February i6, 1905] 



NA TURE 



383 



of finding the form of pontoon which, advancing through 

 the fluid at a given speed, would be unaccompanied by any 

 displacement of fluid surface either before or behind. — A 

 comparison of the lakes of Denmark and Scotland : Dr. 

 Wesenbergr-Lund. Dr. Lund had visited Scotland on the 

 invitation of Sir John Murray with the view of making 

 tliis comparative study. The greatest possible contrasts 

 existed between the lakes of Denmark and the typical High- 

 land lakes of Scotland, the Danish lakes being, for ex- 

 ample, comparatively small and shallow, with great varia- 

 tions of temperature from season to season, the water being 

 rich in lime, and the littoral region being characterised in 

 most cases by luxurious vegetation forming the home of 

 numerous animals. Scottish lakes like Loch Leven, how- 

 ever, approximated more closely in character to the lakes 

 of Denmark. The paper contained an important discussion 

 of the fauna of the two types of lakes, and of its influence 

 on the lakes themselves and their surroundings. The 

 Danish lakes are gradually being silted up, and will before 

 long disappear, while the lochs of Highland Scotland will 

 remain practically unaltered through long ages. — On a new 

 family and twelve new species of Rotifera of the order 

 Bdelloida : J. Murray. The great uniformity of structure 

 hitherto observed throughout the order Bdelloida gives 

 much interest to the discovery in the Scottish lochs of an 

 animal showing great divergence from the general type. 

 The new family, which is called Microdinada;, is peculiar 

 in the structure of head and jaws. The discs and wreaths 

 ■ire quite absent, so that there is no corona, unless the 

 terminal cilia of the throat are regarded as such. The 

 rostrum and toes are as in the genus Philodina. The jaws 

 of all other Bdelloida are ramate ; those of Microdina are 

 between ramate and malleo-ramate or malleate. The 

 large teeth are all towards the anterior end of the jaws, 

 .Tnd there are usually from one to two loops on the manu- 

 brium. A remarkable feature of the animal by which alone 

 it could be distinguished from all other Bdelloida is a large 

 crimson gland attached to the oesophagus. — Variations in 

 the crystallisation of potassium hydrogen succinate due to 

 the presence of other metallic compounds in the solution : 

 A. T. Cameron. The crystals were obtained from solu- 

 tions containing small quantities of ferric and chromic 

 compounds, and may be described as oblique elliptic double 

 cones showing curved surfaces only. The crystals belong 

 to the same system as those of the acid succinate, and are 

 evidently modifications due to the presence in small variable 

 quantities of the other metallic compounds possibly in a 

 state of solid solution. — (i) Continuants whose main 

 diagonal is univarial ; (2) the eliminant of a set of general 

 ternary quadrics : Dr. Thomas Muir. 



Manxhester. 

 Literary and Philosophical Society, January 24 — 

 Rigidity of gelatin : H. Morris-Airey. After describing 

 some of the properties of aqueous solutions of gelatin, 

 the results of a series of measurements of the rigidity of 

 these media were given. — The cause of the period of 

 ■ chemical induction : C. H. Burgess and D. L. Chapman 

 (see p. 380). 



Paris. 

 Academy of Sciences, February 6. — M. H. Poincare in 

 the chair. — On the stability of ships : E. Bertin. — On the 

 I action of hail cannons : J. Violle. There are in the Beau- 

 I jolais twenty-eight societies for breaking up the hail-storms 

 common in that region by means of the hail cannon. A com- 

 parison of the damage done during the period 1S91-1900 with 

 the losses through hail subsequent to the introduction of the 

 cannon (1900-1904) shows marked evidence in favour of the 

 use of this means of dispersing the hail clouds. It has been 

 I frequently noticed that both lightning and thunder are sup- 

 I pressed within the protected zone, although they may be 

 raging just outside this area. — Syntheses in the anthracene 

 series. Symmetrical diamido-tetra-a^kyl derivatives of the 

 dihydride of 7-tetraphenyl-anthracene : A. Haller and A. 

