case of aberration u, the velocity of the earth relatively to the stars has a maximum value of about 18 m.p.s., while v, the velocity of light, is 186,000 m.p.s. Thus the value of u/v is about 1/10,000. It is quite impossible in any kind of aberrational observation to distinguish between the sine and tangent of an angle of this dimension. As far as observation goes u/v might be either sine or tangent of E.

Apart, therefore, from the objective value of the theory of ether strains and the rest it would seem that such a conception enables us to represent to ourselves in some way a physical basis for the equations of Einstein. We may conclude with a word concerning the optical effect which was foretold as a deduction from the theory of relativity. Arising from the equations and the application of the general theory of relativity, it appeared that a beam of light passing near the sun would necessarily be deflected. Half this deflection is, according to the theory, due to the 'curvature of space,' produced by a strong gravitational field. The curvature of space simply means that lines, which in free space would appear to an observer as straight lines, would, when passing through a gravitational field, appear curved. This effect is due to the influence of the gravitational field on the 'space' surrounding a great body like the sun. In the case of smaller masses the effect is too small to be observed. Einstein tells us that this ether or space is such that its state is in every place determined by connexions with matter in neighbouring places.' It is of interest to inquire if there is any physical cause to be assigned for the influence of a massive body on the ether.

The bending of a ray of light near the sun is equivalent to the statement that the velocity of light near the sun is somewhat less than in free space, and that the diminution of velocity at any point is proportional to the distance from the sun. According to the theory of relativity such a diminution of velocity exists.

Can any cause for such an effect be assigned? We are not here discussing the influence of a material atmosphere surrounding the sun. We are here concerned with purely

etherial or space considerations. According to Einstein, in common with all scientists, one and the same medium is concerned in the propagation of light and in producing gravitational effects. The enormous forces of a gravitational field are located in the ether, and evidently the nearer the sun the greater is the gravitational strain on the ether. There is thus a difference between the state of the ether near the sun and that in open space.1

It is reasonable to conclude that this modification of the light-propagating medium modifies to some extent those physical properties of the ether on which the propagation of light waves depends. The necessary condition for the bending of the beam of light passing near the sun is fulfilled if we suppose that the effect of the gravitational strain is to lessen to a very slight extent the velocity of light as it passes through a gravitational field near a large mass. This progressive decrease in the velocity of light as we approach the sun would give rise to that 'slewing round' of the wave front which constitutes the deflection of the beam.

In thus attempting to represent to the imagination the physical workings of nature we are not intruding on the domain of the mathematician. Mathematics as such is indifferent to the physical nature of the phenomena it concerns. The mathematician deals with the laws deduced by observation, and in considering, for example, the motion of a falling body does not in the least examine the physical

1 In 1912 the present writer expressed the same idea in a magazine article : 'In every theory of radiation a source of radiant energy is the centre of a disturbance which is transmitted or propagated through the ether according to the general law of inverse squares. It follows from this that every portion of the ether immediately surrounding such a source of radiation is in a state of internal tension and activity depending on its distance from the centre of disturbance. This is evident in the case of light, heat, magnetism, and the rest, but it must also be true of every portion of matter which has mass. every portion of matter is subject to the law of gravitation, and since we suppose the force of gravitation to be propagated through the ether, it follows that the energy of gravitation must be stored up in the ether. Thus, near a great mass like our earth the ether must be modified in some way which appears to arise from the very presence of the attracting body.'-' The Principle of Relativity,' Studies, September, 1912.

For

nature of the force which gives rise to the motion of the body. In his treatment of his subject he makes use of whatever mathematical machinery may seem most suitable. Einstein has made use of a special system founded on suppositions which may or may not correspond to objective realities. The following passage from an essay of Henri Poincaré, in which he deals with the modern conceptions of time and space which underlie the theory of relativity, seems to be of interest in this connexion :—

What will be our attitude in face of these newer conceptions? Shall we be forced to modify our conclusions? By no means: we had adopted a certain convention because it appeared useful, and we used to say that nothing could compel us to abandon it; to-day some physicists wish to adopt a new convention. It is not because they are forced to do so; they consider this convention more useful, nothing more; and those who are not of this opinion are fully entitled to retain the old one rather than disturb their habitual ways of looking at things. And I believe, between ourselves, that they will continue to do so for a long time to come.1

