, 21.

Felling time, 4, 24.

Parts of tree, 20, 21, 31.

Seasoning, 4, 21, 27.

Service, lengtli of, 5, 30.

Soil, 4, 20.

Support, manner of, 21.

Tapi>iug for turjientine, 30.

Resilience, 36,37.

Shrinkage, 48.

Sound, 21.

Toughness, .36.

Working cajiacity, 23, 24. 25.
TEST.S Citeb:

Barlow (strength of materials), 1.23.

Banschinger (elasticity and density of spru.-e and

pine timber), 23
Belidor (general test work), 20.
Bevan (torsion), 20.

Bufl'on (mechanical projierties of oak), 20.
Bull (fuel value of woods), 26.
Burr (elasticity and resist.-iuce). 2.5, 26.
Chevandier & Werthein (coniprehcnsiv.. test work)

32.
Corliss (seasoning of hickory), 27.
Day (microscopic tests of strength), 27.
Dupin (elastic limit), 20.
Ebliels (general test work), 20.
Estrada (prop(>rties of Cuban woods), 27.
Flint (tests of Nicaraguan woods), 27.
Fowke (experiments on British and ol her woods), 23.
Girard (oak colunms), 20.
Hageu (strength and moisture), 21.
Hartig (Gc^rmaii i-onifers), 25.
Hatfield (tranverso strain), 26, 27, 28.
Tlodgkinson (elastic changes), 21.
Ihlseng (testing l)y sound), 27.
Jenny (careful test work), 23.
Johnson (strength of colunms), 27.
Karmarsch (nu'chanical technology), 24.
Kidder (transverse strength), 27.
Laidley (navy tests), 26.
Lanza (long columns), 26, 27.
Laslett (timber and timber trees), 25.
Mikolaschek (mechanical iirop.Tti.s i,f Boln'niian

timbers), 23.
Moeller (wood anatomy), 25.
Mu.schenbroe<-k (ditlerences of streiiglh in same

tree), 20.
Nordliuger(ainiual rings, 25; properties and apjdica-

tion), 22, 23.
Norton (set, after a tninsverso set), 28.
Paceinotti (coelTiclent of elasficify), 21.
Parent (stn^ngfli of oak an<l fir). 20.
J'arker (tests at Watertown), 28.

IV

Tests cited — Continued.

Peri (ciiefficit'iit ofohistirity), 21.

Perroniiet (proldiigi'd stress), 20.

Pike (tests of white ])ine), 28.

Poneclet (torsion), 21.

Pru.ssiaii investigation, 24.

Raukine (manuals of engineering, ete.), 25.

Rodman (ordnance nianual), 26.

Rondclet (general test work), 20.

Rothrock (mieroseoj)ie tests), 28.

Sachs (porosity of wood), 2.5.

Savart (tests hy .sound), 20.

Sharpies (Census report), 26.

Smith (tests of largo pine columns), 28.

Tetniajer (Swiss building timbers), 2.3.

Thurston (torsion, nuiterials of engineering), 27, 28.

Treilgold (carpentry), 20, 25.

Unwin (testing materials), 25.

Watertown Arsenal, tests at, 28.

Te.sts cited — Continued.

Wellington (impregnated timber). 28.

Wheatstone (tests by vibrations), 21.

Wiesner (raw materials of the vegetable kingdom),
25.

AVood (general treatise), 26.
TiMHER Physics:

American work. 26-28.

Bibliography of American work, 27.

Considerations for proposed work, 3.

Conspectus, lit.

Definition. 17.

Dilferentiation, 18.

History and publii-ations, 20-28.

Methods proposed. 3, 29.

Objects. 3. 18.

Origin of the science, 22.

J'russian investigations, 24.

Relation to forestry, 18.

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