REVIEWS 687 



Astronomers, particularly amateurs, will be grateful to him for having undertaken 

 what was not an easy task, and for having, on the whole, achieved success. 



H. S. J. 



Astronomical Consequences of the Electrical Theory of Matter. By Sir 

 Oliver Lodge. (From the Philosophical Magazine, Vol. XXXIV. August 

 1917.) 



In the year 1859 Leverrier, from a discussion of all the observed transits of 

 Mercury, found that the apsidal line of its orbit has a movement, which cannot be 

 accounted for by the action of the known planets. It amounts to 43" in a century. 

 This has long been a difficulty between gravitational theory and observation. On 

 the electrical theory of matter, a body in motion at a high speed through the 

 aether has an extra inertia, not dependent upon its mass, but on the aether, and 

 hence not subject to gravity. From this extra inertia due to motion through the 

 aether there results virtually mass without weight. But an increased inertia 

 means a diminished acceleration, just as if the gravitational pull on a planet were 

 diminished. It follows that the acceleration acting on a planet will not only be 

 less than in the Newtonian law of variation as the inverse square of the distance, 

 but will vary in different parts of the planet's orbit round the Sun. This must give 

 rise to a perturbation of its orbit. 



Starting with this ascertained fact, Sir Oliver Lodge, in the paper under review, 

 discusses mathematically the effect of this extra and varying mass upon a planet's 

 orbit. He shows that it introduces a revolution of the orbit in its own plane, which 

 is equivalent to a progression of its apsidal line. According to modern determina- 

 tions the line of the Sun's way is directed towards an apex near Vega, and the 

 velocity of the Sun is about 12 miles a second This is tantamount to regarding 

 the star group of which the Sun is a member, and relatively to which the direction 

 and velocity of the Sun's way has been determined, as fixed, in which case the 

 apse of Mercury would, according to Sir Oliver Lodge, progress 2'4" in a century. 



But if the whole system, or group of stars of which the Sun is but one member, 

 was advancing through the stagnant aether, as the background of reference of 

 motion, towards longitude 294", with a velocity of about 56 miles a second, then 

 the revolution of the orbit of Mercury would square with observation. Such a 

 motion would also reconcile with observation the motion of the apsidal line of 

 Mars. Sir Oliver Lodge also asserts that, according to this theory, there would 

 be nothing excessive in the apsidal progressions of the Earth and Venus. Prof. 

 Eddington, however, in the September number of the Philosophical Magazine, 

 demurs, and shows that this supposed value of the solar motion relatively to the 

 aether would introduce corrections into the observed elements of the orbits of the 

 Earth and Venus, which are quite inadmissible. 



Einstein's Theory of Relativity equally explains this anomaly in the motion of 

 the perihelion of Mercury, without introducing any anomalies into those of the 

 Earth and Venus. This has considerably cheered the upholders of a mathematical 

 conception, which entirely transcends, and is independent of, any preconceived 

 physical notions. In fact, according to one of its protagonists, De Sitter, no one 

 has ever measured a pure distance, or a pure interval of time. However this may 

 be, a straightforward physical theory, as that advanced by Sir Oliver Lodge, to 

 account for the one great puzzle of gravitational astronomy, may be preferred by 

 many to a mathematical hypothesis, which demands that we should abandon the 

 whole of our previous conceptions about space and time. At any rate, it is a 



