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Thurston, Robert Henry

On Flint fs investigation
of the Nicaraguan woods

LIBRARY

FACULTY OF FORESTRY
UNIVERSITY OF TORONTO

[Reprinted from the JOURNAL OF THE FRANKLIN INSTITUTE, Oct., 1887.]

; w-Al

ON FLINT'S INVESTIGATION OF THE NICARAGUAN

WOODS.

By R. H. THURSTON, Director of the Sibley College of Cornell University.

[Presented to the American Association for the Advancement ofr
New York Meeting, August, i8Sj.~]

PRELIMINARY REMARKS. BY R. H. THURSTON. — It had long
been a conviction of the writer that the tropical and semi-tropical
countries of America possess a large number of valuable timber
trees of which nothing is known by our engineers or builders., but
which, for some of the more important purposes, as well as for
ornamental and exceptional constructions, may have extraordinary
value. As the process of stripping our own land of timber goes
on, and as our pines and finer grades of timber trees become
gradually more and more difficult and costly of procurement, the
necessity will become more and more pressing of going into the
more heavily forested countries nearer the equator for our supplies
of lumber. It is thus becoming continually more important that
we learn something of the resources of such countries, and
especially of the useful qualities of the woods available for building
purposes. A knowledge of the extraordinary strength, and of
the other valuable properties of some of these timbers, will un-
questionably, in time, lead to the opening of our markets to them,
and to a trade that may prove to be of inestimable advantage to
both purchaser and vendor. A few years more will see the great
forests of the Northwest stripped of their best timber, and the
supply will then be mainly drawn from the South and the Pacific
Coast ; but the enormous rate of growth of the country in popula-
tion, and still more in manufactures, will sweep those districts
clean at a rapidly increasing rate of destruction, and it will be
found, probably much sooner than is now generally imagined, that
we must look elsewhere for the enormous supplies demanded by
our markets. The growth of this demand is a geometrical one.

That most remarkable of recent works on economical subjects,
that romance of statistics, Triumphant Democracy, gives some
striking facts abstracted from the last census. Mr. Carnegie finds

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tliat our lumber trade has quadrupled within the generation, the
business now employing about 150,000 men, and producing nearly
$250,000,000 worth of lumber. About $40,000,000 is invested in
this trade in Michigan alone, and the three states, Michigan,
Minnesota and Wisconsin cut, in the year 1880, over 7,000,000,000
feet of timber, in the form of marketable lumber, besides millions
of feet in the shape of railroad ties and other minor products. It
is estimated that the pine forests of the northwest will be gone in
about twenty or twenty-five years ; but the southern forests are of
much greater extent. It is not certain that we shall very soon be
entirely deprived of the light and comparatively soft growing
woods; but their extinction would seem to be but a matter of
time, and, as the lives of nations are counted, not a long time.

Mr. Jessup has collected for the New York Museum of Natural
History some 400 varieties of North American woods, including
very many which are of very great value for constructive purposes;
some of these, as the sycamore, have not been as yet much used,
but are now being found to have peculiar value for special pur-
poses. The consumption of these hitherto neglected timbers will
continually and rapidly increase. Others, as the live oak of our
Gulf States, have been used exclusively for special purposes, as in
ship-building, and have, by the progress of improvement in the art,
been thrown out of use, to come in again at some later time in a
way as yet unforeseen. The soft woods are those which, from their
soundness and especially from the ease with which they can be
worked, are in greatest demand, and, fortunately, they are those
which have hitherto been most plentiful and cheap in our markets;
but they are gradually becoming less accessible and more difficult
of procurement; their cost is thus threatening to become seriously
increased, and we are likely to be compelled to find ways of sub-
stituting the hard woods for the soft in our constructions. A
century ago, oak was the most common of building timbers in the
older countries of the world ; it seems now possible that it, and
the other hard woods, may, in time, again come into general use ;
but, if so, we must, after a time, go into the southern and neigh-
boring states for such woods. Once we are brought to the use of
such hard woods again, we shall, perforce, be brought to the con-
struction of buildings capable of withstanding the teeth of time as
effectively as did those of our ancestors of the middle ages.

We are to-day sending out into the markets of the world,
annually, something like $30,000,000 worth, probably, of wood, in
the form of manufactured articles mainly, particularly as furniture,
and the time is coming when we shall supply a very large part of
the world with its timber and manufactured wood products ; but
this will only hasten the day when we must look to the West
Indies and to Central and Western America, perhaps to South
America, for our own supplies.

It was considerations such as have been above outlined that led
the writer, some years ago, to endeavor to secure such data rela-
tive to the useful qualities of the tropical and semi-tropical woods
as would, in the course of time, prove useful to our own people as
well as to the citizens of those neighboring countries to which we
shall be likely to first look for our supplies of the heavier sorts of
timber ; for it will be seen that nearly all of the semi-tropical and
tropical woods are of the hardier varieties and are distinguished
rather by their hardness and strength than by lightness and ease
of working — the peculiar qualities of the varieties of the coniferae
from which we obtain the greater part of our timber to-day. The;
first attempt to investigate these hard woods of the warmer lati-
tudes in a systematic and satisfactory manner was probably that
undertaken some ten or fifteen years ago by French engineers and
naturalists studying the trees of New Caledonia. Later investiga- j
tions of a similar character have been made, usually since the wor.k^
directed by the writer about to be referred to as initiating his own.
researches, by British authorities, in India and in the Australasian.
colonies of Great Britain. The first systematic study of these
classes of woods in America, so far as the writer has observed, was
made at the suggestion and request of the writer by Mr. E. D.
Estrada and published in Van Nostrand's Magazine for November
and December, 1883. Recently, another investigation has been
undertaken in the Mechanical Laboratory of the Sibley College,
Cornell University, by Mr. Rufus Flint, the results of which will
here be presented. Mr. Flint, although by descent on the father's
side an American, is a native of Nicaragua, and, until coming into
the United States to obtain his education, has been a resident of
that country. Through his relatives and friends and assisted by
the liberality of the Government, which allows such material to
enter duty free, Mr. Flint has been able to secure a fine collection

of the woods of Nicaragua, and thus to enter upon a research as
important in its bearing upon the business interests of his own
country and of the United States as that conducted by Mr.
Estrada.

Examining the data thus secured by these investigators, we
find that the tropical woods are distinguished by their extraordi-
nary strength, elasticity, beauty of grain and durability. The few
already known to us, such as mahogany, rosewood and some of
the cedars, may be taken as illustrations of the several principal
classes of timbers to be found in the forests of Central America
and the Islands of the Caribbean Sea. These woods are all coming
into demand very rapidly already, for house decoration, and in the
construction of the finer grades of furniture, and an examination
of the magnificent collection gathered at New York, by Mr.
Jessup, will reveal the fact that we have but begun to make appli-
cation of the enormous variety of woods which are readily obtain-
able and available for such purposes. These statements will be
seen to be true of the woods of Central America here to be
described, as well as of the Cuban woods already reported upon.
In both cases, but a few of an immense number of woods have
been taken for investigation ; but these selected samples may be
taken as illustrative of the whole product of this vast arboretum.
The tropical trees attain enormous sizes, are extraordinarily solid,
close and firm of grain, excel in the beaut) and variety of their
coloring, in fineness of texture, and especially in their wonderful
durability, whether exposed to the corroding influence of the
atmosphere, to the action of heat and moisture, or to the attacks
of insects. Ironwood and lignum vitae exemplify the first of these
characteristics ; mahogany, rosewood, tulipwood, and others, illus-
trate their beautiful color and grain ; and the live oak and teak are
good examples illustrating their power of resisting the action of
oxygen and the attacks of the teredo and of the limnoria.

