March 29, 1903' 



NA TURE 



521 



of the mistletoe appeared to produce a poisonous effect. Some- 

 what similar results as to-the influence of the nature of the soil 

 on distribution were obtained with the dodder. 



Under the title of "The Temple Cyclopaedic Primers," 

 Messrs. Dent and Co. have commenced the publication of a 

 series of little volumes on scientific and other subjects. "An 

 Introduction to Science" is written by Dr. Alex Hill ; and an 

 *' Ethnology" has been translated by Mr. J. H. Loewe from 

 the German of Dr. Michael Ilaberlandt. The books are both 

 attractive in appearance and instructive in contents ; and they 

 should bring a large public in touch with scientific work and 

 thought. Students of science as well as general readers will 

 find the volumes well worthy of consideration. 



The advantages of quartz as a thermometric substance as 

 compared with glass are well known, and since the well-known 

 experiments of Mr. Boys on the behaviour of quartz near its 

 melting point, numerous attempts have been made to produce 

 quartz tubes. M. Dufour, who describes his experiments in the 

 current number of the Comptes remhis, has been able to con- 

 structs quariE thermometers, two of which are described, one 

 carrying tin as the thermometric liquid, and hence suitable for 

 temperatures from 240° C. upwardi. The second instrument 

 contained mercury, and was constructed with the view of 

 comparing its zero residues with those of a glass thermometer. 



The limiting value for the molecular depression of the 

 freezing point in solutions of non-electrolytes, when these 

 solutions become infinitely dilute, is a constant of great 

 importance in the van 't Hoff theory of solution. Raoult, 

 Abegg and Loomis are among the best known workers in this 

 Tield, and in the current number of the Zeitschrtft fiir 

 physikalische Chemte is a contribution by the last named in 

 which the numerous difficulties surrounding the apparently 

 simple operation of takinsj a freezing point are discussed. The 

 limiting value in extreme dilution for the molecular depression 

 of a considerable number of non-electrolytes of different con- 

 stitution is the same, i -86. This is exactly the figure which is 

 obtained from van 't Hoff's well-known formula, if the latent 

 heat of fusion of ice be taken as 79-3 thermal units. 



The additions to the Zoological Society's Gardens during the 

 past week include a Sooty .Mangabey {Cercocebus fuliginostis, 9 ) 

 from West Africa, presented by the Rev. A. Christopher ; a 

 Jaguar {Felis onea) from Brazil, presented by Mr. Rodriques ; 

 two Martinican Doves (Zenaida attrila) from the West Indies, 

 presented by Mr. G. R. Phillipps ; a Great Bustard {Otis 

 tarda, i ), European, presented by Mr. E. G, B. Meade- 

 Waldo ; a Pine Marten (Mnstela tnartes) from the Spanish 

 Pyrenees, a Snowy Owl {Nyctea scandiaca), European ; a Pin- 

 tailed Sand Grouse {Pteroctes aUhata), a Slender-billed Gull 

 (Lartts geiastes) from Southern Europe, deposited. 



OUR ASTRONOMICAL COLUMN 



.\STRONOMICAI, OCCURRENCES IN APRIL. 



April 2 ■3h. Venus in conjunction with the moon. Venus 

 o" 46' N. 



2. I3h. 2m. Jupiter's Sat. IV. in conjunction with N. 



pole of planet. 



3. 8h. 47m. to 9h. 44m. Moon occults B.A.C. 1373 



"lag- 57)- 



3. Venus 2° S. of the Pleiades. 



4. 9h- 30m. to loh. 22m. Moon occults o Tauri (mag. 



4-8). ^ 



-S. iih. 46m. to I2h. 45m. Moon occults a Cancri 

 (mag. 43). 

 15. Illuminated portion of disc, Venus = 0-576 ; Mars, 



0985. 

 17. I2h. 56m. Minimum of Algol (/3 Persei). 

 NO. 1587, VOL. 61] 



18. 



20. 

 20. 

 22. 

