610 



SCIENCE. 



[N. S. Vol. XXIV. No. 620. 



A New Type of Young's Modulus and 

 Hooke's Law Apparatus: B. B. Brack- 

 ETT, Clarkson School of Technology. 

 This apparatus has a horizontal bed or 

 base of wood, about 1.8 m. long, 20 cm. 

 wide and 5 cm. thick. At one end is a 

 clamp elevated 6 cm. to hold the wire 

 tested, and at the other end is a rather 

 large disk pulley over which the wire is 

 drawn, while weights attached to the ver- 

 tical portion of the wire beyond the pulley 

 supply the desired tensions. 



To compensate for the springing of the 

 light and not very rigid base, an easily 

 rolling platform is placed upon the base, 

 between it and the wire. One end of this 

 platform is held by a spring in firm contact 

 with the clamp just at the point where it 

 grips the wire, but the platform is entirely 

 free from the wire at all other points. 



A micrometer microscope is placed on 

 the end of the platform next to the pulley 

 to read the elongations of the wire. This 

 arrangement keeps the microscope at the 

 same distance from the fixed end of the 

 wire, however much the plank base may 

 be warped or shortened by the tensions 

 placed on the wire. 



The apparatus is of very simple con- 

 struction, is easily used, quickly adjusted 

 and gives results of the most satisfactory 

 kind. 



A Convenient Lecture Boom Resistance for 

 Electrical Experiments : B. B. Brackett, 

 Clarkson School of Technology. 

 The resistance is to be used for control- 

 ling the current from a dynamo circuit. 

 Usually a tap is made from the lighting 

 mains. 



Twelve incandescent lamps are arranged 

 within a partially open box, 70 cm. long 

 and 25 cm. square. Single pole, double 

 throw switches are connected to the lamps 

 so that all possible parallel, series and com- 

 bination groupings are readily obtained. 



While open enough for ventilation and 

 to make the switches easily accessible, the 

 containing box protects both lamps and 

 switches from all the usual accidents to 

 such apparatus, and enables one to use it 

 in any place or position, on either end or 

 on any side. 



All the connecting wires are plainly vis- 

 ible and this, with the regular arrangement 

 of the switches, shows at a glance what 

 grouping of the lamps is being used. 

 Hence there is little probability of making 

 a mistake. Short circuits can not be made 

 by any position of the switches. 



Ttvo Neglected Factors in the Determina- 

 tion of Musical Quality: W. C. Sabine, 

 Harvard University. 



The musical quality of a sound in an 

 ordinary room or other confined space is 

 very greatly affected by the character of 

 the walls. Diagrams are presented show- 

 ing the effects of various wall surfaces and 

 substances. The other factor is the sensi- 

 tiveness of the ear to sounds of different 

 pitch and a diagram is presented showing 

 the relative intensity for equal loudness 

 under ordinary musical conditions. 



Silver Perchlorate as the Electrolyte for 

 the Silver Coulometer: Henry S. Car- 

 hart, H. H. WiLLARD and "W. D. Hen- 

 derson, University of Michigan. 



A New Alternating-current Galvanometer: 

 L. A. Freudenberger, Lehigh Univer- 

 sity. 



A Lecture Experiment in Electrolytic 

 Thermo-Electromotive Force: Henry S. 

 Carhart, University' of Michigan, 



Note on the Graphical Representation of 

 Non-Sinusoidal Alternating Currents : 

 Frederick Bedell., Cornell University. 



Spark Potentials in Liquid Dielectrics: 

 Robert F. Earhart, Ohio State Uni- 

 versity. 

 Measurements on the potential required 



