October 13, 1923] 



NA TURE 



555 



Bibliography of meteorological literature, No. 4, 

 has recently been issued by the Royal ^Meteorological 

 Society, having" been prepared with the collaboration 

 of the Meteorological Office. It deals with all 

 meteorological publications and articles on meteoro- 

 logy recently received, giving the titles and references 

 ?here the literature is to be found. The division 

 )f the subject-matter under specified heads enables 

 would-be student to determine the helpful line of 

 Reading which he is desirous of prosecuting, without 

 3SS of time. Divisions are given for the several 

 leteorological elements, such as atmospheric pressure, 

 temperature, solar radiation, aqueous vapour and 

 :loud, rain, wind, storms, and weather forecasting, 

 with other allied subjects. 



We have received a copy of the Report of the 

 Proceedings of the Natural History Society of Bishop 

 Stortford College for 1922. It is the first report 

 published by the Society, and contains a list of the 

 plants found in the district during the years 1920- 



" 1922, an account of the more interesting Lepidoptera 

 occurring during 1922, and a note on the birds of the 

 year. A list of the more important additions to the 

 school museum during the year and a general account 

 of the activities of the Society, especially in the 

 maintenance of vivaria and aquaria, are added. 



• The successful attempt to induce the viper to breed 

 in captivity is a notable achievement. The Society 

 can be congratulated on having got together a nucleus 

 of enthusiastic and active workers, and we hope the 



publication of this report will stimulate its members 

 to increased and more sustained work on the fauna 

 and flora of the district. 



We have received from Messrs. Watson and Sons, 

 Bulletin 29 S. on diathermy apparatus. The intro- 

 ductory remarks are reprinted from an article by 

 Dr. E. P. Cumberbatch, who has made important 

 contributions to this subject. This foreword explains 

 clearly the methods which are necessary for the pro- 

 duction of sustained oscillations of the right frequency 

 for the purposes in view, and also gives some account 

 of the surgical and medical uses to which the 

 diathermy currents can be put. The early designs of 

 the instrument have been much improved so as to 

 allow a large output of these currents, and the spark 

 gap, which has often proved the weakest feature of 

 the instruments, is now run in an atmosphere of coal 

 gas ; if this is not available, petrol or acetone may 

 be used. The bulletin is illustrated by various parts 

 of these machines and by a great variety of electrodes 

 for the various cavities of the body. 



The Cambridge University Press announces the 

 forthcoming publication of " The Archaeology of the 

 Cambridge Region," by C. Fox, which will form a 

 topographical study of the bronze, early iron, Roman, 

 and Anglo-Saxon ages, with an introductory note 

 on the neolithic age. The object of the work is to 

 provide a basis for future detailed study, period by 

 period, of the archaeological remains of the district 

 and of the many problems connected with them. 



Our Astronomical Column. 



Photogr.\phic Magnitudes of Satellites of 

 Jupiter. — Mr. Seth B. Nicholson has made a careful 

 study by photography of the magnitudes of the eighth 

 and ninth satellites of Jupiter. Reduced to mean 

 opposition they are 17-6 mag. and i8-6 mag. respect- 

 ively. Assuming albedoes similar to that of Jupiter 

 III (Ganymede), the diameters are about 30 miles 

 and 20 miles. 



Perturbations by the Method of Quadratures. 

 — In 1908, Dr. P. H. Cowell introduced the method 

 of following the perturbed motion of a planet or 

 ' omet by calculating the forces acting in three 



lirections mutually at right angles, and so obtaining 

 the second differences of the x, y, z co-ordinates of 

 the body; being given the initial values, the suc- 

 cessive ones are then formed by addition of the 

 differences. 



Mr. B. V. Noumeroff has lately improved the 

 method in a paper in vol. ii. of Publications de 

 rObservatoire Astrophysique de Russie. Mr. Com- 

 mendantoff contributes a paper to Astr. Nach., 

 Xo. 5249, explaining the method and applying it to 

 form positions of Ceres from 191 3 to the present time. 



I he Nautical Almanac has discontinued its ephemeris 

 of the four bright asteroids, and since then regular 

 cphemerides have not been available. 



The point of the method is the use of new co- 

 ordinates formed from x, y, z by multiplying them by 



i factor so chosen that the differences between the 



'cond and the sixth disappear, which greatly 



simplifies the calculation. The first approximation, 



using Jupiter perturbations only, at 40-day intervals, 



presents the place of Ceres for ten years with no 



■ iror exceeding 15 seconds of time, which is sufficient 



NO. 28 I 5. VOL. I I 2] 



for a finding ephemeris ; it is further shown how 

 the calculated co-ordinates may be improved when 

 later observations are available. The method appears 

 to be worthy of careful study. 



Studies in Stellar Masses. — Many recent studies 

 in this field have been mentioned in this column. Dr. 

 E. Hertzsprung contributes another to Bulletin No. 

 43, Astron. Instit. of Netherlands. He classifies 14 

 pairs of known orbit elements and parallax ; they 

 include the interferometer results for Capella and the 

 eclipsing variable /3 Aurigas ; the mass of each com- 

 ponent is deduced and the logarithm of the mass 

 plotted against the quantity ni +5 log p, where m and 

 p are the apparent magnitude and parallax respect- 

 ively. The graph connecting the two is nearly 

 linear, showing a close correlation between mass and 

 absolute magnitude, a result reached by other investi- 

 gators. An expression using first and second powers 

 of log mass is preferred, as it gives a better fit ; it is 

 noted that the formula fits well for the sun. 



A table is given enabling the parallax to be deduced 

 when the magnitudes and orbit elements are known. 

 The star f Orionis is discussed. This star has a 

 motion in position angle of 1° in 9 years, but the arc 

 described is too short for finding an orbit. Jackson 

 found the hypothetical parallax o-oi6" assuming a 

 mass double that of the sun. The parallax found 

 from the new formula is 0-0038", which is regarded as 

 more trustworthy. It agrees well with other esti- 

 mates of the distance of the Orion group. 



Dr. Hertzsprung appeals to parallax observers to 

 pay special attention to stars the orbit elements of 

 which are either known or are likely to be determin- 

 able before long. 



