and comprehensive manner, such tests and examinations as would furnish us not only with reliable data as to the range of capacity of our timbers, but also as to the exact relation of their properties to their structure and physical condition.

In order to establish fully for any one species the possibilities of its adaption to our use, it is necessary to test a very large number of specimens. In order to formulate laws of relation between physical condition, anatomical structure, and mechanical properties, each test specimen must be carefully examined. In order to establish laws of relation between the physical and mechanical qualities and the conditions under which the specimen has grown, it is necessary to perform the testing and the examination on a large number of specimens of known origin.

Almost all the investigations made in this line are deficient in one or more or all of those points. Not only have there been few tests made on a sufficient quantity of material to allow generalization, but rarely have there been sufficient data furnished regarding the nature and origin of the test specimens to enable us to form a judgment.

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

It is to supply this absolute gap in our knowledge-which causes thousands and millions of dollars of waste annually-that the Forestry Division has entered upon a comprehensive and systematic investigation which has become known under the name of "the Government timber tests."

This investigation, the most comprehensive of the kind ever undertaken anywhere, in this country or in Europe, differs from all former attempts in similar direction in this, that it starts out with the fullest recognition of three facts:

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

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

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

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

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

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

further investigation. We know that there are differences in quality, at least for some timbers, in sticks from different parts of the tree: not only the heartwood differs from the sapwood, but also the butt log from the top log.

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

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

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

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

ABSTRACTS OF LETTERS.

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

(1) The information now available regarding the value, properties, and adaptations of our timbers is scanty in amount and unreliable in character.

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

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

M. H. Rogers, chief engineer, Denver and Rio Grande Railway Company, Denver, Colo.: When the fact is considered that the information published on this subject at present, even in our most advanced works on engineering, is very meager and unsatisfactory, more especially since such tests as have been made are with reference to the superior specimens of the different species of woods and that a great many of our native timbers are omitted altogether, but little further argument is needed to show the advisability of such investigations by the Department. Since the work will be conducted by experts under the direction of the Government, the results will be most satisfactory and become an invaluable standard for engineers and others in the construction of all works wherein wood forms an important part.

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

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

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

H. S. Jacoby, professor of graphics and bridge engineering, Cornell University, Ithaca, N. Y.: I was interested quite recently in a brief description, in one of the engineering papers, of the series of tests which your Department has inaugurated relative to the strength of American timbers. In my class work in structural details I am constantly reminded of the very meager knowledge concerning the strength of even a few species of woods that is now available in the designing of wooden structures. Such investigations made with special care, on an extensive plan, are essential to economy in design.

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

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

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

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F. C. Osborn, chief engineer, King Iron Bridge and Manufacturing Company, Cleveland, Ohio: I wish to urge upon you the importance of this investigation both in regard to consumers of timber and to engineering profession as well. The data that are at present at hand in regard to strength of American timbers in various positions are very meager, and the large amount of timber used in connection with structures of importance makes it very desirable that some satisfactory resuits should be arrived at in regard to the strength of the same. F. W. Skinner, Am. Soc. C. E., New York City:

There is a great scarcity of such data available for engineers, and as a bridge engineer I heartily appreciate its value and hope that it will be fully supported.

The Phoenix Bridge Company, engineers and builders of bridges, viaducts, etc., Phoenixville, Pa.: We hope that these investigations may be continued until we have complete data in regard to the timbers used in construction. At present this information is very meager and the investigation undertaken by the Department of Agriculture will be watched with great interest. In the line of bridge construction the information secured by these tests will be particularly valuable.

(2) The results of European tests, which form the principal basis of our engineers' tables, are inapplicable to timber grown here.

G. Lindenthal, chief engineer North River Bridge Company, New York City:

There has not been so far an elaborate and continuous investigation of American timbers such as is now pursued by the Forestry Division, and the meagerness of data relating to the subject has been repeatedly the cause of great vexation and embarrassment to engineers. The absence of authentic and reliable knowledge of the physical properties of American timbers has been the cause of great losses, by reason of incorrect application and design, mistaken judgment in the preservation of such timbers, and of their strength and durability. * The information engineers possess from similar tests in Europe naturally can not be applied to the timbers grown in this country, and we ought not to be behind in this respect the information of the "Old Country."

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

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

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

When the English formula of Mr. Hodgkinson, their greatest authority, was shown by Mr. Smith's experiments on large pillars to give results double what should be given, as stated in Trautwine's Pocket Book, engineers felt a longing for full, accurate, and modern experiments, on large sizes, that they might not be in any doubt as regards the strength of their work. The only method that will secure the information required is for the Government to seek it in the manner proposed. It is just such work that will keep it more in touch with the mass of the people.

G. Bouscaren, consulting engineer, Cincinnati, Ohio:

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

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

William H. Burr, vice-president Company of Constructing Engineers, New York:

It is true that a considerable number of examinations and tests have heretofore been made under the auspices of the Government, but almost or quite entirely on small and specially prepared specimens, quite different in character from the pieces of the same material used in engineering practice and in the entire field of structural operations. There are at present few results of investigations made under conditions which fit them to serve practical purposes. Permit me to say, therefore, that I trust you will encourage, in every legitimate and proper manner, this physical and mechanical investigation of the different varieties of American timber; and I can confidently assure you that the engineering and building portion of the public will be served in a most efficient and valuable manner thereby.

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John C. Trautwine, jr., C. E., Philadelphia, Pa.:

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

Louis De Coppet Berg, architect, Trinity Building, New York:

I beg to say that I deem these tests of the utmost importance to architects and engineers. You will remember that up to within a few years ago we were using constants for the strength of timber which were proven by Prof. Lanza's limited tests on full-sized timbers to be utterly beyond the strength of the beams. These constants were derived from tests on small specimens, made by Hatfield and others, and if it had not been for the large factor of safety used many accidents would have happened. A series of tests such as you propose will give us an intimate knowledge of the action of our American timbers in large sizes when under strain, and will not only enable us to calculate more accurately and safely the strength of our buildings, but will prove a great economy to all builders in allowing us to use smaller factors of safety, which can safely be done where the actual strength and behavior of the timber are accurately known.

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

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

E. L. Corthell, C. E., Chicago, Ill., and Broadway, New York:

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

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

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

Henry B. Seaman, C. E., 10 West Twenty-ninth street, New York City:

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

J. B. Davis, assistant professor civil engineering, University of Michigan, Ann Arbor, Mich. : I hope now to see results from tests of commercial shapes and sizes, bought in the open market, substituted in our text-books and works of reference for those derived from plaything sticks (splinters really) chosen from the choicest spot in the best piece to be found.