9 




U?^ 



1 17 



.M3S 



PROGRESS REPORT ON THE STRENGTH 
OF STRUCTURAL TIMBER. 



CIVIL ENOINEER IN THE BUREAU OF FORESTRY. 




United States Department of Agriculture, 

BUREAU OF FORESTRY.— Circular No. 32. 
GIFFORD PINCHOT, Forester, 



U. S. Department of Agriculture, 

Bureau of Forestry, 
Tfashington, D. C, August 8, IG04. 
Sir: I have the honor to transmit herewith a paper entitled "Progress Report on 
the Strength of Structural Timber," by Dr. AV. Kendrick Hatt, Civil Engineer in 
the Bureau of Forestry, and to recommend its publication as Circular No. 32 of the 
Bureau of Forestry. 

Very respectfully, 

GiFFORD PixcHOT, Forestcr. 
Hon. James Wilsox, 

Secretary of Agriculture. 



PROGRESS REPORT OX THE STRENGTH OP STRUCTURAL TIMBER. 

The Bureau of Forestry has received man}" requests from lumber 
operators, engineers, and architects for the partial results of the tim- 
ber tests now being carried on by the Bureau to determine the 
mechanical properties of the various commercial timbers of the United 
States. The present circular is issued in response to this demand, 
and contains, among other things, the results of cross-bending tests 
on about 250 large beams of structural timber. These results are 
being added to from da}" to day, and the figures given below will t>e 
modified in later publications in accordance with the results of further 
tests. The tests here presented are, however, safficiently numerous 
to indicate the structural values of the various species specified in 
Table I, and to serve as a basis for a revision of opinion, particularly 
with regard to the strength of such species as loblolly pine and west- 
ern hemlock. 

A more formal publication will follow shortly in the form of a bulle- 
tin, in which a detailed account of the methods and machines used in 
obtaining these results will be given, the individual tests tabulated, 
and a thorough analysis of the results themselves presented. The 
data on hand will allow the formulation of certain relations between 
the knots and strength and between the rate of growth and strength, 
and will form the basis for an intelligent revision of the present rules 
for the inspection and grading of timber. 

3 



TIMBER TESTS OF THE BUREAU OF FORESTRY. 

In arranging these tests the Bureau of Forestry has limited its pres- 
ent programme (1) to those species that promise to be on the market for 
an indefinite period, (2) to actual market products, and (3) to such 
purely scientific work as forms the basis for correct methods of test. 

The present knowledge of the structural value of the timbers of the 
United States in the form of large sticks is astonishingly meager. 
What tests have been made have been incomplete and defective in 
many respects. After the programme of the Bureau of Forestr}^ is 
carried out there will exist authoritative and complete information con- 
cerning the mechanical properties of the commercial timbers of the 
United States. One object of the tests is to aid in the framing of 
definite inspection rules for the various grades of structural timber. 

Special problems, like the determination of the proper species and 
sizes for forest products, such as box lumber and cross-arms for poles, 
are undertaken in cooperation with corporations whenever the results 
fit in .with the general interests of forestry. Such information not 
onl}^ results in economy of design, but also clears away misconceptions 
and promotes the removal from specifications of man}^ clauses which 
prevent the use of timber of high structural merit. 

The programme also includes tests to determine the effect of artificial 
seasoning, such as is used in the operations preliminary to the preserv- 
ing processes, and the effect of the presence of the preservatives 
themselves. 

A limited amount of work of a purel}^ scientific nature is carried on, 
involving a critical examination of the methods used in the general 
programme, and assuring that the programme will be guided to its 
most useful end. 

The timber tests of the Bureau of Forestr}^ have been made at the 
following timber-testing stations, in cooperation with the laboratories 
of the respective institutions whose equipment is made available for 
this work: University of California, Berkeley, Cal., L. E. Hunt in 
charge; Purdue University, Lafayette, Ind., W. K. Hatt in charge, 
H. D. Hartley, assistant: Division of Tests, Bureau of Chemistry, 
Washington, D. C, H. S. Betts in charge; Yale Forest School, New 
Haven, Conn., J. W. Toume}- in charge, H. D. Tiemann, assistant. 

The programme of the work, as planned at the present time, is as 
follows: 

Tests to determine properties of structural timber: 

Series I. Tests of the mechanical and physical properties of timber in forma 
found on the market. The material will be of actual sizes and grades of 
commercial produ{;ts. The purpose is to determine moduli for design; to 
determine the value of woods now considered inferior; to determine the 
lialjility to knots, and the reducing factors due to these; to arrange a table 
of standard weights, and rules of inspection and grading; and jnirtly to 
compare the properties of species from different regions. 



Tests to determine the effect of variations in the conditions: 

Series II. Effect of rate of application of load, including impact tests. 

Series III. Effect of moisture. 
Studies of the effect of technological processes: 

Series IV. Preservatives. 

Series V. Methods of seasoning. 

Series VI. Fire retardants. 

In Series I, for instance, the structural value of the loblolh^ pine 
and of the Pacific Coast timbers will be fully determined. These spe- 
cies are tested in the form of large sticks, such as bridge stringers, in 
which knots, crooked grain, and other defects that occur in structural 
sticks are present. The origin of the sticks and their condition of 
seasoning are carefull}^ described. Photographs of the stick are taken 
and drawings made, locating all the knots and showing the amount of 
heart, sap, wane, etc. The sticks are graded by an experienced lum- 
ber inspector. The analysis of the tests of a large number of sticks 
will serve to determine relations between strength and kind and num- 
ber of knots, and between strength and rate of growth. 

In an investigation of a wood like red gum (Liquidamhar styraci- 
fluci) the tests include not only building material, such as floor joists, 
but also an examination of the merits of the wood in the form of small 
clear stock, such as is used for carriage construction, implements, etc. 
The ability of the wood to withstand the operations of steaming and 
bending is also investigated. In the case of this timber, the tests have 
been made on specimens taken directly from the forest. 

It is the intention to test structural timber generalh^ in the green 
state. Certain sticks will be set aside, for the length of time necessary 
for a thorough drjing, in order to develop the defects arising during 
seasoning. The question of the distribution of moisture in the large 
sticks and the relative strength of green lumber and lumber that has 
been onh^ partially dried on the surface will be taken up. It is appar- 
ent that lumber dealers do not keep large sticks on hand long enough 
to allow them to dr}^ out thoroughly, and it does not seem at the present 
time that the surface dryness increases the strength of these large 
sticks in any marked degree. 

SPECIES UNDER INVESTIGATION. 

The species under investigation at the present time are: The Pacific 
Coast red fir {Pseudotsuga taxifolki)^ otherwise called Oregon pine or 
Douglas spruce; the western hemlock {Tsuga lieteropliyllci)\ the red 
gum {Liquidamhar styvaciflaa)\ the longleaf pine {Pinus palustris)'^ 
and the loblolly pine {Pinus txdct). Later on, the redwood {Sequoia 
sempervirens) and western yellow pine {Pinus ponderosa) will be tested. 



DESCRIPTION OF TESTS. 

TESTS OF LOBLOLLY PINE. 

Loblolly pine has not only a wide range of distribution but also a 
wide range of structural merit. 

It is found locally on the markets of Washington, D. C, and Norfolk, 
Va., under the name of Virginia pine, in small sticks 8 by 8 inches or 
10 by 10 inches in cross section, showing almost entirelj^ sapwood of 
so rapid a rate of growth that sometimes only 4 rings occur in 3 inches. 
This is second-growth timber, grown since the civil war, and usually 
very knotty. The same species occurs on the Charleston market, 
whence it is shipped to Philadelphia and the North under the name of 
North Carolina pine. In this case it is forest-grown lumber of large 
size, fairl}^ free from knots, and of a high order of structural merit. 

The lobloll}^ pine as a tree is prolific, grows vigorously, and success- 
fully holds its place in competition with other species in the forest. 
The operations of conservative forest management, such as are under- 
taken by lumber companies that look upon their forest holdings as part 
of their capital and reap periodic harvests of timber from them, con- 
cern themselves in the Southern States notablj^ with loblolly pine. It 
is, therefore, a timber that engineers and architects may expect to find 
on the market for an indefinite period. The chief objection to lob- 
lolly pine is that, being usually sapwood, it decays rapidly when 
exposed. It is, however, a timber that may be treated with preserv- 
atives very successfully, on account of its open grain. For such 
treatment many of the inferior timbers can be used more successfully 
than the more solid timbers like longleaf pine. 

Tables I, 11a, 115, lie, and III give the results of tests on loblolly 
pine obtained on the market of Washington and from a mill at Charles- 
ton, S. C. 

The 8 by 8 inch green Virginia pine entered in the tables was cut 
about March, 1903, and tested about one month after cutting. This 
timber was "sap-stained." It has been shown that this staining, or 
"bluing," does not injure the sti'ength of the wood. The modulus of 
rupture of these beams was 3,281 pounds per square inch, the modulus 
of elasticity 729,000 pounds per square inch, and the dry weight per 
cubic foot 26.3 pounds. 

The 8 by 8 inch and 4 b}^ 8 inch air-dried Virginia pine were cut in 
Staffoi'd Count}^, Va., and had been dr3^ing in the j^ard for two years and 
one year, respectively. The 8 b}^ 8 inch showed a modulus of rupture 
of 4,874 pounds per square inch, a modulus of elasticity of 1,104,000 
pounds per square inch, and a dry weight per cubic foot of 28.8 pounds. 
The 4 by 8 was timber of denser structure and of slower growth than the 
8 by 8 inch. The air-dried pieces show a modulus of rupture of 0,319 
pounds per square inch, a modulus of elasticity of 1,219,000 pounds 
per square inch, and a dry weight per cubic foot of 29.4 pounds. 



