Miscellaneous Intelligence. 163 



sensation ; determination of the numbers of beats throughout the 

 musical scale which produce the greatest dissonances ; applica- 

 tion of these laws by means of rotating perforated disks, and 

 quantitative application of them to musical harmony (1874) : 

 experiments on the reflection of sound from heated flames and 

 heated gases (1874) : obliteration of one sound by simultaneous 

 action of a more intense and lower sound ; discovery that a sound 

 even intense cannot obliterate sensation of a sound of lower pitch 

 (1876) : acoustic repulsion (1878) : determination of the smallest 

 consonant intervals among simple tones, and application to deduce 

 the duration of residual sonorous sensations (1894) : variation in 

 the modulus of elasticity with change of temperature determined 

 by transverse vibrations of bars at various temperatures ; the 

 acoustical properties of aluminium, showing that the metal is 

 unsuited for musical instruments on account of the rapid and 

 large changes in its elasticity by change of temperature (1896). 

 In an elaborate paper published in the third volume of the 

 Memoirs of the National Academy of Sciences, 1884, he gave a 

 method of precisely measuring the vibratory periods of tuning- 

 forks and determining the laws of their vibration, with their 

 applications in chronoscopes for measuring the velocity of pro- 

 jectiles. 



Among other papers published by Professor Mayer in this 

 Journal may be mentioned: Researches in electro-magnetism , 

 showing the changes in dimensions of iron and steel bars by 

 magnetization ; method of measuring electrical conductivity 

 by means of two equal and opposed electrical currents (1870, 

 1873): on the electro-tonic state; on a method of fixing mag- 

 netic spectra (1871) : new form of lantern galvanometer; mode 

 of tracing the boundary of a wave of conducted heat (1872) : on 

 the composite nature of the electric discharge (1874) : method of 

 delineating the isothermal lines of the solar disk (1875) : experi- 

 ments with floating magnets (1878): the well-spherometer (1886): 

 the pendulum electrometer ; electric potential as measured by 

 work; the spring balance electrometer; experimental proof 

 of Ohm's law ; cubical expansion of solids, by vessels or 

 hydrometers made of the material of these solids (1890) : illu- 

 minating power of flat petroleum flames ; physical properties of 

 hard rubber (1891) : simultaneous contrast-color; photometer for 

 lights of different color (1893) : researches on the Rontgen rays 

 (1896) ; equilibrium of forces acting in the flotation of disks and 

 rings of metal, with determinations of surface tension (1897). 



He also published " Lecture Notes on Physics" (Philadel- 

 phia, 1868) ; " The Earth a Great Magnet" (New Haven, 1872) ; 

 « Light" (New York, 1877); " Sound" (New York, 1878); 

 "Sport with Gun and Rod in American Woods and Waters" 

 (1883). 



Professor Mayer received the degree of Ph.D. from the Penn- 

 sylvania College in 1866. During the year 1873 he was one of 

 the associate editors of this Journal. In 1872 he was elected a 



