March 31, 



1898] 



NA TURE 



527 



which X-rays from a vacuum lube are falling emits secondary 

 radiations differing in penetrative power from the original rays, 

 and also differing according to the nature of the reflective sub- 

 stance. Thus aluminium gives off secondary rays which are 

 much more penetrating than those of zinc. — Some applications 

 of photographic irradiation, by M. Ch. Fery. On the hypo- 

 thesis that the upper portion of the sensitive plate when illu- 

 minated by a ray acts as a true secondary source for neighbouring 

 portions of the film, the conclusion is drawn that the apparent 

 width of the line due to halation ought to grow in arithmetical 

 progression when the quantities of light increase in geometrical 

 progression, and this conclusion was verified completely by 

 experiment. — Remarks on the preceding communication, by 

 M. A. Cornu. This research throws light upon the diver- 

 gences obtained in different observatories in the measurement of 

 stellar magnitudes by photographic observations, although part 

 of the observed variation is probably due to aberrations of 

 the mirror. — On a universal magnifier for use in photographic 

 enlargements, by M. J. Carpentier. — Determination of the 

 density of gases with very small volumes, by M. Th. Schloesing, 

 junr. A detailed description of the apparatus used for the 

 determination of gaseous densities by the hydrostatic method, 

 together with the results obtained for air, nitrogen, carbon 

 dioxide and sulphur dioxide. The results are accurate to one 

 part in a thousand. — On neodymium, by M. O. Boudouard. 

 Neodymium forms a double sulphate with potassium, which 

 is more soluble than the corresponding salt of praseodymium, 

 the difference in solubility being sufficiently great to allow of a 

 fairly rapid separation. — On the explosion of mixtures of marsh 

 gas and air by the electric spark, by MM. H. Couriot and J. 

 Meunier. To avoid explosion, it is necessary to join up the 

 two points between which the spark is produced by a 

 secondary conductor. — On the properties of the phosphor- 

 escent sulphide of strontium, by M. Jose Rodriguez Mourelo. 

 — On the oxidation of some amido- and thio-amido-com- 

 pounds, by M. Oichsner de Coninck. A study of the 

 oxidation of acetamide, thio-urea, phenyl-urea, phenyl-thiourea, 

 sarcosine, and carbamic ether by alkaline hypochlorite solution. 

 — On the chlorine derivatives of phenyl carbonate, by M. E. 

 Barral. By the action of chlorine in presence of iodine upon 

 phenyl carbonate dissolved in carbon tetrachloride, the di-chlor- 

 derivative, CO(O.CgH4.Cl)j is obtained. — On the cholesterins of 

 the lower plants, by M. E. Gerard. — Study of the anatomy and 

 histology of the rectum and rectal glands of the Orthoptera, by 

 M. L. Bordas. — On the reserve material in Ficaria ranunculoides, 

 by M. Leclerc du Sablon. Estimations of the reducing and 

 non-reducing sugars, dextrin and starch in the tubers of Ficaria 

 were made monthly, and the results expressed in curves. — The 

 tectonic of the secondary and mountainous region comprised 

 between the valleys of the Ouzom and Aspe (Basse-Pyrenees), 

 by M. J. Seunes. — On the phyilogenic classification of the 

 Lamellibranchs, by M. H. Douville. — On the visibility of 

 the X-rays to certain young blind persons, by M. Foveau de 

 Courmelles. Only nine out of two hundred subjects examined 

 were able to distinguish when the Crookes' tube was or was not 

 excited. No sensation was perceived by those totally blind, 

 only those blind by a peripheral lesion, or having a vague per- 

 ception of light, being sensitive to the X-rays. — Applications of 

 radiography to the study of digital malformations, by MM. 

 Albert Londe and Henry Meige. — Application of radiography 

 to the study of a case of myxoedema ; development of the osseous 

 system under the influence of the thyroid treatment, by MM. 

 Georges Gasne and Albert Londe. — Experimental paralysis 

 under the influences of venoms, by MM. Charrin and Claude. — 

 On the eruptions of Vesuvius, by M. E. Semmola. — Com- 

 munication from the Directeur des Services de la Compagnie 

 des Messageries Maritimes, concerning a Dugong captured in 

 the Red Sea, of a species supposed to be extinct. 



St. Louis. 



Academy of Science, February 21. — Dr. R. J. Terry 

 exhibited a specimen of a cervical rib from a human subject, and 

 discussed the occurrence of structural anomalies of this character. 



