December 8, 1898] 



NA TURE 



m 



Stornoway (Hebrides) the fall was about double the average, the 

 excess being 5 inches ; while at Sumburgh Head (Shetlands) 

 there was a deficiency of 0-27 inch. At North Shields there 

 was an excess of 0'95 inch above the mean for the month, while 

 at Leith there was a small deficiency. The following values 

 above or below the monthly mean are noteworthy : — Valencia, 

 + I '26 inch ; Roches Point, -o'96 inch ; Hurst Castle, + i"25 

 inch; Dungeness, -I '83 inch; Holyhead, + 0'o8 inch; and 

 Liverpool, — I'I2 inch. Generally speaking, the rainfall since 

 the beginning of the year is still considerably deficient, except 

 in the north of Scotland, where the excess is above 9 inches. 



At the meeting of the French Meteorological Society on 

 November 3, under the presidency of M. Poincare, M. Teisserenc 

 de Bort presented the first part of a very important work by 

 Dr. Hildebrandsson and himself, entitled " Les bases de la 

 meteorologie dynamique. Historique, etat de nos connaissances." 

 This part contains the history of all the ancient researches from 

 the time of Aristotle to the present date. In the second part, 

 now in the press, the history will be continued, and will be 

 followed by theoretical questions, such as the distribution of 

 aqueous vapour in the atmosphere, and that of the meteorological 

 elements over the surface of the globe. A paper by M. Coeur 

 de Vache was read on the atmospheric electricity of the months 

 of March 18S6-1895, or during a period of 213 days. This 

 investigation shows that the diurnal oscillation of atmospheric 

 electricity depends especially upon the humidity of the air, both 

 with regard to its amplitude and to the normal hourly values. 

 The other papers read related to the unmanned balloon ascents 

 of October 3 last, by M. Teisserenc de Bort, and to the action 

 of the moon on the movements of the atmosphere, by M. 

 Poincare. 



We have received a copy of " Observations and Researches" 

 made at the Hong Kong Observatory during the year 1897, 

 under the superintendence of Dr. W. Doberck, the director. 

 In addition to the usual observations and results of the meteor- 

 ological and magnetic instruments, the report contains detailed 

 information upon the other valuable work carried on at the 

 observatory. For the daily weather forecasts a complete success 

 of 65 per cent., and a partial success of 31 per cent., are claimed. 

 Following the method used in some other meteorological 

 establishments, and adding together the sum of total and partial 

 success, the high figure of 96 per cent, is obtained. During the 

 year 1897, besides the meteorological registers kept at forty 

 .stations on shore, the log-books of 283 vessels have been copied, 

 for use in the construction of trustworthy pilot charts of the 

 Eastern seas. The report also contains the third edition of the 

 law of storms in the Far East, to which we briefly alluded in our 

 issue of October 20. Dr. Doberck is very sanguine about the 

 results of this investigation, and states that the typhoons, about 

 which little was known when the observatory was built, in 

 1883, are now among the best understood atmospheric dis- 

 turbances. A chart is given showing the average tracks of 

 these storms. 



The question of the porosity of thin steel plates under heavy 

 hydraulic pressure having been raised (says Engineering), 

 experiments have been carried out at the Washington Navy 

 Yard with the view of settling the point in a practical way. 

 Pieces of sheet steel of \ inch, ^ inch, iV inch, and jV inch in 

 thickness were subjected to a water pressure of 6000 lb. per 

 square inch, and in no case was any percolation found. A 

 I inch rivet joining two J-inch plates also proved tight under 

 the same pressure. A test was also made to determine the 

 friction of water under high pressure, and, while it was in- 

 conclusive, there was no evidence that the friction of water 

 under high pressure was any greater than the friction of water 

 not under pressure. 



NO. I 519, VOL. 59] 



Amonc. the methods of reducing a compressed gas to a lower 

 pressure by irreversible transformations, those of Joule's well- 

 known experiment of expansion into a vacuum, and Lord 

 Kelvin's experiment of expansion through a porous plug are the 

 most important, and the recent applications of the Kelvin effect 

 to the liquefaction of gases has added fresh interest to the 

 latter. An investigation of the thermodynamics of the process 

 in question is given by M. A. Witkowski in the Bulletin 

 of the Cracow Academy, pp. 282-295. These observations 

 support the view that beyond certain limits of temperature and 

 pressure, expansion of a gas is accompanied by heating instead 

 of cooling, and the author investigates the temperature of 

 reversal for air and for hydrogen. The conclusions tend to 

 show that in liquefying gases by expansion there is no advantage 

 in making the initial pressure too great ; a pressure of 200 

 atmospheres, as employed in Linde's machine, being amply 

 sufficient. The cooling resulting from expansion into a vacuum 

 is rather greater than would be obtained for the same pressures 

 in the Kelvin-Joule apparatus. 



The study of hydrodynamics has been greatly facilitated by 

 the series of reports which have been from time to time brought 

 out dealing with the progress made in the subject during various 

 periods. These include Sir G. G. Stokes' report to the British 

 Association of 1846, Prof. Hicks' reports of 1881-82, Mr. Love's 

 paper on Vortex Motion in the Matheinatische Annaleniot 1887, 

 Prof. Hicks' account of the same subject in his sectional address 

 to the British Association at Ipswich in 1895, and Prof. Darwin's 

 Encyclopaedia article of 1888, on Tides. In Science (or Novem- 

 ber II, Prof. Ernest W. Brown, F. R.S., gives an interesting 

 account of recent progress towards the solution of problems 

 in hydrodynamics which have not been included in these 

 previous reports. The author deals at considerable length 

 with wave motion, viscosity, and two-dimensional discontinuous 

 motion, pointing out that no case 01 three-dimensional 

 discontinuous motion has been solved. In connection with 

 viscosity Prof. Brown remarks that " in all problems hitherto 

 solved, only the first powers of the velocities are taken into 

 consideration." But a paper was published by Mr. Whitehead, 

 in the Qiiarterty Journal of Mathematics (vol. xxiii. p. 78), deal- 

 ing with second approximations to viscous motion, notably for the 

 fluid surrounding a rotating sphere ; and the conclusions arrived 

 at seem rather to cast doubts on the validity of the ordinary first 

 approximations. As Mr. Whitehead's paper seems little known, 

 the present reference may save some mathematician the trouble 

 of solving the same problem (as did the writer of the present 

 note), and then finding that he has been anticipated. 



A RECENT number of the Revue Scientijique contains the 

 continuation of an article by M. P. L. Simond on the trans- 

 mission of plague-virus. It is now well recognised that rats not 

 only herald the advent of plague, but are themselves largely 

 responsible asdirect disseminators of the morbific material ; but, 

 as M. Simond points out, they do not account for all the subtle 

 means by which the virus finds its way to the human subject. 

 Further careful researches now show that parasites in the shape 

 of fleas are extremely dangerous disseminators of plague-bacilli. 

 Suspicion fell on these vermin, inasmuch as it is far easier to 

 infect an animal with plague by subcutaneous inoculation than 

 it is through the alimentary canal. A large number of experi- 

 ments have been carried out by M. Simond to test the validity of 

 his hypothesis, and just as Versin showed that flies could 

 transmit virulent plague-bacilli, so Simond has found that fleas 

 taken from plague-stricken rats can communicate the disease to 

 healthy animals, vermin froiu such sources containing in their 

 excreta the virulent plague microbes. We have long known 

 that dirt and plague go hand in hand, and M. Simond's 

 instructive researches furnish yet another proof of the cardinal 



