April 28, 1898] 



NA TURE 



607 



The answer is, of course, that there is not one. Government 

 exacts multiple marks of vaccination, but in Gloucester it is clear 

 that there was a belter case for the single than for the multiple 

 marks. Government exacts re-vaccination in the services, but 

 here there is a large number of re-vaccinated cases, and twice 

 Von Swieten's fatality in them. 



Then, again, it is clear that the eruption has, as of old, every- 

 thing to do with the fatality, and nothing can be clearer in the 

 Gloucester cases. Unless, therefore, you have taken the precau- 

 tion of giving reference to the register of vaccinations, you are 

 in the fix of having almost certainly got wrong with your classi- 

 fication. Is there any test of this? There most certainly is. 

 For in the variety of the disease, in which there is not so much 

 damage to the skin as discoloration of it, where the poison is 

 damaging the whole system, and internally more than externally, 

 we have still the vaccination marks, if they are noted. I gave 

 before the Commissioners all these cases that I had been able 

 to trace in a large number of reports. And here is the fatality 

 of these " malignant " cases. 



Per cent. died. 



Vaccinated malignant cases ... ... ... 83 5 



Unvaccinated cases ... ... ... ... 90 



The first line divides thus — 



Vaccinated, no evidence ... ... ... 82 



Doubtfully vaccinated ... ... ... ... 81 



Indifferent vaccination marks ... ... ... 84 



Good vaccination marks ... ... ... 85 



It is very clear, therefore, that there is not the slightest 

 influence in vaccination, good, bad, or indifferent, to abate the 

 fatality of these cases. in some of the hospitals the whole of 

 the vaccinated in this class died, without any recoveries. But 

 that way of returning the cases is only followed occasionally, so 

 that there is no possibility of taking all the hospital experience. 

 There is however, no reason to suppose that it would show any 

 different results. All these cases, with the almost unvarying 

 total fatality, show that there is high time for a reference of 

 every possible case returned as unvaccinated to the vaccination 

 officer for his verification, and for information as to whether 

 there had been the payment for successful vaccination. Till 

 that is done, we have the right to say that there is not the 

 slightest gain accruing from vaccination in the cures of the 

 small-pox, and that there is all reason for declaring the present 

 classification by skin marks in this eruptive disease unscientific 

 and erroneous. Alex. Wheeler. 



Darlington, April 17. 



[In deference to the wishes of Mr. Wheeler we print the enclosed 

 letter, after which our columns must be closed to the subject un- 

 less something very important is brought forward. Of course, as 

 Mr. Wheeler says, he has completely departed from the original 

 controversy ; and it is necessary to call attention to the fact that 

 no amountof statistical jugglery, orieference to assumed historical 

 data, can be held sufficient to refute the unquestioned fact that 

 in Gloucester the unvaccinated children were attacked with 

 small-pox and died in overwhelming disproportion to the vac- 

 cinated. Epidemics, as we know, cannot be compared with one 

 . another as regards their severity, but the incidence of attack in 

 the same epidemic may always be taken as being fairly com- 

 parable throughout. — Ed. Nature.] 



RONTGEN RAYS AND ORDINARY LIGHT. 



ACCORDING to the theory of the Rontgen rays 

 suggested by Sir G. Stokes,^ and recently developed 

 by Prof J. J. Thomson,^ their origin is to be sought m 

 impacts of the charged atouis constituting the kathode- 

 stream, whereby pulses of disturbance are generated in 

 the ether. This theory has certainly much to recommend 

 it ; but I cannot see that it carries with it some of the 

 consequences which have been deduced as to the dis- 

 tinction between Rontgen rays and ordinary luminous 

 and non-luminous radiation. The conclusion of the 

 authors above mentioned,^ " that the Rontgen rays are 

 not waves of very short wave-length, but impulses," sur- 

 prises me. From the fact of their being highly condensed 



1 Manchester yieiiwirs, vol. xli. No. 15, 1897. 

 - Phil. Mag., vol. xlv. p. 172, 1898. 



3 See also Prof. S. P. Thompson's " Light Visible and Invisible " (Londcn, 

 1897), p 273. 



impulses, I should conclude on the contrary that they 

 are waves of short wave-length. If short waves are 

 inadmissible, longer waves are still more inadmissible. 

 What then becomes of Fourier's theorem and its asser- 

 tion that any disturbance may be analysed into regular 

 waves ? 



Is it contended that previous to resolution (whether 

 merely theoretical, or practically effected by the spectro- 

 scope) the vibrations of ordinary [e.g. white) light are 

 regular, and thus distinguished from disturbances made 

 up of impulses ? This view was certainly supported in 

 the past by high authorities, but it has been shown to be 

 untenable by Gouy,^ Schuster,^ and the present writer.* 

 A curve representative of white light, if it were drawn 

 upon paper, would show no sequences of similar waves. 



In the second of the papers referred to, I endeavoured 

 to show in detail that white light might be supposed to 

 have the very constitution now ascribed to the Rontgen 

 radiation, except that of course the impulses would have 

 to be less condensed. The peculiar behaviour of the 

 Rontgen radiation with respect to diffraction and re- 

 fraction would thus be attributable merely to the extreme 

 shortness of the waves composing it. R.WLEIGH. 



April 18. 



THE BAKERIAN LECTURE.*' 



THE purpose of the lecture was to show that certain 

 metals and certain organic bodies can act on 

 a photographic plate in such a manner that, on 

 treating it exactly as if it had been acted on by- 

 light, a picture is developed. When carrying on some 

 experiments with photographic plates, a piece of per- 

 forated zinc was found not to act as a screen and give a 

 picture of the holes, but to give a picture of the metallic 

 part ; and further, it was found that a bright piece of 

 zinc, when coated with copal varnish, with the object of 

 stopping any emanation of vapour from it, became 

 more, not less, active ; these were the accidental 

 observations which gave rise to the present investiga- 

 tion. With regard to the action of the organic bodies : 

 their activity is greater than that of the metals, and the 

 experiments with them are more easily carried out, hence 

 it was advisable to investigate to a considerable extent 

 their action before undertaking the more intricate and, 

 probably, more important action of the metals. 



Printing ink is one of the many substances which will, 

 both when in contact and when at a distance, act on a 

 photographic plate, and it was shown that remarkably 

 clear pictures can be obtained of ordinary printing and of 

 lithographic pictures. Printing ink varies in composi- 

 tion, and if the ordinary newspaper's, for instance, be 

 used, the density of the pictures obtained will vary con- 

 siderably. I The varnish known as picture copal is also 

 an active substance producing a dark picture. The 

 active constituent of the printing ink was proved to be 

 boiled oil, and in the varnish to be turpentine ; and these 

 bodies alone can be used in place of the more compli- 

 cated substance above named. If then boiled or drying- 

 oil was active, it was natural to try linseed oil in its 

 ordinary state, and this proved also to be active ; different 

 specimens, however, of so-called pure oil vary very 

 considerably in the amount of their activity. Passing 

 from linseed oil to other vegetable oils, they were found 

 also to be active, but apparently none so active as the 

 linseed oil. Then, with regard to turpentine, a body- 

 belonging to a very different class of organic substances, 

 it was found that bodies analogous to it — all the terpines, 



"^ Journal lie Physique, 1886, p. 354. 



- Phil. Mag., vol. xxxvii. p. 509, 1894. 



3 Enc. Brit., Art. " Wave Theory," 1888 ; Phil. Mag., vol. xxvii. p. 461, 

 1889. 



* Delivered before the Royal Society, March 24, by Dr. W. J. Russell, 

 V.P.R S. 



NO. 1487. VOL. 57] 



