Fekruarv 2 1, 1901] 



NA TURE 



195 



in obliterating dark lines than bright ones. Prof. Wood's sug- 

 gestion as to reducing the effective intensity of the truly con- 

 tinuous spectrum by passing the light through a suitably placed 

 Nicol's prism, would accordingly be specially applicable to the 

 inner corona. 



Prof. Wood has obtained experimental evidence on a point to 

 which attention was drawn many years ago by Ranyard (Mem. 

 R.A.S., vol. .\li. p. 353), namely, that if the solar light be re- 

 flected by small particles in the corona, the reflected rays will be 

 deficient in the rays of greater wave-length. In this way the 

 bolometric observations indicating that the corona was cooler 

 than the bolometer are partly explained. Is it possible that the 

 observations are to be completely explained by further supposing 

 that the bolometer strip was outside the image of the shallow 

 inner corona, which is probably the chief part of the corona 

 directly emitting light and heat ? The image thrown on the strip 

 appears to have been little more than one-third of an inch in 

 diameter, and in the account of the observations Mr. Abbot 

 simply states that the image was brought almost tangent to the 

 strip, so that the strip may very well have been 4 or 5 minutes 

 from the sun's limb. 



At all events, there seems to be no sufficient ground, as yet, for 

 rejecting the view that the luminosity of the outer corona is 

 largely due to reflected solar light, while that, of the inner 

 corona is partly due to the incandescence of solid or liquid 

 particles and partly to gaseous radiations. A. Fowler. 



Royal College of Science, South Kensington, February 9. 



Malaria and Mosquitoes. 



I THINK most of those who have had much experience of 

 the Indian jungles would be prepared to corroborate the re- 

 marks made by Mr. D. E. Hutchins in last week's Nature 

 (p. 371), and would perhaps be inclined to think there may be 

 something in the opinion alluded to by him, that "Dr. Ross's 

 splendid discovery does not quite cover the whole ground." In 

 1873-4 I spent some months in the notoriously malarious region 

 at the foot of the Darjiling Himalayas, which contained some 

 tea gardens here and there at that period, while many new 

 ones were being opened out. The planters suffered greatly 

 from malarial fever, and I was told by several that it was far 

 more prevalent, and of a worse type, on gardens in process of 

 formation, by clearing the jungle and breaking up the ground, 

 than on either the undisturbed jungle itself or on gardens that 

 had existed for some time. In other parts of India my camp 

 has suffered badly from malarial fever when mosquitoes were 

 certainly not prevalent, and when, to the best of my belief, 

 there were none, or perhaps I should rather say, none made 

 themselves noticeable by stinging. 



On the other hand, when in. Upper Assam in 1874-5, I was 

 informed by some of the planters there, and it seemed to be a 

 commonly received opinion, that mosquito curtains were a valu- 

 able protection from malaria. Of course at that period no 

 explanation could be given for the supposed fact, which seemed 

 a very mysterious one, as for the invisible ' germs,' which were 

 thought by some to float in the air, to be excluded by curtains 

 of ordinary mesh would be something like a man being pre- 

 vented from crossing a road through inability to squeeze himself 

 between the milestones. 



18 The Common, Ealing, February 12. F. R. Mallet. 



Audibility of the Sound of Firing on February i. 



The following note was recorded here (at Littlemore, Oxford) 

 immediately after I was called away from listening ; and as it is 

 more detailed than any I have seen, I daresay you will think it 

 worth printing. 



I held my watch in my hand and observed the sequence of 

 the booms for some ten or twelve successive minutes. The 

 second one showed there was regularity, and after the third the 

 facts were clear. The sounds reached us thus : 



OS. to 7.05., continuous unbroken roll of guns of slightly 

 different strength. 



20s. to ± 24s. , silence for 4s. or 5s. 



+ 24s. to + 29s., similar roll. 



+ 29s. to + 34s., silence for 3s. or 4s. 



+ 34s. to + 38s., a similar roll. 



+ 38s. to 42s., silence to just the 42s. 



42s. to 45s. exactly, a short roll culminating in three or four 

 guns much louder than any of the preceding ones. 



