670 



SCIENCE 



[N. S. Vol. XXXVII. No. 954 



Notes oil Some Properties of Explosive Mixtures 

 of Air and Gas: F. H. VoSE, professor of me- 

 chanical engineering, Case Scliool of Applied 

 Science. 



The paper refers particularly to some experi- 

 ments performed with explosive mixtures of air 

 and illuminating gas. These experiments were 

 conducted at Washington University, St. Louis, 

 Mo., the gas used being the illuminating gas from 

 the city mains. 



The investigation was undertaken to determine 

 the effect of the presence of water vapor on the 

 properties of explosive mixtures, such as pressure 

 ratio resulting from combustion as well as the time 

 increment involved for the completion of combus- 

 tion. 



While the investigation covered a wide range 

 of mixtures, the paper was written to cover a 

 mixture containing 4.75 parts of air to 1 part of 

 gas by volume. This mixture approximates the 

 theoretically best mixture for complete combus- 

 tion. 



Pressure rise was measured by means of the 

 ordinary gas-engine indicator and time records 

 obtained from tuning-fork records on the indicator 

 card. The indicator drum was driven at a con- 

 stant rate. 



Slides made from original cards are shown to 

 indicate the character of the results. Curves were 

 also presented giving the results in graphic form. 

 When water vapor is present in the ratio of 

 0.05 parts by weight to the gas mixture a pressure 

 ratio from explosion = 5.5 results ; when the quan- 

 tity of water vapor present represents 0.35 parts 

 by weight the pressure ratio resulting from ex- 

 plosion is only 2.3. The retarding effect on flame 

 propagation is correspondingly great. 

 The Manufacturing Organisation: Hugo Diemer, 

 State College, Pa. 



Organization defined. Organization distinct from 

 system and management. To lay out a new organ- 

 ization or to analyze an existing one, Numerical 

 military type. Specialized type, Funetionalized 

 type. Staff principle applied to industry. Selecting 

 the type or organization and control to be applied 

 to a given industry. Determining the will of the 

 organization as a whole. Setting forth specific 

 duties, A typical conventional industrial organiza- 

 tion. Department of records, Department of ma- 

 terials. Department of plant, equipment and proc- 

 esses, Eouting, Scheduling, Motion and time stu- 

 dies. Preparing instruction, instruction cards and 

 instruction sheets. Standardization of equipment. 

 Department of men, Hygiene and efficiency, Psy- 



chology and efficiency. Industrial education. De- 

 velopment of loyalty through social and religious 

 activities. Line organization. Progress of an order 

 through an industrial establishment, Carrying into 

 effect the above principles. 



A Further Analysis of the Deflections and Stresses 

 in Reinforced Concrete Floor Slais Constructed 

 on the Turner Mushroom System: H. T. Eddy, 

 dean of the graduate school. University of Min- 

 nesota. 



At the Washington meeting last year the pres- 

 ent writer gave an account of his success in de- 

 veloping a rational analysis of this kind of flat 

 slabs. That analysis was based upon the applica- 

 tion of the theory of circular plates to this form 

 of construction. 



In making such application, it is implicitly as- 

 sumed that any one of the panels of a slab is 

 supported by surrounding columns in such a sym- 

 metrical manner that the central part of a panel 

 carries its loading approximately in the same 

 manner as a circular plate would do when suitably 

 supported at its circumfernce. This supposition 

 will be nearly exact at points near the center of 

 the panel and less so the greater the distance 

 from the center. 



Again the part of the slab at and near a column 

 head in a slab of many continuous panels will have 

 the loading and supports so symmetrically disposed 

 about it that it will act nearly like a circular plate 

 with a central support at the column, at least for 

 points near the column. 



While the application of these principles was 

 found to give sufficiently precise values of the 

 central deflections of panels, and of the stresses at 

 the same points, and over the columns, at other 

 points than these the results were not and could 

 not be expected to reproduce the results of tests. 

 It therefore appeared desirable to develop a more 

 closely approximate general theory of the flexure 

 of the reinforced concrete flat slab. 



The writer has had unexpected success in de- 

 veloping this general theory from the fundamental 

 differential equation of flexure of slabs, by the help 

 of which its deflections at any points are readily 

 computed, as well as the stresses in reinforcing 

 rods and concrete, notwithstanding the extreme 

 irregularity of distribution of the reinforcement. 

 This last fact requires certain hypotheses in the 

 adaptation of the general solution for a uniform 

 slab to the actual slab, which are proved to be ad- 

 missible approximations by the agreement of 

 actual tests with numerical computations. 



