244 



NA TURE 



[July i i, 189- 



ol>serve<i. With a great many observalinns ihe anticyclonic 

 inflow can be lirought out by a system of averaging, as shi»\vn in 

 the Ameriian MiUorologiial Jcuriuxl iot August 1S93. 



H.HeI.M Cl-AYTOX. 

 Blue Hill Meteorological Observaton'. lune i". 



EfTects of a Lightning Flash in Ben Nevis Observatory. 



Whenever a thunderstorm passes the summit of the Ben, 

 there occurs almost invariably a discharge from metallic bodies in 

 the Obser\atory, as the cloud is |iassing away. K Hash of greater 

 or less extent is given off the stoves, accomivanied by a sharp 

 crack. In January 1S90 there was an exceptionally severe 

 flash; " one of the observers was almost knocked down when 

 sitting writing, and the telegraph wire was fused, and all com- 

 munication stop|x*d for five days." But more destructive than 

 any previous flash was that which occurred this year on June 19, 

 when the Observatory narrowly escaped being ilestroyed by fire. 

 Between two and three o'clock on that .afternoon, rejwated 

 clicks on the telegraph instrument were heard by one of the 

 assistants who was sitting in the oftice : he had been carefully 

 noting the times at which the clicks occurred, when suddenly 

 the whole office was filled with a brilliant flash and deafening 

 roar. A pillar of smoke was discharged from the telegraph 

 instrument and from the stove|)ipe, filling the room. So severe 

 was the flash that the .assistant, who w,as quite deafened by the 

 repirl, thought that his hair had been singed. \ second slighter 

 discharge took place immediately after, when the writer had 

 entered the ofiice to commence the fifteen hours observations. 

 The discharge hurled two Ixixcs and a small picture, that were in 

 the vicinity of the lightning protector, across the kitchen, and 

 blew off the button and outer casement of the electric bell in the 

 visitors' room. The solder on the kitchen cliimney outside, a 

 copper fastening of the lightning conduct<5r, and many portions 

 of the telegraphic wire and apparatus were fused, and the wood- 

 work of the OI)ser\atory was scorched in several i)laces. The 

 great flash occurred at 14 hours 57A minutes, and the hourly 

 barometric reading wa_s taken at 15 hours, as usual. There was 

 a very heavy fall of snow at the time, equivalent to 0^470 inches 

 of rainfall for the hour, but in the confusion the writer omitted to 

 take the rain-gauge with him, and had to return for it. This w.is 

 a fortunate incident ; for it was only on leaving the oflice for a 

 second time, that he observed smoke and flame issuing from be- 

 hind the panelling between the kitchen and the office. Assistance 

 was secured, and the fire — which was in a very awkward and 

 <langerous place — was overcome in good time, and the dam-tge 

 done was very slight. 



The damage done to the telegraphic apparatus, however, was 

 serious, and Mr. Crompton, engineer of the Post Office tele- 

 graphs, has supplied me with the following inform.ation. 



The lightning protector w.xs badly fused, the plates showing 

 a patch of fusion as large as a sixpence. This saved the cable 

 from serious damage. .\ll connecting wires within Ihe building 

 were rendered useless. The majority were so heated as to melt 

 the insulation off. and, in one or twocases, the copper conductors 

 were melted by the discharge. In one case, the fusion set fire 

 to the wfKMlwork. 



The coils of Nealc's .sounder were fused and rendered useless. 

 The keys suffered worst of all, the left pedal or "tapper" 

 bearing Ihe strongest evidence of the severity of the discharge. 

 The Ijack contact (platinum), the brass extension holding the 

 >ame, and the steel spring (plalinum-lipped) above, all being 

 fused into one solid ainalgam. The pillar, to which the zinc 

 le.vling wire from the battery was connected, had a large p.ilch 

 of fusion near its base, and the front platinum contacts of the 

 same (left-hand) pedal were consumed entirely. There were 

 small traces r)f fusion on the right pedal, but of a trifling 

 character. The line wire connected to the left-hand terminal 

 of the coil had Ixien fused close to the terminal. The interior of 

 t*^ ■ nt c.Tse was considerably blackened, as also the 



r 'H of the keys, as a result of the "arc" caused by 



li ^'- at the moment of fusion. 



The vacuum protector at .Aslimtee, the l)a.se of the cable, also 

 Ihe plate protector in Kort William I'ost f )fficc, were fused, but 

 only slightly, the main discharge having expended itself on Ihe 

 summit. The I^w I^vel Oljservalory instrument and protector 

 were uniin|i.iired, and crmimunication lielwcen there an<l Fori 

 William \'><-\ < )llicc ».vs carried on as usual after the removal of 

 the fault in the Tost Office protector. 