Part of the 4 by 8 inch stuff was soaked to bring it to the green 
state, in order to obtain the relations between air-dry and green tim- 
ber. Tlie moisture was increased from 19.4 per cent to 46.3 per cent. 
The modulus of rupture of the soaked timber w^as decreased about 20 
per cent, and the modulus of elasticity about 2 per cent. 

This Virginia pine is usuall}^ second-grow^th timber, showing all sap- 
w^ood on faces, very knotty, and w^ide ringed. It is not a timber for 
important engineering structures, but is used in the minor work of 
architects. 

The 8 by 14 inch North Carolina pine was cut from the holdings of 
a lumber companj^ near Charleston, S. C, about September 1, 1903, 
sawed September 15 to 18, 1903, and tested from tw^o to five months 
after. sawing. It is an average air-dry timber showing sapwood on 
all four faces, of "square edge" grade according to the standard 
inspection rules of 1902 of the Georgia Saw^mill Association. The 
timber represents good structural timber, such as is used in ware- 
houses, mills, and other structures where the conditions do not demand 
longleaf pine. The modulus of rupture was 6,187 pounds per square 
inch, the modulus of elasticity 1,479,000 pounds per square inch, and 
the dr}^ weight per cubic foot 31.2 pounds. The distribution of moist- 
ure at the center of these 8 by 14 inch North Carolina sticks was 
determined by sawing out a section 1 inch thick halfway between the 
ends, dividing it into nine parts by cutting lengthwise and crosswise at 
the quarter points, and determining the moisture in the several parts. 
The average of the results on the ten sections from as many sticks is 
shown in Diagram I. The figures in the various parts of the section 
show the percentage of moisture in each part. 



14 inclies 



32.6 
per cent. 


31.9 per cent. 


29.3 
per cent. 


30.7 
per cent. 


39.6 per cent. 


33.2 
percent. 


28.6 
per cent. 


30.9 per cent. 


29 
per cent. 



Average 31.7 per cent. 

Diagram I.— Distribution of moisture in cross section midway of the length of North Carolina lob- 
lolly pine sticks. (Average of ten sections taken from sticks 8 by li inches by 16 feet.) 



TESTS OF LONGLEAF PINE. 



Longleaf pine has been for a long time the standard timber of con- 
struction, not only on account of its strength, hardness, and durability, 
but also on account of the long lengths of heartwood that can be 
obtained free from knots. At present the difficulty in obtaining long- 
timbers of this wood has led manufacturers, notably in the case of car 
sills, to consider the efficiency of splices or to use the Pacific Coast 



8 

woods. Longleaf pine timber has been tested very largel}^ not only 
in the form of small sticks, but more rarely in large sticks as well. 

In the markets at present any hard pine, whether longleaf, short- 
leaf, or loblolly, which shows a close-ringed, hard texture, goes under 
the name of longleaf pine. The names Georgia pine and Alabama 
pine are often used to designate timber coming from virgin tracts of 
longleaf pine in those States. 

The tests quoted represent longleaf pine sticks of an excellent mer- 
chantable quality, the better part of them being nearly clear stock. 
Some of the sticks from Georgia were obtained in the New Haven 
market, having been shipped there from southern Georgia, and hav- 
ing been in the New Haven market for from three to six months. 
The remainder were obtained in yards at Washington, D. C, whither 
the sticks were shipped from Clinch Count}^, Ga., about one 5^ ear 
before testing. The longleaf pine from South Carolina was also 
excellent material. It is very noticeable in the tests that longleaf 
pine tends to check upon drying out and to fail by longitudinal shear. 
This is one reason for the belief that an engineer is not justified in 
using unit stresses larger than those obtained by tests upon green 
timber. The modulus of rupture of the Georgia longleaf was 8,384 
pounds per square inch, the modulus of elasticity 1,820,000 pounds 
per square inch, and the dry weight per cubic foot 42.9 pounds. 

In the case of both longleaf and loblolly pine, small sticks were 
sawed from the uninjured portion of the large sticks after testing. 
Further tests were made on these small sticks to determine the rela- 
tion between the strength of the large and the small sticks, the relative 
strength of pieces of various rates of grjwth, and the effect of moist- 
ure when the variations due to knots and defects were eliminated. 
These minor tests were also made on sticks cut from red fir and west- 
ern hemlock, as noted below. 

Table III shows a comparison of these tests on the smaller sticks 
sawed from the larger sticks with the tests on the large sticks. It 
appears from this table that the modulus of rupture of the small clear 
sticks 2 by 2 inches in cross section is on an average about 30 per cent 
higher than that of the sticks from which they were cut. This increase 
varies from 100 per cent to 2 per cent. The modulus of elasticity, 
however, of small beams is only 92 per cent of that .of the large beams. 
These values are based on a comparison of the average results of tests 
of sticks of various grades. Of course, the small clear sticks are rel- 
atively strong(u* than the parent sticks when the latter are of second 
grade— that is, contain large knots. Further facts may be determined 
from an inspcH'tion of Table IH. It is reserved for a future bulletin 
to fornuilate rules governing the strength as affected by knots, crooked 
grain, rate of growth, and moisture. 



TESTS OF RED FIR. 



The red tir of the Pacific Coast is known commercially under various 
names. In California and Oregon it is usuall}^ designated as Oregon 
pine; in the region of Puget Sound as 3"ellow fir, Douglas spruce, and 
Puget Sound pine; while in northern Oregon and southern Washing- 
ton, along the Columbia Kiver, and in the eastern markets the name 
red fir is gradually becoming established and universal. 

Botanically, the timber is derived from a single species, Pseudotsuga 
taxifolia. The range of its growth extends from Lower California to 
central British Columbia, and from the Pacific Ocean to the Rocky 
Monntains. It reaches its best development in western Washington 
and Oregon, between the summit of the Cascade Mountains and the 
Pacific. Almost pure forests are found here, which frequently yield 
from fifty to one hundred thousand board feet per acre. In these 
regions the tree will average 5 or 6 feet in diameter at the butt, with a 
height up to 300 feet. 

The trunk of the tree is straight, and readily clears itself of branches. 
It is possible, therefore, to obtain exceptionally large and long pieces 
for structural purposes. Sticks 21: inches square and up to 100 feet 
long are regularly listed and obtainable in the merchantable grades. 
The possibility of procuring long and large pieces, combined with the 
exceptional strength and stiffness of the material compared with its 
weight, renders the red fir an ideal structural timber. Being almost 
entirely heartwood, the red fir is durable on exposure to the weather. 

In the green logs from mature trees the sapwood is distinguished as 
a narrow light-colored ring, extending, usually, not more than 2 
inches beneath the bark. In the seasoned timber one seldom encoun- 
ters sapwood that is distinguishable; and although the adopted grading 
rules allow, for the merchantable grades, sapwood only on the corners, 
lumbermen have no difficulty in meeting the requirements. 

Small trees var3^ing from 1 to 3 feet in diameter are unsurpassed 
for spars, owing to the straightness of the trunk, the small angle 
of taper, and the length obtainable. Lengths from 50 to 110 feet 
are found on the market, while even longer ones are easily obtain- 
able. Red fir is used on the Pacific Coast to the exclusion of other 
species for piling for docks and foundations for heavy structures in 
soft ground. The standard dimensions for this purpose are 12 inches 
in diameter and from 60 to 70 feet long. 

The wood of the red fir varies in color from a light yellow to a pro- 
nounced red; and in grain from one so coarse that there are sometimes 
not more than -1 or 5 rings per inch in small trees or in heartwood to 
a fine, even grain with upward of 40 rings per inch. The rings are 
usually strong!}^ marked, the summer wood being very dense and dark 
in color, while the springwood is much softer; and the wide-ringed 
wood is somewhat spongy. Owing to this marked difference in the 



10 

texture of the alternate rings and to the long, regular fiber, the wood 
splits easil}^, especially when dry, rendering it unlit for box shooks. 
This same characteristic makes it particularly^ pleasing for inside 
finish, paneling, etc., when slash-sawed. The porous springwood 
readily absorbs wood stains, wdiile the dense summer rings are little 
affected, giving a beautiful finish in every shade desired. 

Since it is comparativel}^ free from resin and pitch pockets, the 
wood is adapted to dr^^-kiln seasoning. It is cut into ever}' form of 
lumber, from rough structural timbers, used in the framing of heavy 
constructions of all kinds where strength and durability are required, 
to the fine-grained, clear stock of flooring. 

The mechanical tests, a summary of the results of which is given in 
Tables I to III hereafter, were made upon market products. The 
sticks were graded by an experienced lumber inspector according to 
the Pacific Coast standard of 1900. As has been the experience in 
the timber tests of the Bureau of Forestry with other timbers, the 
grading of the inspector was found to correspond closely to the 
average results of the mechanical tests. The sizes given in Table I 
are those usualh^ used in railroad work, in bridge and trestle construc- 
tion, and in car construction. 

Reference to the origin of the three shipments in Table I is omitted 
until the results of the tests are complete. Shipment B was of poorer 
quality than A and C. 

It is evident from Table I that red fir is of varied quality, and that 
specifications need to be drawn somewhat more carefully than in the 
case of longleaf pine to exclude the wider-ringed quick growth and 
knotty sticks. Taking the 6 by 8 inch and 8 by IG inch sticks of ship- 
ment C as representing an average quality of red fir, and including 
select, merchantable, and seconds, it appears that the modulus of rup- 
ture is 7,790 pounds per square inch, the modulus of elasticity 
1,783,000 pounds per square inch, and the dry weight per cubic foot 
28.5 pounds. The average rate of growth was nearly 19 rings per inch; 
that is to say, the tree added 1 inch to its radius, or 2 inches to its 
diameter, in 19 years. 

