20 
Chase.] 132 [May 18, 
garded as functions of time, mass and distance, The mean daily disturbances 
take place at 7’; == 3962.8 miles from the virial centre; the mean annual 
disturbances ato, = Earth’s semi-axis major from their virial centre, The 
disturbed atmospheric mass and the equilibrating value of g are the same 
‘ 
in both cases. The virtual potential of daily rotation is A X 86164.08? = 
22,559,593.75 miles. Gen. Sabine’s means of five years’ observations at, 
22 
St. Helena, show a daily barometric range of .067 in., and an annual 
range of .185 in. (see Proc. Am. Phil. Soc., x, 375, foot-note). The geo- 
graphical, magnetic and climatic situation of St. Helena is such as to give 
the following simple harmonic approximation for p, (Note 877 ; 5). 
0672 : 1852 : : 22,559,593.'75 : 91,590,200 miles. 
406. Hneke’s Comet. 
Dr. O. Backlund (Oopernicus, Feb. 1883 ; cited in Setence, 531), says 
that ‘the investigations hitherto made of the theory of Encke’s comet 
really prove nothing as to the existence of a resisting medium in space. 
Evenif we should succeed by such an hypothesis to explain sufficiently the 
increase of the mean motion and the decrease of the eccentricity during the 
period 1819-48, a simple hypothesis like this will not at the same time suf- 
fice for the motion of the comet after 1865, as the variation of the mean 
movement after that time has most probably become different. Not until 
the period 1865-81, and its connection with the earlier one have been fully 
discussed, will it perhaps become possible to find indications of the 
nature of the unknown forces which act on the comet.’’ If an ethereal 
medium is set in vibration by the passage of comets or other cosmical bodies, 
there will be, as in the case of tidal disturbances, both accelerating and re- 
tarding influences. We must know more than we now do, of the nature 
of the medium as well as of the laws of elasticity, before it will be safe to 
dogmatize about a resisting medium or about the second law of thermody - 
namics. The equality of action and reaction may, perhaps, set limits both 
to nucleal condensation and to ethereal expansion, the two limits being op- 
posite phases of cyclical changes which all matter is always undergoing. 
The unity,of energy which is indicated by ethereal relations of mass and 
velocity (Notes 388, 400), gives great likelihood to this hypothesis. 
407. Sound- Spectra. 
Frazer’s ‘‘Examination of the phonograph record under the micro- 
scope’ (Jour. of the Franklin Inst., \xxv, 848; Proc. Am. Phil. Soc., xiii, 
581), showed that each of the alphabetic sounds has a special combination 
of vibrations, which may be visibly impressed upon a metallic sheet. The 
harmonic correspondence between the wave-lengths of musical notes 
and those of the principal lines in the visible spectrum (Proc, Am. Phil. 
Soe., xiii, 149), increases the probability that there may be an unbroken series 
of waves, from the lowest audible sound to the highest actinic impulse. 
Mayer’s experiments with the antennxe of mosquitos and Langley’s ob- 
ena 
