i88 



NATURE 



[Dec. 26, 1 8; 8 



Fellows of the Society. — The following communications were 

 read: — On some mica-traps from the Kendal and Sedbergh 

 districts, by Prof. T. G. Bonney, F.R.S., and F. T. S. Hough- 

 ton, B. A. The rocks described by the authors are mapped by 

 the Geological Survey on quarter sheets 98 N.E., 98 S.E., and 

 97 N.W., and in parts briefly mentioned in the accompanying 

 memoirs, under the generic name mica-trap. Seventeen examples 

 are described macroscopically and microscopically, and of eight 

 chemical analyses are given. It appears better to call one a 

 porphyrite and two diorites (micaceous varieties). The re- 

 mainder are all characterised by abundance of mica (biotite). 

 Augite also appears to have been generally a constituent ; but it 

 has almost invariably been replaced by secondary products, 

 calcite, dolomite, viridite, &c. Three are crystalline in struc- 

 ture ; one of these is named minette, the others kersantite. The 

 remaining eleven show a microcrystalline or cryptocrystalline 

 base. It is proposed to call eight of them minette-felsite, the 

 rest kersantite-porphyrite. These rocks commonly occur in 

 rather narrow dykes ; they are intrusive in Silurian strata, and, 

 in the authors' opinion, are undoubtedly true igneous rocks. — 

 Pleistocene notes on the Cornish coast near Padstow, by 

 W. A. E. Ussher, F.G.S. In this paper the author described 

 certain deposits seen in a small bay near St. Enodock's chapel, 

 and known as Daymer Bay, and in section at Greenway cliffs. — 

 The pleistocene history of Cornwall, by W. A. E. Ussher, 

 F.G.S. In the first part of this paper the author, from his own 

 observations and the writings of other geologists, gave detailed 

 descriptions of the various superficial deposits of Cornwall, as 

 exposed in numerous coast-sections. In the second part he dis- 

 cussed the relative ages of these deposits, and proposed a classi- 

 fication. 



Physical Society, December 14. — Prof. W. G. Adams, 

 president, in the chair. — Mr. W. Gleed and Mr. J. G. McGregor 

 were elected members of the Society. — Prof. Guthrie read a note 

 by Mr. C. Boys on a condenser of variable capacity. This con- 

 denser was designed for use in connection with the Holtz 

 electrical machine to show the effect of condensation on the 

 length of the spark. It consists of a test-tube coated externally 

 with tinfoil to form the inner armature and a glass tube inclosing 

 the test-tube, and having its outer surface covered with tinfoil 

 for the outer armature. The inner tube can be slid out or in 

 along the length of the external tube, and the capacity thereby 

 varied. Prof. Guthrie showed that a spark from the Holtz machine 

 could by its means be gradually reduced. Prof. Macdonnel stated 

 that he had for some years used a similar apparatus, the inner 

 coating, however, being strong sulphuric acid. — Dr. O. J. Lodge 

 exhibited a differential thermometer in which saturated water 

 vapour takes the place of air or other gas. This application is 

 based on the fact that the pressure of a saturated vapour in con- 

 tact with its liquid depends only on the temperature. An ordi- 

 nary cryophorous answers the purpose when held so that the 

 water occupies part of one bulb and a part of the stem next it ; 

 the greater the length of the water column in the latter, that is, 

 the more horizontal the cryophorous is held, the greater the sensi- 

 tiveness of the instrument. If, now, there be a difference of 

 temperatiure between the two bulbs there will be a difference of 

 pressure in the vapour in their interiors, and the level of the 

 water will change until the pressure is equilibriated. When 

 both bulbs are at one temperature the water in tube and bulb is 

 on a level. Unlike air thermometers, the sensitiveness does not 

 depend on the size of the bulbs or tube, and there is no increase 

 of volume of the vapour. Another fonn consists of a U-tube, 

 with bulbs at the end of each arm, each bulb having some liquid 

 and the bend of the tube containing a short column of it, or, for 

 greater sensitiveness, a series of films across the tube like dia- 

 phragms. This thermometer is found to be correct for tempera- 

 tures below that of the ordinary temperature of the water and 

 vapour, but inexact for high temperatures. With these latter the 

 vapour tension is not the same throughout the tube, and distillation 

 is set up. The instrument is a much more sensitive thermoscope 

 than the air thermometer, and there is almost no limit to its 

 sen-itiveness to low temperatures. The radiation from the hand, 

 held six inches from it, sensibly affects it, as also does the radia- 

 tion from a piece of ice. For class purposes it is likely to be 

 useful, from its simplicity and range of delicacy. — Mr. W. 