The investigations of the Central American woods were made
in the several testing machines and the workshops of the Sibley
College, and the results were reported to the writer in a paper
presented in June last, the substance of which is here given. The
report is so well written and so complete that it has been thought
best to give the whole in the words of the observer. The figures
have been very carefully checked, and are believed to be perfectly

reliable throughout. The machines used had been standardized!
and were known to be practically exact, and it is thought that the
data thus obtained, as here given, may be of real value to the pro-
fession, as well as to the two countries most nearly interested in
the results of the research. The native nomenclature is given
throughout. It was found difficult to obtain the botanical names
of all these woods, and, in many cases, those obtained were subject
to some question in consequence of the fact that the botanists
seem to have had comparatively few opportunities of study of
these woods ; but the introduction of the timbers of these regions
into our own markets will undoubtedly lead to the adoption of the
nomenclature obtained in their homes, and no inconvenience will
arise, it is thought, from the omission of the technical names.

The examination of the Cuban woods, to which reference has
been made, showed moduli of elasticity as deduced from the experi-
ments on transverse stress and strain, varying from 1,500,000 to
2,500,000, British measure, the great majority of the dozen and
a-half varieties studied ranging above 2,000,000, or equalling the
stiffness of the Indian teak, and exceeding that of any known
variety of our native timber, with the exception of an occasional
sample of the strongest and stiffest of the choicest of Southern
long-leaved, yellow pine. The figures for the best of the Cuban,
woods are above those of any known North American woods,
exceeding their best figures by fifty per cent., nearly. Three-
fourths of them are stiffer than the best teak. The moduli of rup-
ture by transverse stress vary between 15,000 and 20,000 pounds
per square inch, as a rule, in but one case falling to 8,000, and in
several exceeding 20,000, the average being not far from 18,000.
The densities average above that of water, and many samples
exceed that unit by some twenty per cent. Quite a number of
these woods have just the qualities which distinguish yellow pine
of the finer grades; for example, Baria (Cordia gerascanthoides)
and Caobilla (Crotos lucidani},z.s representing the lighter varieties,
and Majagua (Paritium elatuni), an even lighter and stronger wood ;
Dagame (Colycophylluin candidissimuni), one of the most common
of West Indian woods, weighing but fifty-six pounds per cubic
foot, and having a modulus of rupture of 16,000 pounds.

Sabicu {Mimosa adorantissimd) has just the weight of water, or
a trifle less, and, with a modulus of elasticity of about 2,400,000,

exhibits a modulus of rupture exceeding 20,000. A dozen of
these varieties are higher in rank than the best building material
found in our native forests.

The Central American woods, growing on a more widely dis-
tributed area, in a soil of less uniform character and in a greater
variety of climate, are naturally of more widely differing character
than those of Cuba. The high and dry atmosphere and more
innutritious soil of the interior, and the rich bottom lands of the
swampy regions of the coast, with every intermediate condition of
soil, climate and exposure, produce timber of soft as well as hard
varieties, of less as well as of greater strength or elasticity, and
thus yield to the market a larger assortment of useful woods than
could any insular district. The moduli of rupture, as determined
by Mr. Flint, vary from 7,000 to nearly 30,000, and the moduli of
elasticity from about 600,000 to about 2,500,000, usually approxi-
mating 2,000,000, the modulus of rupture commonly falling at
about 22,000.

INTRODUCTION BY RUFUS FLINT, M.E.

The woods of Nicaragua, grown under the sunny sky of the
Torrid Zone, and in the mountains, valleys and on the sandy shores
of the Atlantic and Pacific Oceans, are many in number and of
widely different character in nature, strength and color. Unre-
stricted in their growth, in the exuberant and wild forests and
woods of the country they attain enormous sizes, and exhibit
great strength and solidity.

As a general rule, they are of delicate hues and beautiful colors,
exhibit extreme fineness of grain and have marked peculiarities in
texture and general appearance.

The investigation of their strength and natural properties is a
matter of great interest. With the facilities offered in the
Mechanical Laboratory of Sibley College for complete investiga-
tion of the materials of construction, I have thought it advisable
to conduct such an investigation of a few of the Nicaraguan woods
so as to make known the characteristics, net only of those that have
found their way into the markets of this country and of Europe,
mainly because of their worth as dye woods or for ornament, but
also some others, perhaps of better if not equally prized proper-
ties, which have yet remained unknown in the industries.

In undertaking this investigation, I hope to find results which
may prove of value and interest to the artisans of my native land»
and also aid in developing, to a certain extent, the commerce and
industries of Nicaragua, by making some of its natural products
known in the United States and Europe.

I have restricted myself to the study of those woods which are
most used in engineering construction and decoration, leaving
out the dye and other woods, which, perhaps, may be of equal
interest and value, there being quite as many unknown, or at least
unused, valuable woods and plants of this latter kind.

I was encouraged from the start by Prof. Thurston, who very
kindly wrote to the Government of Nicaragua, asking for a collec-
tion of the most important woods of the country, expecting that its
officials would take, or at least show, some interest, and thus secure
a good collection of the woods. But unfortunately we were in
this disappointed. It was by my father's interest, kindness and
persistence, and through my friend Miguel Ugarte's active and
courteous help, that I was supplied with as good a collection as
could be obtained in the short time allowed to collect them. Steps
were taken to get the woods, seasoned and sound, from persons
engaged in working them, but they failed to obtain them. It is
for this reason that the woods tested have not been entirely satis-
factory, as they were cut green, and the men could not in most
cases fell large trees to get the heart or the best of the wood ; as
a consequence, they checked on the way, and many of them were
found to be knotty. The woods were collected in one month,
within a circuit of three leagues, on the hills about Belen in the
agricultural and chocolate-raising " Departmento," of Rivas,
between Lake Nicaragua and the Pacific Ocean. Some few, obtained
from a carpenter, are seasoned. My collection of fifty different
varieties represent about half the number of the useful woods of
the country.

The terms used may be thus defined : The modulus of rupture
for tension is the force necessary to pull asunder a bar whose
section is one square inch, when acting in the direction of the axis
of the bar.

The modulus of rupture for compression is the pressure neces-
sary to crush a piece of any material whose section is unity and
whose length does not exceed about five times its diameter.

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The modulus of rupture for transverse stress is the stress at the
instant of rupture upon a unit of the section which is most remote
from the neutral axis on the side which first ruptures.

The modulus of elasticity is a value which expresses the rela-
tion between the extension, compression, or other deformation of
a bar, and the force which produces the deformation.

Resilience is a measure of the capacity of a material to resist
shock, and its value is equal to the amount of energy expended, or
the " work " performed in producing distortion or rupture.

GENERAL DESCRIPTION OF THE WOODS.

(I.) Carbon. — Extraordinarily solid, equalled only by the Piedra
and the Quiebra-hacha. Is almost imperishable when used for
posts, and is supposed to be very good for railroad ties. The tree
attains a height of 30 feet, and measures 12 inches in diameter.
Is common in most of the wooded districts. The wood is of a very
fine grain, with peculiar dark streaks; very much like the
mahogany in appearance and in color, but heavier and much hand-
somer. Is easy of working, and turns very smoothly.

