54 



3. Apparatus for Showing to an Audience the Phosphor- 



ESENCE of Fluorite and other Minerals by Heat. 



Nos. I, 2 and 3 were designed and are exhibited by 

 Wallace Goold Levison. 



4. Set of Photographs Demonstrating the Regular Re- 



flection OF THE X-RAYS. Exhibited by O. N. Rood. 



5. Two X-RAY Detectors (fluoroscopes) , new form especially 



adapted to research. Exhibited by C. C. Trowbridge. 



6. Set of Low Resistance Shunts for Electrical Work. 



Exhibited by H. C. Parker. 



7. Mechanism for Illustrating Double Refraction in 



Crystals. 



8. Mechanism for Illustrating the Interference of Light. 



9. Thermometers of New Design for Subterranean Tem- 



perature Work. 



10. Hydraulic Illustration of the Wheatestone Bridge. 



Nos. 7 to 10 are exhibited by W. Hallock. 



11. A Device to Obtain a Beam of Light for the Adjust- 



ment OF A Spectroscope, etc. 

 13. Apparatus for Determining the Velocity of Sound 

 by Resonance. 



13. Apparatus for Studying Vibrating Strings. 



Nos. II, 12 and 13 are exhibited by the Department of 

 Physics of Columbia University. 



14. Long-focus Camera and Photographs. Exhibited by 



H. S. Curtis. 



15. A Variable Graphite-asbestos Resistance. Exhibited 



by W. Hallock. 



16. A Set of Graphite High Resistances. Exhibited by 



H. C. Parker. 



17. Apparatus for the Study of Color Phenomena. 



18. A Physical Projection Lantern. 



Nos. 17 and 18 are exhibited by Ernest R. vonNardroff. 



