credit, must have been derived from Mary herself. But whether the fourth gospel was written by John the son of Zebedee, or, as seems more probable, by John the Elder or Presbyter of Ephesus, the fact remains that, although this gospel was compiled for the express purpose of setting forth and insisting upon the divine side or aspect of Christ's nature, the writer of it had no knowledge of his miraculous or divine birth. Now let us first turn to the account given in Luke's gospel (i. 26-56): here we have no dream, but the actual appearance of a heavenly messenger who makes an announcement to Mary which necessarily cannot long be kept secret ; in fact, Mary does not attempt to keep it secret, but proceeds to sing what is plainly a paraphrase of Hannah's song or prayer, recorded in 1 Samuel ii. 1-11, except that in Mary's hymn there seems to be less exultation than appears in Hannah's song, though Hannah was rejoicing only in the birth of a human son. Next, look at the terms in which the communication is made to Mary by Gabriel; now, if the narrative intends us to understand, as it clearly appears to do, that the prediction uttered in verse 35 did, in fact, come to pass, then it is plain that Jesus Christ never was 'the son of the man -never was the true typical man, and the title which he chose before all others was therefore misleading and difficult to understand. Moreover, it is certain that nowhere in the gospel narratives is Christ ever represented as claiming for himself a miraculous or virgin-birth (Luke iv. 22-24). Then, again, Gabriel says to Mary: 'The Lord God shall give unto him the throne of his father David.' Could any divine messenger have spoken thus of him who was to live the life of a village carpenter, and to die the death of a malefactor? Such words would have been a stumbling-block in Mary's path all her days. So with regard to the name Jesus.' Gabriel could never have used this word, which is a Greek rendering of the Hebrew name 'Joshua;'-thus in the Septuagint or Greek version of the Old Testament the Book of Joshua is the Book of Jesus. Gabriel in addressing the Hebrew maid Mary must have used the Hebrew name Joshua (Yehoshua), not the Greek rendering of it, Jesus (Iesous). If so, Christ's name never was Jesus, but Joshua. Now, the meaning of the word Jesus seems to be 'healer; if, therefore, 'Inooûs (in Latin 'Jesus') is derived from ta, the root in iáoμai, to heal or cure, it is not impossible that, Christ being known as 'the healer' of Nazareth, his true name soon became lost, and thus to the earliest Greek converts-Greek Jews of the Dispersion-he was known only by the name of the healer,'' the Jesus of Nazareth.' Or is it possible that IHC was a mystic word used in the ancient Greek mysteries, and was by the early converts from mysticism given to Christ as the true fount of the 'healing' water of life? (John iv. 14). Certain it is that immortality or life beyond the grave was the great object of attainment held out in the Greek mysteries, and no one can read Christ's discourses, as given in the fourth gospel, without noting the

insistence with which He urges His power to grant eternal life (John vi. 27-58); so much so is this the case that it would almost appear as though some of these discourses were written with the object of supplanting or superseding the Greek mysteries, that is to say, of drawing into the Christian fold all those who had made trial of the mysteries and found them wanting; in fact, the mysticism is at times so pronounced, and the invitation to come to Christ so persistent, that we seem to be listening to one who had himself passed through the mysteries and had experienced their emptiness and futility (xii. 24-27; ch. x.). However, the consideration of questions such as these relates to the subject of the passing of Christianity from the Jew to the Greek, rather than to the particular matter now under discussion. To return, then, to Luke's account: even in the narrative itself we seem to find evidence against the story of Gabriel and the miraculous birth. Thus, how could the writer of verse 35 (ch. i.) repeatedly speak of Joseph as Christ's father (ii. 27, 33, 41, 43, 48), and why should Joseph and Mary marvel at the things which were spoken (v. 33), if Gabriel's prediction had become true? Or how could Mary, in speaking of Joseph (v. 48), say to Christ: Thy father and I sought thee,' if the tremendous experience of a miraculous birth had been hers? Now let us turn to the account in Matthew, and the first question that will occur to any reader of ch. i. is this: Why should the life of Christ commence with the genealogy of Joseph (v. 16), if Joseph were not Christ's father? Another point is that the writer of this chapter, or of verses 18 to 25, seems never to have heard of Gabriel's mission to Mary, for here in Matthew the vision or dream happens to Joseph, and not to Mary, and the name of Jesus is communicated to Joseph, and not to Mary, and an explanation of the name is given to Joseph which was certainly not given by Gabriel. But what can be said of the writer of verses 22 and 23 (Matt i.) in citing a passage from Isaiah which cannot support or bear the construction for which it is quoted? For it is clear that the woman (translated 'virgin') in Isaiah vii. 14 is the same woman—the prophetess-who is spoken of in viii. 3 (Isaiah), and equally clear is it that no virgin-birth in her case is even suggested, but quite the contrary. The whole point of the prophecy in Isaiah is that before the child shall know to refuse evil and choose the good, the land, whose two kings thou abhorrest, shall be forsaken' (vii. 16; viii. 4), not, that the child is to have a miraculous birth. Moreover, the writer in Matthew does not quote correctly the passage which he professes to cite (i. 23), for the words in the Septuagint are ' and thou shalt call [kaλéoɛis—not they shall call] his name Immanuel,' that is to say, 'you (Isaiah) shall name your son Immanuel;' this is clear from viii. 3, καὶ προσῆλθον πρὸς τὴν προφῆτιν. The fact seems to be that this passage in Matthew (i. 18-25) is an interpolation, though possibly an early one; but whether this be so or not, it is plain that the information on which the story of Joseph's dream is