H. V. GILL, S.J.

P.S. Since the above article was written Professor Campbell, of the Lick Observatory, has wired the results of his measurements of the photographs taken last September at Wallal, W. Australia, during the solar eclipse, He is quite satisfied that a deflection of almost the exact amount predicted by Einstein has been registered on the plates. The whole subject is, however, further complicated by a letter from Sir Joseph Larmor to the Times of April 24th, 1923, in which he says: My reasons are on record for concluding that the existing theory of Einstein requires modification when it comes to application to the actual facts, in order to avoid contradictions, and when thus modified can only account for half of the ascertained deflection of light, and perhaps give no definite value for the rotation of the perihilion of Mercury; other critics, without trying to amend the theory, insist for like reasons that it cannot, on its original basis, lead to any definite result at all.' From the recent work of Weyl, Eddington, and others, Professor Larmor concludes the necessity of a formulation, expressing local structure, in a continuum, which would be describable more than ever as the ether of space.'-H. V. G.

1 Dernières Pensées.

SOME ASPECTS OF THE TRINITY

OF GOD

BY VERY REV. DENIS J. CANON O'RIORDAN, P.P., V.F.

WHE

a

HEN we gaze on the starry heavens on a cloudless night a vision of a marvellous character is unfolded to our view. That every star is a world larger, with few exceptions, than this one on which we dwell-that their number is apparently countless-that the distance which separates them from each other and from us, though an attempt may be made to express it in figures, cannot be grasped and realized by us-that the vast space through which they move seems to us to be illimitable, that each one of them, and all of them together, move in their prescribed orbits through that apparently boundless space with wonderful order and regularity and in conformity with very definite laws-all this presents to our minds an idea of vastness and immensity, whose greatness and astounding character we recognize and acknowledge, though we feel that we can but imperfectly comprehend it. But when, from that marvellous assemblage of great worlds, moving with such order through that incomprehensible space, we turn our attention to the fact that outside them, distinct from them, absolutely independent of them, there exists a Being whose almighty power called them into existence, 'Who,' as the Prophet Isaias says, ‘hath measured the waters in the hollow of His hand and weighed the Heavens with His palm' (Isaias xl. 12); Who alone, as the Psalmist says, 'telleth the number of the stars and calleth them all by their names' (Psalm cxlvi. 4), to whose infinite knowledge and wisdom they bear such striking testimony, we feel that we stand in the presence of a Power of surpassing majesty and greatness, as Jeremías says, 'great in counsel and incomprehensible in thought' (Jer. xxxii. 19),

and we realize that our human mind, limited as is its horizon and its power, could never hope to ascertain of itself the nature of His Almighty Being, nor understand the elements, so to speak, of which it is composed.

Still there ought to be no more interesting study for us than to learn what we can about Him, to discover whence He came and what He is like, for it was He who gave us the life which we possess, and in His hand, as Job says, 'is the soul of every living thing and the spirit of all flesh of man' (Job xii. 10). In this matter human research can help us little. Our reason tells us that He exists. St. Paul, in the first chapter of his Epistle to the Romans, says: The invisible things of Him, from the creation of the world, are clearly seen, being understood by the things that are made; His eternal power also and divinity' (Rom. i. 20). Our human reason tells us from 'the things that are made' that He exists; that His power is almighty, that His knowledge must be infinite; that, in the words of the Prophet Jeremias, 'He is the living God and everlasting King' (Jer. x. 10); but it also tells us that for us, constituted as we are, to ascertain or comprehend by our unaided power the nature of His Being is beyond our capabilities. But we also know that He has condescended to reveal to us certain facts regarding Himself. To ascertain what these facts are, to bring them home to our minds, and realize them, ought to be a most attractive and interesting study for us, as it would undoubtedly be a useful one. For if the acquisition of knowledge regarding the marvellous works of God, whether in the vast dome of Heaven or in this world in which they lie around us in such profusion, is always attractive and always interesting, much more so ought it to be to acquire, so far as may be, a knowledge of Him who has so wonderfully created and fashioned all things as they are. Besides, we have been created and destined for God's kingdom in Heaven. As the Apostle says: 'We have not here a lasting city, but seek one that is to come.' Now, it is said that in that city of God it is the vision of God, as He really