It does not appear from the results of the tests that there is an}' 
marked difference in the strength of fir of red and 3'cllow color, pro- 
vided the sticks have the same rate of growth and are equally free 
from defects. 

A series of tests on small clear sticks of straight grain indicates 
that a rate of growth corresponding to 21 rings per inch 3-iclds the 
greatest density and strength. 

These red fir sticks were tested from six months to one 3'oar from 
the time of sawing. They were kept in a shed and sprinkled to pre- 
vent drying out. The exterior parts of the beams contained less 
moisture than the center, but the difference was not marked. An 



11 



examination of the distribution of the moisture throughout the cross 
section of the six 8 by 16 inch beams showed relations which are exhib- 
ited in Diagram II. A 1-inch cross section taken midway of the stick 
was divided into 9 parts at third points, as shown, and the moisture 
in the several parts of the sections determined. The figures recorded 
in the diagram are the average percentages of moisture found in each 
part. 

•< If) inches. > 



22.7 
per cent. 


24.2 
per cent. 


22.6 
per cent. 


25.1 
per cent. 


27.2 
per cent. 


24.5 
per cent. 


22.3 
per cent. 


24.8 
per cent. 


22.4 
per cent. 



Average 23.9 per cent. 

Diagram II. — Distribution of moisture in cross section midway of the length of red fir sticks. 
(Average of six sections taken from sticks 8 by IG inches by 16 feet.) 

TESTS OF WESTERN HEMLOCK. 

The introduction of western hemlock to the market as a building 
material has met with man}^ obstacles. Without doubt the one offer- 
ing the greatest opposition to. the introduction has been the strong 
prejudice aroused hy the name of hemlock, which is merited only by 
the Eastern species. So great is this prejudice even now that, although 
large quantities of the timber are cut and sold, it is sold under false 
or fictitious names, such as Alaska pine and Washington pine, spruce, 
or fir. Western hemlock, as such, has no market standing. 

Western hemlock reaches its best development in Washington, in 
the region lying between the summit of the Cascade Mountains and 
the coast, but is also found from Alaska to central California and as 
far east as Idaho and Montana. The tree, where conditions have best 
favored its growth and development, will aA^erage 4 feet in diameter 
at the butt and 200 feet in height. The trunk is straight and C3^iin- 
drical, but does not readily clear itself of branches. This causes the 
defect of small knots in the timber and makes it impossible to obtain 
much clear lumber except from large trees. The small proportion of 
clear sticks of hemlock in Table I is noticeable. 

The wood of the mature tree is hard, straight and even grained, and 
nearly white in color. The sour odor of the lumber is unmistakable. 
There is not the marked difference in either color or hardness 
between the spring and summer rings that is noticeable in red fir. 
The wood does not split readily, and is light and tough. These quali- 
ties make it especially suitable for box manufacture. Knots are 
rather frequent, often dark brown to almost black in color, but usu- 
all}^ tight and sound. The regular and even structure of the wood and 
the total absence of pitch render it capable of rapid kiln drying at 
high temperature without injury. 



12 

For flooring, molding, paneling, and all inside finish western hem- 
lock makes a superior lumber, not easily scratched, susceptible of a 
high polish, and of excellent wearing qualities. 

The results of the mechanical tests, although the data are not as 3'et 
sufficiently numerous for positive conclusions, indicate a qualit}^ of 
timber averaging about 70 per cent of the strength of red fir of the 
same grade, and suitable for all except the heaviest structures. 

The tests of western hemlock recorded below were made upon tim- 
bers cut on the west slope of the Cascade Mountains, in Lane Count}^, 
Greg., and tested from two to six months after sawing. The sticks 
were stored in a shed and sprinkled from time to time. It is difficult 
to apply to the western hemlock the grading rules adopted for red fir. 
Their application throws most of the hemlock sticks into the "seconds'^ 
grade. New rules should be made for western hemlock to bring the 
better qualit}^ of sticks into the "merchantable" grade. The average 
of the results shown in Table I gives a modulus of rupture of 5,530 
pounds per square inch, a modulus of elasticit}^ of 1,261,000 pounds 
per square inch, and a dry weight per cubic foot of 26.8 pounds. The 
rate of growth of these sticks was 10.2 rings per inch. 

RESULTS OF TESTS IX GENERAL. 

SUMMARY OF TABLE I. 



A digest of the results in Table I may conveniently be shown in the 
following table, which presents the strength and stifi'ness of beams 
such as are found in the market and are used'lw engineers. More 
detailed information will be found in Table I. The modulus of rup- 
ture is a factor which represents fairh^ well the strength of the timber. 
The modulus of elasticity is a factor which represents its stiffness. 

Summary of Table I, showing cross-hcncUng strength of structural timber. 



Species. 


Grade. 


Average 
number 
of .sticks. 


Time sea- 
soned. 


Moist- 


Weight per 
cubic foot. 


Modulus 
of rup- 
ture. 


Modulus 
of elas- 
ticity. 


ure. 


As 
tested. 


Dry. 


Red fir: 

Shipments A 
and 0. 


Select 


22 
29 
16 
14 
15 
25 
36 
44 
41 
121 

30 
20 

26 


Monlhs. 
I 6 to 12 

1 ^ 
I 


Pa- 
cent. 
f 22.6 
\ 20. 8 
1 19.5 
1 27.6 
26.5 
1 26.2 

\ 'He 

23. 6 

32. 2 
37.2 

26.7 


Pounds. 
37.1 
34. 5 
31.9 
30.9 
33.7 
35.1 
34.7 
34. 8 
33.8 
33. 4 

35.4 

42.8 

53. 3 


Pounds. 
30.2 
28. 4 
26.7 
24.2 
26. 6 
27.8 
27.9 
28.4 
27.4 
27.8 

26. 8 
31.2 

42. 1 


Pounds 
per 

square 
inch. 
8,810 
7,730 
6,290 
6, 250 
5,340 
4,280 
7, 780 
6, 920 

5, 070 

6, 580 

5, 505 
6, 187 

8, 210 


1,000 
lbs. per 
square 

inch. 
1 , 925 


Merchantable 

Seconds 


1,825 
1 630 




Select 


1,280 


ShipmentB.... 

Shipments A, 
B, and C. 


■^Merchantable 

[Seconds 

Select 


1,320 

1,400 

. 1 , 675 


Merchantable 

Seconds 


1,660 


1 


1,490 


Average of 


All grades 


1,570 


sliipmentsA, 
B, and C. 
Western hornloek 


do 


3 to C. 
3 

6 to 12 


1 "60 


North Carolijia 

loblolly pine. 
Longleai pine 


S>iuare edge 

:Mcrchantablc 


1,479 
1,790 



^ 



13 

This table is not considered to be a final statement of the relative 
structural value of the various species tested. The great ranoe of 
values found in tests of timber render it necessaiy to perform tests on 
a large number of sticks. Furthermore, the moisture condition of 
the beams varies somewhat in the different species entered in Table I. 
The question of the effect of a longer time of dr3^ing in inci'easing or 
decreasing the strength of beams has not been satisfactorily investi- 
gated. Certain elements of the question may be noted. The moisture 
content is different in green timber of various species; for instance, 
about 50 per cent of the dr}^ weight in the case of red fir, and up to 100 
per cent in the case of loblolly pine; so that the same moisture content 
in these two species does not represent an equal degree of seasoning. 
Again, the red fir seasons more rapidly in the dry climate of California 
than does the loblollv pine in the moist climate of the Atlantic Coast. 
It is surprising how much moisture is found in well-seasoned timber. 
Attention is called to the fact that sticks of longleaf pine 10 b}- 12 inches 
in cross section which had been dr^^ing in the Washington 3'ard for one 
3^ear contained 35 per cent of moisture, and that sticks of loblollj^ 
pine from Virginia, 8 b}' 8 inches in cross section, that had been dr^'ing 
in the same situation for two 3^ears and were almost black on the sur- 
face, contained 31 per cent of moisture. The small sticks dr3^ out 
more uniformh' than do the large sticks, and after the moisture has 
been reduced to nearl3^ 26 per cent the strength begins to increase 
upon a further reduction of moisture. The laws expressing the rela- 
tion of strength and moisture in the case of small sticks, however, do 
Eot necessarih' apph' to large sticks. It is believed that the tests 
quoted in the above table were made on timber as delivered to the 
engineer under the ordinar3^ conditions of the market. 

A future bulletin will present the results on the individual sticks 
and give full information concerning the proportion of the results 
falling within a given range of strength. Photographs of the sticks 
will also be published. 

STRENGTH AXD COMPRESSIOX. 

Table lla contains the results of tests in compression parallel to the 
fiber of various species of timber. These are on material derived 
from the beams listed in Table I. Tlie3^ are to be regarded as minor 
tests. The Bureau of Forestr3^ has not 3^et installed a testing machine 
of sufficient capacity to allow tests on full-sized columns. 

Table 11^ contains the results of tests in compression at right angles 
to the fiber. Loads were applied to a steel plate for 4 inches aloug 
the stick under test, and measurements were taken to determine the 
amount of yielding of the stick in the direction of the loading due to 
crushing of the surface or general compression of the stick. The 
elastic limit of the wood under this kind of loading is given in Table 
11^. The values represent the strength of wood against the bearing- 
pressure of a washer. 



14 



LONGITUDINAL SHEAR. 



