486 



NATURE 



{April i8, 1878 



initial and final s were quite lost, and the action of the mutes, 

 c, t, was almost nil. 



The invention is highly interesting, the effects at present pro- 

 duced are sometimes startling (as in cries, coughs, laughter, 

 music), the philosophy of the process (taking a permanent im- 

 pression of a very complex compound vibration, and using it as 

 a mould to reproduce that vibration) is exceedingly attractive, 

 but at present the instrument — at least that one which I saw, 

 differing in many respects from the one described by Prof. 

 Mayer — has not risen beyond a lecture illustration or a philoso- 

 phical toy, Alexander J. Ellis 



April 13 



Phoneidoscopic Representation of Vowels and 

 Diphthongs 



Perhaps your corresjMndent, Mr. Sedley Taylor, would 

 kindly test with his phoneidoscope the propriety of calling the 

 English combinations ea, ae, oe, ie diphthongs, and the simple 

 vowel /, as pronounced in the personal pronoun, a simple sound. 

 Perhaps also the English a (as in " name") may be regarded as 

 a diphthong. In Otto's German Grammar, the German com- 

 binations ae, oe, ue, are classed as modified vowels. I fancy oe 

 is a diphthong, though in rapid speech it becomes more like the 

 simple sound ue. J. H. BlAKESLEY 



Linden, Hannover, April li 



The Acoustical Properties of Soap Films. 



In connection with the interesting results recently obtained 

 by Mr, Sedley Taylor upon the acoustic properties of soap- 

 films, as exhibited in the simple and beautiful instrument which 

 he has termed the Phoneidoscope, I should like to call attention 

 to the following passage published in 1873 by Prof. E. Mach, 

 of Prague, in his Optisch-Akustische Versuche: — 



" Bei dieser Gelegenheit kann erwahnt werden, dass -die 

 Plateau'schen FlUssigkeitshautchen sich vorzUglich zum Studium 

 der Membranschwingungen eignen. Eine solche FlUssigkeits- 

 haut vor eine tonende Pfeife gebracht zeigt meist mehrere 

 Bauche. Ein Lichtpunkt, der sich in der Membran spiegelt, 

 gibt mehrere glanzende geschlossene Curven." 



After some remarks on the low tones to which these films 

 vibrate, and on their vibrations to the upper partial tones, the 

 author passes on to another subject with the remark: — " Ich 

 erwiihne diese Experimente, weil sie vielleicht, weiter verfolgt, 

 zur Beantwortung mancher Fragen liber Membranschwingungen 

 beitragen konnen." 



There is no mention, however, of the rotating pairs of 

 coloured vortices noticed by Mr. Sedley Taylor. _ Brewster 

 appears to have observed similar phenomena (see Edin. Irans. , 

 vol. xxiv, " On Colours of Soap Bubbles," &c,) as the result of 

 directed currents of air upon films. I have found that the 

 vortices are also produced when a small lightly vibrating tuning- 

 fork, having its prongs previously wetted with soap solution, is 

 made to touch a flat soap film produced in the ordinary manner. 



SiLVANUs P. Thompson 



University College, Bristol, April 5 



Cumulative Temperature 



' The idea of a clock with an uncompensated pendulum for 

 temperature integration referred to by Mr. Cooke (Nature, 

 vol. xvii. p. 323 and p. 448) has probably occurred to many 

 persons, and was proposed by me in 1840 ; I found, however, 

 that it was not new then. Forbes says in his Report on 

 Meteorology (Brit. Assoc. Report, 1832, p. 213) : — " A me- 

 chanical mode of taking the mean of an infinite number of 

 temperatures has been proposed by M. Grassman, by observing 

 the change of rate caused by the influence of temperature upon 

 the uncompensated pendulum of a clock {Poggendorff, 1825). 

 The idea is a good one, but was proposed long ago by Dr. 

 Brewster (' Edinburgh Encyclopaedia,' art. Atmospheric 

 Clock)." The chief merit in this matter will belong to the 

 person who puts the idea into a working form which can be 

 proved capable of giving accurate results. 



April 9 B. 