based must have been derived from a source entirely unknown to every other writer of the life of Christ-even to Luke, who, though narrating in considerable detail the history of the apparition to Zacharias, does not say a word about any vision or dream occurring to Joseph. It seems, therefore, that the idea of a divine or miraculous birth is of Greek rather than of Hebrew or Jewish origin; to the Hebrew mind it seemed enough that their Messiah should be the son of David' according to the flesh,' but to the Greeks a divine birth for their heroes or saviours was a necessity. It would appear as though this notion of a miraculous or virgin-birth arose at the time of the passing of Christianity from the 'world of Syrian peasants' to the 'world of Greek philosophers,' and gained acceptance as filling a want vaguely felt by the Greek converts. But that the first followers of Christ knew nothing of the story of the virgin-birth seems plain from the fact that there is not the smallest allusion to it in any of the Epistles; in fact, in some of them both the argument and the words used are distinctly against any idea of a miraculous birth (Romans i. 3; viii. 3). If, then, the writers of the earliest treatises dealing with the principles of the Christian faith never heard of the virgin-birth, and felt no necessity for it, why should belief in such a doctrine, resting as it does on scanty and unsatisfactory evidence, any longer be insisted on ?

SLADE BUTLER

INVISIBLE RADIATIONS

THERE exist radiations which differ from the whole category to which radiant heat and light belong, not so much in their effects as in their nature; indeed, they can only be called radiations at all by an extension of the meaning of that word, for they are really streams of particles bearing an electric charge and moving in straight lines at various rates of speed. The extended meaning of the word radiation to include all ray-like projections, whether material or otherwise, has now been universally adopted, the word emanation, which might perhaps have served, being reserved to denote those outgoings from a substance which diffuse away from it after the manner of a vapour or scent. That there are such radiations was, in the first instance, perceived by the phenomena which accompany the passage of an electric current through a tube containing highly rarefied air. That radiations similar to those which are thus artificially produced in the laboratory also exist spontaneously in nature, is a discovery made within the last few years, the theoretical importance of which can hardly be overrated.

It is now known that all the compounds of uranium, thorium, and radium continuously emit such radiations, independently of any known supply of energy from without, and unaffected by temperature or pressure, or any physical conditions whatsoever. Nor is this radioactivity, as it is called, the result of chemical action or combination. The property, which is probably due to changes taking place within the atom itself, is most clearly manifested in the case of radium, and therefore it is easiest to study radio-activity by means of radium; even as it is easiest to study magnetism by means of iron, although nickel and cobalt are magnetic substances too, and all substances show traces of magnetism in an exceedingly slight degree. Very probably radioactivity is also a property of matter as such, but the feeble manifestations upon which this surmise is founded were never discovered until now because there was no reason until now to suspect their existence.

There are three kinds of rays which are produced together by an electric current in a vacuum tube and found together in radium radiation. They are: Rays bearing a positive charge, rays bearing a negative charge, and uncharged rays, which apparently always accompany these electric rays, but which belong to a totally different

category. In any general survey of these radiations it is difficult to know what to call them because of the many names they bear. The negatively charged rays which issue from the cathode of the vacuum tube are called cathode rays inside the tube, but outside the tube they are called Lenard rays, because Lenard succeeded in causing them to pass through a thin window of aluminium, and was thus enabled to study them under conditions other than those in which they were produced. Positively charged rays, which appear simultaneously with the cathode rays, but are much more difficult to identify, are called channel rays (Kanalstrahlen), because they were first observed by using as cathode a piece of metal pierced with holes, so placed that the positively charged particles passed through the holes. Being thus sharply separated from the negative cathode rays which moved in the opposite direction, the positive radiation could be rendered distinctly manifest. The marvellously penetrating rays which arise where the cathode rays strike glass or metal were called by their discoverer X-rays. It is now more usual to speak of them as Röntgen rays. Radiations which are spontaneously emitted are collectively called Becquerel rays, in honour of the discoverer of radio-activity; and, individually, the positively charged rays are called a-rays, the negatively charged rays B-rays, and the uncharged rays, which resemble the Röntgen rays, are called y-rays-a notation suggested by Rutherford. This multiplicity of names is of historic interest, and may be convenient for the physicist, but it tends to obscure the essential identity. The first two classes can be called positive and negative radiation, but no generic name seems yet to be in use for the X-rays type.

As

These radiations are invisible, and were detected by their effects; in the first instance, many years ago, by the effect of fluorescence during the passage of an electric current through a tube in which the air was so highly rarefied that it could not absorb and check the radiation proceeding from the cathode. Where the glass wall did check that radiation the visible effect was brilliant fluorescence. all the radiations produce fluorescent effects if they are sufficiently intense, it is possible to make their path evident by means of fluorescent screens. The self-luminosity of the purer salts of radium is believed to be due to phosphorescence caused by the radiations within the substance itself, but what the connection between the radiations and phosphorescence really is we cannot tell. Phosphorescence—which differs from fluorescence only in that it continues for an appreciable time after the cause which has produced it has ceased to act-is called forth by the more refrangible rays of ordinary light. If the ultraviolet part of the spectrum of sunlight, or preferably electric arc light, be thrown upon a suitable phosphorescent screen, the invisible rays become visible as violet, blue, or green, and sometimes even as yellow or red. Stokes gave the explanation of this when he showed that in every case the incident light is changed by the phosphorescent sub