August 24, igi 1] 



NATURE 



2S7 



bv Mr. J. Sato. The author gives the history of the 

 works of some of the principal writers on this subject, and 

 describes a gauge devised by himself, which is a modifica- 

 tion of one adopted by the late Dr. Billwiller in the Swiss 

 Meteorological Service. (2) An analysis by Mr. H. 

 Maruoka of the Osaka seismogram at the time of the 

 earthquake felt in Mexico on June 7. The time of 

 its commencement in Osaka was qh. 17m. 48s. (135th 

 meridian); its total duration was 2h. 34m. 31s. in the 

 E.-W. component, and 2h. 31m. 23s. in the other com- 

 ponent. (3) Discussion of rainfall observations at Osaka 

 for the years 18S3-1910, by Mr. K. Vamada. The results 

 of this valuable investigation are not given in English. 



The experiments of Profs. Boltwood and Strutt, and of 

 Dr. Eve, on the amounts of uranium and radium present 

 in radio-active minerals, have led to the conclusion that 

 the ratio of the amounts of the two present is a constant 

 independent of the nature of the mineral so long as its 

 age was considerable. A long series of measurements 

 made in Madame Curie's laboratory by Miss Ellen 

 Gleditsch seem now to cast doubt on the constancy of the 

 ratio. The methods used by Miss Gleditsch appear to 

 offer little ground for criticism, and her results show a 

 variation of the ratio of radium to uranium from 

 l'8xio- 7 to 3-7x10-' for the twenty-one minerals 

 examined. These differences she is disposed to attribute 

 to the existence of the long-period ionium and possibly 

 another long-period element between the parent uranium 

 and radium, but does not exclude the further possibility of 

 the " constants " of radio-activity being influenced by 

 Eternal circumstances more than we at present believe. 



The sensation produced on the retina by a source of 

 light of short duration has for the last three-quarters of a 

 century been taken as proportional to the product of the 

 intensity of the source into its duration. The early experi- 

 ment- -if Talbot and of Swan, and the later ones of Bloch 

 and of Charpentier, provided ample justification for the 

 law so far as it related to sources of considerable intensity. 

 In the Journal de Physique for July, MM. A. Blondel and 

 J. Rev point out that for weak sources the intensities of 

 which are not much greater than the lowest perceptible 

 <the statement cannot be true, or there would be no lower 

 limit to perception. On this ground they argue that the 

 sensation should be proportional to the product of the 

 exii-^s of the intensity of the source over the minimum 

 just perceptible into the duration of the source, and this 

 conclusion they have verified by means of the measure- 

 ments made by seventeen observers by two independent 

 methods of observation. 



We learn from The Engineer for August 11 that the new 

 Italian Dreadnought Conte di Cavour was successfully 

 launched at Spezia on August 10. Admiral Mirabello's 

 Brusade against lack of homogeneousness is beginning to 

 produce its fruits ; it is not likely that Italy will add to its 

 .11 Minn 1 cruisers, as opinion has turned in favour of 

 Dreadnoughts, of which four were designed by General 

 Rasdea. The Conte di Cavour is the second example of 

 these. She will have a displacement of 21,500 tons, and 

 her turbine machinery, of 24,500 horse-power, is designed 

 for a speed of 22 knots. There will be twenty water-tube 

 boilers of the Blechynden type. The normal coal and 

 petroleum capacity will be 1000 tons. The armament will 

 comprise thirteen guns of 305 mm., twenty guns of 

 120 mm., and thirteen guns of 76 mm. There will be three 

 submarine torpedo tubes, two lateral and one stern. 



A copy of the " Reports and Transactions," for the year 

 ending September 30, 1910, of the East Kent Scientific and 

 Natural History Society has been received. Among much 

 NO. 2l82, VOL. 87] 



other interesting information contained in the report, some 

 facts about salt rains, contributed by Mr. W. H. Ham- 

 mond, may be mentioned. On December 14, 1910, a very 

 heavy gale from the south-east with a deluge of rain in 

 the night occurred ; on the following day all the windows 

 which faced south-east had quite a frosted appearance when 

 dry. Some of the substance scraped off and dissolved in 

 distilled water was proved to consist of common salt. At 

 Milton Chapel some years ago, in the 'eighties, on one 

 occasion a north-east window was coated with salt after 

 a gale, and on the Dane John about the same time a salt 

 gale was experienced ; it made the young leaves look as if 

 they had been scorched by fire. Mr. Hammond states 

 that in 1S71, when a student at the Royal Agricultural 

 College, Cirencester, Prof. Church told his class that the 

 rain which came in a gale one day from the direction of 

 the Bristol Channel was loaded with salt ; this must have 

 travelled about sixty miles. The report also contains 

 observations of the " nailbournes " in the Elham Valley, 

 Petham, and Drillingore in the Alkham Valley, Dover. 

 Useful meteorological statistics and notes for the year 19 10 

 from various observing stations throughout east Kent are 

 also included, as well as natural history notes and reports 

 of lectures and addresses. 



OUR ASTRONOMICAL COLUMN. 



The Comets 19116 and 1911c. — Numerous observations 

 of the comets discovered by Kiess and Brooks, respectively, 

 are now being recorded, but they contain nothing that is 

 strikingly new ; the Kiess comet is now invisible in these 

 northern latitudes. 



In No. 4517 of the Astronomische Nachrichten Prof. 

 Pickering reports that a photograph of the spectrum of 

 comet 19116, secured with the 8-inch Draper telescope on 

 July 7, shows the bands at W 3883 and 4737 as bright, 

 and of nearly equal strength ; the latter was much the 

 brighter in the case of Daniel's comet, 1907^ 



From Mr. F. C. Leonard, of Berlamont, Mich., U.S.A., 

 we have received a lengthy report of observations of both 

 comets made during July. Kiess's comet developed 

 appendages on both the preceding and following sides, 

 and on July 26 a long streamer was seen to extend for 

 -mil distance in a direction perpendicular to the axis. 



Brooks's comet, observed on July 25, 26, 27, and 20- 

 presented the mottled appearance of a condensed nebulous 

 cluster, and was 3' or 3-5' in diameter. 