(2.) Cedro (Cedar.) — The wood, on account of its peculiar
properties, has found a place in all the markets abroad. In Nica-
ragua, it is found abundantly, and attains enormous sizes. Is used
extensively for furniture, frames, book cases, etc. It is even used
by the Indians for boats, which they work out entire from the
trunk of the tree.

(3.) Chaperno. — Dark red color, turns and planes very smoothly.
It has a fine grain and great strength and is susceptible of high
polish. It is used extensively for cross pieces of drawers and
tables. Is extremely durable. There are two varieties of this
wood, black and white, as they are called respectively. The tree
attains a height of forty feet.

(4.) Chiquirin. — Dark yellowish wood with a strong cedar
smell. Is heavy, fine grained and planes smoothly. Th,e tree
attains a height of thirty feet, and one foot in diameter. It has
various uses, is durable, and having odor is probably not subject
to attacks by insects.

(5.) Cortes. — Extremely heavy and very fine-grained, of a very
dark yellowish color. When broken in splinters, it gives off a
fine yellow powder, which has similar properties to litmus ; it turns

bright red when mixed with soap water. It is a large tree like
the Nacascolo. It is used in cabinet work, for framing, etc. The
only place in which I can remember to have seen it growing is on
a rocky hill at the foot of the volcano Mombacho, near the shore
of Lake Nicaragua. The hill is covered with these trees, which,
in the beginning of every spring, are a beautiful sight, being cov-
ered with yellow flowers.

(6.) GranadiUo-negro. — Wood very much esteemed for interior
decoration, on account of its handsome dark color, fineness of
grain and ease of working. The tree attains a height of thirty
feet, and is found on the shores of the rivers which flow into the
eastern side of Lake Nicaragua.

(/.) Gauchipilin. — Fine grained wood of a light yellowish color,
heavy and tough. The tree attains a height of 30 or 40 feet, and
has a diameter of 15 inches. It is irregularly branched. Much
used by the artisans for durable work, as it resists moisture for
years. It is also used for telegraph poles and railroad ties. Is
abundant all over the country.

(8.) Guapmot. — The tree is nearly as large as the Jenisero, and
its branches large but more erect. The wood is of a light mahog-
any color, long grained, but very compact, heavy and tough. Is
used almost exclusively for cylinders of sugar cane mills, while the
teeth moving them are made of guachipilin, guayacan or other
similar wood.

(9.) Guayabo de Monte. — Attains a height of sixty feet, is of irre-
gular diameter, and seldom over two feet above the lateral roots, acting
as braces, which support the trunk. It has a fine grain and is very
tenacious. The test made probably does not show full strength,
as it was an inferior sample. It is used for small masts and the
weather streaks of boats. According to Mr. D. L. Murray, who
preferred it above all others for launch guards, it resists wear and
tear better than any other wood.

(10.) Guiligidste. — A wood unknown to commerce. Has a light
brown color in the heart, is fine and fibrous of grain. It ran above
the average in compression. It is not as durable as the other hard
woods, but from its beautiful grain and color, and from its ease of
working, it would seem that it should be used for interior house
work. The tree is small, growing only about 30 feet high, with a
diameter from 15 to 18 inches.

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(u.) Jenisero. — One of the most useful trees, and one of the
largest in the country. Attains a height of 90 feet, with 7 in
diameter, and its large branches cover a space of over 100 feet in
diameter. In Nagarote. a town in the Departmento de Leon, at
the junction of one of its streets with the large road from the
western departmentos, there is a Jenisero whose branches cover a
circumference of 348 feet (about 9,498 feet area) ; it is 90 feet high,
and has a circumference of 21 feet at 4 feet from the ground,
according to Senor F. Guerreo Raster.

The wood has a light to dark color, and a peculiar grain ; it
is open and wide in the annual rings, but very compact between.
It is used for cart wheels, lasting for years without tires on clay
soil. Used also by the carpenters in various ways. Its fruit is
eaten by the cattle, and is used to sour the milk. It is fairly well
distributed over the country.

( 1 2.) Jicaro-^acaguacal. — Attains a height of 20 feet, and a dia-
meter from iotoi2 inches. Common on marshy land. It is of
a nearly white color and very tough, used in saddlery and for
boat-knees. Resists moisture, and is durable in salt water. The
shells of its fruits, after being worked, are used by the natives for
drinking vessels. They carve them very beautifully and artistically.

(13) Latirel. — Dark color, light, strong and elastic wood and
very easy of working. There are two varieties, male and female,
as they are popularly called. Used mostly in frames for cots, and
for work where elasticity is required. The dark kind is preferable.
Both have a spicy smell. The tree attains a height of 40 feet, and
a diameter from 8 to 12 inches, seldom over 8.

(14.) Llignaltil. — This is one of the trees having many peculiar
natural properties. Its fruits have a rich fragrance and flavor, and
when green give out a coloring substance. From its bark a
bluish and sometimes a purple substance is obtained, and from its
sap thirty per cent, sugar may be obtained; is one of the most
elastic woods found in Nicaragua. It is used for drum hoops,
canes, etc. The tree seldom attains a height of twenty feet, and
about twelve inches in diameter.

(15.) Madera-Negra. — One of the most useful trees found in
Nicaragua, not only on account of its durability, strength and
excellency for fire wood, giving out intense heat; but also from its
method of growth. It is about the only tree used to shade the

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chocolate trees. It has a rapid growth, and is early produced from
the seed. Mostly used for railroad ties, posts for houses, fence
posts, foundations, etc. Has a dark, yellowish color in the heart,
is fine grained, heavy and tough. It grows with oblong cavi-
ties wasting a good deal of the wood when being dressed.
However, straight logs, I foot square and 30 feet high can be
obtained.

(1 6). Madrono. — There are two kinds, white and dark. It has
a fine grain, and is heavy. Its strength may be seen from the tests
in torsion and by transverse stress. Its growth is irregular and
branching.

(17.) Mahogany. — This is too well known to demand descrip-
tion. In Nicaragua it is' fairly well distributed. The best and
most valuable is exported to a considerable extent from the Mos-
quito territory, where it grows abundantly, and to its fullest size.
It is also found along the Pacific Coast in considerable quantities

(18.) Moran. — Solid and fine grained wood of a beautiful yellow
color. After it has been turned, it looks as if it had been polished;
planes very easily. It is exported in great quantities as a dye-wood.
Is often used for columns. Attains a height of from 30 to 35 feet,
and a diameter of from 12 to 1 8 inches.

(19.) Nacascolo. — The wood is extremely heavy, very fine
grained, and of a handsome dark color. Its toughness is shown
by the test in torsion. The fruit is known by the names of Nacas-
colo or Dividi, and used for dyeing purposes when dry. It is one
of the largest of hard-wood trees. Its trunk, although irregular
in growth, and seldom over twenty feet to the point where it
branches, is 6 feet in diameter. It attains a height of 60 feet, and
is found more abundantly on the Atlantic Coast. Is an excellent
wood for railroad ties.

(20.) Nancite. — Has a soft pink color, fine grain and works very
easily. The tree is small, grows on arid hills, and seldom attains
30 feet height. Its bark is used for tanning, and its fruits are
to the Nicaraguenses what cherries are to the North Americans.

