Apbil 11, 1913] 



SCIENCE 



571 



Many interesting and unexpected results appear 

 as part of this investigation whose main conclu- 

 sions have been already reached. Among these 

 is the fact that the point of maximum stress in 

 steel is midway directly between columns and not 

 at the center of the panel. 



It is the intention of the writer to prepare and 

 publish a treatise upon this subject after con- 

 cluding his investigations upon flat slabs and upon 

 the theory of combined beam and slab floors. 

 These forms of construction have been ordinarily 

 treated by American engineers by applying some 

 form of beam theory to their computations. This 

 has been a fruitful source of bad design and error, 

 because in beam theory the moment of the applied 

 forces is equal to that of the resistance of the 

 beam,whereas in slab theory such an equality does 

 not exist, since these may differ by 100 per cent. 



It has been found that slabs are in fact per- 

 fectly safe which beam theory would regard as far 

 otherwise. Correct theory is therefore of extreme 

 importance in slab design. 



The Significance of Empirical Tests to the Appli- 

 cation of Explosives in Practise: Clarence 



Hail, U. S. Bureau of Mines, Pittsburgh. 



Bead by title. 

 Sampling Coal Deliveries: G. S. Pope, Washington, 



D. C. 



Bead by title. 

 Smoke Prevention in Cleveland: E. P. Roberts, 



city smoke inspector, Cleveland, Ohio. 



A brief account of the routine of city depart- 

 ment of smoke inspection and results accomplished 

 at prominent plants, with locomotives and steam- 

 ships. 



When possible plans for boiler settings are re- 

 viewed before installation to prevent unnecessary 

 expense to the owner. 



Cleveland has noticeably improved in the matter 

 of smoke during the past few years. 



Mr. Eoberts also exhibited a novel and valuable 

 smoke chart intended to overcome the objections 

 to the Ringelman charts. 



papers on highway engineering 

 Bond Issues for the Construction of State High- 

 ways: JAS. B. Marker, state highway commis- 

 sioner, Columbus, Ohio. 

 Bead by title. 

 The Design of Various Types of Highway Bridges 

 from the Standpoint of Modern Traffic: Frank 

 H. Neff, professor of civil engineering. Case 

 School of Applied Science, Cleveland, Ohio. 



Subject discussed at length by the author and 

 liberally illustrated with lantern slides. 



Methods of Repairing Cement Concrete Pavements : 

 Frank F. Bogers, deputy commissioner. State 

 Highway Department, Lansing, Mich. 

 In practise repairs to these pavements are made 

 by two distinct methods, depending on whether the 

 defects are on the surface or extend deeper into 

 the mass. Surface treatment is given by first 

 cleaning the defective places, then filling, or cover- 

 ing them with hot bitumen, preferably refined tar, 

 and coating with sand. This applies to wear at 

 the expansion joints and to cracks caused by 

 natural causes as well as to a pitted condition of 

 the surface, and tends to prevent further deteri- 

 oration of the places repaired. As a rule, repairs 

 of this kind have to be made annually. In Wayne 

 County, Michigan, the cost of such repairs has 

 been about $50 a mile. When the defects lie deeper 

 a portion of the concrete is chiseled out, usually to 

 the sub grade, the exposed edges thoroughly 

 cleaned and given a wash coat of neat cement, 

 after which the excavation is filled with the same 

 kind of concrete that was used in the original con- 

 struction. Bepairs of this kind generally prove 

 satisfactory. Bellefontaine, Ohio, reports that 

 repairs on 4,400 square yards of cement concrete 

 pavement laid in 1893 and 1894 have cost only 

 about $200. 



Belative Advantages of Laying BricTc Pavements 

 on Sand Foundations and Cement-Concrete 

 Foundations: Bobert Hoffman, chief engineer, 

 Department of Public Service, Cleveland, Ohio. 

 Belative economy of using a sand or concrete 

 foundation for a brick pavement depends upon its 

 first cost, cost of maintenance and life. Accurate 

 data relative to maintenance and effect of traffic is 

 not at hand. Becords of cities which show the 

 time that has elapsed between the laying and re- 

 laying of a pavement affords the best available 

 evidence upon which to base estimates of relative 

 economy. 



In Cleveland, which is chosen as a representative 

 city with reference to brick paving, prices paid 

 per square yard of brick pavement, have varied as 

 follows : 

 5 in. brick laid on natural sand foundation, 



$1.18 to $1.56. 

 5 in. brick on 8 in. sand or gravel ballast founda- 

 tion, $1.40 to $1.97. 

 5 in. brick on 6 in. concrete foimdation, $1.94 to 

 $2.48. 



