June 2 1, 1888] 



NA TURE 



191 



viscosity, and temperature of the electrolyte, as well as the 

 previous history of the electrode, have considerable influence on 

 the current density at which the insulating condition occurs. 

 The seat of the insulating layer is found to be at the anode ; and 

 the authors believe it due to very concentrated' acid formed 

 around the electrode, whose specific resistance is very high. 

 Experiments were also made with carbon and gold electrodes, 

 and phosphoric acid, caustic potash, soap, and sodium benzoate 

 were used as electrolytes, the results of which seem compatible 

 with the concentration hypothesis above stated. The paper 

 contains an historical and critical account of allied phenomena, 

 and tables expressing the numerical results obtained by the 

 authors are given. 



Linnean Society, June 7. — Mr. Carruthers, President, in 

 the chair. — The following were nominated Vice-Presidents : 

 Mr. F. Crisp, Dr. Maxwell Masters, Dr. John Anderson, Mr. 

 C. B. Clarke. — An exhibition under the microscope of decalcified 

 and stained portions of the test of Laganum depression was then 

 given by Prof. Martin Duncan, who made some very instructive 

 remarks on the structural characters to be relied on for discrim- 

 inating the species. — Mr. D. Morris, of Kew, exhibited some 

 drawings of a Fungus {Exobasidiutn) causing a singular distortion 

 of the leaves of Lyonia, from Jamaica. — A- paper was then read, 

 by Mr. II. N. Ridley, on the natural history of Fernando 

 Noronha, in which he gave the general results of his investigations 

 into the geology, botany, and zoology of this hitherto little 

 explored island. 



Royal Meteorological Society, May 16. — Dr. W. Marcet, 



F. R.S., President, in the chair. — The following communications 

 were read : — Report of the Wind Force Committee on experi- 

 ments with anemometers conducted at Hersham, by Mr. 



G. M. Whipple and Mr. W. H. Dines. A whirling 

 apparatus, with arms 29 feet radius, was rotated by means of a 

 small steam-engine. On the arms of the whirler four different 

 anemometers were placed. Each experiment lasted fifteen 

 minutes, the steam-pressure remaining constant during the run. 

 For the Kew standard anemometer, with arms 2 feet long, the 

 experiments give a mean value for Robinson's factor of 2'I5 > 

 and for two smaller instruments the factor is 2 '51 and 2 "96. 

 Mr. Dine's helicoid anemometer gave very satisfactory results, 

 the mean factor being o - 996. — On the measurement of the 

 increase of humidity in rooms by the emission of steam from the 

 so called bronchitis kettle, by Dr. W. Marcet, F. R. S. The author 

 described a number of experiments which he had made by steam- 

 ing a room with a bronchitis kettle, and ascertaining the rise and 

 fall of the relative humidity from readings of the dry- and wet- 

 bulb thermometers. He found that the air in the room could 

 not be saturated, the relative humidity not exceeding 85 per 

 cent. 



Entomological Society, June 6. — Dr. D. Sharp, President, 

 in the chair. — Mr. Pascoe brought for exhibition a book of fine 

 plates of Mantidtc, drawn by Prof. Westwood, which it had been 

 hoped would have been published by the Ray Society. — Mr. E. 

 Saunders exhibited a species of Hemiptera, Monanthia angustata, 

 H-S., new to Britain, which he had captured by sweeping, near 

 Cisbury, Worthing. The insect is rather closely allied to the com- 

 mon Monanthia cardui, L.— Mr. McLachlan exhibited a species 

 of Ilalticidie, which had been sent him by Mr. D. Morris, Assist- 

 ant Director of the Royal Gardens, Kew, who had received them 

 from Mr. J. H. Hart, of the Botanic Gardens, Trinidad, with a 

 note to the effect that they had attacked young tobacco and egg- 

 plants badly in that island. Mr. Jacoby had, with some reserve, 

 given as his opinion that it might possibly turn out to be Epitrix 

 fuscata, Duv., a species which had been described from Cuba. — 

 The Rev. II. S. Gorham exhibited a collection of beetles lately 

 captured in Brittany including Diachrotnus germamts, L., 

 Ontliophagus taunts, L., Hister simialns, 111., and other 

 species which are exceedingly rare, or altogether wanting in 

 Britain, and yet occur very commonly in the north of France. — 

 Mr. White exhibited living larva; of Endromis versicolora, 

 from near Bristol, and remarked that when quite young they are 

 nearly black, owing to being very thickly spotted with that colour ; 

 the body-colour is green, and after two or three changes of skin 

 the spots disappear. Mr. White also exhibited two preserved 

 larva; of Phorodesma smaragdaria, which he had recently taken, 

 and made some remarks concerning the so-called " case," which 

 this insect is said to construct from the leaves of its food-plant, 

 Artemisia maritima. This he did not consider to be really a 

 case, but he had discovered that the larva possessed on its 



segments certain secretory glands, at the apex of each of which 

 there is a bristly hair ; this appears to retain pieces of the plant, 

 which are probably fixed firmly afterwards by means of the 

 secreted fluid. These pieces are very irregularly distributed, and 

 their purpose does not seem quite evident. — Mr. Lewis exhibited 

 about three hundred specimens of the genera Hetarius, Er., and 

 Eretmotus, Mars. The most remarkable of these was EUtmritu 

 acntangulus, Lewis, discovered last year by Mr. J. J. Walker 

 near Tangier, and recently taken by him at San Roche, in 

 Spain. 



