May^, 1 88 1 J 



NATURE 



5 



the thermometer rose to o", but nroer exceeded that point ; when 

 not, the bulb of the thermometer, by the voIatiUsing of the ice, 

 was partly laid bare. As it appears by the detailed description 

 of Dr. Carnelley's experiments in Nature, vol. xxiii. p. 341, 

 that the success depends for a great part on the size of the 

 condenser, we have made another apparatus with a condenser of 

 half a litre ; the results we may obtain therewith will be related 

 shortly. 



We have also made some experiments on naphthalene. The 

 pressure of the naphthalene vapour at the melting-point, nearly 

 80°, being ±9 mm., as was found by a preliminary proof, it 

 was expected that it would not be very diflicult to obtain and 

 to maintain a vacuum sufficient to observe the demeanour of 

 naphthalene under similar circumstances as ice. The apparatus 

 we used resembles in its principal features that we made use of 

 in experimenting on ice ; alone, the condensing surface was 

 much greater. The thermometer bulb being imbedded in a 

 cylinder of pure naphthalene 13 mm. in diameter, the thermo- 

 meter was fixed in the axis of the gla^^s tube, and this latter 

 drawn out. A small quantity of «ater being brought in the 

 tube, the pressure was reduced by means of an ordinary air- 

 pump to 5 mm., and the drawn-out end of the tube melted 

 through. In another instance the tube was several times filled 

 with carefully-dried carbonic acid and exhausted, and lastly, 

 when the pressure had been reduced to 7 mm., sealed. To 

 remove the remaining carbonic acid and aqueous vapour a cer- 

 tain quantity of caustic potash and some pieces of oxide of 

 calcium were inclosed in the tube. In what manner the tube 

 had been prepared, the results when heat was applied, the upper 

 part of the tube being cooled in a freezing-mixture or simply in 

 snow, were always the same. The thermometer rose very 

 rapidly to about 79°, and stayed at that point as long as no part 

 of the thermometer bulb was denuded of naphthalene. At the 

 same time the naphthalene sublimed very regularly, covering the 

 sides of the tube next to the heated part with a beautiful layer 

 of naphthalene crystals. 



C. J. E. Brutei. de la RiVlfeRE 

 A. VAN Hasselt 



Assen (Netherlands), April 14 



Sound of the Aurora 



The interesting communications which have lately appeared 

 in your periodical regarding the supposed connection between 

 "sound" and the "aurora" (Nature, vol. xxiii. pp. 4S4, 529, 

 556), lead me to suppose that the following notes may be con- 

 sidered by you and your readers worthy of record. They were 

 copied la^t autumn by myself from the Strangers' or Visitors' 

 Book at the Hotel on the ^-Eggischorn, and bore the date July 10, 

 1863 :— 



"Visit to the Col de la Jungfrau described: On descent 

 surrounded by thunderclouds evidently charged with electricity. 

 At 12.15 a sound similar to that made by a boiling kettle was 

 heard to issue from one of the alpenstocks, and very soon a 

 similar sound issued from all the batons. On shaking the hands 

 similar sounds issued from the fingers. Observing that the veil 

 of one of the party stood upright on his hat, one of the gentle- 

 men and one of the guides, v;ho had experienced prickly sensa- 

 tions on the crown of the head, removed their hats, when their 

 hair stood up as if under a powerful electrical machine. When- 

 ever there was a peal of thunder all of the phenomena ceased, 

 to be speedily renewed when the peal w as over. At such times 

 all the members of the party felt severe shocks in the parts of 

 the body which were most affected ; and one gentleman had his 

 right arm paralysed and rendered useless for several minutes. 

 The clouds passed away and the phenomena finally ceased at 

 12.30. The guides with us were Joseph Marie Claret of 

 Chamouni, and Smith of this house, and they were as much 

 affected by the electricity as we were. At the top of the Col 

 the aneroid barometer stood at iS"S3." 



I believe the above statement, clear and pointed as it is, was 

 signed by the names of Watson, Sowerby, and Adams. 



It will te seen that other phenomena are mentioned, in 

 addition to the founds heard in connection with the electrical 

 ones, which are worthy of regard. I would, among other 

 points, draw attention to the effect produced on the arm of one 

 of the travellers, and should be glad to know from any of your 

 correspondents whether they have met with other like results of 

 electrical interference with the actions of muscles in mountain 

 trivelling. 



