26o 



NATURE 



[July A,, 1878 



gilt pith balls by silk fibres and then electrify them with 

 the same electricity. 



If suspended configurations be brought near each other 

 we will cause the vibrations of their component magnets 

 (atoms), and thus we may illustrate the atomic vibrations 

 in molecules. If a suspended configuration be brought 

 in contact with a piece of paper, supported vertically, the 

 interaction of the suspended magnet may force it from the 



vertical, and cause it to fall, and thus may be illustrated 

 the molecular pressure of gases. 



I will here point out the stable and unstable configura- 

 tions. 5fl is more stable than 5^, and da is more stable 

 than db. The latter is sent into da on vibrating it. Zc is 



very unstable Hike . V and goes into %b on vibra- 

 tion, caused by elevating and lowering the superposed 

 magnet. A. M. Mayer 



P.S.' — As to the configuration 



it is so very un- 



stable that I have not reproduced it in these configura- 

 tions, for it is really too unstable to exist except for an 

 instant. 



The hexagon only exists with a central magnet. Mr. 

 C. S. Pierce and I have had several discussions about 



the stability of 



I always have maintained 



that it was impossible to get this form, for a central 

 repellant body was necessary to the tension of the . 

 which is like a soap bubble without cohesion of con- 

 tiguous elements. Seven magnets form only . . . 



.is more stable than . 



ON A REMARKABLE FLASH OF 

 LIGHTNING^ 



r\^ the evening of August 16 last year (1877) a heavy 

 ^-^ thunderstorm took place in this vicinity (South- 

 port). It was preceded by a fall of the barometer not 

 exceding one-tenth of an inch, the wind at i o'clock 

 P.M. being west, backing gradually until at 9 o'clock P.M. 

 It was south. At the time of the storm to which my 

 present observations refer it was south-west, and conse- 



' Addressed to Sir Wm. Thomson. 



■' Paper by B. St. J. B. Jou'e, at the Lit. and PhH. Soc, Manchester. 



quently its direction was nearly parallel with the coast 

 line. 



I was standing at the shore-end of Leicester Street, 

 watching the approach of the storm, and observing the 

 progress and direction of the more important flashes, 

 when about 8 o'clock a vivid flash of lightning fell appa- 

 rently into the channel (the water being not much above 

 low water mark of a neap tide) about one-sixth of a mile 

 north of the end of the pier. In about a minute after- 

 wards another fell about one-sixth of a mile north-east of 

 the previous one, and after a similar interval a third 

 stream of electricity descended about another one-sixth 

 of a mile in the same direction. The first and third 

 flashes were of the usual character of forked lightning, 

 but the second presented an appearance which I do not 

 recollect to have witnessed before. From its exit from 

 the clouds to its fall into the sea it seemed composed of 

 small detached fragments which caused it to assume the 

 aspect depicted below. 



On the following day, in the course of a conversation 

 respecting the storm of the previous evening, I mentioned 

 the phenomenon to Mr. Thistlethwaite, who informed me 

 that he had been particularly struck by the extraordinary 



appearance of this singular flash, which he had observed 

 whilst sitting in the "parsonage" (the house adjoining 

 the south-west side of the Manchester and Liverpool 

 District Bank), and which to him appeared exactly as I 

 have depicted it. This gentleman could, however, have 

 seen the upper portion of the flash only, as the houses in 

 Lord Street and on the Promenade intervened between 

 his point of observation and the shore. 



Heavy rain seemed to follow in the wake of the third 

 flash, and came on with a noise Hke that of a great rush 

 of wind, but as the direction of the storm was nearly 

 coincident with the water-line, inclining but slightly 

 towards the beach, about ten minutes elapsed before the 

 downfall reached the place where I stood. 



From the information I afterwards obtained the thunder- 

 storm was subsequently, a few miles to the north-east of 

 Southport, more severe than it was in Southport itself. 



Southport, March 11 B. St. J. B. Joui.K 



