June 12, 19 13] 



NATURE 



cylinder petrol engine, the mileage per gallon of petrol 

 being seven to eight. The average daily run for each 

 car is about seventy miles. The total cost of car is 

 from 985/. to 1 150/. The Leyland Motor Company, 

 which built the cars, gave a five years' guarantee that 

 the costs of working, exclusive of wages, upkeep of 

 car body, and administration expenses, should not 

 exceed ^\S.. per car-mile so long as the price of petrol 

 did not exceed gd. per gallon. Birmingham, Coven- 

 try, and London were also visited, and as the 

 result of the inquiries, the deputation recommends the 

 introduction experimentally of petrol-driven cars in 

 Edinburgh. 



Among the latest additions to the " Cambridge 

 Manuals of Science and Literature " are five volumes 

 dealing with scientific subjects. Prof. John Cox, 

 under the title " Beyond the Atom," tells the story 

 of discoveries in radio-activity, and his brief summary 

 of the work of Rutherford, Curie, and many others 

 will prove of interest to students and general readers 

 alike. Dr. Gadow's book on "The Wanderings of 

 Animals " gives the main facts of geographical dis- 

 tribution in a readable form. Prof. Fortescue writes 

 on wireless telegraphy for readers with a general 

 scientific knowledge who desire to know something, 

 not only of the accomplishments of wireless, but also 

 of the means by which they are attained. Mr. O. H. 

 Latter's book on "Bees and Wasps" deals with 

 British species of Hymenoptera in a thoroughly prac- 

 tical manner, and Mr. Clement Reid's " Submerged 

 Forests " gives a simply worded account of a very 

 interesting series of geological researches. The 

 " manuals " are one shilling net each, and at the rate 

 the library grows the student will be able soon to 

 secure at this small cost an authoritative account of 

 every branch of modern scientific research. 



Owing to the development of their optical business, 

 Messrs. Newton and Co., 72 Wigmore Street, Lon- 

 don, W., are unable to find space for their philo- 

 sophical and physical apparatus department, and are 

 consequently disposing of their stock at low prices. 

 The catalogue of apparatus for sale is comprehensive, 

 and includes particulars of shop-soiled and second- 

 hand instruments used in the study of physics and 

 chemistry, lanterns and lantern apparatus, and micro- 

 scopes and accessories. 



OUR ASTRONOMICAL COLUMN. 

 The Variation of Solar Radiation. — With the per- 

 mission of the secretary of the Smithsonian Institu- 

 tion, a definite and important statement under the 

 names of Messrs. C. G. Abbot, F. E. Fowle, and 

 L. B. Aldrich is published in the Astronomischc 

 Nachrichten, No. 4656, with the title "The Variation 

 of the Sun." The observations from which the con- 

 clusions are drawn were begun in the year 1902, 

 when preliminary experiments were made at Wash- 

 ington to determine the solar constant of radiation. 

 About 700 determinations of it have now been secured, 

 and they depend on observations made at altitudes 

 ranging from sea-level to 4420 metres. The results, 

 some of which are mentioned in this communication, 

 will be published in detail in the Annals of the Astro- 

 NO. 2276, VOL. 91] 



physical Observatory of the Smithsonian Institution 

 (vol. iii.) now in the press, and will probably appear 

 next month. The authors nevertheless publish in this 

 statement some of the more important conclusions, 

 which are as follows : — 



(1) The mean value of the solar constant of radia- 

 tion for the epoch 1905-12 is 1-929 cal. per sq. cm. 

 per min. (2) An increase of 0-07 cal. per sq. cm. 

 per min. in the " solar-constant " accompanies an in- 

 crease of 100 sun-spot numbers (Wolfer). (3) An 

 irregular variation frequently ranging from more than 

 0-07 cal. per sq. cm. per min. within an interval of 

 ten days is established by numerous nearly simul- 

 taneous measurements at Mount Wilson, California, 

 and Bassour, Algeria. (4) Indications of two wholly 

 independent kinds incline the authors to think that 

 these variations of solar radiation are caused within 

 the sun, and not by interposing meteoric or other 

 matter. 



The extreme importance of the conclusions here 

 stated cannot be overrated, and students of solar 

 physics in its broadest sense will await with eager- 

 ness the publication of the detailed investigation. 



Prominences Associated with Sun-spots. — The 

 discovery of radial motion in sun-spots by Mr. Ever- 

 shed revealed the fact that there are two opposite 

 movements in the penumbra of every spot, the gases 

 at the level of the reversing layer flowing outwards 

 away from the umbra, while those at the higher levels 

 of hydrogen and calcium flow inwards. It was thought 

 that a study of the higher solar region, namely that 

 of the prominences, might shed some light on these 

 remarkable motions, and with this object Mrs. Ever- 

 shed undertook a study of the fine prominence photo- 

 graphs taken at the Kodaikanal Observatory. The 

 results of this investigation are described in the cur- 

 rent number of the Monthly Notices of the R.A.S. 

 (vol. lxxiii.. No. 6), and they are accompanied by a 

 series of fine reproductions of numerous types of 

 prominences explained in the paper. 



Mrs. Evershed states that the investigation sug- 

 gests more problems than it solves, yet some pre- 

 liminary conclusions are nevertheless drawn. The 

 most general result seems to indicate that the move- 

 ments observed in the prominences situated directly 

 above sun-spot groups are of quite a different kind 

 from those in the penumbra? of spots, being inter- 

 mittent and variable in direction and amount instead 

 of uniform and constant. Reference is also made 

 to the presence of forces other than those of an erup- 

 tive and gravitational nature, which is responsible 

 for such a peculiarity as was observed in some rising 

 prominences which moved with an accelerating velo- 

 city into space by a force opposed to gravity. 



Studies in Stellar Statistics. — The general ques- 

 tion of the distribution and motion of stars in space 

 is perhaps the most important problem of the day, 

 and the attention of astronomers has been turned 

 more and more towards it since the initial investiga- 

 tion of Kapteyn in 1904, who determined for the first 

 time the elements of the two star-streams. Space 

 will only allow here of a list of a few of the more 

 recent papers connected with this subject. Mr. F. W. 

 Dyson has contributed to the two last numbers of 

 the Monthly Notices of the R.A.S. (vol lxxiii., Nos. 5 

 and 6) two important researches on the distribution 

 in space of the stars in Carrington's circumpolar cata- 

 logue, discussing in the first the proper motions in a 

 direction perpendicular to the solar motion, and in 

 the second the proper motions in the direction of the 

 solar motion. In the same publication (No. 6) Mr. 

 H. C. Plummer continues his series of papers on 



