Book digitized by Google from the library of Harvard University and uploaded to the Internet Archive by user tpb. On cover: The new polarizing photo-chronograph "Originally appeared in the Journal of the United States artillery." Experiments with a new polarizing photo-chronograph applied to the measurement of the velocity of projectiles.--Experimental determination of the motion of projectiles inside the bore of a gun with the polarizing photo-chronograph.--The new polarizing photo-chronograph at the U.S. Artillery school, Fort Monroe, Va., and some experiments with it.--Appendix: A reliable method of recording variable current curves. [A paper presented at the annual meeting of the American institute of electrical engineers, Philadelphia, May 17, 1894, by Dr. Crehore]