The Southern Trought 



In response to your question appended to my letter in the 

 last number of Nature, I am able to give you the time of the 



last great drought in the Gilbert Islands. In 1870 I visited 

 these and several other islands in the South Pacific (an ac- 

 count of my cruise appeared in Dr. Petermann's Mittheilungcn 

 for June, 1871), and atjthat time there was a very general 

 drought. I was among the jGilbert Islands during October, and 

 found that no rain had fallen there for several months. The 

 cocoa-nut and pandanus -trees, upon which the people almost 

 entirely depend for food, were very much dried up, and the fniit 

 upon them were small, both in quantity and in size. This 

 drought continued for two years after my visit, and the famine 

 became so severe that many of the people were starved to death. 

 Had it not been for the fish they procured, it is doubtful whether 

 any of them would have survived, for the cocoa-nut and pandanus- 

 trees ceased to yield fruit, and the poor people were obliged to 

 chew the roots of the trees. 



Since that time I have heard of another season during which 

 there was little rain, in consequence of which there was com- 

 parative scarcity, but this was not to be compared with the great 

 drought of 1870-1872. 



I regret to say no long-continued observations on the rainfall 

 have been made in Samoa. My own time was so fully occupied 

 with other matters, during my residence there, that I neglected 

 this one. As the droughts there have not been great enough to 

 cause anything like distress, the periods of their occurrence have, 

 unfortunately, not been recorded. S, J. Whitmee 



Blackheath, April 5 



Research in Libraries 



Before this "voice from Australia" can reach London, I 

 hope that some steps will have been taken towards carrying out 

 Dr. Mallet's valuable suggestion (Nature, vol. xvi. p, 457) so 

 far as regards the British Museum and other leading European 

 libraries. 



The benefit of the proposed arrangement would, I am sure, 

 be felt in Australia as much as in America, Anybody living 

 here, in the North of Queensland, who may wish to consult a 

 scientific book must take a sea voyage of 700 or 1,100 miles at 

 a cost of 16/, or 20/, in money and at least a fortnight or three 

 weeks in time. It may happen that one has a busy friend in 

 the library city who will undertake the search through good- 

 nature, but most people would prefer to employ a competent 

 man who would do so as a matter of business. 



Shoiild the trustees or directors of the great libraries hesitate 

 (and they may) to accept the responsibility of recommending 

 searchers, probably it would answer nearly as well if the 

 searchers were to advertise references to well-known scientific or 

 literary men. Perhaps a hint might be taken from the Register 

 Hoirse in Edinburgh. Titles to land in Scotland require registra- 

 tion for their completion. A purchaser, to satisfy himself that the 

 seller has not previously alienated or burdened the subjects, has to 

 overhaul the books of the register. This is done for him as a rule 

 by professional searchers, some of whom are official and some 

 unofficial. The system has worked admirably for some centuries 

 I believe. Any Scotch lawyer could explain its details. 



The subdivision of labour suggested by Dr. Mallet would 

 enable a much higher use to be made of the system than the 

 mere hunting-up of references. For example, if there were a 

 searcher in Paris— a well-read geologist— to whom I could 

 intrust an order for "any references in French geographical 

 works bearing on the date of the erosion of the terrace between 

 the Queensland coast range and the Pacific," or some such 

 information, what possibilities would open out to the d\\ ellers in 

 distant isles, nay, even to the comparatively privileged inhabitants 

 of London itself? Robert L. Jack 



Geological Survey Office, Townsville, Queensland, Jan, 14 



Mimicry in Birds 



With reference to the coiTespondence on this subject which 

 has recently apeared in Nature, may I add the following 

 instance, which has fallen under my own observation ? — 



On the coast of Kent is a tract of land protected from the sea 

 by an embankment of shingle, and known as the " Reculver 

 Marsh," It is frequented by skylarks and ring-plovers. Almost 

 all these larks have incorporated the well-known alarm note of 

 the plovers into their song. With such distinctness is this double 

 note brought in, that the first time I heard it I could with diffi- 

 culty convince myself that it was not uttered by j^palitis 

 hiaticula. 



