June 9, 1892] 



NATURE 



h: 



contained a revision of the Antelopes of the genus Cephalolophus, 

 of which eighteen species were recognized as valid. A new 

 species was described as Cephalolophtis jentincki, from Liberia. — 

 Prof, Bell called attention to the remarkable amount of variation 

 jiresented by Pontastcr tenuispinis, numerous examples of which 

 he had been able to examine and compare. He came to the 

 conclusion that several North-Atlantic species, which had been 

 described as distinct, should be reijarded as belonging to it. — A 

 communication was read from Mr. H. li. Druce givin» an 

 account of the Butterflies of the family Lycaenidte, of the South 

 Pacific Islands. Of thirty-one species mentioned, seven were 

 described as new to science. 



Linnean Society, May 24. — Anniversary Meeting.— Prof. 

 Stewart, President, in the chair. — The Treasurer presented his 

 annual report duly audited, and the Secretary having announced 

 the elections and deaths during the past twelve months, the 

 usual ballot took place for new members of Council, when the 

 following were elected : Messrs. E. L. Batters, William 

 Carruthers, Herbert Druce, Spencer Moore, and Dr.D, H. Scott. 

 The President and officers were re-elected. The Librarian's 

 report having been read, and certain formal business having 

 been transacted, the President delivered his annual address, 

 taking for his subject " Commensalism and Symbiosis." On 

 the motion of Dr. R. C. A. Prior, seconded by Mr. Jenner 

 Weir, a cordial vote of thanks was accorded to the President 

 for his able address, with a request that he would allow it to be 

 printed. — The Society's Gold Medal was then formally presented 

 to Dr. Alfred Russel Wallace in recognition of the service 

 rendered by him to zoological science by numerous valuable 

 publications. After Dr. Wallace had replied, the President 

 announced the gift by Dr. R. C. A. Prior of an oxyhydrogen 

 lantern for use at the evening meetings, and moved a vote of 

 thanks to him for his valuable donation. This having been 

 carried by acclamation, the proceedings terminated. 

 Cambridge. 



Philosophical Society, Maya. — Prof G. H. Darwin, Presi- 

 dent, in the chair. — The following communication was made: — 

 Note on the application of the spherometer to surfaces not 

 spherical, by Mr. J. Larmor. The ordinary form of sphero- 

 meter, with equilateral triangular frame, gives a detinite reading, 

 when applied to a surface of double curvature, which corre- 

 sponds to the arithmetic mean of the principal curvatures at the 

 point ; thus on a cylinder it will indicate half the curvature. It 

 may be modified in various ways so as to measure both the prin- 

 cipal curvatures by two observations. 



May 16. — Prof. G. H. Darwin, President, in the chair. — The 

 following communications were made : — Recent advances in 

 astronomy with photographic illustrations, by Mr. H. F. 

 Newall. A series of photographs was exhibited by the lantern 

 and described, to illustrate recent progress in astronomical photo- 

 graphy. The series included some interesting specimens taken 

 with the Newall telescope, in which the object-glass is not 

 specially corrected for photographic purposes. — On the pressure 

 at which the electric strength of a gas is a minimum, by Prof. 

 J. J. Thomson. The author showed that when no electrodes are 

 present, the discharge passes through air at a pressure somewhat 

 less than that due to 1/250 mm. of mercury ; the discharge passes 

 with greater ease than it does at either ahigher or a lower pressure. 

 Mr. Peace has lately shown that when electrodes are used, the 

 critical pressure may be as high as that due to 250 mm. of mer- 

 cury ; so that as the spark length is altered the critical pressure 

 may range from 250 mm. to 1/250 of a mm. It was pointed out 

 that this involved the possession by a gas conveying the discharge 

 of a structure much coarser than any recognized by the kinetic 

 theory of gases. The author suggested a theory of such a struc- 

 ture, and showed that the theory would account for the influence 

 of spark length and pressure on the potential difference required 

 to produce discharge. — On a compound magnetometer for test- 

 ing the magnetic properties of iron and steel, by Mr. G. F. C. 

 Searle. An aluminium wire, 30 inches long, suspended 

 vertically by a fibre, carries at the top a magnet fixed at right 

 angles to the wire. The lower end carries a light fork across 

 which a fibre is stretched horizontally. A mirror attached to 

 this fibre carries a magnet at right angles to the fibre. The 

 mirror is thus capable of two independent motions. The speci- 

 men of iron is placed in a magnetizing coil near the mirror, and 

 the magnetizing current passes also round a coil placed near the 

 upper magnet. The motion of the mirror is observed by the aid 

 of a spot of light. On gradually increasing and diminishing the 

 current, the spot traces out the well-known hysteresis curves. 



