172 



NA TURE 



[February 14, iqoi 



malarial fever is unknown on the spot, but a man may turn over 

 the ground in certain marshy localities and get fever certainly 

 whenever he does so. It was common experience in India that 

 the drinking of certain water, such as that from the highly 

 malarious Western Ghaut forests, would inevitably cause malarial 

 fever. 



In many malarious localities, especially parts of China, it is 

 sufficient to turn the ground over to apparently poison the 

 atmosphere and induce malaria in those who are near. There is 

 a medically authenticated case of fever being contracted from 

 newly turned-up earth carried in baskets by coolies past a 

 window. When this and other cases come to be re-examined 

 they may be found traceable to mosquito-born Hsemamoebidtie ; 

 but it is difficult to account for them all in this way, and, as I 

 mentioned, there seems to be an opinion amongst Northern men 

 here that all cases of malarial fever cannot be attributed to 

 Anopheles infection. D. E. HuTCHiNS, 



Conservator of Forests, Cape Town, January 19. 



Audibility of the Sound of Firing on February i. 



I ENCLOSE a record of the sound of the guns heard at East- 

 bourne, commencing at 3h. 14m. and ending at 3h. 57m. As 

 you will see, the sounds came with great regularity every minute, 

 but the period which the sound covered in each minute grad- 

 ually fell off from eleven to about five seconds. My observa- 

 tions were checked by a friend, and we were stationed on the 

 summit of a down some 500 feet above sea level with a clear 

 sea horizon out to Newhaven. The distance to the Solent 

 is about sixty-five miles, and there was a slight wind from the 

 North- West. I should like to try to describe the sounds which, 

 though faint, were perfectly distinct — er-er-er-pup-er-er-pup-pup, 

 the detonation sound being more marked towards the end of 

 eich period. I need not say that the sounds were indescribably 

 mournful to listen to. H. D. G. 



Audibility of the Sound of Firing on February ist. 



Sound com 

 menced at 

 h. m. s. 



14 

 15 

 16 



17 



18 



19 



Sound 

 ended at 

 h. m. s. 

 14 18 



15 19 



16 18 



17 19 



18 19 



19 19 



Duration 

 of sound 



10 

 II 



Observations interrupted by the 

 rumbling of the wheels of a 

 cart about a quarter of a mile 



distant. 



3 23 II 3 23 19 8 



3 24 12 3 24 19 7 



Observations again broken by 



sounds of a distant cart. 



Sound com- Sound Duration 



menced at ended at of sound 



h. m. s. h. m. s. s. 



27 13 



28 13 



29 II 



30 II 



31 12 



32 12 



33 12 



34 J I 



35 " 



3 27 19 

 3 28 18 

 3 29 17 

 3 30 16 

 3 31 16 

 3 32 13 (?) 

 3 33 16 

 3 34 15 

 3 35 15 



3 36 15 

 3 37 15 

 3 38 16 

 3 39 17 

 3 40 15 

 3 41 15 

 3 42 15 

 3 43 15 

 _ .. 3 44.15 



Observations again interrupted 

 3 46 II 3 46 14 3 



3 47 16 6 



3 48 IS 6 



3 49 15 6 



3 50 15 5 



Failed to hear sound — -reports 

 growing fewer and very faint. 

 3 52 13 3 52 16 3 



3 53 10 3 S3 15 5 



3 54 II 3 54 14 .3 



Reports continued until 

 3 57 — but impossible to time 

 — so very faint. 



3 36 II 

 3 37 II 

 3 38 10 

 3 39 10 

 3 40 II 

 3 41 10 

 3 42 10 

 3 43 10 

 3 44 10 



3 47 10 

 3 48 9 

 3 49 9 

 3 50 10 



Sensational Newspaper Reports as to Physiological 

 Action of Common Salt. 



In the interest of the dignity of scientific research I venture 

 to hope you will print the following statement. Some American 

 papers have recently published sensational and absurd reports of 

 physiological theories and experiments whose authorship they 

 attributed to me. These reports, which in America nobody takes 

 seriously, were reprinted and discussed in European papers. I 

 hardly need to state that I am in no way responsible for the 

 journalistic idiosyncrasies of newspaper reporters and that for 

 the publication of my experiments or views I choose scientific 

 journals and not the daily Press. Jacques Loeb. 



