56 



SCIENCE. 



[Vol. XIV. No. 338 



ing the storm on June 6. Two flashes, seen on one plate, show 

 complicated and beautiful structure : one of them is a multiple 

 flash, and flame-like appendages point upwards from every angle ; 

 the other is a broad ribbon, and, although the plate shows signs of 

 movement, the displacement is not in a direction such as would 

 produce a ribbon-like effect from a linear flash. The second plate 

 shows four flashes, none of which are ribbon-like, though the 

 camera had moved considerably. The third plate was exposed to 

 six flashes, one of which was believed to pass down the middle of 

 the plate ; but, on development, only a triple flash in one corner of 

 the plate was seen. Careful search, however, revealed the central 

 flash as a dark one with a white core, and other dark flashes were 

 subsequently found. The plate was very much over-exposed, and 

 this suggested that black flashes might be due to a sort of cumu- 

 lative action caused by the superposition of the glare from a white 

 cloud upon the normal image of the flash. To test this, sparks 

 from a Wimshurst machine were photographed, and, before de- 

 velopment, the plates were exposed to diffused gaslight for a short 

 time. The bright sparks yielded normal images with reversed 

 margins, and the famt ones were completely reversed. Other ex- 

 periments showed the reversal to spread inwards as the time of 

 exposure to gaslight increased. Finally, reversal was effected by 

 placing a white screen behind the spark, to represent a white 

 cloud, the only illumination being that of the spark itself. 



In the discussion which followed, Mr. W. N. Shaw exhibited a 

 photograph taken during the same storm, which is particularly rich 

 in dark flashes branching outwards from an intensely bright one. 

 In some places the bright line has dark edges, and in one part a 

 thin bright line runs along the middle of an otherwise dark portion 

 of the flash. In answer to Mr. Inwards, Mr. Shaw said the plate 

 was exposed about half a minute ; and the former thought, that, 

 under those conditions, the appearance of the plate did not contra- 

 dict Mr. Clayden's hypothesis. Speaking of the same photograph. 

 Professor Perry considered that Mr. Clayden's observations would 

 explain the result, for a bright flash required more exposure to 

 diffused light to reverse it than a faint one did. Professor Ramsay 

 reminded the meeting that Professor Stokes's " oxides of nitrogen " 

 explanation was still a possible one ; and Mr. C. V. Burton asked 

 whether they may be due to faint sparks cutting off light from 

 brightly illuminated clouds, just as a gas-flame absorbs light from 

 a brighter source. In reply, Mr. Clayden thought the "oxides of 

 nitrogen " hypothesis improbable, and said his experiments did not 

 enable him to answer Mr. Burton's question. As regards Mr. 

 Shaw's plate, he believed the diffused light from the clouds would 

 be sufficient to reverse the fainter tributary flashes, although it was 

 insufficient to reverse the primary one. From data obtained when 

 the ribbon-flash was taken, he had made some calculations which 

 gave the height of the clouds about 1,000 yards, and the ribbon- 

 flash 1,300 yards long and 100 yards wide. 



Permeability OF Iron. — From experiments conducted dur- 

 ing the last two years, J. T. Bottomley, F.R.S., finds that the per- 

 meability of iron can be enormously reduced by repeated heatings 

 and coolings while undergoing magnetic cycles of small range. 



Automatic Electric Railway-Lamps. — Mr. H. J. Dows- 

 ing, in a letter to the Electrical Review of July 12 (London), claims 

 to have invented a lamp for train use. A penny is dropped into 

 the apparatus, a handle half turned, and the light immediately 

 shines forth ; and without any arrangement of clockwork trains, 

 springs, etc., the time is controlled and the light goes out at the end 

 of half an hour. An advantage which perhaps could not be so 

 easily managed by clockwork is, that one can arrange the appara- 

 tus to burn any time, from two minutes to say ten hours, by one 

 half-turn of the handle. 



supplies enjoyed in any town of Europe. According to the last 

 report, Paris was receiving 121,000 cubic metres of the Vannes 

 water, 21,000 cubic metres derived from theDhuis, and 5,000 cubic 

 metres from the St. Maur springs, — in all, 147,000 cubic metres of 

 pure and excellent spring-water. This, however, is not enough. 