(21.) Nispero. — It may be said that there are two kinds, wild
and cultivated. Large fruit tree of a thick and handsome foliage.
The trunk is straight and free from limbs. The tree attains a
height of 60 feet and a diameter of 2 feet. It is abundant all
through the country in farms near the towns and in the wild

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forests. Exclusively used for wharves, bridges and posts. Resists
moisture equal to any of the hard woods, and is said to petrify in
the water. The wood is of an exceedingly fine grain, has a beauti-
ful red color, and is very easy working. It behaved the best of
any under compression, bulging out considerably before showing
any sign of shearing or split.

(22.) Oja-tostada. — Has a very light pink color, is fine grained
and light. It is one of the most elastic and tough woods tested, as
may be seen from the tests by transverse stress and by compres-
sion. It is very good for light and strong constructions.

(23.) Palo de Arco. — The sample tested planed easily in parts,
and in parts less readily, probably on account of being green. Is
hard, has a fine grain, and a light red color. It is used for con-
struction where easy of access. It grows along the coast, and in
the coast range of mountains, attaining a height of 30 feet and 15
inches in diameter.

(24.) Piedra. (Stone.) — Has a fine grain, is heavy and strong,
of a yellowish color in the sap, and deep red in the heart. Turns
very smoothly and is one of the hardest and heaviest woods known
and yet not difficult to turn or plane. The tree attains a height of
40 feet, and has a diameter of from 15 to 18 inches. It is imperish-
able. Used in many places for pillars and transverse beams of
houses on farms distant from towns where it is easy of access. Is
abundant on the hills along the coast on the Pacific slope. There
are two varieties. It is an excellent wood not only for interior
decoration or for heavy furniture on account of its beautiful color
and fineness of grain, but also for heavy constructions, as for foun-
dations for engines or heavy machinery.

(25.) Pochote. — Tree of enormous dimensions. The wood is sim-
ilar to the cedar, but much softer. It is used, however, in house-
work for doors, walls, floors, shingles, etc.

(26.) Quiebra-hacha (axe-breaker). There are two kinds, red
and black. The latter, which was tested in three ways, is a most
wonderfully tough wood. It has a color and appearance like the
black-walnut, and its grain is similar to that of the oak. It planes
beautifully smooth, and has a pleasing appearance, on account of
its dark streaks. The red kind, which grows very straight and
spreads considerably, reaches a height of 50 feet, and from 12
to 15 inches diameter. The dark kind, which spreads still

13

more, seldom attains a height of 40 feet. Their name, axe-
breaker, indicates their toughness ; for in cutting or felling them,
the axe is often broken. In cutting the samples received, two axes
were nicked to the extent of one-half to three-fourths of an inch.
The wood is durable and used for ties, poles, etc., and in posts for
houses. One piece that had been for sixty-seven years in a clay
soil was found still sound when sawed. The tree is common
throughout the state.

(27 ) Qinta-Calson — Its powder acts as a purgative. The tree
attains a height of 30 or 35 feet, branching at 15 or 20 feet from
the trunk, and often has a diameter of 2 feet. It is abundant along
the coast. It is used for boards where not exposed to the weather ;
it will 'not resist moisture.

(28.) Roble. — Light colored wood of a curly and beautiful grain.
It is pink in color and used in house-building. The tree has
exceedingly large leaves, 14 inches long and about 7 inches wide,
is often 50 feet high, and from 12 to 15 inches diameter. Is abun-
dant along the coast.

(29.) Ron-ran. — This is one of the largest of hard-wood trees
growing on the shores of the rivers of the Departmento of Chon-
tales on the Atlantic slope. It reaches a height of 50 or 60 feet,
and often a diameter of 3 feet. Dark, fine-grained wood, strong,
heavy and durable. Is used in cabinet work, turns very easily, and
is susceptible of polish. It turns dark with age.

(30.) Tempisque. — This tree is of historical interest in Nicaragua,
and is one of the largest found in the tropical forests. It attains a
height of seventy-five feet or more. The trunk is irregular and
seldom reaches twenty feet to the beginning of the largest branches.
It has a diameter of 6 feet. The wood is fine grained, hard and
very excellent for desks and other articles of cabinet work. Like
the mahogany, it turns dark in a few years, and is equally durable.
The cattle eat its fruit.

(31.) Tiguilote. — Light wood, grows about 30 feet high, and
over 1 2 inches in diameter ; good wood for carriages. It is used
for fence posts, it easily roots when set with care, thus making a
permanent fence and a pretty grove.

(32.) Zapotillo. — Of a light mahogany color, has a fine grain,
and is light. Attains a height of 40 feet and I foot in diameter.
It is not very much used.

14

(33-) 7'Opilote (Buzzard). — Coarse, long-grained wood, but of
compact layers when viewed in cross-section. It has a greenish
color. Turns and planes fairly well. The wood is used only in
neighborhoods where more useful woods are scarce. When unex-
posed or when well seasoned and protected with paint, it would
probably be a valuable wood, as it ran above the average in torsion,
was among the highest in compression, and stood well under
transverse stress. It attains a height of about 40 feet and I foot
in diameter.

The Transverse Stress tests were made in the Transverse test-
ing machine of the Messrs. Fairbanks, designed for Prof. Thurston.
It consists of a Fairbanks' scale combination with a pointer and
beam at the end to secure perfect balance. The whole machine
rests upon a wooden frame ; upon the platform rests a cast iron
cross beam, and upon this slide the supports, which are set
and secured by bolts at the required distance apart. The
test piece is placed upon the mandrels, which rest on the supports
set at the required distance. The loads are put in the scale, and
equilibrium is established by the elastic resistance of the piece
offered against the pressure transmitted through the screw and
pressure block by means of the lever. The screw passes through
a nut, and terminates in a sliding piece. The cast iron columns
serve as guides to the pressure block. The whole is made stable
by wrought iron braces bolted to the wooden frame. The deflec-
tions of the piece are measured by the linear advance of the screw,
by means of a graduated wheel. The pitch of the screw was
found to be equal to 0-33297 inches, and the wheel was graduated
into 333 equal divisions, thus reading to j^-^ of an inch, with an
error of ooooi of an inch. The pointer clamped 1o the screw is
placed over the starting division in each case, and after the wheel
has been turned and equilibrium established, the reading is taken.
This is a very convenient way of reading the deflections, giving the
difference directly. The test pieces were planed by hand by an
expert, Mr. Kerr, and afterwards measured by means of a
micrometer screw reading to y^^ of an inch.

With all the data required, we obtained the results in the same
way as in compression tests, by plotting the curve to each test,
with loads as ordinates and the deflections as abscissas. This
gives the elastic limit more exactly than in any other way. It also

shows at a glance the behavior, strength, elasticity, etc., of the
material tested.

DETAILS OF TRANSVERSE STRESS TESTS.

(I.) Carbon. — 28-inch supports. Green sample from the sap,
.and with a few small knots on top. Like the other, it broke
just after having brought the beam up by its elastic resistance,
under 650 pounds, and deflected roil inches. Remained un-
broken.

(2.) . — 25-inch supports. A very well seasoned

piece, but slightly weakened by a knot where it first gave way.
The first rupture occurred at 950 pounds on the weak part. The
second under 1,150 pounds with a long and several other small
splinters on tension side. Total deflection, 1-687 inches.

(3.) Chaperno. — 24-inch. A very good sample as regards
soundness and seasoning. Cross grained. Broke under 3,700
pounds, with a deflection of 0-496 inch. Broke gradually in small
splinters from the bottom side upwards, and crushed slightly
on top also.

