35-5 



NATURE 



{August I, 1878 



clear and thoroughly appreciative description of Edison's carbon 

 telephone, and published it in the printed reports of his lecture 

 which appeared in the public journals. The beautiful results 

 shown since the beginning of the present year by Mr. Hughes 

 with his microphone were described by himself in such 

 a manner as to leave no doubt but that he had worked them 

 out quite independently, and that he had not the slightest inten- 

 tion of appropriating any credit due to Mr. Edison, It does 

 seem to me that Jthe physical principle used by Edison in his 

 carbon telephone and by Hughes in the microphone is one and 

 the same, and that it is the same as that used by M. Clerac, of 

 the French " Administi-ation des Lignes Telegfraphiques," in the 

 "variable resistance carbon tubes," which he had given to Mr. 

 Hughes and others for important practical applications as early 

 as 1 866, and that it depends entirely on the fact long ago pointed 

 out by Du Moncel, that increase of pressure between two con- 

 ductors in contact produces diminution of electric resistance 

 between them. 



I cannot but think that Mr. Edison will see that he has let 

 liimself be hurried into an injustice, and that he will therefore 

 not rest until he retracts his accusations of bad faith publicly 

 and amply as he made them. William Thomson 



Yacht Lalla Rookh, Cowe?, July 30 



It may be of interest at the present time to recall the fact that 

 the word "microphone" was first employed by Sir Chas. 

 Wheatstone upwards of fifty years ago. In a paper entitled 

 " Experiments on Audition," published in the Quarterly Journal 

 of Science for 1827, Wheatstone remarks : — " The great intensity 

 with which sound is transmitted by solid rods at the same time 

 that its diffusion is prevented affords a ready means of effecting 

 this purpose [augmenting the loudness of external sounds], and 

 of constructing an instrument which from its rendering audible 

 the weakest sounds may with propriety be named a microphone." 

 As the original paper may not be readily accessible, an extract 

 from it is appended to this letter, wherein will be found a 

 description of the simple arrangement proposed by Wheatstone — 

 it is in fact a metallic binaural stethoscope — together with some 

 experiments with the instrument given by the author. The 

 ■entire paper will appear in the republication of Wheatstone's 

 scientific papers, which the Physical Society will shortly issue, 

 and the instrument itself can be obtained for a trifling sum from 

 Mr. Yeates, of King Street, Covent Garden. 



Monlcstown, Dublin, July 29 W. F. Barrett 



"Procure two flat pieces of plated metal, each sufficiently 

 large to cover the external ear, to the form also of which they 

 may be adapted ; on the outside of each plate, directly opposite 

 the meatus, rivet a rod of iron or brass wire about 16 inches in 

 length, and one-eighth of an inch in diameter, and fasten the 

 two rods together at their unfixed extremities, so as to meet in a 

 single point. 



The rods must be so curved, that when the plates are applied to 

 the ears, each rod may at one end be per- 

 pendicularly inserted into its corresponding 

 plate, and at the other end may meet before 

 the head in the plane of the medial line. 



The spring of the rods will be sufficient 

 to fix the plates to the ears ; but for greater 

 security ribands may be attached to each 

 rod near its insertion in the plate, and be 

 tied behind the head. A more simple in- 

 strument may be constructed to be applied 

 to one ear only, by inserting a straight rod 

 perpendicularly into a similar plate to those 

 described above. 



The microphone is calculated only for 

 hearing sounds when it is in immediate con- 

 tact with sonorous bodies ; when they are 

 diffiised by their transmission through the air this instrument will 

 not afford the slightest assistance. It is not my intention in this 

 place to detail all the various experiments which may be made 

 with this instrument; a few will suffice to enable the experi- 

 menter to vary them at his pleasure : — 



1. If a bell be rung in a vessel of water and the point of the 

 microphone be placed in the water at different distances from 

 the bell, the difference of intensity will be very sensible. 



2. If the point of the microphone be applied to the sides of a 

 vessel contaming a boiling liquid, or if it be placed in the liquid 



Wheatstone's micro- 

 phone, 1827. 



itself, the various sounds which are rendered may be heard very 

 distinctly. 