 The daily consumption is estimated at 158,000 cubic metres. The 

 deficiency is not very great : still it is enough to compromise the 

 whole town ; for, when the store of good water is exhausted, the 

 Seine water is provided, and this through the same channels and 

 without warning. Thus, though a person may, as a rule, drink 

 wholesome water, he will receive for a week or so, during the course 

 of the year, water taken from the Seine, which is very likely to be 

 contaminated. Again : a person may drink a glass of water in one 

 quarter of Paris which is perfectly pure, while in another district he 

 may, on the same day, get water that is certainly not free from the 

 occasional presence of injurious organic matter. At the present 

 moment, the supply of spring-water having reached a low ebb, the 

 Seine water is turned on in four arrondissements. For twenty days 

 these unfortunate districts are to receive only the Seine water ; then 

 three other arrondissements are to be served in the same way. 



In the pavilion of the prefecture of the Seine, situated in the 

 central court or garden of the exhibition, will be seen three glass 

 tanks of water side by side. One receives the water of the Ourcq 

 Canal, another of the Seine, and the third of the Vannes. The first 

 two are more or less opaque, are of a green-yellowish tint, and vary 

 more or less in aspect from day to day ; but that which contains 

 the water of the Vannes is always perfectly transparent, and never 

 changes. Members of the Municipal Council have urged, so far in 

 vain, that the water-supply should be increased. There are nu- 

 merous projects, and recently a resolution was passed by the coun- 

 cil, calling upon the legislative chambers to discuss at once the 

 scheme for bringing the waters of the Avre to Paris. 



That the Seine water may be dangerous will be obvious to all 

 who are acquainted with the neighborhood of Paris. The intake 

 for the supply is, of course, outside the town, and some little dis- 

 tance up the stream, but it is unpleasantly near the large manufac- 

 tories of potidreite, or human guano. Also there are boats con- 

 taining tanks which are filled with the contents of cesspools, and 

 the manure is thus conveyed up the river to the works. A few 

 years ago some scavengers, in their impatience to finish their day's 

 toil, instead of conveying all the soil the barges contained to the 

 works, simply threw a considerable portion over into the river. 

 Fortunately this was discovered ; and now there is a service of in- 

 spection organized both day and night, and careful watch is kept 

 that these tank-barges should not again contaminate the water. 

 But there are other causes of pollution, and it is an undeniable fact 

 that many outbreaks of typhoid-fever in Paris have occurred about 

 a fortnight after the substitution of Seine water for the usual and 

 pure supply of water from the Vannes or the Dhuis. The question 

 of water-supply is a very serious problem, which the French au- 

 thorities should lose no time in settling. 



The Naphtha Habit. — The Medical Standard calls atten- 

 tion to the growth of the " naphtha habit " among the female em- 

 ployees of rubber-factories. The inhalation of naphtha-fumes 

 produces a peculiarly agreeable inebriation. Naphtha is used to 

 clean rubbers, and is kept in large boilers, to the valve of which 

 the female employees obtain access, and breathe the fumes. The 

 habit was introduced from Germany, and is chiefly found in the 

 New England States. 



NOTES AND NEWS. 



HEALTH MATTERS. 

 Water-Supply of Paris. 



The Paris correspondent of the Lancet, writing in the issue for 

 June 22, says that a great danger to visitors to Paris is due to the 

 insufficiency of the water-supply. Paris is in a most unfortunate 

 position. It cannot be said that the water-supply is bad. On the 

 contrary, at immense cost, Paris has secured one of the bestwater- 



Through the efforts of Dr. Filip Trybom, the Swedish Oyster- 

 Culture Society is attempting to acclimatize the American oyster, 

 imported from Connecticut, in several places along the coast of the 

 province of Bohus. The young oysters seem to thrive well. 



— The Victorian Government statist has published a return of 

 the estimated population of the Australian colonies for 1888. In 

 Victoria the estimated population on Dec. 31 last was 1,090,869 ; 

 New South Wales, 1,085,356; Queensland, 387,463; South Aus- 

 tralia, 313,065; western Australia, 42,137; Tasmania, 146,149; 

 New Zealand, 607,380; making a total of 3,672,419 for the whole 