 23- 



24. 



28. 

 28. 

 29. 



ih. 42m. 



2Sm. 



Moon occults 24 Ophiuchi 

 Moon occults B.A.C. 6088 



loh. 36m. to 



(mag. 5-6). 

 I5h. 9m. to i6h, 



(mag. 6*o). 

 9h. 45m. Minimum of Algol (5 Persei), 

 I2h. 37m. to I3h. 30m. Moon occults 33 Sagittarii 



(mag. 60). 

 I4h 27m. to I5h. 42m. Moon occults (^ Sagittarii 



(mag. 3-5). 

 Epoch of the April meteoric shower (Lyrids, radiant 



271° + 33°)- 

 Saturn. Outer major axis of outer ring, 4o"£8. 

 Saturn. Outer minor axis of outer ring, I7"'52. 

 I2h. 12m. to I3h. 49m. Transit of Jupiter's Sat. III. 

 I5h. 23m. to I5h. 57m. Moon occults c^ Capri- 



cornii (mag. 52). 

 I4h. 20m. to I5h. 12m. Moon occults k Aquarii 



(mag. 5-5). 

 I2h. Venus at greatest elongation, 45° 30' E 

 Perihelion passage of Giacobini's comet 11900a). 

 I5h. 37m. to I7h. 14m Transit of Jupiter's Sat. 



Comet 1899 V.— Herr S. K. Winther continues his 

 ephemeris of this comet in the current issue of the Astro- 

 nomische Nachrichlen (Bd. 152. No. 3631). 



Et>henteris for izh. Berlin Mean Time. 



New 

 Astropk 



Prof. D. B. Brace, of Nebraska University, describes a new 

 system of spectral photometric work, the foundation of which 

 depends on a novel method of bringing into juxtaposition 

 the two illuminated areas, the intensities of which are to be 

 compared. This is done by using for the dispersion-piece of 

 the spectro- photometer a compound prism, one-half of which 

 has been silvered along a narrow strip of its face before being 

 cemented to the other. Two collimators are then used, one 

 sending light through the prism in the customary manner, the 

 other so arranged that after internal reflection from the silvered 

 strip and subsequent refraction, the resulting spectrum is re- 

 ceived in the same telescope as that from the first source. The 

 two spectra will thus be seen in absolute juxtaposition, and 

 perfect equality will be denoted by the disappearance of the 

 junction line between them. The instrument is stated to be so 

 sensitive that good comparisons could be made on the star 

 Capella, using a 4-inch telescope, so that with larger telescopes 

 the spectra of all the brighter stars could be accurately 

 compared. 



Variable Stars of the Algol Type.— In Popular Astro- 

 nomy for March 1900, Mr. H. C. Wilson, of Goodsell Observa- 

 tory, Minnesota, U.S.A., gives a very complete synopsis of 

 the eclipse theory of the Algol type of variables. In the com- 

 putations of the po.ssible light curves due to eclipses, formulas 

 are given for both circular and elliptic orbits, and for direct and 

 oblique line of sight. Using Vogel's values for the ra<lial 

 velocity of the star during the period, there is some little 

 disagreement in the resultant curves, which is too systematic to 

 be put down to errors of observation. Dr. Vogel considering 

 that part of this might be due to the possibly existing atmospheres 

 surrounding the stars having been neglected, Dr. Wilsing 

 calculated anew the resultant light curve, which is .so nearly in 

 accordance with the actual one observed as to leave little doubt 

 of the accuracy of the assumption. In this particular Mr. 

 Wilson makes an interesting suggestion with respect to the light 

 curve of the class of variables represented by & Lyrre, showing 

 how, by considering certain values of distance, intensity, ^nd 

 extent of atmosphere of two bodies, a curve of light variahon 

 may be found very closely agreeing with that deduced spectro- 

 scopically. 



Computation of Orbits of Spectroscopic Doubles. — 

 Dr. K. Schwarzschild, of Munich, contributes to the Astrono- 



