December 12, 1901J 



NA TURE 



129 



some definite knowledge of their origin and so throw fresh light 

 on the whole problem. C. T. Whitmell. 



Leeds, November 23. 



P.S. — For sunrise {in accordance with p. 57) I take the tip of 

 the visible sun to be 2' above the local horizon. 



Change of Pitch in certain Sounds with Distance. 



Skverai. years ago the late Prebendary Simpson, of Fittle- 

 worlh, Sussex, told me of an interesting observation he had 

 made, which some of your readers may be able to explain. 

 While walking up and down the platform of a railway station, 

 he noticed a peculiarity in the sound of a steam jet from an 

 engine standing on the lines. The pitch of the sound appeared 

 to rise as he retreated from the engine and to fall as he drew 

 near to it. Some time after, Mr. Simpson observed the same 

 thing again, but in this instance the noise was made by a gas 

 flare in the open air, about which some men were at work. 

 Since then I have found that this alteration of pitch with 

 distance occurs with any fizzing noise of the kind, such as that 

 of air jets, burning logs, frying fat, pouring rice or coffee beans, 

 waterfalls, or even the rustling leaves of a single tree ; with all 

 those noises, in fact, whose sources are sufficiently localised to 

 admit of observations of the kind being made. I found, also, 

 on withdrawing from such a source that a point is reached after 

 which the pitch ceases to rise, and remains practically stationary 

 as far onward as the sound continues audible. This point is 

 sometimes pretty definitely marked, and varies in distance from 

 the source with different sounds, and the pitch of the stationary 

 portion also varies in the same way. I do not think, however, 

 that the pitch of the whole volume of sound changes, though it 

 often appears to do so, tor a similar impression is created by 

 moving a fizzing air jet to and fro close to a wall. As it nears 

 the wall, the whole sound seems gradually to rise in pitch and 

 to sink again as the jet is withdrawn. But here the efi'ect 

 is clearly due to successive reinforcement of one part of 

 the noise after another in the order of their wave-lengths. 

 r. is only a shifting of the point of greatest intensity, and not 

 an actual change of pitch at all. Assuming, then, that the effect 

 noticed by Mr. Simpson is of the same nature, that is to say, 

 caused by a readjustment of the relative intensity of the parts, 

 how is it to be accounted for ? Is it simply a process of sifting 

 by distance, the weaker groups of small noises, of which the 

 fizzing sound is composed, dropping out of earshot in succession, 

 as the observer retires from the source, till only the largest and 

 loudest group is left, which last continues to be heard for the 

 remainder of the distance without sensible change of pitch ? 

 If that is so, then the deeper tones of such noises vvould seem 

 to have a proportionally shorter range of audibility than the 

 higher ones ; for, so far as I have observed, the pitch always 

 sinks on approach to the source and rises on withdrawal from 

 it, never the reverse way, as might be expected in the case of 

 very bass roaring sounds. Perhaps, however, others may have 

 noticed instances of the latter sort. The behaviour of the air- 

 jet fizz at the wall illustrates a kind of reciprocal action, which 

 no doubt plays an important part in the adjustment of the pitch. 

 The tone which is loudest for the moment appears to dominate 

 and obscure the rest, so that, near the source, where the deeper 

 tones are most powerful, these latter, to some extent, subdue 

 and lower the principal one, while further off, where they 

 become enfeebled by distance, they are in their turn still more 

 diminished by the presence of the principal far-reaching tone. 



Downshire Square, Reading. Frederick M. \Vp:st. 



Pine Grosbeak in Berkshire. 



Is it not of rare occurrence that a pine grosbeak {/)'/v^«/(Z 

 t-nttt-Uator) has been seen here, not on one day, but on two ? 

 I was informed this morning that Mr. O. T. Perkins had seen 

 this handsome bird out of his window, apparently either easing 

 beech buds or else hunting for insects on them. During this the 

 bird was attacked by three sparrows, who began making a great 

 noise and eventually drove him off. This morning I saw' the same 

 grosbeak, or another one, in a like manner feeding on beech. And 

 what is more strange he was again attacked by sparrows and 

 had to beat a hasty retreat. I may add that the bird, to all ap- 

 pearances, was in excellent condition, its plumage being brilliant. 

 I wonder if any other of your readers have noticed any of 

 these handsome but rare birds ? C. M. Rogers. 



P.lucher, Wellington College, Berks. 



THE "ARMORL" ELECTRO-CAPILLARY 

 RELA Y. 



Al rE commented in our notes columns a short time 

 '' ' ago upon the announcement that a new system of 

 wireless telegraphy had been worked out by Messrs. 

 Orling and Armstrong. From what could be gathered 

 from the information at that time available we judged 

 that the method made use of earth conduction ; we have 

 since learned that this is the case and that the inventors 

 rely upon the novel design of their transmitting and 

 receiving apparatus for the efficiency of their results. 

 We have had an opportunity of inspecting drawings of 

 the receiving apparatus, and are enabled to give a 

 description of it, though we have not seen the actual 

 apparatus itself, but only a working model. We under- 

 stand that it is proposed to read a paper shortly on 

 the transmitter before one of the scientific societies and 

 that in consequence it is not desired to publish the 

 details of its construction as yet. It is to be hoped that 



Flc. I. — "Armorl" Electro-capillary Relay. Syphon form. 



at the same time an account will be given of the experi- 

 mental results obtained, with trustworthy data from which 

 the probable value of the invention may be gauged, for 

 as yet there is nothing to go upon but the statements of 

 the inventors. 



In the meantime we must content ourselves with giving 

 a description of the receiver, which is of interest inde- 

 pendently of its use with the Orling-Armstrong or any 

 other wireless telegraph, as it could be used for the 

 detection of any sort of electrical current. The instru- 

 ment consists essentially of a capillary electrometer 

 which is arranged so that it can actuate a relay. The 

 extreme sensitiveness of the capillary electrometer for 

 very small currents and low electromotive forces is welt 

 known, and the instrument is used considerably, especially 

 for physiological work. The arrangement adopted in 

 the present mstance is shown in Fig. i. A syphon,/, is 



NO. 1676. VOL. 65J 



