$50 



NATURE 



[June 5, 1913 



6-o. M. Bauer attributes these high values to 

 erroneous determinations of the corrections to be 

 applied to the observations for the reflecting power 

 of lamp black. He gives as the most probable value 

 of a- deduced from his own and other observations 

 (5-60+0-04) x 10- 1 - watt/(degree) 4 . 



An interesting account of the survey of the Alaskan 

 boundary, by Mr. J. A. Flemer, 'appears in The 

 Engineering Magazine for May. The northern sec- 

 tion of this line follows the 141st meridian. The 

 initial point, determined by telegraphic longitude, is 

 at the crossing of this meridian and the Yukon 

 River. The azimuth of the meridian at this station 

 was determined astronomically, and the line itself 

 is being projected both north and south by two 

 observers, one an American and the other a Canadian. 

 The international projection party is being followed 

 by a triangulation party. The topographical work 

 is being executed by the plane-table method, since 

 the climatic conditions in this part of Alaska have 

 not that extreme character inherent to south-east 

 Alaska, where the photo-topographic surveying 

 method had to be employed. The triangulation party 

 which precedes the topographic party furnishes the 

 latter with the needed geodetic control, based on the 

 field computations. The plane-table sheets are on 

 1 : 45,000 scale, with a horizontal contour interval of 

 100 ft., and the topographic details are mapped with 

 the 141st meridian as the median line of a strip four 

 miles wide. The boundary is being marked with 

 aluminium-bronze monuments, the monument-setting 

 party cutting a vista through wooded "areas 10 ft. on 

 each side of the meridian. 



The Academy of Natural Sciences of Philadelphia 

 commemorated its centenary in March, 1912, 

 by a number of conferences, of which an 

 account was published in the issue of Nature for 

 April 11, 1912 (vol. lxxxix., p. 143). On that occa- 

 sion the academy decided to publish several volumes 

 in commemoration of the centenary, and one of these 

 — an index to the entire series of its Journal and Pro- 

 ceedings, from the first volume issued in 1S17 to 

 the close of 1910 — recently made its appearance. The 

 index forms a volume of 1433 pages, and consists of 

 a catalogue of the contributions under the names of 

 authors, and a reference to all species, genera, fami- 

 lies, &c, described or mentioned in the several I 

 volumes, arranged alphabetically. The expense in- 1 

 curred in the preparation and publication of the work 

 has compelled the publication committee to make a 

 charge for it. The price, 3.50 dollars, carriage paid, 

 is less than the cost of production. Copies may be 

 obtained from the editor, Dr. E. J. Nolan, Academy 

 of Natural Sciences, Logan Square, Philadelphia, Pa., 

 U.S.A. 



A classified catalogue of second-hand books, 

 journals, and monographs on zoology and other 

 branches of natural science, including works from the 

 library of the late Mr. Robert Shelford, sometime 

 curator of the museum, Sarawak, and afterwards 

 assistant in the Hope Museum of Zoology, Oxford, 

 has been issued by Messrs. Bowes and Bowes, Cam- 

 bridge, who have the works on sale. Mr. F. Edwards, 

 NO. 2275. VOL. 91] 



Marylebone, London, \V., has just issued a catalogue 

 of books on ornithology and oology, including copies 

 of the works of John Gould, H. E. Dresser, Lord 

 Lilford, Henry Seebohm, &c. ; also a series of native 

 original drawings, in colours, of birds of India and 

 Malaysia. 



We have received the first number of a new period- 

 ical, La Science et la Vie (April, 1913), the object of 

 which is to popularise science. The principal con- 

 tributions are : — Time measurements and signals, by 

 M. G. Bigourdan; the construction and life of a big 

 gun, by Lieut.-Col. Picard ; the little agents of death 

 (dealing with insect carriers of disease), by M. J. Paul 

 Dupuy; and "Can the onset of old age be retarded? " 

 by Dr. Toulouse. The periodical is profusely illustrated, 

 and is issued at the price of one franc the number. 

 The list of collaborators includes the names of many- 

 well-known men of science. 



OUR ASTRONOMICAL COLUMN. 

 Periodic Spectrum of 12 Canes Venatici. — A Kiel 



telegram, dated May 30, states that Belopolsky has 

 found that the star 12 Canes Venatici exhibits a 

 spectrum that is periodic. Lines appeared on the 

 following dates, April 22, 278, May 4, 9, and 22-5, 

 but on seventeen days they have been invisible. 



Position' of the Axis of Mars.— Prof. Percival 

 Lowell publishes, in the Bulletin No. 56 of the Lowell 

 Observatory, his observations and those of Mr. 

 Slipher of the position of the polar cap of Mars for 

 the determination of the axis of this planet. The 

 observations were made towards the end of the year 

 191 1, but they include others made by Mr. Slipher in 

 1909. The values of the position of the axis are 

 given in the case of each observer for every alternate 

 year from 1901 to 1909. As regards the results and 

 their accuracy, it is stated at the end of the paper 

 that the mean of all Prof. Lowell's measures for the 

 last fourteen years gives for the tilt of the Martian 

 equator to the Martian ecliptic the value 23-5°, while 

 that obtained by Mr. Slipher for 1909 and 191 1 gives 

 precisely the same value. In this publication Prof. 

 Lowell refers to Prof. H. Struve's communication to 

 the Berlin Academy, in which it is stated that the 

 motion of the satellites affords a better determination 

 of the Martian axis than direct measurement of the 

 polar caps. This view is not acceptable to Prof. 

 Lowell, who says, "it seems advisable to here 

 correct a few misapprehensions," and these are con- 

 tained in the present bulletin. 



The Solar Eclipse of April 16-17, 1912.— A com- 

 munication by M. Simonin to the Comptes rendus 

 for April 28 contains the results of the discussion of 

 observations made during the eclipse of the sun on 

 April 16-17 °f last year. It will be remembered that 

 the central line extended from Portugal to Russia, 

 and along that line, scattered at various points, a 

 great number of observers noted the times of interior 

 and exterior contacts. In fact, a large amount of 

 material was available for discussion, and this has 

 now been completed. The conclusions may be summed 

 up as follows : — 



The right ascension and declination of the moon's 

 centre, published for April 17. 1012, bv the Connais- 

 sance des Temp,, and corrected after Newcomb, ousrht 

 to be increased respectively bv 063s. and 43". The 

 calculated values of the semi-diameters of the sun and 

 moon at the earth's mean distance e^ive the figures 

 T S' 59'96" and 15' 32-16". The sun's semi-diameter 