When a beam becomes weakened b}^ wind-shakes or season checks 
it is apt to fail under longitudinal shear. That is to say, it splits from 
the end of the beam toward the center, instead of failing in tension or 
compression at the center of the span. The liability to failure under 
long'itudinal shear decides the strength of a beam of short span. Table 
lid indicates the strength of the various sticks in longitudinal shear. 
The strength is given in pounds per square inch of horizontal section 
of beam. The strength of the area of wood actually sheared off is 
greater than these values. The latter include the effect of openings 
in the wood between the fibers due to checks, etc. The values are 
those that should be used in desig-ninor beams to carrv loads. 



SHEARING STRENGTH. 



The results of the tests to determine the actual shearing strength of 
the wood will be found in Table 11^^. These tests were made on small 
test pieces, a projecting bead on each of which was sheared off. The 
test piece was so designed as to yield a failure in true shear without an 
accompanying failure in compression or bending. 

TESTS OF RED GUM.^ 

Red gum is found in abundant quantities, principally in the river 
bottomlands of all the Mississippi Valley States south of the Ohio 
River and east of Texas, where the stumpage is estimated to be 
greater than the combined stumpage of all the other hardwoods, and 
along the swamps of the Atlantic Coast. Although at the present 
time a comparatively small amount is being cut, owing to the great 
care necessary in seasoning the wood, its future is most promising. 
As a forest tree the red gum is very tall and straight, varying, 
according to soil and climatic conditions, from 30 to 60 inches in 
diameter at the stump, and in height to the first limb from 40 to 80 
feet. The percentage of waste, in comparison with other hardwoods, 
is very small, and for clear, wide lumber this is as valuable a tree as 
poplar or cottonwood. Red gum is now being used extensivel}^ for 
barrel staves, for which purpose it is rapidly replacing elm. Some 
tight barrels are being made from red gum, but, owing to the more 
favorable properties of the oaks for this purpose, its future use will 
probably be limited for some time to the slack barrel. 

Another important use of red gum, where strength is an essential 
feature, is in the manufacture of tobacco and canncrs' boxes and for 
crating for heavy machinery. For boxes the wood has, within 
the last few years, been used along with sycamore, poplar, and 
cottonwood. 

a Also called sweet gum and star-leaved gmn. 



15 

Owing to the value of the clear, wide lumber cut from the red g'lim 
loo", it is too expensive a wood to use for construction timber while 
the suppl}" of pine, fir, and hemlock is so great. However, the red 
o'um has local uses for building material, such as joists, sills, and 
common frames. The material is usually cut from the heart of the 
tree, which, on account of shakes, etc., is not used for other purposes. 
Results of tests on a few of these joists are shown in Table IV. The 
supply of red gum timber for this use is so limited that it is hardly 
available for general engineering construction. 

The tests of red gum, quoted in Table V, are on 4 by 4: inch sticks 
sawed from trees selected from the forest b}^ agents of the Bureau of 
Forestry in the Tennessee River bottoms at Hollywood, Ala. Both 
mature and 3^oung trees are represented. These tests form part of a 
series which will eventually cover the Atlantic Coast and the Missis- 
sippi Valley ranges of the tree. It will be noticed that there was a 
considerable number of culls from the logs. Fifty-three per cent of 
the heart pieces sawed out were discarded. 

The results of compression tests parallel to the grain on specimens 
of red gum cut from 10 trees at Risco, Mo., are added to Table V. 

The tests include an examination of the relative strength of the 
wood at various parts of both young and mature trees from various 
localities, which will form a portion of a general bulletin on red gum 
to be issued in the near future by the Bureau of Forestry. In the 
tables given in this circular the strength of the red gum is given as 
ascertained from the general run of the trees from the Tennessee 
River bottoms at Hollywood, Ala. Five mature and 5 immature trees 
were cut. Three logs 16 feet long were taken from each trunk. Four 
by four inch test pieces were cut from a plank which was sawed from 
the trunk, to include the center of the heart of the tree. Part of the 
material is to be tested green, part kiln-dried, and part air-dried, in 
cross bending, compression parallel to the fiber, and compression at 
right angles to the fiber. An analysis of the results will attempt a 
determination of the relative strength of the fiber throughout the 
height of the tree, and of the relative strength from the heart center 
to the bark. While it is possible to ascertain these relations in the 
case of a tree of straight-grained trunk like the coniferous woods, the 
present indications are that it is impracticable to obtain all these rela- 
tions in the case of cross-grained woods like red gum. The outcome 
of the work depends on the degree to which the cull material from 
the heart near the butt of the tree is excluded on account of shakes, 
rot, etc. 

The following table shows the relative percentage of culls in heart- 
wood and sapwood of the specimens cut from logs procured in Alabama 
and tested in cross bending, as reported in Table V: 



16 



Culls in red gum logs used In cross-he) idlng tests. 





Hcartwood. 


Sap wood. 


Total. 




32 
69 
53 


16 
17 
6 


48 


Total number of specimens tested 


86 


Per cent of waste in culls 


44 







The general procedure in taking samples of red gum from various 
parts of the country is to select a bolt from the trunk at a distance 
from the ground sufficient to avoid rot and shakes. This bolt will 
furnish test pieces for the determination of the strength of the heart- 
wood and sapwood. The problem of determining the proportion of 
merchantable material in a tree is for the inspector, forester, or mill 
man — not a problem for the testing machine. The test pieces from the 
bolt will also serve to determine the difference of strenp-th between 
vigorous young trees and mature trees. 

That portion of the results of the tests on the Alabama logs which is 
of interest in connection with this circular is given in Table V. This 
table gives a general summary of the strength of red gum heart and sap 
pieces. The logs were shipped from Alabama to the timber-testing 
station of the Bureau of Forestry at Lafayette, Ind., and there sawed 
up into 4 by 4 inch test pieces. The green pieces were tested as soon as 
possible after sawing. The time elapsing from the sawing of the logs 
until the end of the tests was about five weeks. The test pieces were 
kept at the moisture of green timber by a cover of sacking, which was 
sprinkled day by day. Each test piece was put in a moist closet for 
two days preceding the actual test. As timber has to dr\^ to a degree 
of moisture below 33 per cent before any subsequent drying begins 
to affect the strength of the fiber, and the average moisture of these 
green specimens was 86.4 per cent, it is evident that the values given 
are those for green timber. The partially kiln-dried material was the 
result of an attempt to dry some of these 4 by 4 inch gum sticks 
in a kiln without subsequent air dr3^ing. The kiln drying consisted 
of the following operations: The sticks were steamed for forty - 
eight hours with live steam, producing a temperature in the kiln 
of 110° to 125° F. The steam was then shut off", and the kiln heated 
for 35 days to a temperature var^^ing from 85° F. on the first few 
days to 150° and 160° F. at the last. Checking and twisting were 
most noticeable during the first four or five days in the kiln, after 
which no large increase was observed. It was noticed upon removal 
from the kiln that the surfaces of all the timber were apparently drv, 
having the convex surface peculiar to kiln-dried timber. Upon cutting 
into the pieces it was found that the heartwood had dried only to a 
depth of three-quarters of an inch. The sapwood had dried from 
a depth of 1\ inches to thorough dryness. Subsequent kiln-drying 



17 

tests on 2 by 2 inch red gum heartwood stock have shown satisfactory^ 
results. In the latter case a much slower and drier heat was given 
the specimens, which were afterwards steamed and bent into carriage- 
wood stock. 

To determine the effect of close piling on green wood 34 specimens- 
of heartwood and 22 specimens of sapwood were close-piled in a 
green condition in the laborator}^ and allowed to remain for six 
months, developing sap-stain and fungus growth. These specimens 
were afterwards tested. The results of the tests on this "blued'' 
timber are compared in Table VI with the results of the tests given in- 
Table V. As has been shown in previous tests with pine, both in. 
German}^ and in the United States, the effect of this "bluing" is not 
detrimental to the strength of the timber. 

It was desired to ascertain if red gum had the mechanical proper- 
ties which woidd fit it for use in the vehicle industry. Factor}^ tests. 
showed that this wood could be steamed and bent, and that it took a. 
good linish. A series of tests was made of hickory in comparison, 
with red gum. Table VII shows the relative bending and compression, 
strength of the four grades of dr}' commercial hickorv. The speci- 
mens were all kiln-dried and then seasoned in the laboratory to 
nearly the same per cent of moisture. The results are all based on. 
specimens nominall}^ 1^ inches square in cross section by 30 inches, 
long, selected b}" an expert grader in the mill yard, all specimens free 
from knots, cross grain, and other defects. The strength of the red 
gum in Table VII represents tests on clear heartwood practically 2^ 
inches square in cross section by 30 inches long', kiln-dried to 13.. 5 per 
cent moisture. The actual values obtained in the tests are increased 
b}^ 12 per cent so as to represent the strength of this red gum at 8. 
per cent of moisture, in order to form a fair comparison with the 
hickor3^ 

The difference between red gum and hickory is more marked in. 
impact tests than in tests under gradual loading. Torsion tests. 
bring out very well the difference in the structure of the two woods. 
The better grades of hickory develop a long fiber, which "brooms out'^ 
after rupture, the test piece submitting to a large degree of twisting 
before rupture. Red gum, on the contrary, opens up longitudinally 
at a small angle of twist, showing a crooked grain and short fiber. 
The results of a careful examination of the mechanical properties of 
the red gum indicate that it is inferior in strength to the poorest 
grade of hickory. Further discussion will appear in the bulletin on 
red gum. 

5168— No. 32—04^2 



APPENDIX. 

NOTES ON TABLE I. 

