530 



NA TURE 



[Seftember 29, 1904 



but I want to emphasise them. The words quoted are from 

 an article on the " Result of Crossing Japanese Waltzing 

 with Albino Mice " in Biomctrika, vol. iii. p. 20. The 

 writer appears to be a Mr. A. D. Darbishire of Oxford, 

 not of Manchester. The one Mr. Darbishire considers 

 that the proportions cannot be regarded as a possible 

 quarter, the other that a rough quarter, or *' one mouse 

 in every four," is waltzing. Mr. Darbishire of Man- 

 chester expects that one in every si.Kteen of the offspring 

 of the hybrids will be an albino waltzer, and thc'n proceeds 

 to state that he has so far been unable to breed from these 

 albino waltzers. Reading his paper, I presumed he would 

 have told us had he not found albino waltzers to be i in 16. 

 Consulting, however, Mr. Darbishire of O.xford, I find he 

 had 20 instead of 35 albino waltzers among his 555 off- 

 spring. 1 presume that 20 = 35 '* ^ " rough " sixteenth 

 to our Manchester author, while he of Oxford would doubt- 

 less have been able to tell us that the odds against such 

 an underestimate were two or three hundred to one ! Which 

 writer shall a member of the inquiring general public trust? 

 Or, if the two writers should be the same, must we assume 

 that in Oxford, under the influence of some recessive 

 biometer, Mr. Darbishire failed to see that 97 in 555 was 

 a reasonable quarter, or 20 in 555 a reasonable sixteenth, 

 but that he has learnt in Manchester, or perhaps in Cam- 

 bridge from some dominant anaesthetist, that these things 

 really are so ? 



But if 97 be not even roughly 139, or 20 approximately 

 35, would it not be well at once to admit that the waltzing 

 habit corresponds to a compound allelomorph, one element 

 of which, the chorophore, may be credited to any mouse, 

 but only becomes patent when combined with the chorogen 

 to form the true waltzing habit? I am not sure this will 

 work, but perhaps Mr. Darbishire will give it a trial. 

 Should this in turn fail, a metaphysician might help him 

 out of these procrustean difficulties by analysing straight- 

 forward advance into right-handed and left-handed elements, 

 each with its own chorophore and chorogen — but I must 

 not anticipate the details of such a remarkable progression 

 at present. Karl Pearson. 



The «.Rays. 



The inability of a large number of skilful experimental 

 physicists to obtain any evidence whatever of the existence 

 of the H-rays, and the continued publication of papers 

 announcing new and still more remarkable properties of the 

 rays, prompted me to pay a visit to one of the laboratories 

 in which the apparently peculiar conditions necessary for 

 the manifestation of this most elusive form of radiation 

 appear to exist. I went, I must confess, in a doubting 

 frame of mind, but with the hope that I might be convinced 

 of the reality of the phenomena, the accounts of which 

 have been read with so much scepticism. 



Aiter spending three hours or more in witnessing various 

 experiments, I am not only unable to report a single observ- 

 ation which appeared to indicate the existence of the rays, 

 but left with a very firm conviction that the few experi- 

 menters who have obtained positive results, have been in 

 some way deluded. 



A somewhat detailed report of the experiments which 

 were shown to me, together with my own observations, may 

 be of interest to the many physicists who have spent days 

 and weeks in fruitless efforts to repeat the remarkable ex- 

 periments which have been described in the scientific journals 

 of the past year. 



The first experiment which it was my privilege to witness 

 was the supposed brightening of a small electric spark when 

 the n-rays were concentrated on it by means of an aluminium 

 lens. The spark was placed behind a small screen of 

 ground glass to diffuse the light, the luminosity of which 

 was supposed to change when the hand was interposed 

 between the spark and the source of the n-rays. 



It was claimed that this was most distinctly noticeable, 

 yet I was unable to detect the slightest change. This was 

 explained as due to a lack of sensitiveness of my eyes, and 

 to test the matter I suggested that the attempt be made to 

 announce the exact moments al ■which I introduced my hand 

 into the path of the rays, by observing the screen. In no 

 case was a correct answer given, the screen being announced 

 as bright and dark in alternation when mv hand was held 



NO. 1822, VOL. 70] 



motionless in the path of the rays, while the lluctuations 

 observed when I moved my hand bore no relation whatever 

 to its movements. 