 Clarke, Cooper's Hill College, from a series of experiments 

 which he is making on the surface-tension of liquid gases, by 

 means of their capillarity, gave the surface-tension of sulphurous 

 anhydride as 2*3 milligrammes per square millimetre at - 15° C. 



Royal Microscopical Society, November 13. — Mr. H. [. 



Slack, president, in the chair. — A paper was read by lie. 

 Royston Pigott on some further inquiry into the limits of micro- 

 scopic vision and the delusive application of Fraunhofer's 

 optical law of vision, in the course of which he described 

 numerous experiments to show that this well-known formula 

 depends upon the laws of diffraction from rays reflected by 

 bright discs or objects, but that it failed when applied to dark 

 lines which were capable of being rendered visible far beyond 

 the limits therein laid down. The subject was illustrated by 

 numerous diagrams and by objects and apparatus exhibited ia 

 the room. — The President detailed the result of some recent 

 experiments to determine the distance at which a human hair 

 could be seen under various conditions by ordinary unassisted 

 vision. — Mr. F. H. W^enham read a paper on the measurement 

 of the angle of aperture of objectives, in which he described the 

 method of measuring the true angle of aperture as distinguished 

 from that of the angle of field with which it was commonly 

 confused. — Mr. Henry Davis read a paper on the pygidium of 

 insects, showing the organ commonly known by this name 

 had its representatives in the Neuroptera, Gryllidae, and other 

 groups of insects, as well as in the flea and lacewing fly. He 

 gave reasons for regarding it as a special organ of sensation 

 conveying to the insect an intimation of the presence of dangerous 

 enemies. Some discussion upon the subject took place between 

 Mr. C. Stewart, Mr. Beck, Mr. Slack, and the author of the 

 paper. — Some further communications, arising out of correspond- 

 ence with Mr. Bedwell, were laid before the meeting by the 

 .Secretaries. — Three new Fellows Mere elected. 



Institution of Civil Engineers, December 3. — Mr. Aber- 

 nethy, vice-president, in the chair. — A paper was read on the 

 heating and ventilating apparatus of the Glasgow Universitv, 

 by Mr. Wilson W. Phipson, M. Inst. C.E. ^ 



Vienna 



Imperial Academy of Sciences, October 17. — The fol- 

 lowing among other papers were read : — Remarks on Stephan's 

 fundamental formulas of electrodynamics, by Dr. Margules. — A 

 hypothesis on the physical state of the sun, by Prof. Puschl. — 

 Light as a reagent, by Herr Bohatta. — On the Tonsilla and 

 Bursa pharyngea, by Dr. Ganghofner. 



October 24. — On a simple apparatus for obtaining a con- 

 stant gas pressure, by Dr. Handl. — A contribution to the doctrine 

 of conic sections in descriptive geometi-y, by Prof. Miksic. — On 

 meteorology of Alpine heights, by Dr. Hann. — On the forma- 

 tion of a space-curve of the fourth order, with a double point 

 on a conic section. 



November 7. — On the Venus transit of December 6, 1882, by 

 Dr. Friesach. — Contribution to knowledge of internal friction in 

 iron, by Herr Klemencic. — On the pitch of a tuning-fork in an 

 incompressible liquid, by Prof. Kolacek. — Determination of 

 orbit of the sixth comet of 1874. 



CONTENTS Page 



The Association OF Local Societies. By J. Clifton Ward . . 165 



Newco.mb's Lunar Researches 166 



RoscoE AND Schorlemmer's Chemistry 169 



Our Book Shelk :— 



Gurney's " Manuals of Elementary Science — Crystallography" . 171 

 Letters to the Editor :— 



On the Ancient Pitch of Organs. — Alexander J. Ellis, F.R S. . 171 



The Formation of Mountains. — Rev. O. Fisher 172 



Magnetic Storm, May 14, 1878. — W. H. Preece 173 



The Derivation of Life from the North.— J. W. Barry .... 173 



Glaciation of the Italian Lakes. — Geo. A, Gibson 174 



Electric Lighting. — J. Hopkinson 174 



The Reproduction of the Eel. — Prof. A. S. Packard, Jun. . . . 174. 



Aerated Bread. By Prof. A. H. Church 174 



On the Co.mbustion of Different Kinds of Fuel. By I. 



LowTHiAN Bell, M.P., F.R.S 1-5 



Papuan Herpefology 176 



The Meteorological Society Lectures 177 



The Motion of a Luminous Souice as aTestof theUndulatory 



Theory OF Light. By S. Tolver Preston 178 



Gbuokafmical Notes 380 



Notes iSo 



Absorption of Water by the Leaves of Plants 1 83 



Undertones 183 



The Disruptive Discharge of Electricity. By Dr. A. M.-\CF.iR- 



LANE {lyith Illustration) 184 



Scientific Serials 1S5 



Societies and Academies 186 