The moisture in the beams was determined by the section method. 
An inch section was sawed from the middle and from one of the quar- 
ter points of the span and dried at 100'^ C. to a constant weight. To 
determine the amount of moisture driven off by the saw a section one- 
half inch thick was sawed next to the section 1 inch thick. It appears 
that the difference between the moisture at the middle and the one- 
quarter points of the span is negligible, and that the moisture driven 
off from a 1-inch section by the saw is also negligible. A very careful 
examination of longleaf pine and red fir shows that the same is true of 
the correction to the moisture per cent due to the volatile oil driven off 
from the sections in the oven. The per cent of moisture is computed 
with reference to the dry weight of the wood. 

The annual rings per inch are a measure of the rapidit}^ of growth. 
A ring consists of the light springwood and the dense summer wood 
added by the tree in one year. Thus 20 rings per inch means that the 
tree added 2 inches to its diameter in twenty years. 

The dry weight per cubic foot is the number of pounds of wood in 
1 cubic foot. The weight of 1,000 feet board measure may be obtained 
by multiplying the weight per cubic foot b}^ 83^. 

The modulus of rupture and the fiber stress at elastic limit are meas- 
ures of the strength of the wood in cross bending, and the modulus of 
elasticity is the measure of the stiffness in cross bending. The method 
of computing these is described in Bulletin No. 8 of the Bureau of 
Forestry. The elastic limit is the real elastic limit, not the apparent 
elastic limit defined in Bulletin No. 8. Loads were applied continu- 
ousl}^ at a speed of one-quarter inch per minute for beams 6 b}^ 8 inches 
in cross section and at a speed of one-eighth inch per minute for beams 
8 by 16 inches in cross section. 

RULES FOR INSPECTION AND GRADING. 

The rules of inspection and grading referred to in this circular are 
here reproduced. 

From the classification and insj^ection rules for yellow pine lumber, adopted by tlie Georgia 
Sawmill Association at Jacksonville, Fla., 1902. 

MERCHANTABLE INSPECTION, 1902. 

Dimension sizes. — All square lumber shall show two-thirds heart on two opposite 
sides; other sizes shall show two-thirds heart on faces, except for lengths exceeding 
18 



19 

40 feet, then to show half heart on two opposite sides or faces for the additional 
length — all free from round shakes that show on the surface or through shakes or 
unsound knots. 

STANDARD INSPECTION, 1902. « 

Dimension. — Shall be square edge, except that sizes 10-inch or over may have 2-iiich 
wane one-third the length on one corner, or one-sixth the length on two corners, or 
one-ninth the length on three corners, or one-twelfth the length on four corners; 
wane to be measured on face side. All free from round or through shakes or unsound 
knots. 

From the Pacific Coast standard grading rules for Douglas fir, adopted WOO. 

MERCHANTABLE. 

This grade shall consist of sound, strong lumber, free from shakes, large, loose, or 
rotten knots, and defects that materially impair its strength ; well manufactured and 
suitable for good substantial constructional purposes. 

^Yill allow — 
Occasional variations in sawing or occasional scant thicknesses, sound knots, i:)itch 
seams, and sap on corners, one-third the width and one-half the thickness. Defects 
in all cases to be considered in connection with the size of the piece and its general 
quality. 

SECONDS. 

This grade shall consist of lumber having defects which exclude it from grading as 
merchantable. 

Will allou- — 

Knots and defects which render it unfit for good substantial constructional pur- 
poses, but suitable for an inferior class of work. 



Shall be sound, strong lumber, good grain, well sawn. 

^Y^ll alloic — 

In sizes 6 by 6 and less, knots not to exceed 1 inch in diameter; sap on corners 
one-fourth the width and one-half the thickness; small pitch seams when not exceed- 
ing 6 inches in length. 

In sizes over 6 by 6, knots not to exceed 2 inches in diameter, varying according 
to the size of the piece; sap on corner not to exceed 3 inches on both face and edge; 
pitch seams not to exceed 8 inches in length. 

Defects in all cases to be considered in connection with the size of the piece and 
its general quality. 

DESCRIPTION or BEAMS. 

The limits of this circular will not allow a detailed description of 
the sticks the results of tests of which are given in Table I. The stick 
whose modulus of rupture corresponds to the average modulus of rup- 
ture of the merchantable or square edge grade in Table I is selected 
for description in each case. 

HISTORY OF SHIPMENT '^'a" RED FIR. 

Cut in township 17 south, range 2 east, Willamette Meridian, on 
McKenzie River, west slope Cascade Mountains, Lane County, Greg. 
Shipped from Coburg, Oreg., May 8; received at Berkelev, Cal., May 

25, 1903. 

"Called "square edge" in Charleston and in this circular. 



20 

INDIVIDUAL DESCRIPTION OF TIMBERS TESTED. 

Red fir, shipment '^A,^^ 6 by 8 average select. 

Rings per inch, 13; color, medium 3^ellow; imperfections: Side a, 
one weather check; side J, pitch seam; side ^, pitch seam, weather 
checks; side c/, pitch seam, weather checks. 

Red fir, shipment "^1," 6 by 8 inaximinn select. 

Rings per inch, 20.5; color, medimn yellow; imperfections: Side ^, 
three knots 0.5 to 0.7 inches in diameter, small weather checks; side J, 
clear; side i\ weather checks; side d^ clear. 

Red fir, shipment 'L-1," 6 by S minimum select. 

Rings per inch, 21; color, medium yellow; imperfections: Side a^ 
weather checks; side ^, pitch seam; side c, one-half -inch knot and 
weather checks; side d^ pitch seam. 

Red fir, shipment "^1," 6 by 8 average merchantable. 

Rings per inch, 22; color, medium red; imperfections: Side a^ 2 
knots about 1 inch in diameter, weather checks; side J, 1 knot 3 by 2^ 
inches, broken out; side (?, 6 knots 1 to li inches in diameter, checks; 
side d^ 1 small knot. 

Red fir, shipment '',.4," 6 by 8 ma.vimum merchantable. 

Rings per inch, 22; color, medium yellow; imperfections: Side a., 
clear; side J, clear; side c, two ^-inch sound knots; side <:/, clear. 

Red fir, shipment ".-I," 6 by 8 minimum merchantable. 

Rings per inch, 25; color, medium yellow; imperfections: Side a, 
one i-inch sound knot; side 5, clear; side ^, 8 knots from i to 1 inch in 
diameter; side d^ 2 knots. 

Red fir, shipment "A,'' 6 by 8 average seconds. 

Rings per inch, 8; color, medium red; imperfections: Side «, 16 
sound knots i to 2 inches in diameter, check; side J, 4 knots 1 to li 
inches in diameter, sound; side <?, 6 loose knots 1 to l^ inches in 
diameter, checked; side d^ 5 knots from 1 to 1^^ inches in diameter, 
all sound. 

Redfiir, shipment "^4," 6 by 8 maximum seconds. 

Rings per inch, 18; color, medium red; imperfections: Side a, 3 
knots 1 to 22" inches in diameter, 2 loose; side I), 7 knots 1 to 3 inches 
in diameter, loose; side c, 1 loose knots 1 inch in diameter, pitch seam; 
side d, no knots, pitch seam and check. 



21 

Bedjii\ shipment ^^A,^' 6 by 8 minimum seconds. 

Rings per inch, 5.4; color, medium red; imperfections: Side a^ 13 
knots i to li inches in diameter, 2 loose, weather checks; side Z>, 5 
knots i to li inches in diameter, 2 loose, weather checks; side c\ 5 
knots k to li inches in diameter, 1 loose, weather checks; side d, 11 
knots i to 2 inches in diameter, 3 loose, weather checks. 

Lohlolly pine, 8 by 8 average square edge, green. 

History: From Urban Wharf, King and Queen Count}', Ya. ; in 
yard one week. Rings per inch, 2.6; color, light yellow; imperfec- 
tions: Side a, 11 knots from 1 to 3 inches in diameter, all sap; side 5, 

6 knots about 2 inches in diameter, all sap; side <?, 6 knots from 2i to 
4i inches in diameter, all sap; side <:?, 9 knots from l^- to 3 inches in 
diameter, all sap. 

Loblolly 'pine, 8 by 8 maximum square edge, green. 

Rings per inch, 3.2; color, light yellow; imperfections: Side «, 8 
knots from 1 to 2^ inches in diameter; side 5, T knots from li to 3 
inches in diameter; side c\ 5 knots from i^ to 3 inches in diameter; 
side dy 7 knots from 1 to 4 inches in diameter, sap on all four faces. 

Loblolly pine, 8 by 8 minimum square edge, green. 

Rings per inch, 3; color, light yellow, turning to ^^ellowish white 
on exposure; imperfections: Side «, 3 knots; side Z», 6 knots; side c, 

7 knots; side d, 8 knots from 3 to 5 inches in diameter. 

Western hemlock-, 8 by 16 maximum merchantable. 

History: Cut in township 20 south, range 1 east, Willamette Merid- 
ian, west slope Cascade Mountains, Lane Count}", Oreg. Shipped 
from Saginaw May 12, received at Berkeley, Cal., May 25, 1903. 
Rings per inch, 11.8; imperfections: Side a^ 11 knots i to 1 inch in 
diameter, 3 loose, weather checks; side J, badly weather checked; side 
c, 10 knots \ to 1 inch in diameter, 6 loose, weather checked; side <:Z, 
2 knots li inches in diameter, sound, weather checked. 

Westeim hemlock, 8 by 16 minimum merchantable. 

Rings per inch, 11; imperfections: Side «, 10 small knots i to li 
inches in diameter, 4 loose, 6 sound; side 5, 3 knots, 2 loose; side c, 

8 knots, all sound, checked; side <:Z, 2 knots, both loose, weather 
checked. 