45s. to 605. exactly, dead silence for a quarter minute. 



NO. 1634, VOL. 63] 



This recurred with such perfect regularity that there was no 

 doubt whatever about the precision of the observation. 



Then I had to ride away on a bicycle about a mile, where I 

 met another cyclist, and we stopped and listened again. The 

 long 20s. roll was now missing, but punctual to the second or 

 two came all the others, the last one with big guns precise. 



It seems likely that the long roll was the simultaneous salute 

 of the long line of ships ; but I have not yet noticed any 

 authoritative statement as to how the saluting was done. It 

 was interesting to think that at any moment while we were 

 listening there were no fewer than six other such salutes 

 travelling up towards us from the Solent. 



From the strength of the sounds I should quite agree with the 

 opinion expressed in Oxford that ihey might well be heard 

 another twenty miles. W. J. Hkrschbl. 



February 12. 



The Origin of the "Tumbling" of Pigeons. 



In reading the account of turribler pigeons in Darwin's 

 " Animals and Plants under Domestication," the question arose 

 to what the habit of " tumbling" might be due. 



I have since seen, in a report of an address by Prof. J. A. 

 Thomson to the North British Branch of the Pharmaceutical 

 Society, a statement that the peculiarities of movement of the 

 Japanese waltzing mouse are due to the fact that only one of its 

 semi-circular canals is developed. 



It occurred to me that a similar condition might explain the 

 movements of the tumbler. I should be much obliged if you 

 or any of your readers could tell me where information con- 

 cerning either of these examples is to be found. E. P. 



February 3. 



[Prof. Thomson's statement is not quite accurate. The 

 paper to which he referred is undoulitedly that by Rawitz, in 

 Archiv. f. Anat. anU Physiol. (Physiol. Abth.), 1899, pp. 236- 

 244, where it is shown that of the three canals the anterior is 

 alone normal, and that the other two — though reduced and 

 abnormal in their inter-relationship — are present. 



The physiology of the organ has been since experimentally 

 investigated by Alexander and Kreidl, whose paper is in 

 Pfluger's Archiv. f. Ges. Physiologic (Bd. 82, pp. 541-552) ; 

 and as to the pigeons, they, too, have all three canals well 

 developed. Concerning their membranous labyrinth, some ex- 

 periments of interest were made in, I think, the early nineties 

 by Spamer and others, and an account of these and of allied in- 

 vestigations bearing on the question raised (by McBride) will be 

 found in the /(?«r«. Anat. and Physiol, (vol. xvii. pp. 211-217). 

 There does not appear to be any foundation for the view to which 

 the writer of the letter inclines. — G. B. Howes.] 



Lummer's " Photographic Optics." 



The interesting review of Prof. Silvanus Thompson's trans- 

 lation of Dr. Otto Lummer's " Photographic Optics," which was 

 published in Nature on January 3, has come under my notice. 

 I should be obliged if you would permit me to correct a mistake 

 which occurs both in Prof. Thompson's book and the review. 

 Concerning the two views of Munich published in Prof. Thomp- 

 son's work, which are there attributed to Dr. Miethe, you 

 remark : " Miethe's two views of Munich from a distance of 

 about two miles — the one taken with an ordinary lens, the other 

 with the teleobjective — show what a powerful weapon the latter 

 is." 



Both the views in question were taken by my firm, one with 

 an antiplanet and the other with this antiplanet in combination 

 with a magnifying system (negative lens) as a teleobjective of 

 our own construction and manufacture. I send you a prospectus 

 of my firm concerning the said teleobjective and containing also 

 the two views of Munich. 



I also observe another error in Prof. Thompson's work ; the 

 lenses recently introduced by Messrs. R. and J. Beck being de- 

 scribed on p. 80 as Messrs. Voigtlander.s' CoUinears, instead of 

 our orthostigmats, for which I have given them a manufacturing 

 license, as you will see in the notice on page i of the prospectus 

 I also send by book post. Rudolf Steinheil. 



Mlinchen, February 5. 



Nothing could have been further from my intention than to 

 do any injustice to Dr. Steinheil or his firm, and I hasten to 

 acknowledge the justice of his criticisms upon the slips 