(5.) Cortez. — 24-inch. A large sample from near the
heart. Excepting two knots on thickness and bottom sides
respectively, and checked on sap line on top, it was a fine sample.
Its toughness is shown by its behavior under load. Reached the
elastic limit at 2,500 pounds, broke at 4,300 pounds, with a defle. -
' tion of O 443 inch. Second rupture occurred under 4,650, with a
deflection of 1-3975 inch. By diminishing the loads it might have
given more ruptures without breaking completely. Broke in
several adhering splinters on tension side.

(7.) Guachipilin.' — ii-inch supports. Good sample. Tbe
first rupture occurred under 1,800 pounds load with 0-462 inch
deflection. After the first rupture it showed a good deal of
elasticity in resisting the loads and gradually ruptured slightly
under 2,050 pounds. The reason we took this latter for the
rupturing load is on account of the behavior after the first rupture,
which latter was very light, and on account of a weak point.
Both ruptures were very light splinters, and the piece might have
shown still more tenacity if the load had been diminished. But
here, as in most cases, we were after first rupture only. Almost
any kind of wood will behave in the same way if so treated, unless
it is very brittle.

i6

(8.) Guapinol. — 24-inch supports. An inferior sample, knotty
near the middle, checked on top, and with a few worm holes.
Broke under 1,600 pounds with a deflection of 0-699 inch and with
a few splinters on tension side.

(9) Guayabo de Monte. — 24-inch supports. The test piece was
planed from a green limb. It was checked and knotty on either
side of middle line in tension side. The first rupture occurred on
account of cross-grain at 660 pounds, with a deflection of 0-477
inch. Ruptured with only one splinter across the bottom side.

(ii.) Jenisero. — 24-inch. Broke at 1, 600 pounds, with a deflec-
tion of 0426 inches. When under 1,600 pounds load, brought
the scale up when pulling the lever arm, but immediately after-
wards broke suddenly in two splinters. It evidently is very brittle.

(1 8.) Moran. — 1 5-inch supports. A very sound and beautiful
natural-colored piece of wood. Ruptured in light splinters under
2,600 pounds, with a deflection of 0-432 inches. Remained un-
broken and could have still shown tenacity in successive ruptures.

(20.) Nancite. — 32-inch supports. A good sample. Broke
square on tension side, in two pieces, and very suddenly, after
having offered elastic resistance to 2,200 pounds, and deflected
1-0765 inches.

(23.) Arco. — 24-inch. Straight-grained sample, with two knots
on bottom side. Broke at 2,000 pounds, with a deflection of 0-679
inches. Second rupture occurred under 1,100 pounds load, with
a deflection of 1-116 inches. Ruptured with close splinters on
tension or bottom side.

(26.) Quiebra hacha negro. — 25-inch supports. Excepting a
light streak of sap wood on bottom side, where it first gave away,
it was a very sound sample. Its first rupture occurred when under
2,450 pounds, with a deflection of 1-693 inches. A second rupture
occurred at 2,550 pounds, with a sudden crash and with a deflec-
tion of 2-080 inches. It is worth observing that the second rup-
ture occurred with a larger stress than in the first one. The very
finely intermingled narrow and regular splinters across the bottom
side very fairly exhibit the high tenacity, ductility, as I may be
allowed to say, and the uniformity of strength, cohesion and grain
of this peculiar wood. Its rupture could very well be taken as the
standard rupture of tough woods.

(27.) Quita-Calson. — 21 -inch supports. Season-checked on top,

TESTS BY TRANSVERSE STRESS.

WOOD.

Dist'nce
between
supports
I

Depth
h

Breadth
b

STRESS.

DEFLECTION AT —

E. Limit
P

Rupture
P

E. Limit.
d

Rupture.
d'

I Carbon,

in.
28

25
24
24
24

12
24
24
24
28
30

*5

32

24
24
25

21
30
24
28
II

3°
3°

in.

i'235
1-225

2-000
1-772
1-740
1-237
1-498

1-495
1-742
1-775
1-218
1-627
1-98
1-239

1-459
1-479
1-224
1-772
0-995

J-734
1-225
1-48
1-745

1-470
1-215
1-994
1-779

1745
1-237

1-498

1-495
1-742
1-730
1-218
1-620
1-983
1-239
1-492

i '473
1.225
1-768
0-978
1-734
1-233
1-480
1-741

300
500

2800
I800
2500
1200
900
300
IOOO

1400
300
1600

I2OO
40O
I2OO
1200
400
IOOO
300
900
1450
500

650
1050
3700
2400
4300
2050
l6oo
7IO
I&00
2150

75°
2600

2200
850
2OOO
2450

75°
1600
700

2100

255°
1170
1850

0-392
0-478
0-36
0-420

0-443
0-277

0-335
0-157
0-426
0-139
0-552
0-237

0-4385
0-352
0-382

o-395
0322

0-015

0-459
0-318

0-202
0-438
O-2I6

I-OI1

1-354
0-496
0-611
1-073
0-761
0-699

0-810
0-265
3-284
0-432
1-076
1-656
0-679
1-693
0-8 1 1
1-217
1-605
1-139
0-462
1-526
0-826

2

3 Chaperno,

4 Chiquirin,

7 Guachipilin,

9 Guayabo de Monte, . .
1 1 Tenisero,

13 Laurel bianco, ....
14 Lligualtil,

18 Moran, . .

20 Nancite,

22 Oja-tostada, ....
23 Palo de Arco, ....
26 Quiebra-hacha-negro, .
27 Quita-calson, ....
28 Roble,

30 Tempisque,

32 Zapotillo,

•?•? Zopilote.

35 Escobillo,

WOOD.

Stress in outermost Fibre
per Square Inch, at —

Total
Elastic
Resilience

TT Pd

Modulus of
Elasticity.

FP

E. Limit.
3 PI

Rupture.
SPl

p~2bh*

P'^2 6k*

U~ 2

•k=48 d 1

I
2

3

4
5
7
8

9
ii

18
20

22

23
26

27
3°

33

Ibs.

5613
10272

12575
Il6oo
17025
II4II
12206

3232
6803

8385
7409
7571
13602
13966
6865
III54
12479

I2I62

21571
16617

15467
29294
19490
21699
7649
6803
13624

13583
16088
22670
28514
12872
20026
22730

58
119

5°4
378

553
1 66

'5°
23
213
189
263
70
229

237
64
68
141

1514400
1824400
1672500
1496300
2119800

6I4550
1858400
1322000
879780
815100
1456500
1665500
2342900
2490200
1280300
2344600
1017100

Chaperno,

Cortez,

Guachipilin,

Guapinol,

Guayabo de Mcnte, ....
Jenisero,

Moran,

Nancite,

Oja-tostada, .

Palo de Arco,

Quiebra-hacha-negro,

Quita-calson,

Zopilote,

18

and knotty on either side of middle line on the thickness side.
Broke just under 750 pounds, with 0-8 1 1 inches deflection.

(33.) Zopilote. — 1 1 -inch supports. With a knot near one sup-
port gave away by shearing at the place when under 2, 5 50 pounds.
Stopped the test at this point and took this as the rupturing load.

The compression tests were made on the Olsen machine of
14,000 pounds capacity. The machine consists of four columns
bolted to a plain cast-iron bed, and supporting on top a plate, in
the middle of which one end of the test piece, if for tension, or the
rod which holds the measuring apparatus are held by means of steel
wedges.