March 7. — Prof. C. M. Woodward presented a paper emlx>dy- 

 ing an analytical discussion of the efficiency of gearing under 

 friction. Few works on applied mechanics, the speaker stated, 

 give any discussion of the matter. Only spur wheels with 

 epicycloidal and involute teeth were considered. For the sake 

 of comparison, a table was produced giving the efficiency for 



NO. 1483, VOL. 5;] 



different values of the coefficient of friction /, and for equal 

 wheels and for the same number of teeth, 12, on each wheel. 



Efficiency of Spur Wheels. 



Equal wheels with tz teeth each. 



Kind ... /■003 f 010 fo-iS / 0*20 /o-25 

 Epicycloidal 09915 09693 0-9514 09318 0-9103 

 Involute ... 09923 09746 09622 09501 0-9381 



— Dr. Amand Ravold demonstrated the method, recently intro 

 duced by Hiss, of differentiating the typhoid bacillus from 

 bacillus coli-communis, by the use of semi-solid acidulated media, 

 in which, at blood temperature, the round colonies of the typhoid 

 bacillus assume a peculiar fimbriated form of growth, because of 

 the motility of the bacteria in the slightly yielding medium, which 

 in most cases readily distinguishes them from the more whet- 

 stone-shaped colonies of the colon bacillus, which does not 

 produce the peculiar fimbriation in plate cultures. In tube 

 cultures in the same general medium, but prepared with a 

 slighter acidity and somewhat less solidity, a uniform clouding 

 of the entire tube, due to the swarming of the bacteria, was 

 shown to be characteristic of the typhoid bacillus, while the 

 colon bacillus was definitely confined to the immediate vicinity 



of the thrust. The media in both cases are made up without 



peptone. The formulae are : — 



For plate cultures. 

 Agar ... ... 10 grams. 



Gelatine ... ... 25 ,, 



Beef extract ... 5 ,, 



Glucose ... ... 10 ,, 



Salt 5 



Normal acid ... 20 cc. 

 The whole increa.<-ed to 

 1000 cc. 



For tube cultures. 



Agar 5 grams. 



Gelatine ... ... 80 ,, 



Beef extract ... 5 ,, 



Glucose ... ... 10 ,, 



Salt 5 „ 



Normal acid ... 15 cc. 

 The whole increased to 

 1000 cc. 



The growth of the two species in question, on potato and in milk 

 cultures with litmus, was also demonstrated. 



Amsterdam. 

 Royal Academy of Sciences, February 26. — Prof, van 

 de Sande Bakhuyzen in the chair.— Prof. Schoute, Necrology of 

 Dr. F. J. van den Berg (1833-1892), Professor of Mathematics 

 at the Polytechnic School of Delft (1864- 1884).— Mr. Muller, 

 correspondent of the Academy in the Dutch East Indies, made 

 a communication on the triangulation of Sumatra. When, on 

 the completion of the triangulation of the " Government of the 

 West Coast of Sumatra," the triangulation of South Sumatra 

 was to be commenced, the intention was to start from the 

 triangulation points, determined in 1868 and 1869 in the 

 Lampong districts by the staff of the then Geographical 

 Service. On inquiry being made towards the end of 1895 into 

 the condition of the pillars erected on those points, they were 

 all found to have disappeared, so that the staff of the Triangu- 

 lation Brigade of the Topographical Service, appointed to carry 

 out the triangulation of Sumatra, had to effect a new connection 

 across the Strait of Sunda. The Langeiland-G. Radja Bara 

 side of the Sumatra chain was therefore connected by means of 

 three triangles with two sides of the Java chain, viz. G. Karang- 

 Batoo Hideung and G. Karang-G. Cede ; by means of four 

 triangles the same side was now connected with the point G. 

 Dempoo in the Lampong districts, which had been selected for 

 astronomical station for the orientation of the Sumatra triangu- 

 lation. In 1896 the building of pillars was commenced, and in 

 the course of 1897 the angular measurements at the nine 

 stations, besides the determination of the latitude and azimuth 

 at G. Dempoo were completed. The mean error of the result 

 of the determination of the latitude of G. Dempoo is o''-2i, 

 and that of the result of the determination of the azimuth o"-27. 

 The latitude of the point G. Karang, as calculated from the 

 Sumatra chain,- differs 6" -5 from that derived from the Java 

 chain, which difference may partly be ascribed to local declin- 

 ation. The azimuths at that point differ 5" -3, which is probably 

 to a great extent due to the accumulation of errors in connection 

 with the great distance of the point Genook in Japara, which 

 served as starting-point for the computations of latitude and 

 azimuth in the Java chain of triangles, and which is 540 km. 

 from Karang. The publication of the determinations 

 of latitude and azimuth carried out by the Geographical 

 Service in West Java, will probably throw more light on the 



