4o8 



NATURE 



[December 9, 1915 



Marine Engineers in New York. Whatever may be 

 the decision of the U.S.A. authorities as to the surface 

 speed necessary, the author of this paper is firmly 

 convinced of the relatively greater importance of the 

 submerged qualities for this type of boat, and believes 

 that battery capacity and submerged radius of action 

 and speed should not be unduly sacrificed either in the 

 interests of durability or first cost. 



OUR ASTRONOMICAL COLUMN. 



A New Comet. — According to a telegram received 

 on December 5 from Prof. Stromgren, Copenhagen, a 

 message from the Cape to the Astronomer Royal 

 announces that a new comet was observed by Taylor 

 on December 2 in a position "three minutes preceding 

 sixteen minutes south of 8 Orionis." It is stated to 

 be moving slowly north, but no indication is given 

 of its magnitude. 



The Solar Rotation. — The detailed account of a 

 valuable spectrographic determination of the latitude 

 variation in velocity of the sun's rotation is presented 

 by Mr. J. B. Hubrecht in a memoir forming part i. 

 of vol. iii. of the Annals of the Solar Physics Observa- 

 tory, Cambridge (see also Monthly Notices, R.A.S., 

 No. 8). Four series of spectrograms were secured 

 during the first fortnight of June, 191 1, with the 

 McClean solar instruments. Each series contained 

 the material — forty-eight plates- — from which velocity 

 differences have been derived for pairs of plates 

 taken in positions separated by 90° at intervals of 15° 

 around the sun's limb. The region studied was 

 A4300-A4400, under a dispersion in fourth order such 

 that I A.U. = i-i3 mm. Attention may be directed to 

 a point regarding the manipulation of the Zeiss 

 comparator; the settings were made by simply push- 

 ing the slide, and the readings were taken to 

 0000 1 mm., with an average probable error per dis- 

 placement of only 00004 mm. 



The results obtained indicate that the velocities 

 probably vary regularly according to wave-length, 

 diminishing towards the red, due to some physical 

 cause residing in the sun itself. The distribution of 

 the velocities appears to be consistent with the require- 

 ments of Emden's theory of the constitution of the 

 sun. 



Galactic Co-ordinates. — The progress made of 

 recent years in stellar astronomy has directed increas- 

 ing attention to the employment of a natural system 

 of co-ordinates in place of those based on the arbi- 

 trary, ever-changing geo-solar planes of reference. 

 The fundamental plane of reference is obviously deter- 

 mined by the Milky Way, but there remains to be 

 fixed the point of departure in longitude. Unfor- 

 tunately, from analogy with the standard system choice 

 of this initial point has fallen on the ascending node 

 of the galaxy. Mr. R. T. A. Innes, in advocating 

 the general introduction of secular co-ordinates, 

 pointed out the great economy of effort they afford in 

 connection with the study of the planetary motions, 

 and proposes to fix the zero of galactic longitude by 

 the apex of the sun's way, thus entirely eliminating 

 the effect of precession. In Circular No. 29 of the 

 Union Observatory, Mr. Innes supplies a convenient 

 table for the conversion of equatorial into galactic 

 co-ordinates. The table is calculated on the basis of 

 Newcomb's position of the pole of the galaxy (a 191-1°, 

 8 + 26-8°, and Campbell's determination of the solar 

 apex (0270-0, 8 + 30-0°), and contains the galactic 

 equivalents of every 5° of declination and twenty 

 minutes of right ascension, also galactic parallactic 

 angles for converting north oole position angles into 



NO. 2406, VOL. 96] 



corresponding position angles referred to the north 

 galactic pole. 



A Martian Calendar. — In Report on Mars, No. 10, 

 Prof. William H. Pickering gives what should prove 

 a convenient calendar for the use of observers of the 

 planet Mars. The Martian year is divided into 669 

 calendar days of 24h. 38m. 42-04S. each, the planet's 

 sidereal day (i.e. time period of rotation) being im. 

 19-39S. shorter. Fifty-six days are allotted to the first 

 nine "months," and one day less to each of the other 

 three. The "week" of seven days is thus retained 

 as a unit. The year commences at vernal equinox, 

 Martian date, March i = terrestrial date, March 20. 

 The same report also contains some remiarks on the 

 possibility of observing gemination of canals during 

 the coming opposition, and concludes with a dis- 

 cussion of colouring of the markings. 



TI/E CENTENARY OF THE 

 SOCIETE HELVETIQUE DES SCIENCES 



NATURELLES. 

 'T^HE centenary of the Swiss Natural Science 

 -*• Society was celebrated on September 12-15. 

 The meeting was a great success, and was marked 

 by two touching ceremonies : the placing of a laurel 

 crown before the monument of Henri Albert Gosse, 

 the gifted apothecary of Geneva, who with Pastor 

 Wyttenbach, of Berne, originated this great national 

 society, and the inauguration of a monument to the 

 Swiss naturalist Forel at Morges. Both these monu- 

 ments consist of fine erratic blocks, with the head of 

 the naturalist carved in the form of a medallion. One 

 stands in the shady garden surrounding the Uni- 

 versity of Geneva ; the other has been placed in one 

 of the most exquisite spots on the banks of Lake 

 Leman. But it is not in these grand stones that we 

 must seek the record of the fame of those they com- 

 memorate. It is in the living society which has 

 carried out the ideals and continued the work of its 

 founders — a society of which Forel formed until three 

 years ago a prominent member — that the glory of 

 these simple lovers of Nature and of their country 

 is to be found. 



The primary idea in founding the society was 

 patriotic; a secondary one, dependent on the success 

 of the undertaking, was that the society would be 

 visited by savants from all countries, and that it 

 might prove itself a source of light the rays of which 

 should spread over the whole scientific world. Both 

 these ideas have been realised in the hundred years 

 that have passed, but it is interesting that the cen- 

 tenary should fall at a moment when the former only 

 could have any prominence. 



There were no ofificial delegates from foreign 

 countries, and practically all the participators were 

 Swiss. The author of the present account was the 

 only member of the English scientific world at the 

 meeting, but she and Prof. W. H. Young, whose 

 absence in America alone prevented his giving per- 

 sonally the communication presented in his name, are 

 accepted by the Genevese scientific circle as almost, 

 if not quite, of them. 



In these circumstances, and in view of certain super- 

 ficial elements of discord between the French and 

 German Swiss, which the war has brought under the 

 eye of the public, the occasion was made one for a 

 manifestation of patriotic feeling. The President of 

 the Confederation was present, and gave a memor- 

 able^ and eloquent address to the society after the 

 official banquet at the Pare des Eaux Vives, lately 

 become the property of the town of Geneva. Presi- 

 dent Motta is a native of Italian Switzerland, a fact 