Edinburgh. 

 Royal Society, May 16. — Sir Douglas Maclagan, President, 

 in the chair. — The Astronomer-Royal for Scotland exhibited a 

 stellar photograph, by Dr. Gill, of the Cape Observatory. — Dr. 

 W. Peddie read a note on the law of transformation of energy 

 and its applications. A generalization of the second law, 

 applicable to forms of energy other than heat, was shown, by 

 special examples, to lead to results already deduced by other 

 methods. — Dr. C. G. Knott and Mr. A. Shand communicated 

 a short note on the volume-effects of magnetization, which was 

 supplementary to results communicated to the Society last year 

 by the former author. When a particular size of iron tube was 

 magnetized, the internal volume was found to undergo the 

 following remarkable series of changes. In very weak fields 

 there was first a slight increase, which, as the field was made 

 stronger, passed through a maximum, then vanished and finally 

 changed sign. From this point (about field 20) up to a field 

 of 120 there was diminution of volume. This diminution was 

 greatest in a field of 64. In fields higher than 120 there was 

 again increase of volume, which attained a maximum about field 

 400, and fell off very slowly in higher fields. This curious 

 variation of cubical dilatation with strength of field was shown 

 to imply a transverse linear dilatation of (in general) opposite 

 sign to the well-known longitudinal linear dilatation. The 

 amounts, the positions of the maximum points, and of the 

 vanishing points, of these correlated linear dilatations differed 

 sufficiently in detail to produce this peculiar repeated change of 

 sign in the cubical dilatation. — Dr. Hunter Stewart read a paper 

 on the ventilation of schools and public buildings. The first 

 part of the paper contained an account of an investigation as to 

 the presence of organic nitrogenous matter in expired air. 

 Several methods were used for absorbing and collecting these 

 products, e.g. breathing through strong sulphuric acid, condens- 

 ing the moisture from the breath, &c. The organic matter was 

 determined by the process of Kjeldahl, by which the nitrogen is 

 converted into ammonia. The results showed that each cubic 

 foot of expired air contained on an average O'OI 149 milligram? 

 of ammonia as such, and 0002 milligra-ns of ammonia derived 

 from organic matter. The water condensed from 10 cubic feet of 

 expired air contained on an average o'5 milligrams of solid residue 

 which entirely disappeared on ignition. These results, con- 

 firmatory of the observations of Hermann and Lehmann, proved 

 that the organic matter in badly ventilated rooms did not come 

 from the breath, but from the skin and clothing of the occupants. 

 Since this must be variable, depending on obvious conditions. 

 Dr. Stewart did not determine it, but relied on the estimation 

 of the carbonic acid and moisture as a measure of the efficiency 

 of the ventilation. The following are some of his results taken 

 as averages : — 



Edinburgh Hospitals, with 2000 cubic 

 feet of space per bed — 



Day 5'5c.c. CO., per 10,000 



Night 5-85 m' .. 



c^-'-'ISer/ ;;: ::: ;:: Vo :; ;; 



Schools, with, per child, 



154 c. ft. space and 9 "8 sq. ft. area 9*9 ,, ,, 



141 ,, „ 8-8 ,, 13-3 „ ,, 



116 ,, ,, 7'i ,, 172 ,, „ 



All the schools and churches were without mechanical ventila- 

 tion. — Prof. James Geikie read a paper on the glacial succession 

 in Europe. The deposits which first give evidence of glacial 

 action are generally referred to the Pliocene period. These are 

 the oldest ground moraines of Central Europe, the ground 

 moraine underlying the " lower diluvium " of Sweden, and the 

 deposits of the Weybourne Crag with their Arctic marine fauna. 

 Genial climatic conditions followed this period, with a wide land 

 area, Britain being joined to the continent. Then followed 

 the epoch of maximum glaciation, the Scottish and Scandinavian 

 ice-sheets being continuous. Genial climatic conditions followed, 

 Britain being again continental. Then submergence ensued to 

 the 5oo-feet level, followed by another glacial epoch in which 

 the Scottish and Scandinavian ice-sheets were again continuous. 

 This was succeeded by genial conditions, Britain being once 

 more joined to the continent. Submergence to the lOO-feet 

 level in Scotland followed, and then came Arctic conditions with 

 local ice-sheets, succeeded by temperate conditions and the 

 wide land area, and subsequently by submergence to the 50-feet 

 level. Another cold period followed with local glaciers— the 

 last in Britain. 



NO. II 80, VOL. 46] 



