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I'llVSIC^ AT TlIK BrII'ISII Assik 1a IION. — In 

 ii-fLTrint; In I'hysiis in his fKK|in-nl I'resiileniial 

 addiiss. Professor Sir Michael hosier ren>in<le(l us 

 ihiit ihe year 179() saw Volla's far reachinj; discovery, 

 ihal electricity could lie produceil liy llie simple con- 

 lad of iwo rnetals. Il was only then that modern 

 clectriciiv, vast as now are its applications, had its 

 hirlh. After X'olla, came in iSio, ( )ersled, showing 

 the reniarkahle relations of i-leclticity to magnetism : 

 whence, I iv the laliours of the many illustrious physicists 

 of the present century, has the knowledj^e of electricity 

 advanced hy leaps an<l hounds, into the supreme 

 position it now occupies. .\s Sir Michael Foster 

 said : " Those early ideas developini; durin;.; the years 

 of rest of the century with an ever acccleratini; swift- 

 ness, have wholly changed man's material relations to 

 the circumstances of life, and at the same time carried 

 him far in his knowledge of the rature of things." 

 Professor I'oynting's presidential address to the 

 Mathemttical and Physical section, w.as also a hril- 

 liant resume of the thoughts of .scientific minds, during 

 ;he present century. I'sing an old metaphor, the 

 physicist, he said, is examining the garment ol nature, 

 learning of how many, or rather, of how few, diffeienl 

 kinds of ihreails it is woven, finding how each 

 -eparate thread enters into the pattern, and .seeking 

 from the pattern woven in the past, to know the pat- 

 tern yet to come. So far, we have recognised some 

 eight or nine threads of nature, the.se heing the 

 difl'erent lorms of energy which we are still ohliged to 

 count as distinct. Coming to the constitution of 

 matter. Professor Poynting dilated upon the atomic 

 and molecular hypothesis. •' I'or ages this hypothesis 

 hardly went further than to explain the phenomena of 

 ccmlraction and expansion, and of solution, . . . 

 while light was regarded as corpuscular, the molecular 

 hypothesis served as the one foundation for the 

 mechanical representation of phenomena. When, 

 however, it was shown that infinitely the best account 

 of the properties of light could be given on the .s\ip. 

 position that it consisted of waves, .something was 

 needed to wave, both in the interstellar and in the 

 inlerniolecular spaces. So the hypothesis of an ether 

 was developed, a necessary complement of that form 

 of the molecular hypothesis in which matter consists 

 of discrete panicles with matter-free intervening 

 spaces." What, however, constitutes ether, and 

 what atoms? Many theories have been brought for- 

 ward, but Lord Kelvin's vortex-atom theory gives us 

 the simplest. I lere all space is filled with continuous 

 lluid, and the atoms are mere loci of a particular type 

 .f motion of this frictionless fluid. Where there are 

 w hirls, we call the lluid ntatier : where there are no 

 whirls, we c:ill it ether. .\ similar simplification is 

 given by Dr. Larmor's hypolhcsis, in which .again, 

 all space is filled with continuous substance, all of one 

 kind, but this time .solid rather than fiuid. Tlieatoms 

 are loci of strain instead of whirls, and the ether is 

 that which is strained. These two delightful addres.ses 

 should be read in exlenso. They are very exhilarating 

 and more interesting to the general scientific mind 

 than is sometimes the case. Reference will be made 



iKAi month of the other Physics work done at the 

 meeting. 



l<KSIi)KAT|i«\ iiK P||OII)i:KAI'HII' I'l.ATBS.— .Soille 

 I. lent experiments have been made, ba.sed upon an 

 ■liservation recoriled by Professor luucrson Keyiiolds, 

 lo the elVect that when an exposed unileveloped 

 photographic plate was siibmitteil lo the action of 

 ozone, the image could not be developed, but that the 

 plate was available for re-ex|)<)sure. If ozone is thus 

 able to destroy a latent image, il was thought that it 

 should be able to restore a fogged plate, the assump- 

 tion being that ozinc oxi<lises the silver compounds, 

 which light has reduced. Two dry plates were 

 wrapped one half of each in tinfoil, and then exposed 

 to brilliant sunlight for two .seconds. They were then 

 taken into the dark room an<l ozoni.sed for four minutes. 

 Thev were then used, with the tinfoil removed, to 

 obtain a radiograph. The image was visible on the 

 whole surface: the two halves of the plate were, 

 however, not ei|ually tiansparent. These experiments 

 should prove very iiseful at limes to photographers, 

 who find they have a batch of fi>gged plates to 

 deal w ith, for it is so easy now-a-days to obtain ozone, 

 either from an electrical machine or from a proper ozone 

 tube. 



l';i.Kc run AIJ.V Ol'KKAIIili UkaUIiKII'i.I.-. .\ 

 verv successful electrical engineering feat was accom- 

 plished in electrically operating a 450 ton drawbridge 

 over the Pa.ssiiic River in .\merica. The draw- 

 bridge was opened in I'ebruary, 189S, and h.TS 

 given entire satisfaction. The contr.actors were 

 reipiired to fiiriiish power which would open or close 

 the bridge in thirty seconds, this power not 10 

 be available until the wedges and locking device had 

 been withdrawn. Further the wedging and closing 

 arrangements were to be automatically cut ofl', so they 

 could not be used till the bridge was closed. These 

 conditions have been successfully met, and the bridge 

 operated by three unskilled men, on their regular 

 trips. The conditions laid down to the contractors 

 necessitated intricate electrical circuits for working 

 contact shoes, wedges and other devices. They 

 are all, nevertheless, held under perfect control. The 

 drawbridge structure is 720fl. long, while the 

 draw proper is 227fi. in length and 67ft. wide. 

 Il is suggested that the numerous bridges clo.se 

 10 one another over the Harlem River in \.\'. City, 

 should be electrically operated from one central 

 electrical station which would radiate power and 

 precede a ship in its passage through the .successive 

 draws. .\ll the bridges could then in turn be 

 worked from the one source— which need not 

 then be capable of generating more power than is 

 necessary for one structure. 



MlvTKORdl.diilCAl. AN1> MAGNETIC PllKNOMKNA. 

 — There seems to be some common cause which rules 

 the various meteorological and magnetic phenomena 

 observed in I'.urope, and which influences them all in 

 a similar way and almost simultaneously. Nunieious 

 ob.servations have now been recorded of the annual 

 range of temperature, the rainfall, the barometric 

 pressure ami also the magnetic elements, viz.. 

 horizontal force, declination and the vertical force. 

 Curves of all the.se observations have been plotted 

 and a marked simi'ariiy has been found between 

 them. I'Vom a consideration of the temperature 

 curves for the various stations in Kurope, particularly 

 of the minimum in June and the maximum in July, it 

 is conclude<l that the former is due to some disturbing 

 cause travelling from the West Coast of Scotlantl 

 southwards, and that the latter appears to be due 

 to a .similar disturbance approaching F^urope from the 

 South. 



