128 



NA TURE 



[December 2, 1909 



ing the picture of the upper part of the face, and thus help 

 me to fathom a question which I am persuaded contains 

 the key to many other problems as to the constitution of 

 sound and the organ of sound? 



George Irons Walker. 

 VVestbury Street, Sunderland, October 28. 



With reference to Mr. Walker's interesting letter, which 

 bears out the opinion of Prof. Kunz and others that there 

 is no special development of the other senses in those who 

 have lost the sense of sight, I feel at a loss to give an 

 adequate e.xplanation of the curious experiences described 

 by Mr. Walker. The only suggestion I would venture to 

 rnake is that Mr. Walker may, by long and almost uncon- 

 scious practice, have learned to associate certain tones of the 

 voice, as regards quality of tone, with certain movements of 

 the head that he supposes are made by the speaker at the 

 time he utters the words. Tones of inquiry, surprise, re- 

 proach, affection, interest, have each a certain quality indi- 

 cative of states of feeling (unless they are produced by 

 mimicry), and the blind man may draw conclusions as to 

 movement and state of feeling on the part of the speakers. 

 He has then what Mr. Walker calls " a picture of the 

 play of their emotions." I cannot explain why Mr. Walker 

 has almost invariably a picture of the upper part of the 

 face, nor why he prefers to sit at an angle to a public speaker 

 instead of in front. His experience supports the view that 

 the blind have not more acute sensory perceptions than those 

 who see, but that they have cultivated the habit of close 

 attention. This, in turn, stimulates their imagination, and 

 gives them mental pictures of external things that are of 

 no special importance to those who see. 



John G. McKexdrick. 



Movements of the Red Spot Hollow on Jupiter. 



Transit estimates of the Red Spot Hollow on Jupiter, 

 obtained between 1908 December 20 and 1909 June 12 in- 

 clusive, show that that object exhibited an average monthly 

 increase in longitude of 1-03°. Its motion, however, was 

 not constant, inasmuch as it remained practically stationary 

 in longitude during the last three months (.'Vpril to June) 

 of the apparition. The rotation periods of the three 

 selected points of the Hollow, namely, the two shoulders 

 and the middle, work out as under : — 

 /). Shoulder. 

 No. of Elapsed Mean daily 



Long. 



period 



-0-0376 



The mean rotation period of the Hollow, therefore, 

 appears to have been, as nearly as possible, gh. S5m. 42'OS., 

 a period which is 1-4 seconds longer than that of the 

 adopted value of System II. 



.\t the commencement of the observations, in December, 

 the middle of the Hollow crossed the central meridian 

 about twenty-three minutes subsequent to the passage of 

 the zero meridian, and half an hour at the close of the 

 apparition in June. This lagging behind may be regarded 

 as a distinctly normal movement on the part of the Red 

 Spot. 



When the planet was observed last month as it emerged 

 from the sun's rays, the Hollow was found to have moved 

 at an accelerated rate of velocity during the unobserved 

 interval since June. From transits obtained on October 

 ij, 25, and 30, the deduced mean longitude of the middle 

 of the Hollow was then 16-4°. This shows a decrease of 

 2" when compared with the longitude for June. It is 

 evident, therefore, that the motion of the object had latterly 

 become quickened. Had the Hollow continued to drift at 

 the same rate as was exhibited from December to June, 

 it would have crossed the central meridian ten minutes 

 later than was actually the case last month. Owing to 

 this slight displacement in longitude, the rotation period 

 from June to October was shorter than that for the 

 previous six months, and works out at oh. 55m. 400s. 



Leeds, November 21. Scriven Bolton. 



NO. 2092, VOL. 82] 



Secondary Kathode Rays. 



In a letter to Nature of April 2, 190S (vol. Ixxvii., 

 p. 509), I described some experiments of mine which 

 showed that for the corpuscular rays produced in metals 

 by Rontgen rays there was a lack of symmetry between 

 those coming from the side of the metals on which the 

 primary rays were incident and those coming from the side 

 from which the primary rays emerged. The ionisation pro- 

 duced by the emergence secondary corpuscles was, in general, 

 greater than that produced by the incidence corpuscles. 

 This was in accordance with Prof. Bragg 's results for the 

 corpuscular rays produced by 7 rays (Nature, January 23, 

 lonS, p. 270). 



Since writing the above I have endeavoured to see if 

 this lack of symmetry was dependent on the penetrating 

 power of the primary Rontgen rays. Experiments were 

 carried on only with gold and silver, and gave the follow- 

 ing results. The average of four determinations with soft 

 primary rays on silver showed the ionisation produced by 

 the emergence to be i-ii times as great as that produced 

 by the incidence corpuscular secondary rays ; eight deter- 

 minations with hard primary rays gave an average ratio 

 of I.2I. Five determinations with soft primary rays on 

 gold gave the ratio of emergence to incidence ionisation 

 as 103 ; nine determinations with hard primary rays gave 

 a ratio of i-og. The probable error of the mean in each 

 case was +001. It would seem, therefore, that there is 

 a slight variation of the asymmetry with the hardness of 

 the Rontgen rays, certainly in the case of silver, and very 

 probably in the case of gold, the harder primary rays 

 causing the ratio of the emergence to the incidence cor- 

 puscular ravs to increase. 



Though the hardness of the Rontgen rays could be varied, 

 they were probably always very heterogeneous. I hope 

 soon to repeat my exoeriments, using more homogeneous 

 Rontgen rays, which have been recently made possible by 

 the experiments of Prof. Barkla. 



Charlton D. Cooksey. 



Sheffield Scientific School, Yale University, New 

 Haven, Conn., November 17. 



AN INTERNATION.iL MAP OF THE WORLD. 

 A N International Committee assembled in London 

 •**■ on November 15 to consider the form in which 

 it is desirable to prepare a uniform map of the world 

 on the scale of 1/1,000,000, or about sixteen miles 

 to the inch. 



The proceeding's of thi.s committee have aroused 

 keen interest among- geographers, and the results of 

 its labours will be anxiously awaited. The meeting 

 of this committee marks an epoch in map-making, 

 and if its proposals are generally adopted, as no doubt 

 t'ney will be, there will be prepared a map of the whole 

 world, uniform in design and execution, on a reason- 

 ably large scale. 



Hitherto each country has, in the preparation of 

 its maps, had in view solely its own requirements, and 

 has made no effort to assimilate its maps to those of 

 other countries, either in regard to scale, projection, 

 method of representing hills, or in other points. Maps 

 have been issued differing widely in these respects 

 from those even of the adioiniiig countries. 



The difficulty caused by this diversity of map design 

 has long been felt, not only by those little versed in 

 map readingf, but by those who have constant occasion 

 to work with maps. 



It was not until i8qi that the first important step 

 was taken towards obtaining a more uniform map of 

 the world. In that year the Internationa! Geographi- 

 cal Congress at Bern raised the question, and the 

 London Congress of iSg^ passed a resolution recom- 

 mending the scale of 1/1,000,000, or about sixteen 

 miles to the inch, as suitable for a map of the world. 

 This resolution was communicated to the various 

 Governments in the hope that this scale might be 

 generally adopted. 



