lOO 



NA TURE 



\y71ne 



2, i{ 



square miles as now estimated, to institute efficient 

 systems of observations and warnings, &c., &c. Prof. 

 Riley treats on the natural enemies of the locust, and 

 illustrates the chapter by a remarkably well-executed 

 plate. The general conclusion arrived at is that the evil 

 may be materially modified, although utter extermination 

 is out of the question. 



The lengthy appendices give replies to the official 

 circular from those interested, in -widely-separated dis- 

 tricts, often showing great practical and frequently scien- 

 tific knowledge, sometimes combined with the illogical 

 conclusions at which agriculturists often jump. Then 

 there is list of species of locusts, &c., collected in the 

 Western States in 1877, with descriptions of new species, 

 worked out by Mr. Scudder ; the plate illustrating this is 

 not so good as usual, and scarcely sufficient for scientific 

 purposes. A general bibliography of locusts (chiefly com- 

 piled by Mr. B. Pickman Mann), from 1542 forwards, must 

 have occasioned great labour, and is correspondingly 

 valuable. Other appendices treat on the flight of locusts 

 (translated from the Italian) ; on a journey to Utah and 

 Idaho, by Dr. Packard ; and a translation of Yersin's 

 researches on the function of the nervous system in Artic- 

 ulates. The six large folded maps on thick paper seem 

 to be admirably adapted to illustrate the points to which 

 each is directed. 



We do not think it is pretended that some of the most 

 useful chapters from a scientific point of view have any 

 special, or even indirect, bearing upon the subject of 

 Economic Entomology. The investigation of a locust's 

 brain, for instance, will hardly reveal the mental condi- 

 tion of the insect, and show us why it is prompted to 

 migrate or be so maliciously inclined towards destroying 

 the hopes of the agriculturist. We prefer to regard these 

 portions of the report as an outcome of a liberal endow- 

 ment of research, the application of which to the nominal 

 subject for inquiry is not too rigidly enforced. 



LETTERS TO THE EDITOR 

 [ TTie Editor does not hold himself responsible for opinions expressed 

 by his correspo7idents. Neither can he tmdertake to return, 

 or to correspond ivith the writers of, rejected manuscripts. 

 No notice is taken of anonymous communications. 

 [ The Editor urgently requests correspondents to keep their letters 

 as short as possible. The pressure on his space is so great 

 that it is impossible othenvise to ensure the appearance even 

 of communications containing interesting and novel facts. ] 



Laurentian Gneiss of Ireland 



Allow me to state that since writing the notice which 

 appears in Nature (vol. xxiv. p. 81), I have found that white 

 cry.stalline marble has been described by Sir R. I. Murchison 

 and Prof. Geikie as occurring in the Laurentian gneiss of Loch 

 Maree, in Scotland. I had overlooked this statement, and was 

 imder the impression that limestone was absent from the Scottish 

 Laurentian area. Its occurrence in both countries constitutes an 

 additional point of resemblance. Edward Hull 



Geological Survey of Ireland, May 31 



Resonance of the Mouth-Cavity 

 Will yon give a place in Nature to the inclosed letter 

 which has just reached me? The writer is an organist and 

 teacher of music of great repute in the North of England. The 

 experiments which he describes will, I believe, interest many of 

 your readers as much a^ they do me. 

 Trinity College, Cambridge, May 20 Sedley Taylor 



My Dear Sir, — Travelling the other day by express from 

 Scarborough to London, I found myself unconsciously moving 

 my lips as if whistling a tune, v\hich however I was not actually 

 doing. Without any other action than the simple movement of 

 the lips, I very distinctly heard different sounds in my mouth. 

 Persevering in the practice of this discovered power of pro- 

 ducing sound, I soon accomplished a fairly satisfactory perform- 

 ance — audible only to myself — of " Home, sweet home." 



As soon as the train came to a standstill I found myself 



powerless to repeat the performance, for there was then no 

 response to the contortions which by this time had attracted the 

 attention of my fellow-passengers, who doubtless thought that I 

 was being conveyed to a lunatic asylum. On resuming our 

 former speed the "power of sound" once more responded to 

 my efforts. 



At once I perceived that I had made a discovery of which I 

 had never heard or read in any of the numerous works on 

 acoustics that I have studied. I perceived that I could single 

 out different sounds from the noise of the train by a simple 

 alteration of the size of the resonance-cavity of my mouth. 



On my return home it occurred to me that the force of vibra- 

 tion in the air from the note of a harmonium might be able to 

 set up a sympathetic resonance of the mouth. To my delight I 

 found that I was right. 



It is knov\n that if a tuning-fork of proper size be held to the 

 open mouth the latter can be so shaped as to give a powerful 

 resonance ; but I believe it is not known that the mouth for any 

 sound (above about middle C to/"' or^'") is able to give a very 

 distinct resonance. 



Further experiments showed me that not only can the primes 

 of notes within this limit be heard, but that any of these sounds 

 are very clearly heard when they are upper partials of low notes. 



This can be tested at the harmonium. Holding down, say, G 

 on the first line of the bass, tlie third and foUowmg partials up 

 to about the fifteenth, can be most clearly heard. The same 

 held good when I experimented with men's and boys' voices. 



But the most striking results were obtained at the organ. 

 Holding the low C of the 8 ft. trumpet, the partials from ? to 

 f if were most bright and clear. Other stops, according to their 

 several qualities, yielded corresponding results. I tried in vain 

 however to obtain resonance for a differential and summational 

 tone. 



When the upper partials of a compound sound are generated 

 in the mouth, the sounds are so near that with careful adjustment 

 beats come out very clearly. 



It is well however to observe that the force or weakness of any 

 single sound thus obtained depends greatly upon the distance 

 from the source. John Naylor 



Scarborough, May 13 



Suggestion Relating to the Kew Standard 

 Thermometers 



I SHOULD like to suggest, through your columns, two slight 

 changes in the manufacture of the Kew standard thermometers, 

 which I think will commend themselves to a:iy observers who 

 often have occasion to use these beautiful instruments. 



I. The calibrating chamber at the top of the therm .meter is 

 now made as in the figure, where c ab\s the capillary column 

 which expands at a into the calibrating chamber. Instead of 

 being rounded off at d the capillary column is continued a -hort 

 distance to b. This causes serious inconvenience in the trans- 

 portation of the instrument, or in its cahbration, because a small 

 particle of mercury readily detaches itself from that in the 

 chamber a, and once in b with a cushion of air between it and 

 the remainder of the column, nothing but heat will dislodge it. 



It does not require very great skiU on the part of the glass- 

 blower to form the chamber a by means of the pressure of the 



mercury itself against the walls of the capillary column. The glass- 

 blower, as is perhaps well known, can soften the finished tube at 

 a, and while the glass is in this condition the gentle application of 

 the flame to the bulb will force the mercury into the part at a, 

 and the careful application of both flames w ill then form a pear- 

 shaped cavity of a form which will not retain a particle of 

 mercury, and is exceedingly convenient in use. 



2. It is often desirable to hang these thermometers in a com- 

 parator or other place, and it would facihtate this if a glass ring 

 were attached to the upper end, as is the case with the ordinary 

 chemical thermometers. It is to be observed that the plane of 

 this ring should be parallel to the enamelling in the tube. 



It is often convenient to know the kind of glass used i 1 the 