I w-as shown a number of photographs which showed the 

 brightening of the image, and a plate was exposed in my 

 presence, but they were made, it seems to me, under con- 

 ditions which admit of many sources of error. In the first 

 place, the brilliancy of the spark fluctuates all the time by 

 an amount which I estimated at 25 per cent., which alone 

 would make accurate work impossible. 



Secondly, the two images (with n-rays and without) are 

 built of " instalment exposures " of five seconds each, the 

 plate holder being shifted back and forth by hand every 

 five seconds. It appears to me that it is quite possible that 

 the difference in the brilliancy of the images is due to a 

 cumulative favouring of the exposure of one of the images, 

 which may be quite unconscious, but mav be governed by 

 the previous knowledge of the disposition of the apparatus. 

 The claim is made that all accidents of this nature are made 

 impossible by changing the conditions, i.e. by shifting the 

 positions of the screens ; but it must be remembered that 

 the experimenter is aware of the change, and may be un- 

 consciously influenced to hold the plate holder a fraction of 

 a second longer on one side than on the other. I feel very 

 sure that if a series of experiments were made jointly in 

 this laboratory by the originator of the photographic ex- 

 periments and Profs. Rubens and Lummer, whose failure 

 to repeat them is well known, the source of the error would 

 be found. 



I was ne.xt shown the experiment of the deviation of the 

 ravs by an aluminium prism. The aluminium lens was re- 

 moved, and a screen of wet cardboard furnished with a 

 vertical slit about 3 mm. wide put in its place. In front of 

 the slit stood the prism, which was supposed not only to 

 bend the sheet of rays, but to spread it out into a spectrum. 

 The positions of the deviated rays were located by a narrow 

 vertical line of phosphorescent paint, perhaps 05 mm. wide, 

 on a piece of dry cardboard, which was moved along by 

 means of a small dividing engine. It was claimed that a 

 movement of the screw corresponding to a motion of less 

 than 01 of a millimetre was sufficient to cause the 

 phosphorescent line to change in luminosity when it was 

 moved across the n-ray spectrum, and this with a slit 2 or 

 3 mm. wide. I expressed surprise that a ray bundle 3 mm. 

 in width could be split up into a spectrum with maxima and 

 minima less than 01 of a millimetre apart, and was told 

 that this w-as one of the inexplicable and astounding proper- 

 ties of the rays. I was unaljle to see any change whatever 

 in the brilliancy of the phosphorescent line as I moved it 

 along, and I subsequently found that the removal of the 

 prism (we were in a dark room) did not seem to interfere 

 in any way with the location of the maxima and minima in 

 the deviated ( !) ray bundle. 



I then suggested that an attempt be made to determine 

 by means of the phosphorescent screen whether I had placed 

 the prism with its refracting edge to the right or the left, 

 but neither the experimenter nor his assistant determined 

 the position correctly in a single case (three trials were 

 made). This failure was attributed to fatigue. 



I was next shown an experiment of a different nature. 

 A small screen on which a number of circles had been painted 

 with luminous paint was placed on the table in the dark 

 room. The approach of a large steel file was supposed to 

 alter the appearance of the spots, causing them to appear 

 more distinct and less nebulous. I could see no change 

 myself, though the phenomenon was described as open to no 

 question, the change being very marked. Holding the file 

 behind mv back, I moved my arm slightly towards and 

 away from the screen. The same changes were described 

 by my colleague. A clock face in a dimly lighted room 

 w'as ijelieved to become much more distinct and brighter 

 when the file was held before the eyes, owing to some 

 peculiar effect which the rays emitted by the file exerted 

 on the retina. I was unable to see the slightest change, 

 though my colleague said that he could see the hands dis- 

 tinctly when he held the file near his eyes, while they were 

 quite invisible when the file was removed. The room was 

 dimly lighted by a gas jet turned down low, which made 

 blank experiments impossible. My colleague could see the 

 change just as well when I held the file before his face, and 

 the substitution of a piece of wood of the same size and 