Loblolly pine, 8 by 14 average square edge. 

History: Felled about September 1, 1903; sawed at mill September 
15; tested November 4, 1903. Rings per inch, 7; color, sap, greenish 



22 

white; imperfections: Side «, all sap; side J, three-fourths sap; side <?, 
all sap; side cZ, 7 knots 1 to 2^ inches in diameter, two-thirds sap. 

Loblolly pine, 8 by 14 maximum square edge. 

Rings per inch, 6; color, heart, brown; sap, greenish white; imper- 
fections: Side <2, all sap; side h, 10 knots i to 3i inches in diameter, 
one-half sap; side c^ all sap; side cZ, one i-inch knot, two-thirds sap. 

Loblolly pine, 8 by 14 minimum square edge. 

Rings per inch, 5.75; color, sap, greenish white, heart, brown; 
imperfections: Side <2, all sap; side 5, seven-eighths sap, one 2-inch 
knot; side c, all sap; side d^ nine-tenths sap. 

Longleaf pine, 10 by 12 average merchantable. 

History: Grown in southern Georgia; in lumber yard since Feb- 
ruar}^, 1902; tested September 24, 1902. Rings per inch, 13; imper- 
fections: Side «, li by 2 J inch knot in upper half of side; side h, 
2 small knots in upper half of side, 1.1 by i inch and 1^ by i inch; 
side c, 4 small knots in center of side, 0.2 by 0.25 inch, 1.4 by 0.2 inch, 
1.2 by 2 inch, and 0.7 by 0.5 inch; side d, 4 small knots and slight 
checks near upper end, 1.0 by 0.25 inch, 2.2 by 0.2 inch, 1.1 by 0.25 
inch, 1.0 by 0.6 inch. 

Longleaf pine, 10 by IS maximum merchantable. 

. Rings per inch, 14; imperfections: A few slight checks in each side; 
1 knot in side a, 3 by 4 inches, and 1 in side d, 2.5 hj i inches. 

Longleaf pine, 10 by 12 minimum merchantable. 

Rings per inch, 13; imperfections: Side «, 3 knots, i by ^ inch, i 
by J inch, i by i inch, checks; side 5, 4 knots, li by li inches, li by 
1-2- inches, 1 by 1 inch, 1 by 1 inch; side <?, 6 knots, \ by i inch, i by i 
inch, 1 by li inches, 1 by 1 inch, ^ hj \ inch, 1 by 1 inch; side d^ 1 
knot i by \ inch. 













Dry 




Fibc 


weight 


Num- 


stres 


per 


ber of 


ateli 


cubic 


tests. 


tic 


foot. 




limi 






Lbs.z 


Lbs. 




sq.ii 


30.46 




[4,46 


34.25 


1 ^^ 


\ 5,2( 


27.20 




I 2,7] 


27.2 

28.9 
25.2 

24.29 
















f2,97 


27.0 


l[ 13 


4,04 


21.9 




U.lf 


33.1 


] 


f3,62 


36.9 


\ 12 


i 4,86 


31.9 


J 


[ 2,5£ 


29.4 




f4,35 


30.9 


r ^ 


i 5,86 


27.6 




i 1,98 


25.5 

25.6 
25.4 

27.4 














1 


3,91 


28.0 


\ 16 


\ 5,31 


26.0 


1 


2,65 


28.4 




[3,981 


29.0 


f ^ 


i 4,42 


27.8 


1 


l3,BB 
[1,84' 




1 " 

] 


\ 3,181 
1 871 

[3,08< 




1 '' 

1 


\ 5,30( 
I 67^ 

[2,07J 




1 


1 '■' 

1 


3,76( 
1, C2( 

[3,38^ 


1 
'.'.'.'.'.'.'.'J 


1 ' 

1 


4,90( 
2,40( 

[3,61( 




} » 


\ 5,21( 
I 2,46( 


42.9 

49.4 
31.4 

37.6 

47.5 
33.1 






























s subsen 


pts to t 


he figu 



ik 



Table l.—a-ua-Undini/ tlrn:glh ojlari, 



J™«K,„,„. !„„„„.l,„„^.,i 1n-,™,I nry ^ I r,,,. 






SI.4 10.O 23.65 I 
86.6 26.0 27.9 1 II 



1 |7.460 

I "lis 



Hi 






Umli. '""^ 



%K 



2;;r' 






lU 



i'fi,:;;;^ 










iiiiilli 


t! 


^1 


I} 


S<,„»rctd,,. 








1 ^? ''1 


33.0 


'ss 


Is 


80.0 


; '^ '1 


140.0 


t! 


5:5 


11 



^r 









Num ' 


s 


fi. 


»^ 


a 


— 


— 




— 


^1 


"f 


1 


'^S 


VI 


s 


1-s 


■fi 


•1 


■H 


*skJ 


i«.< 


'"^ 


ffi 


It 


'Is 


fH 


» 


|l 


'is 


!•» 


B 


l3 


tl 


•■■^'^ 


ri 


15 


'■».;5 


Tig 


i 


li 


'li 



6108— No. .'52—04. (To face page 22. ) 



( 

1 



23 



Table Ila. — Compressive strength parallel to the fiber. 



Species. 



Where 
grown. 



Dimensions. 



Grade. 



Num- 
ber of 
tests. 



Stress 
at elas- 
tic 
limit. 



Stress 
at rup- 
ture. 



Mois- 
ture. 



Num- 
ber of 
rings 
per 
inch. 



Weight. 



Red fir 

Eedfir 



Red fir. 



Western hemlock 

Loblolly pine 

Loblolly pine 

Longleaf pine . . . 



Oreg. 



Ya.... 



S. C... 



Ga.... 



W X 5' 



5" X 5' 



5" X 5' 



5"x 



4" X 6' 



All: 

Average . . . 

Maximum . 

Minimum . 
All: 

Average . . . 

Maximum . 

Minimum . 
All: 

Average . . . 

Maximum . 

Minimum . 
All: 

Average . . . 

Maximum. 

Minimum . 
Square edge: 

Average . . . 

Maximum . 

Minimum . 
Square edge: 

Average . . . 

Maximum . 

Minimum. . 
Merchantable 

Average . . 

Maximum 

Minimum 



80 



74 



67 



24 



Lbs. per 
sq. inch, 
■ 51)0 
280 




590 

60 


3,840 

5,220 
2,500 



sq. (Ills I 

f3,51)C 

\ 5,28C 
I 1,97C 

f2,59 
\ 3,76 
[1,27 

I 

It: 

In 

[2, 



2,560 

930 
520 



1,346 

,950 
819 



•2,748 

4,490 

925 



3,650 

5,200 
2,391 



Lbs. per 

sq. inch. 

4,788 

7,070 

2, 780 

3,376 

4,515 
1,620 

4,886 
6,100 
3,440 



4,620 
2,660 

1,988 
2, 485 
1,362 

3,862 

5,600 
3,035 

4,862 

5,950 
3,290 



Per 
cent. 
20.7 

22.7 
17.5 

26.3 

36.5 
20.0 

20.8 
28.3 
15.7 

32.0 

47.1 
22.2 

74.0 

104.6 
61.9 

39.0 

84.0 
22.6 

26.9 

34.8 
21.7 



15.6 

30.0 
4.0 



19.4 

36.0 
7.5 



16.0 
5.0 



Lbs. per 

cubic ft. 

29.0 

36.2 

22.9 

26.0 

31.6 
22.^ 

28.4 
33.2 
23.8 

25.7 

30.6 
22.5 

26.4 

31.9 
20.0 

29.6 

40.0 
24.4 

35.7 

46.8 
31.0 



Table II&. — Compressive strengtli at right angles to the fiber. 













Fiber 






Species. 


Where grovrn. 


Dimensions. 


Grade. 


Num- 
ber of 

tests. 


stress 
at elas- 
tic 
limit. 


Mois- 
ture. 


Dry 
weight. 












Lbs. per 


Per 


Lbs. per 


Red fir 


A,B, C 


4" X 4" X 16'' . . 


All: 




sq. inch. 
( 597 




cubic ft. 
a 28. 8 








Average 




a 19. 5 








Maximum . . . 


I 142 !<! 1,300 


22.4 


35.9 








Minimum ... 


J 402 


17.5 


23.0 


Western hemlock. 


Oregon 


4" X 4" X 16" . . 


All: 














Average 


1 f 478 


34.1 


26.7 








Maximum . . . 


\ 57 j-i 988 


53.3 


34.1 








Minimum ... 




[ 234 


21.0 


2L9 


Loblolly pine 


Virginia 


8'' X 8" X 28" 


Square edge: 
Average 


















f 412 


74.7 


26.1 








Maximum . . . 


1 ^^ 


\ 866 


104.6 


31.9 








Minimum . . . 




195 


61.9 


20.2 


Loblolly pine 


South Carolina . . 


8" X 14" X 28" . 


Square edge: 
















Average 




623 


44.8 


29.7 








Maximum . . . 


I 23 


\ 937 


117.0 


40.0 








Minimum . . . 




375 


23.5 


24.4 


Longleaf pine 


Georgia 


4" X 4" X 16" 


Merchantable' 
















Average 




f 616 


25.1 


36.0 




" 




Maximum . . . 


I 22 


\ 875 


30.9 


43.2 








Minimum . . . 




[ 375 


21.7 


31.0 



a Results of 51 tests. 



24 

Table lie. — Shearing strength. 













Num- 




Shear- 


Species. 


^Yhere grown. 


Dimensions. 


Grade. 


Num- 
ber of 


ber of 
rings 


Mois- 
ture. 


ing 
stress 










tests. 


per 


(ulti- 












inch. 




mate). 














