558 



NATURE 



[July 31, 191, 



hiss. I doubt much whether any pure tone gives the 

 full impression of an "s," having often experimented 

 with bird-calls of about the right pitch. Perhaps a 

 rapid change of pitch is essential. Rayleigh. 



Prof. Armstrong and Atomic Constitution. 



In the April number of the quarterly journal called 

 Science Progress appears an article signed H. E. A., 

 in which that distinguished chemist at length accepts, 

 though not without hesitation and sustained scepticism, 

 some of the results deduced by physicists from the pheno- 

 mena of radio-activity ; but he takes the opportunity 

 of restating and reinforcing his opinion that the inert 

 gases — helium, for instance — are not really monatomic 

 — an opinion expressed by Prof. Armstrong soon after 

 the discovery of argon. 



To maintain this rather strained position in face 

 of experimental facts, a considerable amount of what 

 seems to me gratuitous hypothesis is required ; and 

 since it is desirable to come to a better understanding 

 of this matter, I propose to criticise his attitude, in 

 a friendly way, in the October number of the same 

 journal. Oliver Lodge. 



Distribution of Amphidinium. 



Biological readers of Nature will perhaps recollect 

 the record of the finding of the dinoflagellate, Amphi- 

 dinium operculatiim (previously unknown in Britain), 

 on the beach at Port Erin a couple of years ago. 

 Since then it has been present in great abundance at 

 Port Erin on many occasions; Mr. R. D. Laurie has 

 found it at Hoylake, near Liverpool, two of our 

 young Liverpool zoologists (R. J. Daniel and J. E. 

 Hamilton) now at the Belmullet Whaling Station, co. 

 Mayo, inform me that they have noticed it on the 

 shores of Blacksod Bay, and now I have to-day found 

 it here in abundance, staining slightly in patches and 

 streaks the beautiful white shell-sands of Iona. 



Both the forms found at Port Erin — viz. the shorter 

 discoid (the typical A. operculatum) and the larger 

 more ovate form which I have described from Port 

 Erin — occur here, associated with a few Naviculoid 

 diatoms. 



It seems probable that this curious dinoflagellate, 

 known in the living state so far as I can ascertain to 

 very few biologists, and previously recorded from only 

 three or four far-distant localities, is really very 

 generally distributed, and might be found by careful 

 searching on many sandy beaches. 



W. A. Herdman. 



S.Y. Runa, Sound of Iona, N.B., July 20. 



Gramophone Improvements. 



I have greatly improved my gramophone, at any 

 rate for use in rooms of moderate dimensions, by 

 applying to it both the long tube arrangement for 

 eliminating scraping noises — described by Mr. Ernest 

 De la Rue in Nature of November 14, 1912 — and also 

 the "donkey's ear" form of trumpet, devised by Mr. 

 Sidney G. Brown, which I have the latter's permis- 

 sion to describe. 



The accompanying illustration shows an elevational 

 section through the instrument as altered. From the 

 sound-box, the sound passes through the usual mov- 

 able arm and the socket A into one end of about 

 14 ft. of 2 in. flexible steel pipe, arranged in six 

 vertical lengths, of which four are shown in the illus- 

 tration ; the other end of the pipe, B, being' connected 

 to the trumpet C. As in the case of Mr. De la Rue's 

 machine, the bends in the pipe are made of zinc, and 

 it seems that it is chiefly these bends that almost 

 entirely eliminate the scraping- noise due to the fric- 

 tion of the needle on the record. 



The "donkey's ear" trumpet devised by Mr. Brown 

 NO. 2283, VOL. 91] 



is shown in section at C. It is made of four flat 

 pieces of three-ply Birch fretwork wood of about 

 I in. total thickness. It has an oblong mouth, and 

 its special feature is that, like the ears of donkeys 

 and many other animals, it is shaped with a top and 

 bottom of unequal lengths so as to resonate compara- 

 tively equally to sounds of widely different pitch. 



It has been found desirable to put a felt seating 

 for the lid D to rest on, as though previous to the 

 alteration the amount of scraping noise that cam.- 



out through the trumpet was so considerable that it 

 made very little difference whether the lid was closed 

 or open ; with the new arrangement this scraping is 

 eliminated to so great an extent that until the felt 

 was inserted quite an appreciable amount of noise 

 was found to come out round the lid. 



Though the instrument is not so loud as previously, 

 the reproduction of sounds of all descriptions seems 

 now much more accurate than before, while the 

 objectionable scraping noise has been virtually done 

 away with. A. A. Campbell Swinton. 



66 Victoria Street, London, S.W., July 24. 



The Maximum Density of Water. 



I fear Mr. W. B. Croft will get few to agree with 

 him in supposing that it would make little difference 

 in the conditions existing on the earth whether 

 water was at its maximum density at o° or at 

 4 ahove it (Nature, July 17). If water was 

 densest at o° there would be little surface ice, as 

 water does not change to ice at 0° unless in the 

 presence of ice crystals or other solids. The ice- 

 cold water would therefore, after sinking, freeze when 

 it came in contact with the solid bottom, and we 

 would have much anchor ice and but little on the 

 surface. The small margin of only 4° does not seem 

 to be quite enough entirely to prevent anchor ice ; still 

 we have reason to be thankful for these few degrees. 



John Aitken. 





