JULY 22, 1897] 



NATURE 



279 



A COMPARISON between the magnetisation and associated 

 change of length of iron and steel (Ldngendnderung und 

 Magnetisirung von Risen und Stahl) is the subject discussed 

 by Dr. Klingenberg in his " Inaugural Dissertation " at Rostock 

 University. The magnetisation and elongation of various wires 

 svere measured simultaneously under varied conditions of field- 

 strength, longitudinal loading, and mechanical jarring, and the 

 general conclusion was arrived at that there exists a pronounced 

 similarity between the two associated phenomena. In its 

 details the investigation is, to a large extent, a repetition of the 

 well-known experiments of Joule, Bidwell, Ewing and others ; 

 but the peculiar merit of Dr. Klingenberg's work lies in the 

 coordination of the two classes of phenomena simultaneously 

 studied. It is a careful discussion of a sound piece of ex- 

 perimental work. In his concluding sections the author touches 

 upon the question of magnetic strain, which Dr. Jones has 

 more elaborately worked out in a paper recently published in 

 the Philosophical Transactions. An ingenious attempt is also 

 made to coordinate the curiously contrasted magnetic pheno- 

 mena in iron, nickel, and cobalt in terms of the shape and 

 orientation of the molecular magnets, whose rotations are 

 believed to be the most essential feature in these phenomena. 

 On the assumption that the iron molecules are ellipsoids 

 magnetised, some along the long axis, others along the short 

 axis, the author shows how the former will have preponderating 

 influence in weak fields, while the latter will tell more and 

 more in strong fields. In nickel, the assumption is that the 

 ellipsoids are almost exclusively magnetised along the short 

 axis. On these assumptions the dilatation phenomena in iron 

 and nickel, the Villari Reversal, &c., find ready enough 

 explanation. The peculiarities of cobalt are stated to be 

 explicable on the same lines. 



It" a fused solid substance be cooled below its melting point 

 in a tube, and crystallisation then induced at one end, the rate 

 at which this is propagated along the tube may be taken as a 

 measure of the velocity of crystallisation. Gernez has 

 found, with phosphorus and sulphur, that this velocity 

 is proportional to the degree of super-cooling. Since, 

 however, the surface at which the crystallisation actually 

 takes place is always at the melting temperature of the 

 substance, G. Tammann considers that the velocity ought to be 

 independent of the degree of super-cooling, and in the current 

 number of the Zcitschrift fiir Physikalische Chemie publishes 

 the results of some experiments on the point. Using benzo- 

 phenone, which was not quite pure, he finds that the rate of 

 crystallisation increases with the super-cooling until the latter 

 amounts to about 20° (or less with a purer sample). From this 

 point the velocity remains constant until the super-cooling is 

 so great that the heat evolved by the solidification is insufficient 

 to heat the solid formed to the rnelting temperature. The rate of 

 crystallisation diminishes rapidly from this point onwards. 

 For example, at -40° a crystal ofbenzophenone introduced into 

 the super-cooled substance changes so little that an observer 

 might easily imagine that the liquid was at its melting tempera- 

 ture ; on allowing the temperature to rise crystallisation begins, 

 slowly at - 35°, rapidly at - 25°. Phosphorus, again, solidifies 

 at least one hundred times more slowly at 0° than at 24°. These 

 observaticns seem to provide a fresh point of resemblance 

 between so-called physical and chemical changes, since, of the 

 latter, it has long been known that even the most energetic 

 proceed extremely slowly at sufficiently low temperatures. 



The additions to the Zoological Society's Gardens during the 

 past week include a Rhesus Monkey (Macactis rhesus, <J ) from 

 India, presented by Master Jan. B. Dickson ; a Mozambique 

 Monkey (Cercopithecus pygerythrus) from East Africa, presented 

 by Mr. A. E. Snooks ; a Bonnet Monkey {Macacus sinicus, i ) 

 from India, presented by Mr. W. Meears ; a Black Lemur 

 NO 1447. VOL. 56] 



{Lemur macao), a Black-headed Lemur {.Lemur brunneus), a 

 Grey Lemur {Hapalemur griseus) from Madagascar, presented 

 by Mr. R. A. Todd ; a Roseate Spoonbill {Ajaja rosea) from 

 South America, presented by Mr. E. J. Ghay ; a Common Pea- 

 fowl {^Pavo cristatus, i ) from India, presented by Mr. A. Burnell 

 Tubbs ; a Red-sided Eclectus {Eclectus pectoralis) from- New 



Guinea, presented by Mr. Edward Hawkins ; a Cassowary 



[Casuariusy sp. ?) deposited ; a Thar {Capra jemlaica), a Red 

 Deer (Cervus elaphtis, <J ) born in the Gardens, 



Ol/R ASTRONOMICAL COLUMN. 

 Cambridge Observatory Report.— Sir Robert Ball 

 records the completion and publication of the zone 25° to 30°, 

 which forms part of the " Catalog der Astronomischen Gesell- 

 schaft." In it are the places of 14,464 stars, the result of about 

 47,570 observations, the Observatory having been engaged in 

 this work during the last quarter of a century. The complete 

 catalogue containing the individual observations is very nearly 

 ready for press, and will be printed as soon as the volume 

 already in the printer's hands has been issued. Mr. Hinks has 

 undertaken a detailed com])arison of the places of 671 stars in 

 the Cambridge and Berlin Catalogues lying in the zone -{■ 24" 50' 

 to -f 25° 10'. The result seems to have been very satisfactory, 

 the differences of declination being very small and apparently 

 accidental, while in the case of the right ascensions small but 

 systematic differences depending on the magnitude of the stars 

 have been found. The designs for the new photographic tele- 

 scope have been completed, and the instrument is being pushed 

 forward ; it is mentioned that probably the new building to 

 contain it will be erected during the course of the summer. 

 With regard to the Newall telescope, Mr. H. F. Newall tells 

 us in his report, which is attached, that he has met with great 

 difficulties in bringing his spectroscope into successful working 

 order. The discrepancies were, however, securely traced, and 

 the necessary alterations made, with the result that the photo- 

 graphs now obtained are considered very satisfactory. Some of 

 the results already obtained, with regard to the motion of some 

 stars in the line of sight, are given by him in his report, from 

 which we make the following extract : — 



In the last star in this list Belopolsky obtained the value 

 -57, while Keeler's was slightly larger, namely -6'8. 



The term of five years for which Mr. Newall placed his 

 services at the disposal of the University in connection with this 

 instrument has now been completed, and our readers will be 

 glad to hear that he has renewed his proposal for another similar 

 period. 



New Variable in Coma Berenices. — In a communication 

 to the current number of the Astronomischen Nachrichten 

 (No. 3433), Mr. T. D. Anderson gives details of the variable 

 star he has recently discovered. It seems that on May 29 of 

 this year he observed a star in the constellation of Coma 

 Berenices, in position R.A. = I2h. 23-om., Decl. -f- 32° 17' ±1' 

 (i855'o). This star was not found mentioned in the BD., but 

 its magnitude was estimated as exactly the same as BD. -f 31° 

 •2373, namely 8-8. About ten days afterwards Mr. Anderson 

 again observed the star, but could detect no change whatever in 

 its brightness. Observing with his 24-inch refractor some four 

 weeks later— on July 9 and 10 — he was still unable to see the 

 star, although BD. -I- 32° "2248 and 2253, which were both 

 much brighter than it on May 29, were clearly visible. The 

 magnitude of this new variable must have been lower than 9*5. 