Per 


Lbs. per 


Red fir . . 


A 


1.5" X 3" 


All: 
Average 


1 f l*-9 

\ 104 \{ 34.0 


cent. 
19.8 


sq. inch. 
702 










Maximum... 


22.1 


1,136 








Minimum . . . 


1 5.0 


17.1 


296 


Red fir 


B 


1.5"x 3" 


All: 














Average 


\ !f ^1-1 




720 








Maximum... 


\ 108 \ 27.0 


. 


1,025 








Minimum . . . 


li 30.0 





■ 286 






1.5" X 3" 


All: 


I 












Average 


] if 9.9 


33.4 


764 








Maximum . . . 


\ 120 \\ 23.0 


53.9 


3,058 








Minimum . . . 


1 1 5.0 


20.2 


496 


Loblolly pine 


Virginia 


1.5" X 3" 


Square edge: 














Average 


1 f S-6 


83.0 


657 








Maximum . . . 


\ 77 \\ 11.0 


180.0 


1,047 








Minimum . . . 


1 1 2.0 


36.0 


342 


Loblolly pine 


South Carolina . 


1.5" X 3" 


Square edge: 
Kiln dried- 














Average . . . 


1 ! 6.1 


0.7 


480 








Maximum. 


\ 26 1^ 8.5 


5.7 


779 








Minimum . 


1 2.0 





251 








Soaked— 














Average . . . 


■ 4.6 


73.6 


607 








Maximum. 


\ 27 !^ 1.0 


180.3 


941 








Minimum . 


2.0 


40.3 


276 


Longleaf pine 


Georgia 


1.5" X 3" 


Merchantable* 












Average 


1 f 21.6 


21.4 


992 








Maximum... 


\ 38 W 39.0 


39.4 


1,257 








Minimum . . . 


1 1 8.0 


18.5 


80O 



Table lid. — Resistance to splitting due to longitudinal shear under cross bending. 





Where 
grown. 


Dimensions. 


Sticks failing. 


Sticks not failing. 


Species. 


Num- 
ber. 


Shear. 


Num- 
ber. 


Shear. 




Aver- 
age. 


Maxi- 
mum. 


Mini- 
mum. 


Aver- 
age. 


Maxi- 
mum. 


Mini- 
mum. 


Red fir 

Red fir 


A 

I 


/ 8" X 16" X 16' 
t6"x 8"xl6' 
8" X 16" X 16' 
f 8" X 16" X 16' 
l6"x 8"xl6' 
10" X 12" X 16' 


8 
5 


Lbs. per 

sq. inch. 

297 

343 

223 

247 


Lbs. per 

sq. inch. 

345 

517 

273 

395 

291 


Lbs. per 

sq. inch. 

228 

146 

173 

74 

247 


11 
22 
19 


Lbs. per 
sq. inch. 

170 

201 

171 

243 


L.bs. per 
sq. inch. 

413 

318 

390 

330 


Lbs. per 
sq. inch. 

117 


Red fir 


96 


Longleaf pine.. 


Ga .... 


268 


151 









Compression parallel to the fiber. 












Num- 
ber of 
rings 
per 
inch. 


Mois- 
ture. 


Crushing strength. 


tim- 

Sirof 


Average. 


Maximum. 


Minimum. 




At elas- 
tic limit. 


At rup- 
ture. 


At elas- 
tic limit. 


At rup- 
ture. 

1 


At elas- 
tic limit. 


At rup- 
ture. 


51 
Red fir 104 


16.4 
18.9 


Per cent. 
19.6 
18.3 


Lbs. per 

sq. inch. 

3,550 

3,300 


Lbs. per 

sq. inch. 

4,815 

4,906 


Lbs. per 

sq. inch. 

5,270 

4,770 


i 

Lbs. per 

sq. inch. 

7,070 

6,060 


Lbs. per 

sq. inch. 

1,970 

2,140 


Lbs. per 

sq. inch. 

3,330 

3,235 


Ratio of s: 
Red fir 

Ratio of s] 

Red fir 

Ratio of SI 
Red fir 






.936 


.935 


1.02 


.905 


.858 


1.085 


.971 






















1 


29 
46 


n.8 

14.6 


22.7 
21.0 


3,650 
3,720 


4,740 
5,140 


4,850 
5,170 


6,000 
6,400 


2,140 
2,220 


2,780 
8,500 








1.02 


1.09 


1.07 


1.06 


1.05 


1.26 




















. . I-- 






15 
23 


24.4 
24.2 


25.2 
23.6 


3,120 
2,360 


4, 235 
4,540 


3,690 
3,150 


4,950 

5,175 


2,520 

2,480 


3,440 

3,880 








.95 


1.07 


.874 


1.05 


1.00 


1 13 










48 
90 


17.9 
20.8 


19.4 
18.0 


4,170 
4,050 


5.090 
5,293 


5,220 
4,970 


6,100 
6,220 


2,860 
2,760 


3,885 
3,410 


Ratio of s] 

Western hemlo* 

Ratio of s 








.985 


1.04 


.955 


L02 


.963 


.888 























1 


57 

77 


9.3 
U.4 


32.0 
29.9 


2,556 
2,860 


3,353 
3,841 


3,940 
3,740 


4,620 
4,770 


1,520 
1.550 


2,660 
2,110 






.935 


1.15 


1.14 


.955 


1.305 


1.06 


.793 








Loblolly pine.. 


12 
12 


6.4 


46.3 
46. 3 


1,766 


2,785 
3,216 


2,220 


3,540 
4,450 


1,275 


2,240 
2,320 
















1.00 




1.15 




1.26 




1.03 


Loblolly pine.. 
Ratio of s 

Loblolly pine.. 

Ratio of s 

Longleaf pine . 

Ratio of s 
Ratio of small 














12 


3.1 


74.0 


1,346 


1,988 


1,950 


2,485 


819 


1,362 













































































12 
12 
15 


5.7 
5.1 
8.5 


25.9 
52.2 

72.8 


3,123 
2,373 


4,396 
3,528 
3,635 


4,490 
2,880 


5,600 
4,325 
5,085 


1,955 
1,925 


3,810 
3,035 
2,442 
















.917 




1.02 




.715 




















1 































1 












935 






1 
LOl 


1 
L06 


1 
.952 


1 
L08 


1 
1.03 


1 


on the total n367 






.%9 

























Table III 


-Comparatives 


rmslho/lars. 


7.<i»m<. 


Ittich. 
























— 


Cross bending. 


compression par,tllel.otbo«ber. 




section 


.an. 




S^ 


Average. 


Maximum. 


Minimum. 


— ■ 


?r 


1 




Crashing altength. 


8i»cle». 


Nnm- 
bcrof 


a 


Fiber 

Is" 


"oSir 


"SF 


Fiber 


ModtUus 
1^1 


Modern 


Fiber 


^^ 


Average. 


Maximum. 


Minimum. 




tt^'ifS; 


^.^- 


t^'lfeh^r 


ti'S 


^!.^.- 






{?:-;; 


IS-:::. 


Ji 


Jil 


Tf 


sg 


M 


sg.'iS. 


If 


LbB.per 


lt°T,r 


^M 


-m 


■996 


?:j?;:i??:: 


iS 


li 


'W^ 


3 


^ 




1 


^i"I 


Ra 




m 


iE: 


1 


1 


li 


11 


7,S30 TkIT 


shlillsMlii Is 


::l 


5;;j|:ls; 


=ET,==!===:i=== 






"' ■■ ''" ■ '"•' ■• j-']^ 




" 


m: 


Jf ■■■■ 


" 


Hf 


i 




.,350 1.517 


li li 


l^OSO 


li! li 


T¥ 


' ;; v.;^rr^^„ 


:"z 


Ratio of small .Uckj to large.. 








1.00 


1.21 I 1.33! .95 


1.21 1 1.31 


.995 


1,09! 1,.32| 


,..:-. i .95 


Tt#Htlii^ 






{r'li"; 


^;:; 


S 


"ITIie" 


is^ns 


S' IS 




~s. 


2-X2-.K10".. 


gjasiK 1 a 


Ratio of imall Btlcka to lat^e.. 






.891 




1.22 1 .805 


1.15 1.07 


.93 


1.26 1 1.67 


,10 


1 . . . , 






Oregon 


m 


r.;::; 


i 


i?;§ 


li 


la 


I'M 


■!l 


B i:i 


i;i 


11 


li 


^i 


::, :: ^ ■:■ 


:.:~ 






Ratio of small Micks to large. 






915 




1 if 


1 005 


3,g| 0.24. 


1¥ 


.938 


1 U5 


Of. 








Virginia 


{j;?;?'; 


J?-:::: 


J[ 


...". 


Si 


2.™ 


IS 


^ 




^::^r:;;::'':;: ir,,,",'., l;:;:;^..';:'." 




yp 


- ' -^^^ 


. 


Virgin- 


(;;;::! ;:;; 


^ 


^T 


TJT" 


lISK 


's 


1 


uinr 


Tif 


^\ ^ s 


3-.VX20'. ,=Ti="u^=rrr==;:i„ 


■ ,,.., .:• "iS 








.... 


]::;,, ,:i::.: 






Ratio of small sticks to large.. 






1.02 


1.01 


1.19 


.755 


..■Sl 


1.21 


.97 


.902 1 1,72! .« 








z.:::: 






i 


i;i 


li 


II 


i:| 


ill 


6,210 


ii 


1.920 


1 


HIS 

li 


i 








.■,!,--" '■■:™L':- u 


Ratio of small atlcka to large.. 








