APPENDIX III. 



NOTES BY MR. WALTER G. BERG, PRINCIPAL ASSISTANT ENGI- 

 NEER OF THE LEHIGH VALLEY RAILROAD. 



The first section of the paper contains pertinent criticisms of the 

 existing- practice, and presents valuable suggestions and exceedingly 

 interesting tables. The demonstration of the necessity for a more reg- 

 ular and uniform theoretical practice, based upon scientific research, in 

 place of the chaotic conditions, as exhibited by Table III, is certainly 

 apparent after a perusal of this part of the paper. 



The most valuable information for the profession at large is con- 

 tained in Table IV, which represents the data obtained to date from 

 the very extensive series of timber tests of the United States Forestry 

 Division, supplemented by the best information available in regard to 

 other authenticated tests. This table can be considered in the nature 

 of an advance sheet, giving the grand averages of the results of the 

 tests mentioned up to date, and deserves to be well circulated and 

 reo-arded as the latest authentic information till supplemented by future 

 publications of the Forestry Division. 



The fact, mentioned by the author of the paper, that structural iron 

 and steel is invariably tested with the greatest degree of care, while 

 timber for structural work is seldom given more than a cursory eye 

 inspection for visible defects, is traceable to the fact that very little 

 reliable data have thus far been available on which to base the strength 

 of timber. The great variations existing in the coefficients of strength 

 for the different parts of a timber trestle, as assumed in practice, 

 brought out so clearly in Tables II and III, is a silent but potent argu- 

 ment in favor of timber tests on a large scale, as being conducted by 

 the United States Forestry Division. These investigations, extended 

 to include all the principal varieties of timber in use, and especially 

 tests of large size timber struts, will have a greater tendency to effect 

 a decided economy in the use of timber throughout the country than 

 the presentation of individual views as to how to improve on existing 

 practice in particular cases. With reliable knowledge of the proper 

 coefficients of strength that can be allowed for the various parts of a 

 timber structure, it will be perfectly safe and consistent to expect that 

 the parties interested in the economical construction of a structure 

 will be only too glad to avail themselves of any reasonable economy 

 that can be effected without assuming any undue risks. 



Table III illustrates, in general, that the railroad practice of the day 

 is working with approximately correct units of strength as far as the 



34 