Through the four angles of this bed and through those of that
below pass four screws. To these latter is secured a plate, which pulls
or compresses the piece, as the case may be. The plate rests upon
four knife edges, on three beams or levers, and their ends rest together
upon a link hung from knife-edges on each side of another beam,
which latter is linked to the end of the scale in the same way. The
machine is very sensitive. The scale is divided into divisions of
five pounds. The load is applied by means of a crank or a lever,
^turning a central wheel geared to four others, one on each screw.
A powerful leverage and a steady vertical motion of the plate is
obtained. The deflections were measured by means of micrometer
screws, using the electrical contact. I quote Prof. Thurston's full
description of the instrument :

" The instrument consists essentially of two very accurately-
made micrometer screws, working snugly in nuts secured in a
frame which is fastened to the head of the specimen by a screw
clamp. It is so shaped that the micrometer screws run parallel
to and equidistant from the neck of the specimen on opposite sides.
A similar frame is clamped to the lower head of the specimen, and
from it project two insulated metallic points, each opposite one of
the micrometer screws. Electric connection is made between the
two insulated points and one pole of a voltaic cell, and also between
the micrometer screws and the other pole. As soon as the micro-
meter screw is brought in contact with the opposite insulated point, a
current is established, which fact is immediately revealed by the
stroke of an electric bell placed in the circuit. The pitch of the
screws is 0-02 of an inch, and their heads are divided into 200 equal

19

parts ; hence a rotary advance of one division on the screw head
produces a linear advance of one ten-thousandth (o-oooi) of an
inch.

"A vertical scale, divided into fiftieths of an inch, is fastened to
the frame of the instrument, and set very close to each screw head
and parallel to the axis of the screw ; these serve to mark the
starting point of the former, and also to indicate the number of
revolutions made. By means of this double instrument, the exten-
sions can be measured with great certainty and precision, and
irregularities in the structure of the material, causing one side of
the specimen to stretch more rapidly than the other, do not
diminish the accuracy of the measurements, since half the sum of
the extensions indicated by the two screws is always the true
extension caused by the respective loads."

The size of test pieces advised for compression varies with
different authorities, the limit of the ratio of the length to the
diameter being five times the diameter. The compression test
should crush the piece down or shear it at 45°, but even with the
ratio used — the length equal to twice the diameter, as given and
used by Prof. Thurston — the piece showed a slight buckling in
some cases.

We have obtained the results, from each test by plotting a curve,
taking the loads as ordinates and the deflections as abscissas. In
this way we see the behavior of the piece at a glance, by the
curve, and find the elastic limit very accurately. This latter was
obtained by drawing a straight initial line when necessary, and
taking it as the point where the curve leaves the line.

We have given not only the results derived from the most
common formula used in designing, or used indirectly, but also
the original data of size of test piece, the actual loads, unit strains
and stresses as they may be found convenient in some cases and
for further information if desired. The formulae from which the
results were derived are set at the head of the tables.

TESTS BY COMPRESSION.

N O f>* vot«. ~ ON

to ONOO vo f) f> t^ »« ON >-i r^ ON N "1O
N •* r^ N rj- •rt- ^vO \O ->tvO •* •«!-•«}• N •*

ooopo 09000090000

6660660006606600

Q\"^t-O\O >•
00 fOOOOvO ^»-

•• vO <-> N

IS •*}• CO N i*- roe* «n «*i ^- roop ro »*•
OOOOOOOOOOO999
00606060600000

OO W n O ON !**• t^* W vo ^ PO ftj COvO vO fO
M M fed M M M M M •• M M tl M M M M

0990909990999990
6660066060666666

i-" vo«« "-" « vo

^OO ON N vo TfX) N N 00 voX) ON» vO t".

op 10 r^ r^ « r^op x> oo x> 900 «op «op
OOOO-OOOOO-O-O-O

vO vo N f*J vo
vo N voOO ro
vO vO vo vo

ON

vo VOX) vo ^f vo ON VO
NNwNNN — ON

vO vp N vp N VO N i

MMMM&MMM

So

t3 S

WOOD.

UNIT STRESS.

Unit Strain
Elastic
Limit.

e = x
L

Modulus
of
Elasticity.

e

Modulus
of
Resilience

E. Limit.

1' ''.

Maxim.
""-?

Breaking.

"-?-

I Carbon

5600
2100
7800
6OOO
4OOO
6000
5600
7000
7200

9800
11500
12OOO
8800
7800
8000
10275
14000
10800

9585
I 1500
I2OOO
8800
7800
8000
10000

14000
10500

00069
0-0035
0-0074
00067
0-0096
0-0072
0-0077
0-0087
00099

804860

59354°
1051600
882940
414020
824340

72355°
801050
721370

3
28
20
19

21
21

3°
35

3 Chaperno
8 Guapinol, ....
10 Guiliguiste, ....
1 2 Jicaro-sacaguacal, .

21 Nispero

21 Nispero,

33 Zopilote,

21

*
WOOD.

UNIT STRESS.

Unit Strain
Elastic
Limit.

*•>&

Modulus
of
Elasticity.

E- 2-

e

Modulus
of
Resilience

U--E1-
2L

E. Limit.

*•$

Maxim.

'-'r

Breaking.

P"
V' *==--
F

2 Cedro, ......

4200
IIOOO

8000
6000
6000
6000
8400

IIOOO

9600
7000
5000
10800
5000
8400

3800

6000

4600
I62OO
I3OOO
IOOOO

8500

8000
12700

13400
13200

14000
8000
17200
8000
11800

IOOOO

7400

4600
16200
12140
IOOOO
8500
8100
12650
13300
12000
14000
7800
16740
7600
IISOO
IOOOO

7400

O-OII4
00137
0-0074
0-0064
0-0085
O-OIlS

o-oi 10

O-O2O2
00096
0-0087
00058
0-013846
0-0058

o-oioi

0-0073
00084

367190
797990
1080300
93 '47°
702180
504880
759440
543010

1000000

801050

853320

780000

855310

827270
514210

709730

18

75
29

19
25

3I
46

in

46
30
14
74
H
42
H
25

r Cortez,

6 Granadillo-negro,
7 Guachipilin, ....
9 Guayabo de Monte, .
II Jenisero, .....

14 Lligualtil,

15 Madera-negra, . . .
1 6 Madrono,

21 Nispero,

22 Oja-tostada, ....
26 Quiebra-hacha, . . .
27 Quita-calson, . . .
29 Ron-ron, . . . .
31 Tiguilote,

36 Guanacaste, ....

ORIGINAL.

STRESS.

WOOD.

Length.

Diameter

Final
Length.

E. Limit.

Maxim.

Breaking.

Strain
E. Limit.

L

D

L

P

pt

P"

A

I Carbon, . .

2-242I

I-I28

2-1562

5600

9800

9585

0-0156

3 Chaperno, .

2-26n

1-1245

2-2096

2100

11500

1 1500

0-0080

8 Guapinol, .

2-2516

I-3II5

2-2036

7800

12000

I2OOO

00167

10 Guiliguiste,

2-2515

I-I28

2-2OI2

6000

8800

8800

0-0153

12 Jicaro-sacagua

cal, . . .

