March, 1907.] 



KNOWLEDGE & SCIENTIFIC NEWS. 



'/ 



bridge Phillips relates that he saw this bird in the flesh in 

 the shop of a local gunmaker. It is to be hoped that steps 

 will be taken to secure the conviction of the vandal who 

 killed this bird, who should further be made to forfeit the 

 specimen. 



Bitterns in Suffolk. 



The Rev. Julian Tuck, in the Zoologist for February, re- 

 cords the fact that two Bitterns have recently been shot in 

 Suffolk — one at Bardwell and one, a female, at Thorndon, 

 near Eye. It seems a pity that these birds cannot be left 

 alone, for they might yet be induced to breed here if given 

 the opportunity. 



Sabine's Snipe in Ireland. 



Three samples of the melanic variety of the Common 

 Snipe, known as Sabine's Snipe, were killed in Ireland 

 during December, according to the Zoologist for February 

 one near Ballina, Co. Mayo, on December 10, one in Co. 

 Leitrim, December 15, and one in Co. Clare, December 20. 

 The two latter appear to have been extremely good spei i- 

 mens of this curious variety, lacking the characteristic stripes 

 down the head and back. 



Snow Goose in Ireland. 



Mr. Robert Warren, in tin- Zoologist for February, gives 

 some interesting particulars of a flock of Snow Gei 51 »eer 

 by Captain Kirkwood on Bartragh Island, Killala Bay, on 

 December 30. This Hock appears to have been composed 

 of fourteen birds, four of which were a. lulls, as shown by 

 the white plumage and black-tipped primaries. It is s U o-_ 

 gested that these represented two broods accompanied bv 

 the old birds. 



Snowy Owl in Ireland. 



Captain Kirkwood also reported having seen a Snowy Owl 

 on a hillock anions' f' lc sand-hills in Bartragh, also on 

 December 30. 



These birds appear to have been driven before the great 

 snowstorm and three days' terrific northerly gale which ac- 

 companied it. 



PHYSICAL. 



By Alfred W. Porter, B.Sc. 



Electrons and Radiation. 



Attempts have been made (e.g., by Nagaoka) to explain the 

 existence of banded spectra and of series in line spectra in 

 terms of the theory that the atom is built up of negative 

 and positive charges of electricity. The electrons in such 

 a theory are conceived as rotating, like planets, round a 

 positive nucleus, which corresponds to the central sun. 



G. A. Schott, in the Philosophical Magazine, investigates 

 the possibility of such a system being- the source of bands 

 and series, and he comes, firstly, to the conclusion that a 

 single ring cannot be made to account for them, and hence 

 such a single ring cannot serve as the model of an atom. 

 However, light can be thrown on the conditions which a 

 true model must satisfy, by a study of such a system. 

 Schott concludes from his investigations that radiation ol 

 sufficient intensity and possessing the same range of wave- 

 length as the observed lines in spectra, can consist of a 

 number of waves too small to account for the lines even of 

 one series if emitted l>v a single ring. Hence, he considers 

 it useless to consider further the exact character of the 

 system which will give rise to series of the same type as 

 those of Banner, Rydberg, or Kayser and Runge. 



Acoustical Properties of Halls. 



M. Maragc has been studying several halls in Paris in 

 regard to their acoustical properties. The result of the ex- 

 periments is to confirm Sabine's theory. In any room an 

 auditor hears three kinds of vibrations: til ["he primarj 

 wave, which comes direct from the source; (2) diffuse 

 waves, sent back bv tin- various surfaces in the room; 

 (;) waves reflected regularly by particular surfaces, which 

 give rise 1.. distini 1 ei hoes. In ordei thai a speaker ma) be 

 distinctly heard there musi le no echo, and the diffuse sound 

 must last lor a sufficiently short lime to strengthen the 

 sound which gave rise ti> it, without encroaching on the 

 nest. The duration of the diffuse sound can be expressed 



by the equation t — K/(a + b) where K is proportional to 

 the volume of the hall, and a and 6 refer to the empty 

 room and the spectators, respectively. As sources of sound, 

 M. Marage has employed a vowel-siren, furnished with 

 buccal resonators, in order to imitate the human voice as 

 closelv as possible. 