I may mention in passing that in the same Visitors' Book at 

 the .Eggischorn Inn I found notes to the effect that the Jungfrau 

 and the Alefschorn were first ascended by a lady in August of 

 the year 1863. JOHN W. Ogle 



30, Cavendish Square, W. 



A PRESU.MPTION as to the irue character of the sound of the 

 aurora is perhaps offered by the fact that to many persons a flash 

 of lightning is accompanied by a distinct -cuhishiiig sound. As 

 this is simultaneous with the flash, and therefore evidently sub- 

 jective, it fcems to offer evidence merely of the close connection 

 existing be tween the senses of seeing and hearing. 



April 30 E. Hubbard 



Symbolical Logic 

 In my recent letter on Symbolical Logic (see Nature, 

 vol. xxiii. p. 578) I said that Prof. Peirce's symbol of in- 

 clusion, as defined by him in his "Logic of Relatives," was 

 equivalent to the words "is not greater than." This how- 

 ever is not quite correct ; for though Prof. Peirce speaks 

 of this symbol as equivalent to the words " is as small 

 as," he also speaks of it as denoting " inclusion," and his 

 illustration / — < in may be read. The class f is included 

 in the class m. In my notation the analogous composite 

 symbol / : tn may be read. The statement f implies the statement 

 m. If for/in my notation we read lie belongs to the class f, 

 and for m we read He belongs to the class m, then my/: m will 

 coincide in meaning with Prof. Peirce's/— < m ; but this does 

 not alter the fact that my /differs in meaning from his/ that 

 my : differs from his — <, and my m from his ///. Mr. Venn, 

 in his recent paper in the Proceedings of the Cambridge Philo- 

 sophical Society, speaks of these distinguishing features of my 

 method as unimportant, and he regards my definitions of my 

 elementar)' symbols as "arbitrary restrictions of the full gene- 

 rality of our symbolic language." But Mr. Venn overlooks the 

 fact that all accurate definitions are more or less arbitrary 

 restrictions of language, and he also seems to me, in this parti- 

 cular case, to mi-take vagueness for generality. Philosophical 

 investigations that begin with Let x = anything commonly end 

 with X = anything, a result which, whatever may be thought of 

 its generality, does not add much to our knowledge. 



Hugh McColl 

 ^ 73, Rue Siblequin, Boulogne-sur-Mer, April 26 



The Formation of Cumuli 



This afternoon the air to a great distance above the surface of 

 the 'earth has been filled with fluttering dry leaves. For some 

 weeks no rain has fallen in this vicinity, and a cold northerly 

 wind has prevailed. To day, for the first time during the con- 

 tinuance of this cold and rather clear weather, the hill-sides 

 having a southern exposure have begun to be sufficiently warmed 

 to cause upward currents of air along their rurface. The effect 

 has been curious : piles of cumuli have formed persistently in 

 certain quarters of the sky, and eddying masses of leaves caught 

 up along the hill-sides have been falling apparently from the 

 under surface of the dense masses of cloud. My attention w^as 

 first caught by the fall of che.-tnut and other varieties of leaves, 

 which must have traversed a long distance, as there are no trees 

 of the sort near at hand in the direction from which the w md 

 was blowing at the time. Whilst walking near an elevated 

 ridge of ground an hour later it was my fortune to catch sight of 

 a thick mass of leaves rushing directly up its side and pouring 

 apparently into the bosom of a dark cloud which overhung the 

 hill. This cloud remained almost stationary, .nlthough there 

 appeared to be a lively breeze along its under surface, the leaves 

 darting forward very swiftly. The entire phenomenon was quite 

 interesting as affording an illustration of the method of forma- 

 tion of clouds of the variety named. JL A. Veeder 



Lyons, New Vork, March 20 



"The Oldest Ocean Post Office" 

 In Nature, vol. xxiii. p. 254, ju-t received here, it is stated 

 that in Magellan Straits there has been for some years past, 

 chained to a rock there, a barrel from which passmg ships take 

 letters for the direction they are going in, leaving others for the 

 opposite quarter ; it is added that up to the present no abuse ot 

 the privileges of this primiiive po-t-office has been reported. 