1-625

0-8437

'•5534

2OOO

3900

3900

0-0157

20 Nancite, . . | 2-2532

I-I292

2-2238

6000

8000

8000

00164

21 Nispero, . .

2-26II

I-I235

1-9522

5600

10275

IOOOO

0-0175

21 Nispero, . .

1-625

08281

1-5760

3500

7OOO

7000

0-0142

33 Zopilote, . .

2-2704

I-I26

2-2143

7200

10800

10500

o-oi 80

The torsion tests were made in the autographic testing machine
of Prof. Thurston : It consists of two angle frames united at
their vertices by a cast-iron rod and rigidly bolted to a heavy cast-
iron bed, thus making the machine very firm. These two angles
have the bearings in line with the jaws or wrenches which hold
the piece to be tested by means of steel wedges put from opposite
sides. The test piece is put in line before securing it rigidly
between the jaws, by means of centres in each jaw, one resting on
a spiral spring and the other turned by a screw which projects out
of the frame, thus enabling to place the piece symmetrically and
directly in line with the axis of rotation.

22

The outer end of one of the jaws is connected to a worm-wheel,
the rotation to which is imparted through the worm by means of
the crank. The other jaw carries the pendulum, to which is con-
nected, a little below the jaw, the pencil which is held by a spring,
tight against the sides of the guide curve. This curve is made so
that when the pencil rolls on it, in virtue of the swinging of the
pendulum through the test piece, the ordinates which are recorded
upon a cross-section paper carried by a drum on the opposite jaw
or on the one connected to the worm wheel, are proportional to
the moments about the axis of the test piece. The machine, by
the tracing of a simple curve, tells all the characteristics of the test
piece. The circumference of the drum is equal to thirty-six
inches, and the inches in the paper are divided into ten equal parts,
thus making each inch of paper equal to 10°. The vertical lines
are also divided in inches and each into tenths.

When the piece is secured between the clamps, the crank is
turned by hand with a uniform motion and a slow rotation, inter-
rupted only by the rupturing of the piece, is given to it, causing
the pendulum to swing up on one side. This measures the resis-
tance to torsion of the test piece which is recorded autographically
in the paper.

To make these tests, we took off the bob from the pendulum,
as it offers too large a moment for the torsional resistance of the
woods for the size of test piece used. Before making the tests,
we found the necessary constants of the machine to work out the
results of tests, as follows : The pendulum without the bob was
supported horizontally by a column, which rested on a scale.
Thus, the maximum moment of the pendulum was weighed, and
the corresponding ordinate in the curve observed :

Lever arm, 48 inches.

Weight of column with lever arm 5275 pounds.

" supporting columns 21*5 "

" lever arm, or pendulum 3i'25 "

Hence maximum moment, 1,500 inch-pounds.

Maximum ordinate traced by the pencil, or ordinate corresponding
to horizontal position of the pendulum — 4-3 inches. Therefore,
one inch of ordinate = 348-837 inch-pounds.

We found the friction of the machine by means of a delicate
spring balance, attached at a distance of fifty inches from the

23

centre of suspension. The pendulum was pulled just far enough
to overcome friction alone. After several trials, it was found to be
equal to 0-25 pounds. Thus, the friction of the machine is 12-5
inch-pounds, which friction is added, in every case, to the moments
recorded by the pencil.

The absolute errors in the size of the test pieces vary by excess
from above one-thousandth (yoinr) °^ an mch UP to a little above
one-hundredth (ooi) of an inch.

We have put down the moments at the elastic limit and at the
maximum before rupture ; also the angles of torsion at the elastic
limit, maximum before rupture, and final rupture with the cor-
responding elongations of the outermost fibres for the first three
angles. As a matter of detail, we have observed those which
reached the final rupture with a higher moment after the first
rupture, and those that did not offer a higher resistance. The
names used express the character of the four critical points to
which a material is subjected under an increasing stress.

Not being able to put in the strain diagram, we have endeav-
ored to write out for illustration the behavior of several pieces
under stress, and their mode of rupture as concisely as possible in
the details of torsion tests. These may be more valuable than the
numerical results. The torsion tests give a better and more
general idea of all the properties of strength and elasticity of the
woods than any other test, as, in this case, they are compelled to
write for themselves their " own story."

DETAILS OF TORSION TESTS.

(i.) Carbon, d = 0-6271. — Test piece turned from a large
sample near the heart. Very sound in the turned part. Elastic
limit, maximum and rupture occurred under the same moment.
From this and by breaking in two splinters it shows it is a brittle
wood. It reached a moment at the latter points of 200-87 inch-
pounds, at an angle of 7°-5 and gave away completely at !3°-2
with no higher moment. Its curve was at 45° from the axis of
angles and was short-wavy all along.

(2.) . — With a short wavy and parabolic curve

reached its elastic limit at 7°-ii under a moment of 186 inch-
pounds, and reached a maximum of 190 inch -pounds moment,
which kept constant for about 8°, when it came down and ruptured.
Fairly regular stiff rupture.

24

(3 ) Chaperno. d = 0-6278. — Turned from a large sample and
very sound piece. It rose with a 45° wavy curve up to 104-9
inch-pounds when it reached the elastic limit. Went up to a
maximum of 124-128 inch-pounds, which kept constant until final
rupture, splintered at I7°'3.

(5.) Cortez. d = 0-6278. — Turned from a large sample near the
heart. Very sound piece. It rose with a 45° curve and slightly
wavy but uniform, reaching the elastic limit at 214-82 inch-pounds
at an angle of 50>9. Ruptured at 28° and splintered at 41°,
reaching afterwards a higher moment, which kept constant till
final rupture. Fibrous and stiff rupture, shearing a plug of same
cross section as the turned part from the shoulder.

(8.) Guapinol. d = 0-5645. — With a slightly parabolic curve
at 45° angle, reached its elastic limit at 6° with a 183 inch-pounds
moment, which kept constant until first rupture and reached a
little higher moment before final rupture. Gave away with wide
fibrous splinters.

(12.) Jicaro-sacaguacal. — The test piece was turned from a
green limb. It rose with a parabolic line and very much inclined
toward the axis of strains reaching at the elastic limit a moment of
103-2 inch-pounds. Reached a higher moment, which kept con-
stant until final rupture at 155°, when it completely broke irregu-
lar and stiff.

(13.) Laurel. ^ = 0-631. — Dark color. With a low sloping
curve, but uniform, reached the elastic limit at 4° angle and under
a moment of 82-268 inch-pounds. This was its maximum resist-
ance and kept constant until ruptured at 20°. Uniform square
rupture around the shoulders without projecting splinters. Gave
way entirely at 105° angle.

(17.) Mahogany, d = 0-6358. — A very sound piece, turned from
a large sample. It rose with a long wavy line up to 78-779 inch-
pounds, its elastic limit at 3° angle. Reached a higher moment ot
82- inch-pounds at 6°-7 when it ruptured. It splintered at a still
little larger moment at 27°-6. Fibres wide and stiff, and rupture
irregular.

(18.) Moran. ^ = 0-6256. — A very sound piece. With a curve
above 45° angle with the axis of strains reached its elastic limit at
2° under a moment of 82-27 inch-pounds, which kept constant for
I -5, when it rose to 88-95 inch-pounds moment, and gave away for

25

the first time. However, it still reached about twice as large a
moment which kept constant till final rupture. Fibrous and tough
rapture.