As an example of his result-', we may cite that in the 

 Salle du Trocadero, he finds that when empty, the duration 

 of resonance is about 2 second-; when containing 4,500 

 auditors, it is reduced to 1' seconds. In this hall, in 

 to be heard well, it is necessary to speak slowly, stopping 

 bi Lwi 1 n each phrase. To keep down the disturbance from 

 nice, one should not employ more energy in speaking 

 than in the Physical Theatre at the Sorbonne, which 

 only 250, and which has a remarkably short per' 

 resonance (.6 second). 



The Joule-Thomson Effect. 



Reference has previously been made in these columns to 

 ilie temperatures at which the heating (or cooling) of a gas 

 in being forced through a porous plug (or throttle) may be 

 expected to become zero. The only direct experimental 

 determination of this inversion point had been made- by 

 Olszewski in the case of hydrogen, and then for one initial 

 pressure only. Examination of the necessary conseqi 



of van cler Waals' and other- characteristic equatio 

 gases had led us to believe that a different inversion point 

 would be found in general for every initial pressure. This 

 published expectation has induced Olszewski to make direct 

 determinations in the cases of air and nitrogen, with the 

 result that the expectation is found to be fullv justified. 

 For example, in the case of nitrogen for variations of the 

 pressure on the high pressure side of the throttle, from about 

 160 atmos. to 30 atmos., the temperature at which no heat- 

 ing or cooling took place varied continuously from 24 c C. to 

 r.63 C For higher temperatures than the inversion one the 

 gas became hotter in escaping, jusl as hydrogen d 

 ordinary temperatures; for lower temperatures it cooled. 

 The importance of this arises in part from the fact that a 

 gas must be coeiled by other means below the in\ 

 temperature before if can possil.lv begin to cool in any of 

 the modern liquefying machines. Besides this reason, how- 

 ever, there is the either important one, that additional light 

 is hereby thrown upon the exact behaviour of gases, and 

 we may hope that an extension of such experiments will 

 ultimately lead to a more exact knowledge of the relations 

 between the pressure, volume, and temperature of a gas, a 

 relation which is expressed by the characteristic equation. 



ZOOLOGICAL. 



By R. Lydekker. 



Th^ Bcnte-Quasga. 

 ONE of the larger South African mammals now verging on 

 extinction, if, indeed, it has not already ceased to exist, is 

 the typical race ot Burchell's zebra, the bonte-qu ... 

 " pied quagga ") of the Boers, and the K^u 

 typicus ol zoologists. This race- apparently inhabited the 

 plains to the north of tin- Yuul River, now forming British 

 Bechuanaland. It is charai b) the compli 



of barring on the legs and of strip, s on the lower part of 



the hind-quarters; while between the dark brown body- 

 stripes were fainl "shadow-stripes" on the still paler 

 ground-colour. The original specimen in the British 

 Museum, brought home- by the gnat African traveller, Dr. 

 Burchell, was, unfortunately, destroyed at a time when but 

 little attention was paid to the priceless \ulue of "c 



and there is now no example of this race of th< 



the national collection. According, however, to ,1 paper 

 published bj Mr. Ix. I. Pocock in the Annals and U 

 of Natural History for 1897, there is. however, 



men in the museum at Tring. and .1 second in the Bristol 

 Museum, both of which come ver) 1 lose to the typical form. 



1 ;h neither is ex. utlv similar, and each -hll\ 



from the other. In these circumstances it is int. ■ 

 learn thai 1 specimen exists in tic- An Museum of 



Natural History, which has recently I 



Mi. M. \Y. Lyon in the Hull, tin of that institu- 

 tion. The specimen, which was purch 



