QA RESULTS OF RECENT RESEARCHES ON THE 
mean motion, it is yet indisputable that Darwin was the first writer to treat the problem 
in a systematic, thorough-going and original way. Recognizing that at some epoch in 
the past, the earth was probably a mass of viscous fluid, he set for himself this problem : 
To determine the bodily tidal distortion of the earth, and the effects of this alteration of 
figure upon the orbital motion of the moon, and upon the earth’s rotation. His papers 
were communicated to the Royal Society between 1878 and 1882, and are celebrated con- 
tributions to the general theory of tides. In these papers he has traced the moon back 
to close proximity to the earth, when the two, at the breaking off of the moon, were most 
probably revolving in about 2h. 41m. The moon has since receded from the earth under 
the action of tidal friction, while the rotation of the earth has been slowed up in correspond- 
ing degree. It was rendered certain that in the origin of the Lunar-Terrestrial System, 
the action of tidal friction had played a prominent, if not a paramount part, and the 
question naturally arose whether it had not been equally potent in the development of other 
parts of the solar system. When, however, Prof. Darwin came to apply the results to 
other satellite systems and to the solar system as a whole, it was found that here the 
effects had been much less considerable than in the case of the earth and moon, owing 
chiefly to the small masses of the attendant bodies. Thus the major axes of the orbits 
had perhaps been very slightly increased, and the rotations correspondingly exhausted, 
but no radical change had taken place. Under these circumstances it was natural that 
Darwin should drop the subject without further search for extension of the principle he 
had developed. 
About November 1, 1888, while I was still an undergraduate at the Missouri State 
University I became much interested in the origin of the double stars. The immediate 
cause of my taking up the subject was the Missouri Astronomical Medal, occasionally 
awarded by the University to a graduate of highest standing in the Mathematical and 
Physical Sciences. Having been informed by Prof. W. B. Smith that I was eligible to 
write for the medal, by virtue of my standing in the Physical Sciences, our conversa- 
tion drifted on to the probable subject of the Thesis, and in this way he was led to 
suggest a criticism of Darwin’s work on the origin of the moon. He remarked: “ You 
may find this only a pocket, already worked out, and not a continuous vein of rich ore, 
but it seems to me worth thinking of. At any rate I would not advise you to write on 
the orthodox Laplacean Nebular Hypothesis, for that subject is worn threadbare.” 
The suggestion of a critique of Darwin’s work did not quite meet my approval, for I 
feared the subject was already exhausted and would leaye no field for future progress. 
As I had been observing various double stars for the past two years, and had seen no 
suggestion regarding their mode of development, it occurred to me that perhaps the tidal 
theory might find application among the stars. When I had collected such orbits as were 