(24.) Piedra (Stone), d = 0-6257. — A piece turned from near
the heart and very sound. It rose with a parabolic short wavy line
up to the elastic limit, when it had a moment of 227 inch-pounds
at an angle of 90>7 It reached a maximum moment of 228-7 inch-
pounds at an angle of 11°, and very soon lowered its moment to
221-8 inch-pounds, which kept constant until it splintered at 50°.
Wide splinters and stiff rupture, but square around the shoulders.
(26.) Quiebra-hacha. d =06268. — A very sound piece. It
rose with a parabolic curve above 45°, with the axis of strains up
to 1 66 inch-pounds moment, its elastic limit, and kept reaching
higher and higher moments by regular intervals up to a maximum
after first rupture of 319-479 inch-pounds without giving way com-
pletely. Brushy, regular break and very tough.

(29.) Ron-ran — Dry and sound piece. Rose with a straight line
up to 82-26 inch-pounds moment at an angle of i°-5, and kept a
constant moment till final rupture. Broke with brittle fracture in
two pieces, without showing any fibre.

(32.) Zapotillo. — The test-piece turned from a large sample,
d = 0-6258 inch; had a small knot on one end, but very sound
otherwise. It reached its maximum at the elastic limit at an angle
of 50<5 from the origin, rupturing with the same moment at angle
of 9°. It kept a constant moment for about 80°, when it reached
a little higher moment holding it till final rupture. Fibrous
rupture.

(33.) Zopilote. — At first rose with a straight line below 45°, and
turned parabolic near and after the elastic limit. First ruptured at
28° angle under a 106 inch-pounds moment and raised it slightly,
keeping the latter constant for over 160. A very thready and
tough rupture.

26

TESTS BY TORSION.

Moments of Tor-
sion in in. -Hi-..

Angle of Torsion in
Degrees.

Maximum Shearing Stress.

Max.

Max.

WOOD.

K. Limit.

before
Rupt.

E. Lim

before
Rupt.

First
Rupt.

Elastic Limit.

Maximum before
Rupture.

wi

('.)«

a

*

-

"-.-3r*W.

"•-^rW.

2 Cedar, . .

43-89

4563

3-6

84

8-4

9'5

952

5 Cortez, . .

68-3

71-80

3'3

19

27-5

1424 1497

7 Guachipilin,

82 2 8

148-54

26

49'

49'

1716

3098

9 Guayabo de

Monte, .

54-36

64-82

4'5

5-5

26-5

"33 1352

13 Laurel-

macho, .

68-31

7I-8

28

4-1

4-1

1424 1497

15 Madera-

1

negra, .

141-57

141-57

3-6

'34

17-4

2953

2953

16 Madrono, .

9971

103-19

4'5

29-

35°

2080

2152

19 Nacascolo,

145-06

145-06

2'4

24

16-1

3026

3026

20 Nancite, .

61-34

68-3

2'7

12-

12-

1279

1424

21 Nispero, .

103 89

'9389

7-2

5'

95

4044

4044

22 Oja-tostada,

52-616

54'36

2-7

'45

'95

1097

"33

25 Pochote, .

47-38

5087

5°

5-8

58

988

IOOI

26 Qu i e b ra

h a c h a

(yellow),

152-03

152-03

5-0

5-

9-3

3171

3171

28 Roble, . .

54-36

54-36

3'3

3'3

12-

"33

"33

31 Tiguilote, .

3343

43-87

5'4

17-5

'7-5

697

915

36 Guanacaste,

68-31

71-8

2-25

3-2

1424

'497

28 Roble, . .

54-36

54-36

3'3

3'3

12-

"33

"33

31 Tiguilote, .

3343

43-87

5'4

!7-5

'7-5

697

915

36 Guanacaste,

68-31

71-8

2-25

3-2

1424

'497

Moments of Tor-
sion in in.-lbs.

Angle of Torsion in
Degrees.

Maximum Shearing Stress.

WOOD.

E. Limit

Max.
before
Rupture

E. Limit

Max.

b«-fure
Rupture

First
Rupture

Elastic Limit.

Maximum before
Rupture.

(jjV

(*).

a

*

0.

i

2 ( \

P.-nrt(P*}x

i Carbon, . .

200-8

2008

7'5

75

7

s

4190

4190

2

18692

190-4

711

8-5

3

3899

3972

3 Chaperno, .

1049

124 i

3'4

5'7

7'3

2189 2589

5 Cortez, . .

2148

2148 59 59

28-0

4481 4481

7 Mahogany,

78-7 82-2 3-0 6-7

6-7

1643 1716

8 Guapinol, .

183-4

183-4 6-0 1 8-2

18-

2

3826 3826

1 2 Jicaro-saca -

guacal, .

103-2

1 10- 1

20- 220

] 22-0 2153 ; 2298

13 Laurel, dark,

82-2

822

4O 40

200

1716 1716

18 Moran, . .

82-2

88 9 20

4-2

42 1716 1855

24 Piedra, . .

227 o

228 7 97

11-0

n-

4736 4772

26 Quiebra-

hacha, . .

1 66-

1660 8-0

80

8-0 3463 3463

29 Ron-ron, .

822

82-2 1-5

235

23-5 1716 1716

32 Zapotillo, .

99-7

99-7 5'5

5'5

9-0 2080 2080

33 Zopilote, .

94-4 106-6 5-7

280

28-0 1971 2225

WOOD.

Extension of outer Fibre.

Modulus
of
Elasticity.

r (A)B l.

Total
Elastic
Resistance.

(Pa)E X a

F T . Max. before First
*• Unut' Rupture. Rupture.

A = i/ 1 + of (0-00002D747) — 1

E'~ o. * If

2

46635
79I6I

>52358

46203

933'o
150407
84748

23 "75
86893
102997
74533
36243

116297
63003
23678
116119

I
2

2

2
I

4
4

3

i

12
I

2

6
i

I
i

7 Guachipilin, .
9 Guayabo de

13 Laurel-macho,
15 Madera-negra,

. . .
.

. . .

V ' '

19 Nacascolo, .
20 Nancite, . .

21 Nispero, . .

22 Oja-tostada, .
25 Pochote,

26 Quiebra-hacha

28 Roble, . . .

36 Guanacaste, .

WOOD.

Extension of outer Fibre.

Modulus
of
Elasticity.

K _ (P.)E v *

Total
Elastic
Resistance.

„ ._ (PJE X a

E. Limit.

Max. before First
Rupture. Rupture.

A= 1/1

-(- a? (0'OOJ029747> — 1

JP

2

I

2

3
8

12

•3
17

18

24
26
29
33

33

Carbon, . . .

IO244O
I0055I
118050
139270
116920

19735
78663
IOO44O

!5733°
89522

79363
209750

69339
63390

13
II

3
ii

9
18

2
2
I

19
II
I

04
4

Chaperno, . .
Cortez, . . .

• • •

Guapinol,

Jicaro- saca-
guacal, . .
Laurel (dark),
Mahogany, .
Moran, . . ,
Piedra, . . .

:-.!!

: : :

Quiebra hacha,
Ron-ron, . .
Zapotillo, . .

Zopilote, . .

LIBRARY

FACULTY OF FORESTRY
UNIVERSITY OF T

Forestry

Thurston, Robert Henry

On Flint fs investigation
of the Nicaraguan woods

PLEASE DO NOT REMOVE
CARDS OR SLIPS FROM THIS POCKET

UNIVERSITY OF TORONTO LIBRARY