JULV 27, 1905] 



NA rURE 



303 



show other canals, and Mr. Lampland is to be con- 

 gratulated, in company with Mr. Lowell, upon thus 

 securing unquestionable evidence of the actual existence of 

 these features. 



A point of special interest to planet observers is that 

 whilst trying to obtain these photographs the observers 

 found that the restriction of the aperture employed, by 

 its elimination of the evil effects of atmospheric vibrations, 

 more than counterbalanced the inconvenience caused by the 

 diminution of light-gathering power and the consequent 

 increase of the length of the exposures, a result which 

 confirms the conclusion previously arrived at by .Mr. I,owell 

 from visual observations. 



Dutch Observ.\tions of the Corona. — Parts iii. and iv. 

 of frof. Julius's report on the observations made by the 

 Dutch expedition in Sumatra during the total solar eclipse 

 of .May 18, 1901, minutely describe the apparatus and the 

 methods of procedure employed in examining the coronal 

 radiations for polarisation effects and for the determination 

 of the amount of heat radiated by the eclipsed sun. 



\ double-image polarimeter of the Cornu pattern, slightly 

 modified, was employed to examine the polarisation at 

 different points of an image of the corona. The points 

 examined were situated at different distances from the sun's 

 limb, and the position of each was carefully recorded. 

 The results showed that the coronal rays were more 

 strongly polarised at some distance from the limb than 

 nearer to it, whilst at greater distances the polarisation 

 again decreased. A discussion of some experiments, per- 

 formed after the eclipse, on the depolarising effect of haze 

 and clouds showed that this effect was practically negligible. 



The observations of the total heat radiated by the 

 eclipsed sun were made with a thermopile pointed directly 

 to the corona, but clouds robbed the observations of any 

 definite result. So far as they go, the resulting figures 

 show that the heat radiated at totality is not so great as 

 that received from the full moon, and that a very striking 

 increase occurred after the third contact. 



The North Polar Snow-cap on Mars, 1904-5. — 

 Observations of the north polar cap of Mars were made 

 at the Lowell Observatory by Messrs. Lowell and Lamp- 

 land during the period November, 1904, to May, 1905, 

 and the observers' notes for each night are given in full 

 in No. 20 of the Lowell Observatory Bulh'lins. 



One remarkable feature observed was a white collar 

 which surrounded the cap during the latter half of January. 

 .Mr. Lowell explains this phenomenon by the conjecture 

 thai it is a belt of spring haze which surrounds the cap 

 during the hotter months of the melting, the cap proper 

 being bordered by a blue belt of material (probably water) 

 produced by the melting of the snow. Several subsidiary 

 patches of snow were left behind by the receding polar 

 cap, and became prominent features. 



Of these, one in longitude 206° was especially marked, 

 and was recorded in exactly the same longitude by 

 Schiaparelli in 188S, and independently at the Flagstaff 

 Observatory in 1901 and 1903. 



\'egetation and the Sun-spot Period. — Since 1871 

 M. Camille Flammarion has each year recorded the dates 

 on which the chestnut trees in the avenue of the Paris 

 Observatory have burst into leaf and flowered. Plotting 

 the results of his observations with the sun-spot curve on 

 the same year-scale, he found that the variation of the 

 dates of the different phases of the annual arboreal pheno- 

 mena agreed very closely with the latter curve, the leaf- 

 buds bursting and the flowers appearing earlier at those 

 epochs when the sun-spot maxima occurred. The details 

 of the observations and the method employed in reducing 

 them are given in the July number of the Bulletin de la 

 Societe astronomique de France. 



\"ISIBIL1TV OF THE DaRK HEMISPHERE OF VenUS. — In a 



paper on the influence of the solar-activity variations on 

 the planets, M. Hansky directs attention to the greater 

 visibility of the dark hemisphere of Venus during epochs 

 of maximum solar activity. According to the theory of 

 Arrhenius, electrified ions emitted by the sun cause the 

 phenomena of terrestrial magnetic storms and aurorje. 

 Applying the same theory in the case of Venus, M. Hansky 

 suggests that during the periods of solar maxima the 



NO. 1865, VOL. 72] 



dense atmosphere of that planet is rendered more phos- 

 phorescent, and, therefore, more easily visible, by the in- 

 creased solar activity. He further suggests that, in order 

 to test this theory, astronomers should observe the planet 

 as often as possible during the present sun-spot maximum 

 (Bulletin de la Socii^te astronomique dc France, July). 