3. The instrument affords a means of ascertaining, with con- 

 siderable accuracy, the points of a sonorous body at which the 

 intensity of vibration is the greatest or least ; thus, placing its 

 point on different parts of the sounding-board of a violin or 

 guitar whilst one of its strings is in vibration, the points of 

 greatest and least vibration are easily distinguished. 



4. If the stem of a sounding tuning-fork be brought in contact 

 with any part of the microphone, and at the same time a musical 

 sound be produced by the voice, the most uninitiated ear will be 

 able to perceive the consonance or dissonance of the two 

 sounds ; the roughness of discords and the beatings of imperfect 

 consonances are thereby rendered so extremely disagreeable, and 

 form so evident a contrast to the agreeable harmony and smooth- 

 ness of two perfectly consonant sounds, that it is impossible that 

 they can be confounded." — Quarterly Journal of Science, 1827, 

 Part II. 



The Meteor Shower of Aquarids (July) 



On July 27 ninety-three shooting stars were seen here, be- 

 tween loh. 30m. and I4h. 30m., which, after making allowance 

 for time occupied in charting the paths, is equivalent to about 

 twenty-nine per hour for one observer. There was a rich 

 shower of Aquarids from a point near /it Aquarii, at R.A. 343°, 

 14° S. declination, which gave twenty-two meteors. These 

 were rather bright, not very swift, with moderately long paths 

 (averaging 17°), and quite devoid of streaks. I had seen about 

 five meteors of this system on the preceding night, and on the 

 28th I watched a very hazy condition of sky — in which the stars 

 shone dimly — for four hours, and of forty-four meteors seen five 

 or six others were Aquarids. This active shower was well seen 

 by Capt. Tupman on July 27, 1870, with an accurately-defined 

 radiant at 340° — 14°, from fourteen meteors (see No. 43 of his 

 catalogue), and on the four following nights he traced about 

 forty-seven others from the same shower, though the centre 

 seemed a little further south, at 340° — 19° on the 28th. On the 

 27th he recorded seven meteors of this stream within the twenty- 

 one minutes, from I4h. 3m. to I4h. 24m. It was also seen by 

 me, at 342° — 12° (ten meteors), on August 3-17 last year; and 

 Schmidt gives radiants at 337° — ii° for July 20-31, and at 

 344° — 1 1° for August. Neumayer, in the southern hemisphere, 

 also has a position at 337° — 10° (July), and Heis at 339° — 10° 

 for July 27-31. The average centre from these eight indepen- 

 dent determinations is at 340° — 13° for this important shower, 

 which evidently comes to a strong maximum on about July 27- 

 29. The end of July has long been known as a meteor-epoch 

 of considerable intensity, with a maximum, according to 

 Quetelet, between the 27th and 29th, which is thus amply con- 

 firmed by recent observations, and proves these Aquarids to be 

 but little less in importance to the annually-recurring showers of 

 Lyrids, Orionids, Taurids, and Geminids. 



It should be pointed out that, in future observations of this 

 special shower, care must be taken not to confuse it with other 

 contemporary showers in Aquarius. There are two radiants on 

 or near the equator in about R.A. 334° and 349°, and one (of 

 very slow meteors) at about 336° — 6°, also a fourth at 326° — 12° 

 (mean position of five radiants seen by Schmidt and Tupman). 

 They are distinct showers, though separated with difficulty, 

 owing to proximity of position ; and it is interesting to note 

 that, if we average them with the strong radiant at 340° — 13° 

 referred to above, we have a central radiant at 337° — 6°, which 

 coincides exactly with Mr. Greg's position for the Aquarids 

 (Nos. 109 and 137 in his catalogue of 1876), which apparently 

 continue from July 5 to October 31. W. F. Denning 



Ashleydown, Bristol, July 29 



P.S. — My observations were continued on the night of July 30, 

 when seventy -six shooting stars were seen in four hours; thirteen 

 of these were Aquarids, and seven of them visible in the half 

 an hour preceding midnight, after which few were observed. 

 From this I infer that the maximum had probably occurred on 

 the morning of the 30th, when, unfortunately, a thick haze pre- 

 vented work. — W. F. D. 



Physical Science for Artists 



Will you permit me, through your columns, to tell Mr. 

 Abbay^^that thej phenomena — " les rayons de crepuscule " — he 