I.S 


1,12 1 1.275 1 .W.i 1 1.19.-. 1.35 


1,20 1 ,91 1,02 




■;. 1 -■ .716 


t^nglcafplne 


?s 


1S.0 


s? 


Si 


:;'H;S| I'Si 


■;« ;jsj jSj i^' i-<:s.° 


!:m 






Ratio of small sticks to large. 





33 


rrr 


.85 




~TF': — ^ 


"■l,2c'| l.lOl 1,30 j 1,10 ,915 


.320 


:;:::::::::::;:: 


! 





"Si-ti-rtSKKis."-^ 









{ss 




u 


1.1, 


U| ■918 


!,.| i..| !,.5^ f,lli !.33 


'.73. 


i?l;:::::::;:::;:::| i.oi 


i-»| '-i 1-i H '■» 



6168— No. 32—04. (To face page 24. ) 



i 



25 

Table IV. — Comparative cross-hendiug strength of large sticks from ilie center of green- 
heart red gum and of the general run of 4^' x 4f' sticks. 



\ 

Where grown. Dimensions. 

1 






Specific 
gravit}^ 
(dry). 


Fiber 

stress at 

elastic 

limit. 


Modu- 
lus of 
rup- 
ture. 


Modulus of 
elasticity. 


Missouri 

• 

Missouri and 
Alabama. 

Alabama 


4" X 4" .': 5' . . 

f4"x8"xl6'.. 
•^6" X 6" X 16'.. 
[6"x8"x 16'.. 

■2" V 10" X 16' _ 


Average . . 
niaximum 
[Minimum 
1 Average . . 
^Maximum 
Minimum 
(Average . . 
N Maximum 
[Minimum 






Per 
; cent. 
] i 64.0 
} 184 A 126.0 
1 I 50. 
1 I «78.5 
} 16 ^ 95.4 
1 52. 7 

1 f ^-t-8 
} 4 I 5S.4 
1 [ 31.2 


aAQO 

.498 
.440 


Lbs. per 
sq. inch. 
3,875 
5,770 
2, 010 
2,608 
3,819 
2,100 


Lbs. p)er 
sq. inch. 

6,200 
7,860 
4, 130 

4,570 
5, 550 
3,230 

3.865 
4,060 
3,875 


X6.S. per 

sq. inch. 

1,233,000 

1,890,000 

730, 000 

1,075,000 

1,331,000 

600, 000 





















« Determined on 5 sticks. 



26 















ao«Doo looo eoiot* sooo o"^3o ^loo 

Hr::^^ ^'^^ g-A S^A S-.^ S-- 

.S-rco!N ~r"='''~<^ ^r=*='"<^ >«*>^ 0^T'^^ _rt><N 

r^ -^ 01 CO 0< lO 01 '^ 



-C o-g 



^ c3 O . 

^ rfi OC d 



2 >> • 



a> 



as 

^. o 



^^®'-IK) »iOO OICO'^ lOOO ©OOCO ^oo 

<u~;z:'-i'.'- ■*'-i<=' ryjicco M^i-i S'oo S«oo 
S=^ge©«'^ 0°"^ «="'^ oo'^':" M=^'« S^-^ 



» <M C-5 O « ( 

an o C-) « ^^ ! 
;$^ lO ^ ^m- 



05<NO eOC-llM lOCOcO 

;o 00 c<i i> o o t-» "^ '^^ 

-h^-* _i,iOC0 -(LO-^ 



Per cent. 
f 86.4 

^ 120. 7 
[ 52.8 


t^OO 


»aTj<o 


©CCH 


oi-o 


©Or-I 


§S^ 


:ss^ 


25^S 


^§- 








oo ooo o^o ©oo ©oo ©oo 

88 §88 g88 §88_ §88 §88^ 

h'o .raooT -Tr-^cP jrcTtn ^f^^ ^^^ 

ri CO M -rfi T-( O CO 05 Oat--co 0105 © t^ O 

:> oo oi c^i o 50 cc i- I— lO CT> oi lO i^ x ^n o 

i-< _r_r th _r eo _r rn -- ei _r 



K •^SlOCO r»COCO i=H(Ml> ■.flOO 

Si,iS^^ 2^--=^ M<^^ S'-^'^ 
=^"^«°°^" o'-^'^' ^'^'^ ccS"^" 



^^asCJOC «Dt-'# ©C^-::H ODOCO ©(MOO 

^,-^^^8 2?^§ ;S!$S gg8?§ *'E^s 






©OrtI 

D.00O 

^ t^j t^j ^ "^ >^ C5 ^"^ ^' 

rJoT-* .h:-u'<'(N «rOM" 



© "M c-i u; 00 c 



-.J ■^t^ o oo !>. O O uO ^ o 



to rO O !M 



© CO iH ©t>0 ©Oi 

!ooo 

(MCO 



'O 



■a a' a 









OJ 13 g 



o) s g :;:; <D 5 y rJ 3^:3 aj ;3 g 

|aat|.§a l.gatpa g-sa- 

(D f-( O) fH O) M 

^H oj M 03 f-i oj 

O O^ O ^Pj O Pj_ 



O S 3 



0) pi g .„ w ^ 3 

g^al-^^al 






QCOO ^oo 



©oo 
-i*"^o 



©og ©og 

I— J O O (—,0 

§oo goo 

-ro'c-f ^o~o" 

CO Oi rH ^ 05 CO 

Ol lO 05 rl 00 r- 

oi __r CO _r 



9^o ©oo 



.« g g © p g 

oi 3 33 oo }:^ g 

30 "* --I CO "-^ -^ 

„-0 (N ^O OJ 



©OO 
^ <^ O 



s a ■ s a 

<u 3 g o p! ri 

^sa ^.ia 

I "^ 1^ ^ 4) "^ 1^ (^ 
I ^< 






27 

Table VI. — Effect of dose pil'mg on red gum. 

[Five mature and 5 immature trees from Hollywood, Ala. Test pieces 4" x 4" x 5'. Timber in 
piles for six months after being dressed for testing. Sapwood •• blued " on surface.] 







Dimensions. 


Class. 


Treatment. 

t 


Cross bending. 


Species. 


Where 
grown. 


Num- 
ber of 

tests. 


Mois- 
ture. 


Specific 
gravity 
(dry). 


Modu- 
lus of 
rup- 
ture. 


Modulus 
of elastic- 
ity. 


Red gum 


Ala . . . 


4"x4"s5' 

i 


Heart. 
Sap..J- 


f Piled: 

Average 

Maximum..! 
Minimum ..i 

Original: 

Average ! 

Maximum..', 
Minimum . . 

Piled: 

Average 

Maximum . . 
Minimum . . 

Original: 

Average 

Maximum.. 

Minimum ..! 

1 


■ 34 

1 

22 

i 

1 


Per 

cent. 

[ 60.5 

87.5 
32.6 

86.4 

120.7 
52.8 


0.502 

.581 
.480 

.486 

.562 
.422 


Lbs. per 

so. inch. 

'6,226 

7,810 
5,080 

6,176 

8,515 
4, 693 

7,709 

11,400 
4,G60 

0,341 

8,212 
6,177 


Lbs. per 
sg. inch. 
1,234.000 

1,495,000 
1, 020, 000 

1,110,000 

1, 591, 000 
830, 000 

1,250,000 

1, 650, 000 
935, 000 

1,139.000 

1,361,000 
793, 000 
















54.5 

93.4 
38.0 


.450 

.497 
.362 



28 



c 


-5" . 


^ ^'^OC? 


^g§ 




^88 


g^88 


M 

w 


2 "Six § d 
"7 G « 2 g 


JhS^^^" 






gcot- 




S3 (D a d o 


3g^" 




tH 


iH 




i 


O M 














© 


S?^3 


510g 


ct^oo 

5Sg 


pi 


'3 
"3 


«■>!& 

sss 


^OCl- 


(I^CCl^ 




W be 












.'£ a; 




§gS 




^gl^ 


© 




o 


c i: 


^^c^co 


o^cot^: 


<x^^ 


cc;:;^- 


GC 




E 




. ■ 


' V ' 


' V ' 


■ — ^, — ' 






isi 


o 


00 


00 


CO 


O 


a 










'^ 


o 


-^ 0; aj 












o 


Z-S^ 






_A_^ 




'^_ 




S O^;^^' 


©oo 


OOO 


©oo 


lCOO 










;:: t. g' o -o 


^cctj5 


(jq ^5 1^ 


i-Joo* 


oirH C> 










g^-a^.2 


fH'^ 


1-1'"' 


S««5-< 


S'O^' 








!^ 


_lii 


e*^^^. 


*^-'^'- 


III 


®^.°^ 




^1 


^15;* S3 


-^2^ 




^rgg^ 


©^S 




;3'43 


c^--^oSS 


©o^ 


5q?aS 


T-I^l> 








mC'"'" 


■■Tco^^ 


^.Co'rH 


*l^r^' 


®?JS- 




!N 


(N 


(M 


51 


1 s 


riiii 


lis 




§ii 


ill 




^^1 

s ^ 


si^^^i 


^^-"-" 


^'-- 


ps 


3"^" 








III 


i's X)CO 


d^^'^" 


o 


^g'^ 


pH 


" 




" 


CC^^ 


Ti^^ 


rH-MC^ 


OJO<M 


Oooco 


^ICOiC 






-^^ 


UjiM O 


,>.T-HCO 


©gs^ 




■3'> b 


(»°!'". 


^GOi-_ 


IpCO^ 




aS'S 


d 


• 






• 




cS'bo"^ 












.55 g 




§Sg 


^^S3 




© 






o g 


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LIBRARY OF CONGRESS 



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LIBRARY OF CONGRESS 



019 418 316 1