 Guyot. As a result of the condensation of 7-diphenyl-7-di- 

 hydroxy-anthracene dihydride with dimethylaniline two 

 J stereoisomeric compounds are produced, which, on account 

 I of the wide differences in their properties, are very readilv 

 1, separated. A similar reaction takes place with diethylaniline, 

 but the stereoisomers are more difficult to separate. — The sub- 



NO. 1842, VOL. 71] 



stances producing softness in wine : A. Muntz. A discus- 

 sion of the effect of the gummy matters present in wine on 

 its taste. — On the extension of the Cretaceous seas in Africa : 

 .\. de Lapparent. Traces left by the seas of the Upper 

 Cretaceous have been recognised for some time in the Sahara 

 and the Soudan, but up to the present there has been no 

 direct proof of a communication between this and the 

 .Atlantic. Fossils recently collected by Lieut. Desplagnes 

 and Capt. Th^veniaud make the existence of this communica- 

 tion highly probable. — On the three methylcyclohexanones 

 and the corresponding methyl-cyclohexanols : Paul Sabatier 

 and A. Mailhe. The three cresols are readily reduced to the 

 corresponding cyclohexanols by hydrogen in presence of 

 reduced nickel at 200^-220° C. These were converted by 

 heating with zinc chloride into methylcyclohexenes, and by 

 oxidation into methylcyclohexanones. The latter substances 

 are more conveniently obtained from the alcohol by the 

 reaction discovered by Sabatier and Senderens, passing the 

 vapours of the alcohol over copper heated to 300° C, the 

 yield by this method being nearly theoretical. — On a measure- 

 ment of the height of the reversing layer obtained with the 

 aid of the large telescope of the Observatory of Mont Blanc : 

 M. Millochau. Measurements of two calcium lines under 

 good conditions gave a thickness of o". 15. — Observations of 

 the zodiacal light made at the summit of Mont Blanc : A. 

 Hansky. A detailed account of observations taken under 

 very favourable conditions on September 21-22. — On solu- 

 tions of systems of linear differential equations with mono- 

 drome coefficients : Ed. Maillet. — On Poisson's integral and 

 singular lines of analytical functions : P. Fatou. — On the 

 whole of the curves traced on an algebraic surface, and on 

 the Picard integrals of this surface : Francesco Severi. — 

 On the deviation of freely falling bodies: M. de Sparre. 

 Reply to a paper of M. Maurice Fouch^ on the same sub- 

 ject. — On a new mechanical clutch : M. Herisson. — .\n 

 integrating thermometer : Ch. Fery. — A synchronising elec- 

 tromagnetic brake : Henri Abraham. The axis of the 

 motor carries a toothed wheel of copper, the teeth of which 

 pass between the poles of an electromagnet, actuated by 

 the same current as the motor. If synchronism is estab- 

 lished, each tooth passes this space at the instant when the 

 electromagnetic field is nil, and there is no braking action. 

 If the synchronism is imperfect, the brake absorbs the whole 

 of the extra energy of the motor. — Magnetic hysteresis at 

 high frequencies in nickel and nickel steels : Ch. Eug. Guye 

 and A. Schidlof. — On the direct fixation of ethero-organo- 

 magnesium derivatives on the ethylene linkage of unsaturated 

 esters : E. E. Blaise and A. Courtot. Ethyl methacrylate 

 reacts with magnesium-methyl-iodide giving the tertiary 

 alcohol dimethylpropenylcarbinol, the ketone methyl-ethyl- 

 acetone, and diisopropenyl. The conditions giving a 

 maximum yield of either of these have been worked out. — On 

 the cryoscopy of the sulphates : Albert Colson. — A new 

 method of testing for ammonia : application to the examin- 

 ation of water for sanitary purposes : MM. Trillat and 

 Turchet.' In presence of potassium iodide and sodium 

 hypochlorite, ammonium salts develop a black coloration, due 

 to iodide of nitrogen, which can be estimated colorimetri- 

 cally. The coloration appears to be less liable to be inter- 

 fered with by certain substances commonly present in natural 

 waters than is the case with Nessler's reagent. — On the 

 evolution of carbon in combustibles : Isidore Bay and Just 

 Alix. — Some hereditary anomalies provoked by traumatisms : 

 M. Blaringrhem. — On the use of leucine and tyrosine as 

 sources of nitrogen for plants : L. Lutz. These two nitro- 

 genous substances can be assimilated both by phanerogams 

 and fungi. The difference noted in a previous paper be- 

 tween these two classes of plants was due to the use of sand 

 as a medium for the growth of the former. — On the cause of 

 the impoverishment of springs in plains : M. Houllier. The 

 author draws the conclusion that the progressive impoverish- 

 ment of the springs in the basin of the Somme during recent 

 years is the result of the increased use of the land for agri- 

 cultural purposes, leading to a very considerable increase in 

 the amount of water evaporated by plant transpiration. — The 

 proportions of the gases in arterial blood during the course 

 of anaesthesia due to chloroform, remaining invariable so 

 long as the pulmonary respiration remains very nearly 

 normal : J. Tissot. — The mechanism of accommodation : H. 

 Bertin-Sans and J. Gagrniere. The experiments described, 

 which were carried out with rabbits' eyes, support 



