26 THE 1896 ANNUAL ADDRESS. 



would have been removed. My faith, is strongly fortified by 

 all we have heard from him. In physical science my touch- 

 stone as to truth is, " What does Sir George Stokes think of it ? " 

 (Hear ! hear !) When I hear that he declares for transverse 

 vibrations, and when I hear the strong reasons he has put before 

 us for this conclusion, I myself am very strongly fortified indeed 

 in accepting it. I do not, however, forget that it is put before 

 us not as absolutely demonstrated bnt as his present opinion. 

 There is no one who is so thoroughly secure as a guide in 

 all scientific matters as our President. He will not put 

 forwai'd anything, and say it is certain, unless he has perfect 

 reason for saying so. He has given us strong reason to believe 

 that the Rontgen phenomena consist of transverse vibrations. 

 He does not tell us that this is certainly true ; he leaves our minds 

 open to the possibility of other explanations — indeed he has 

 tantalised us very much with the idea of the possibility of another 

 explanation to which he has alluded. I wish the hands of the 

 clock could be set back for half-an-hour, and that the President 

 could be persuaded to give us some idea of the explanation he 

 has referred to ; he certainly leaves us with the impression that 

 it is exceedingly probable that the Rontgen rays do consist of 

 transverse vibrations. But how are they related to those of 

 ordinary light ? There are, perhaps, a hundredfold more of 

 them in a second of time, so that as there are about 700 million 

 million of vibrations per second in green light, w^e may have 700 

 handi'ed, or 70 thousand, million million vibrations of Rontgen 

 rays in a second of time. Perhaps that does not seem much 

 more marvellous to some than when we talk of 700 million 

 million of vibrations in green light. There is so great a margin 

 that our power of being astonished is at an end, and we are not 

 astonished if we are told that the vibrations of the Rontgen rays 

 are a himdred or a thousand times faster, by mathematicians who 

 have studied the question; but we may feel surprised, indeed, 

 that rays proceeding from the cathode and striking against a 

 target should j^roduce, on their impact, vibrations of a hundred 

 times greater frequency than any of the qualities of light known 

 previously. 



I am sure you must all feel that a curtain has been drawn from 

 before your eyes, and that we have been allowed to look into some 

 of the mysteries and wonders of nature. It is only half a year 

 since these X rays, produced by the impact of electrified particles 