The University of Chicago, Physiological 

 Laboratory, January 16. 



The Publication of Books without Dales. 



Is it not time that men of science should raise a protest 

 against the publication of books without a date on their title- 

 page ? This is a practice which has been common to maps and 

 a certain class of books of reference, and it comes, to my mind, 

 very near to being a deliberate fraud, as it seeks to pass off as 

 new that which is more or less obsolete. We should surely do 

 our utmost to prevent this habit from spreading to scientific 

 books, such as the translation of van 't Hoff's " Physical 

 Chemistry," which is reviewed in Nature of February 7. 



O. Henrici. 



Central Institution, Exhibition Road, February 9. 



NO. 1633, VOL. 63] 



Optical Illusion. 



It seems to me certain that the phenomenon illustrated in 

 Nature of February 7 (p. 353) is dae to (i) fatigue, the cause of 

 the reversed image seen when one looks away from the diagram 

 on to white paper, combined with (2) involuntary and incessant 

 slight movements of the eye. 



Of course the reversed image, white squares and black lines, 

 when one looks away on to white paper, is well known. With 

 me it does not appear to occur at once, but after an interval ; 

 and it is intermittent, fading and recurring several times. 



Now, when one gazes at the diagram, the eye moves inces- 

 santly to a slight extent ; and so it is only the central part of 

 the images of the white spaces that fall always on parts of the 

 retina continually fatigued ; the edges, near the black squares, 

 fall on parts of the retina that have, on the whole, a good dea.1 

 of rest owing to the fact that they are occupied for half the 

 time (or sd) by the images of the black squares. I do, in fact, 

 see dark lines along the central portions of the white spaces, 

 and the dark patches spoken of are where these dark lines 

 cross. 



I can make the horizontal dark lines disappear by purppsely 

 giving my eyes a more than slight movement up and down the 

 vertical white spaces. Then the vertical shadowy lines, in the 

 middle of these spices, remain ; the horizontal dark lines 

 vanish, as should be the case. 



As regards the " vanishing " of a patch looked at, I do not 

 find this to be a correct account of what I observe. I notice that 

 when I- suddenly gaze at any one crossing, the crossing dark 

 lines and dark patch at that place take long.er to appear ; but 

 they do appear in time. Perhaps the "yellow spot" is slower 

 in action than the rest of the retina in questions of fatigue? 

 But these phenomena are difficult to observe, as the eyes soon 

 tire. Avery noticeable phenomenon, I suppose an extreme case 

 of fatigue, is the following. When I gaze for a long time, 

 white spaces here and there disappear altogether in a fitful 

 manner, the squares concerned for the time blending. This 

 occurs with monocular vision as well as binocular, as do all the 

 phenomena mentioned. But I think the eyes must be very tired 

 for this to occur. 



As regards the question of spacing, I imagine that the steadier 

 the eye-muscles, and so the less the involuntary movements, the 

 narrower might be the white spaces. I have noticed a violet 

 margin round an orange on snow, due to the same causes. It 

 increased when the orange was rolled. The explanation is 

 obvious if the view taken above is right. W. Larden. 



R.N.E. College, Devonport. 



Some Animals Exterminated during the Nineteenth 

 Century. 



Re the very interesting article published under the above- 

 mentioned title by Mr. R. Lydekker (p. 252, January 10), may 

 I indicate and correct an error ? Camptolaemus labradorius is 

 certainly exterminated on the North Atlantic coast of America, 

 as Mr. Lydekker says ; but this breed still exists not very far 

 off, but in a somewhat out-of-the-way place, in the island of 

 Anticosti, where M. Paul Combes saw it recently, as he states 

 the fact in his "Exploration de I'lle d' Anticosti," 1896 (J. 

 Andre, publisher, Paris). Henry de Varigny. 



Paris. 



In reference to the foregoing letter, it may be mentioned that 

 the duck in question is entered as extinct in the "A.O. U. 

 Check-list of North American Birds," 2nd ed. p. 56 (1895), 

 and no information has subsequently reached this country as to- 

 its alleged survival in Anticosti. R- L. 