Paris. 



Academy of Sciences, June 11. — M. Janssen, President, in 

 the chair. — A study of the refrigerant mixtures obtained with 

 solid carbonic acid, by MM. Cailletetand E. Colardeau. These 

 researches seem to show that the ether generally used in com- 

 bination with snow and carbonic acid for the purpose of obtain- 

 ing intense cold, plays a much greater part than has been 

 supposed in lowering the temperature of the mixture. — Repre- 

 sentation of the attitudes of human locomotion by means of 

 figures in relief, by M. Marey. The figure of a runner at a given 

 moment is here reproduced from a relief obtained by M. Engrand 

 by means of the photochronograph. It is pointed out that a 

 continuous series of such figures, obtained by this process, would 

 be of great service in determining for artists and physiologists the 

 successive changes of attitude in running and walking. — Deter- 

 mination of the mean level of the sea, by means of a new 

 instrument, by M. Ch. Lallemand. In a previous note {Comptes 

 renins, May 28, 1888) the principle was described of this appara- 

 tus, wdiich is here figured and named the inediinaranetcr. It 

 gives the mean sea- level without any mechanical adjustments, and 

 almost without the need of calculations — On the artificial 

 reproduction of hydrocerusite, on the chemical composition of 

 this mineral species, and on the constitution of white lead, by 

 M. L. Bourgeois. These synthetic researches throw much 

 light on the hitherto problematical nature of hydrocerusite, as 

 well as on the constitu'ion of white lead (ceruse), in which the 

 author distinguishes only two definite substances, both existing 

 in nature — hydrocerusite and cerusite. Analysis shows that the 

 formula of the artificially prepared hydrocerusite is 3PbO, 2C0 2 , 

 HO, or 2(PbO,CO.,) + PbO.HO, which is no doubt that of 

 the natural substance also. — On the variations of the personal 

 equation in the measurement of double stars, by M. G. Bigourdan. 

 Thiele supposes that the personal equation of each observer remains 

 somewhat constant during a "season of observations," and then 

 takes a different value for another period, the duration of the 

 "seasons" varying from a few days to several months. But 

 according to Struve these variations are rapid, occurring in a few 

 hours, and lasting only a single night. The observations of the 

 author tend to show that these apparently contradictory views 

 are capable of being reconciled, both being to a certain extent 

 true. — On the determination of some new rings of Saturn lying 

 beyond those already known, by Dom Lamey. These were first 

 vaguely perceived by theauthorin 1868, and have been repeatedly 

 observed since February 12, 1884, with the 16 cm. refractor 

 in the clearer atmosphere of the Grignon Observatory. They 

 are four in number, and are visible as well-defined elliptical 

 rings in the regions intermediate between Mimas and Titan, first 

 and sixth satellites of Saturn. The semi-diameter of the planet 

 being taken as 1, the semi-diameter of the rings, measured from 

 the middle of the most intense region, would be 2*45 ± C05 ; 

 3'36 ± 0*02 ; 4'90 ± o - 5o ; 8*17 ± o'23. They were also 

 independently observed by two of the author's fellow-workers, 

 and cannot therefore be explained away as optical illusions due 

 to the terrestrial atmosphere or any other sources of error. — On a 

 point in the history of the pendulum, by M. Defforges, with 

 remarks by M. C. Wolf. In connection with Kater's memoir 

 of 1818, presented to the Royal Society, on the " convertible " 

 pendulum, and his repudiation of de Prony's claim to priority of 

 invention, M. Defforges announces the discovery of some 

 documents in the Ecole des Ponts et Chaussees fully confirming 

 de Prony's claim. M. Wolf, however, points out that these 

 documents (undated, but no doubt written in 1800) were never 

 published, and certainly unknown both to Bohnenberger when he 

 announced the project of a pendulum with reciprocal axes (181 1), 

 and : to Kater when he rejected de Prony's claim to priority of 

 inve'ntion (1818). Hence, although de Prony now appears 

 to have been the precursor, the rights of Bohnenberger and 

 Kater remain intact as discoverers of the principles to which 

 is due the revolution effected in the observations of the 

 pendulum during the present century. — On a correction to 