The registering aneroid shows a slight upward kick at the 



NO. 1341. VOL. 52] 



time, but the curve is otherwise fairly ste.idy : the temper.uuif 

 was 317 1"., Ihe wind south-south-east and light. Heavy snow 

 was falling at the time, which, with a fall on the 17th. made a 

 total depth of nine inches on the summit. St. Klmo's Fire wa^ 

 very strongly felt and heard until after seventeen hours. 



Wii.i.iAM S. Brick. 



The Kinetic Theory of Gases. 



It seems to me that Mr. Hurbury's and Trof. Bolt/man n';. 

 last letters will enable us to reconcile all the main differences 

 of opinion which were brought to light in our recent corre- 

 spondence in the columns of X ATI' RE. From Prof. Boll/mann's 

 letter it appears that the Minimum Theorem can only be applied 

 with absolute certainty to gases whose molecules are not toi> 

 closely crowded together. Thus the proof that an aggregation 

 of molecules tends io/;/(';/ho/m/|' towards the Boltzmann- Maxwell 

 distribution dependsquite as much on assumptions as to the mixing 

 of the molecules between collisions as on consideration of whai 

 happens al collisions. We cannot prove for certain thai 

 densely crowded assemblages of molecules such as solids an<l 

 liquids tend to .assume this distribution, .ind this is just as ii 

 should be, for when a substance is capable of existing sinuil 

 laneously in two states, the distiitnition cannot be unique. For 

 Ihe same reason the proof does not a]jply to molecules movini; 

 about in a continuous medium such as the ether. So far from 

 this limitation being a weak point in the proof, it precludes th\ 

 theorem from proving too much, or from leading to resulu 

 which may nol accord with experience. 



If we do not know that solids and liquids satisfy the Boltz- 

 mann-. Maxwell distribution, we, nevertheless, know thai they are 

 subject to the Second l^w of Thermodynamics. It cannot be 

 said that any dynamical " proof of the .Second Law" that has 

 yet been given, is so conclusive as the mere statement of the 

 Law itself, but the proof of the Minimum Theorem subject to 

 " Condition (.\) " le.ads to a result somewhat analogous to the 

 statement that when two or more bodies al unequal temperature 

 are brought into thermal contact, their entropy tends lo increase. 

 For let the probability of the coordinates on momenta of the 

 molecules of one body lying between certain limits be pro- 

 portional to F (i!//the coordinates and moiuenla lieiiig included 

 in the nuilliple difterential by which F is multiplied). Let the 

 corresponding jMobabilily for a second body be |)r<>portional to /'. 

 Then when the two bodies are jilaced in thermal contact, we 

 know of no relation connecting the Iwd simultaneous prob- 

 aliilities, and we may therefore assume them to be independent, 

 so that condition (.\) is satisfied, al any rate initially. The 

 theorem then asserts Ihat al all subsequent instants of time, the 

 value of the Minimum Function will be not greater than it.s 

 initial value, and therefore it either remains stationary or 

 decreases every time the process is repeated. Thus ftir we can 

 get if no further. 



The application of the Second I^w dejiends largely on the 

 distinction lietween availahle and unavailable energy. When 

 we construct a thermodynamic engine for converting heat into 

 work, we introduce just the kind of external disturbances that 

 Mr. Hurbury requires every time that the " working substance" 

 is placed in contact with either the "source" or the 

 refrigerator." C. 11. Brvan. 



An Abnormal Rose. 



I HAVE in my garden al Keigale a -.vhite Mo.ss rose-tree, every 

 blos.soni on which is white except one which is half white and 

 half red, divideil iliametrically in nearly eipial portions. 



The colours are nol shaded one into the other, but are per- 

 fectly distinct, and one petal is half red and half white, the edge 

 of Ihe colouration being cjuite sharp. 



I am told lhat one similar blo.ssom was produced earlier in ihe 

 season. 



I imagine this is an attempt to revert to its ancestral colour, 

 but by what mechanism such a partial result has been accom- 

 pli.shcd seems diflicull to understand. 



Newmiam Hrowne. 



TilKKE are several varieties of rose that sport or revert in the 

 manner described by Mr. Ncwnham Browne. The " York and 

 Lancaster" rose is a familiar exauqile. In this, ihe recognised 

 or genuine condition is red and white slripud ; but the proporlioiis 

 of white and red are rarely exactly the same in any two flower* 