Deter.minations of Meteor Radiants. — Some interest- 

 ing results of meteor observations are recorded in No. 4032 

 of the Astronomische Nachrichten by M. Eginitis, 'of 

 Athens, and by Prof. A. A. Nijland, of Utrecht. 



.M. Eginitis observed the Perseid, Leonid, and Andro- 

 medid showers of 1903 and the Perseid shower of 1904. 

 He gives the time of observation, the number, colour, 

 magnitude and relative velocity of the meteors recorded, 

 and the position of the determined radiant on each date, 

 directing special attention to any objects which were, for 

 any reason, extraordinary. On August 11, 1904, several 

 meteors were seen to proceed from a radiant near to 

 a Persei, and these were, in general, whiter and brighter 

 than those from 7) Persei, the latter being fainter and of 

 a reddish-yellow colour, .->nd generally falling in pairs. 



Prof. Nijland 's results deal with the Lyrid, Perseid, and 

 Leonid showers of 1902, 1903, and 1904, and he gives the 

 results for each night of observation and the positions 

 deduced for the respective radiants. 



THE INSTITUTION OF NAVAL ARCHITECTS. 



HTHE summer meeting of the Institution of Naval 

 Architects was held last week in London, the usual 

 sittings for the reading of papers taking place in the 

 theatre of the Society of Arts. The following papers were 

 on the programme for reading and discussion :— Tactics 

 and strategy at the time of Trafalgar, by Admiral Sir 

 Cvprian Bridge; the ships of the Royal Navy as they 

 existed at the time of Trafalgar, by Sir Philip Watts, 

 Director of Naval Construction ; the classification of 

 merchant shipping, illustrated by a short history of Lloyd js 

 Register, by H. J. Cornish, chief ship surveyor to Lloyd's 

 Register ; experiments with models of constant length and 

 form of cross section, but with varying breadths and 

 draughts, by Lieut. -Colonel B. Rota, Royal Italian Navy ; 

 experiments upon the effect of water on speed having special 

 reference to destroyers recently built, by Harold Yarrow ; 

 deductions from recent and former experiments on the 

 influence of the depth of water on speed, by W. \\ . 

 Marriner; the failure of some large boiler plates, by J. T. 

 Milton, chief engineer surveyor to Lloyd's Register; a 

 comparison of the performances of turbines and recipro- 

 cating engines in the Midland Railway Company's 

 steamers, by William Gray. 



It was also arranged that visits should be paid to 

 the following works: — Siemens Bros, and Co.'s Tele- 

 graph and Electrical Instrument Works, near Woolwich ; 

 Vickers, Sons and Maxim Ordnance Works, Erith ; J. and 

 E. Hall's Refrigerating Machinery Works, Dartford ; 

 Yarrow and Co.'s ship-building yard and marine engine 

 works, Poplar; John I. Thornycroft and Co.'s ship-build- 

 ing yard, marine engine works, and motor-car works, 

 Chiswick. Visits were also paid to the P. and O. mail 

 steamer India, lying in the Tilbury Docks, ^nd H.M.S. 

 Black Prince, built by the Thames Iron Works, and lying 

 in the Victoria Docks. The last day of the meeting, 

 Friday, July 21, was occupied by a visit to Portsmouth 

 Dockvard. 



The first sitting during the meeting, when the three first 

 papers -on the list were presented, was held on \\ ednes- 

 day, July 19, the president of the' institution, the Right 

 Hon. the Earl of Glasgow, occupying the chair. These 

 papers, as will be gathered by the titles, were chiefly of 

 historical interest. In this centennial year of Trafalgar 

 it was, no doubt, appropriate for the institution, which 

 is so largely naval in its composition, to include in its 

 programme papers of the nature of those contributed by 

 Sir Cyprian Bridge and Sir Philip Watts ; but how far 

 they have any scientific bearing on naval strategy or 

 tactics of the present day is a question that is evidently 

 open to discussion. It would appear that a large section 

 of naval officers hold that the lessons of the past era of 

 masts and sails should be applied with little modification 



