32 



HARDWOOD RECORD 



The question has frequently arisen, "What eflfect have the dif- 

 ferent preservative processes upon the strength of tiest" This 

 matter has been investigated by Dr. W. K. Hatt at Purdue Uni- 

 versity. The difference in strength between treated and untreated 

 ties, except in the cases of tliose treated with crude oil, is so slight 

 as to make this a matter of little practical importance. Of course, 

 this statement assumes that the ties are properly treated and not 

 injured by excessive heating or other causes. 



The function of spikes is to hold the rail to the tic, which, an- 

 alyzed, means that they must exert a resistance to pull and re- 

 sistance to lateral tlirust, the former resulting from the so-called 

 "bumping" of the rail, the latter accentuated by the centrifugal 

 force exerted by the train in rounding curves. As in the case of 

 plates, a great many methods have been advocated for fastening 

 rails to ties. The Patent Office is filled with devices aiming to 

 secure this apparent!}- simple end. I cannot even attempt to con- 

 sider all of the various schemes advocated but will call your at- 

 tention to three types of construction in more or less extended 

 use. These involve the use of the cut spike, the screw spike, and 

 the dowel. 



The cut spike is by far the one most generally employed in this 

 country. It is cheap, enables a quick laying of the rail, and is 

 easily applied. When freshly driven in sound, heavy timber it 

 also gives very satisfactory results. It has, however, been sub- 

 ject to severe criticism because it frequently becomes loose in 

 ties and under such condition may cause an unsafe track. This 

 feature has led to considerable experimenting in an effort to over- 

 come these disadvantages. 



The screw spike has been most successful thus far in removing 

 the chief criticism levied against the cut spike, viz., its low hold- 

 ing power. Screw spikes, however, are more costly than cut spikes 

 and more difficult to insert in the track. Their use, however, is 

 growing and will doubtless continue to do so, as this form 

 of spike possesses considerable merit. In a large number of tests 

 made at Purdue University, a part of which were conducted by 

 the Forest Service, it was found that screw spikes had from 1.7 

 to 3.S times the strength of common cut spikes against pull, and 

 from 1.2 to 2.4 times the lateral resistance of the common spike. 

 In round numbers one screw spike is about as efficient as two cut 

 spikes so far as holding the rail to the tie is concerned. 



The large number of ties cut from comparatively soft woods, 

 such as loblolly pine, have encouraged certain roads to experiment 

 with hardwood dowels. These are simply plugs of hardwood, such 

 as red oak, usually creosoted, screwed into the tie. The spike is 

 then driven or screwed into this hardwood dowel. By this method 

 a very firm grasp of the rail to the tie is secured, and should the 

 spike become loose and worn, the hardwood dowel can be un- 

 screwed from the tie and a new one inserted. Of course, such a 

 method of treatment is expensive; and, furthermore, it has a dis- 

 advantage in that it weakens the tie unless the ballast is kept in 

 very good condition. Where it has been put to practical test 

 this method has, however, yielded very satisfactory results. 



This is a feature of preparing ties for service which is also of 

 comparatively recent origin in this countrj'. As by far the larger 

 majority of crossties now in use are hewn, the problem of securing 

 a uniform bearing of the rail or tie-plate on the tie is of great 

 importance. Unfortunately, common practice in this country con- 

 sists in adzing such ties after they have been treated. This re- 

 moves the preserved layer of wood at the very point where its 

 protection is most needed. In order to secure best practice it is 

 absolutely essential to have the rail or tie-plate bear uniformly 

 on the tie and unless the ties are adzed this result is rarely accom- 

 plished. Adzing is, therefore, strongly recommended, particularly 

 on hewn ties, and the proper time to adze is before the ties are 

 treated, and not after. While the mechanical adzing of ties is 

 still in its infancy, it is quite likely machinery to do this work 

 will become a part of the well-equipped tie-treating plant. 



Another feature in too limited use at present is the boring of 

 the ties for the insertion of spikes. When screw spikes are used 

 it is absolutely essential to bore a hole into the tie in order to 



insert them, and if this hole is bored after the tie is treated the 

 unprotected interior is more or less exposed to decay. Boring 

 should, therefore, be preferably done before the ties are treated. 

 Even with the ordinary cut spike, boring is of direct value. The 

 spikes driven into a hole three-eighths inch in diameter has a 

 greater holding power than spikes driven into the tie not bored. 

 This is due to the fact that when a spike is driven into a bored 

 tie the fibers are not crushed to the same extent as when no boring 

 has been made. 



The following general conclusions can be drawn from this paper: 



(1) The increasing number of treated ties being used in this 

 countrj' is increasing the importance of protecting them from 

 mechanical destruction because the problem of protection from 

 decay is being rapidly solved. To secure best results, therefore, 

 a protection of treated ties from rail and spike cutting is strongly 

 recommended. 



(2) It is believed that, other things being equal, the size of 

 the tie-plate should depend upon the kind of tie with which it is 

 to be used. Soft ties demand a larger plate than hard ties. It 

 is felt that this fact should be recognized in fixing upon the price 

 of various timbers for crossties. 



(3) Preservative treatments with creosote and zinc chloride 

 when properly made affect the strength of ties so slightly that 

 any dift"erence in crushing value is of little or no practical im- 

 portance. 



(4) On account of their holding power screw spikes are pre- 

 ferred to cut spikes and can be recommended where high-class 

 construction is desired. 



(5) Adzing and boring ties, particularly the adzing of hewn 

 ties, prior to treatment, is considered of prime importance in pre- 

 paring them for seryice. Adzing after treatment should be classed 

 bad practice, as it exposes or tends to expose the interior of ties 

 to decay at a point where protection is most needed. 



The Value of Wood Structure Investigations 



The study of wood structure which is sometimes referred to as 

 xylology, has slowly but surely taken a definite place in the courses 

 of study in the forest schools in this country. Although work has 

 been done only on the most important native woods now in the 

 markets, it is destined to receive considerable attention as the 

 trade with foreign woods increases. Over two hundred kinds of 

 timber from foreign countries are sold in this country and the 

 question often arises as to the correct name and source of these 

 different kinds. If the botanical specimens (leaves, fruit, and 

 flowers) of the trees from which these woods are derived could be 

 readily procured, it would be a comparatively easy matter to trace 

 down their names by referring to botanical works in which such 

 species are described. With reference to the woods alone it is an 

 entirely different and often a more difficult task. Only a few of 

 the commercial timbers have been thoroughly described and classi- 

 fied according to characters visible to the unaid-sd eye and under 

 the microscope. As the work progresses the various timbers of 

 commerce will be described in detail and analytical kej-s worked 

 out. These descriptions will be of inestimable aid in tracing down 

 their correct names. The possibilities of this work are beginning 

 to be realized and the activities by a few investigators indicate 

 the growing importance of the subject. 



The subject can no longer be regarded as a part of a course in 

 botany or plant histology, but must in the future be treated, 

 studied, and taught as a distinct branch of science. It is of the 

 utmost importance that all well equipped students of botany, for- 

 estry, and related lines of work should be acquainted with the 

 main facts of wood structure. Too much stress cannot be laid on 

 the importance of a knowledge of wood structure to those who 

 have to do with timber preservation, wood pulp industry, tie and 

 timber inspector, contractor, and others. This importance is, 

 however, further enhanced in the work of identifying wood by 

 the structure, in which case it is not only paramount but funda- 

 mental. 



