192 
NATURE 
attention, or on which they may have written original articles. 
Copies of any such articles should also be sent in, The examina- 
tion will comprise (A) Papers of Questions, and (B) Practical 
Work, in Zoclogy, Phy-iology, and Botany, Further and more 
detailed information may be obtained of Mr, Faulkner. 
CAMBRIDGE.—Prof. Stuart has received the offer of an engine 
from Dr. Siemens for his class-rooms of mechanism, The exten- 
sion of the workshops is to be proceeded with at once. 
Practical anatomy will commence next term on January 20. 
Demonstrations on Heat, by Mr. Glazebrook, and Electricity 
and Magnetism (advanced), by Mr. Shaw, will be given next 
term in the Cavendish Laboratory. 
Mr. Garnett will give elementary lectures on Heat in St. 
John’s College, beginning February 2, adapted to the 1st M.B, 
the Special Examination in Mechanism and Applied Science, 
and the first part of the Natural Sciences Tripos. 
Giascow.—The Clark Fellowship in Natural Science (225/. 
per annum for three years) has just been awarded to Mr. John 
H. Fullarton, M.A., B.Sc. 
SOCIETIES AND ACADEMIES 
LONDON 
Chemical Society, December 15.—Prof. Roscoe, president 
in the chair.—The following papers were read :—On some 
higher oxides of manganese and their hydrates, by W. H. 
Veley.—On a new alkaloid from Cinchona bark, by D. Howard 
and J. Hodgkin. The authors have extracted from the bark of 
China Cuprzea an alkaloid closely resembling quinine in its general 
properties. It differs in the:solubility of its salts; and from the 
readiness with which the alkaloid crystallises from ether; they | 
have named it homoquinine. In the discussion which followed 
this paper Mr. Cownley mentioned that he, in co: junction with 
Dr. Paul, had separated apparently the same alkaloid, and that 
the re-ults would be published in the next number of the 
Pharmaceutical Fourna!.—Contributions to the chemistry of the 
rare earth metals, by B. Brauner. This paper gives an account 
of a most thorough investigation of some compounds of cerium 
and didymium, and the determination of the atomic weight of 
lanthanum. The author has prepared a tetrafluoride of cerium 
and a pentoxide of didymium ; he places these metals in the 
eighth series (horizontal) of Mendeljeff’s system, thus: Cesium 
133, barium 137, lanthanum 139, cerium 141°6, didymium 
146°6. 
Royal Horticultural Society, December 12.—Lilies attacked 
by larvee of Brachycerus, sp.: Mr. Maclachlan exhibited larva 
received from Mr. G. F. Wilson of Weybridge, which eat into 
the centre of the bulbs of lilies:—Cocoanut attacked by 
larve of Hylocetus, sp. The same gentleman also showed 
some remarkable larva with a curiously indurated joint be- 
low the head. The species, he observed, was remarkable 
in penetrating the soft wood of palms, as the European species 
attacks hard wood, such as firs. He had met with the 
latter in the Black Forest.—Proliferous fir cone: Dr. M. 
T. Masters exbibited a cone of <Adies Douglasit, in which 
the bracts were foliaceous, but the seed-scale partially atrophied, 
as is usually the case in proliferous cones. He contrasted this 
with a proliferous state of Sciadopitys verticillata (see Veitch’s 
“Manual of Coniferz,” Fig. 46), in which the seed-scale be- 
came foliaceous, the bract remaining normal. The importance 
of this latter specimen in relation to the nature of the so-called 
leaves of Sciadopitys and of the seed-scale of the Abietineze was 
commented on.—Embryo-bud of oak; Mr. W. G. Smith exhi- 
bited a specimen about one and a half inches in diameter. It 
was removed from beneath the bark. Such are extremely com- 
mon in beeches, in which they vary from the size of peas to 
that of one’s fist. 
Society of Telegraph Engineers and of Electricians, 
December 15.—Annual general meeting.—The following gentle- 
men were elected as the council of the Society for the ensuing 
year: —President, Lieut-Col. C. E. Webber, R.E.; Vice- 
presidents :—Willoughby Smith, Prof. W. G. Adams, F.R.S,, 
C. E. Spagnoletti, M. Inst., C.E., Prof. D. E. Hughes, F.R.S., 
Hon. Treasurer, E. Graves ; Hon. Secretary, Lieut.-Col. Frank 
Bolton; Council: W. S. Andrews, William T. Ansell, Sir 
Charles Bright, M. Inst. C.E., C. B. Bright, the Earl of 
Crawford and Balcarres, F.R.S., H. G. Ericksen, H. C. Forde, 
[Dec. 225 1881 
M. Inst. C.E., Matthew Gray, John Fletcher Moulton, F.R. 
Alexander Siemens, Augustus Stroh, C. F, Varley, F.R. 
Associate Members of Council: Capt. J. T. Bucknill, R 
C. H. B. Palen, T. R. Crompton, M. Inst. C.E. 
EDINBURGH 
Royal Society, December 5.—The Right Hon. Lord Mon- 
creiff, president, in the chair.—After a few introductory remarks, 
the president proceeded to read the obituary notices of Dr. J. 
Hill Burton, Dr. Andrew Wood, Prof. Sanders, Dr, Handyside, 
and the Rev, Dr. Cumming.—A quaternion paper on Hamilton’s 
symbolical cubic, by Dr. Gustav Plarr, was presented by Prof, 
Tait, who then made an interesting communication on the subject 
of Mirage. By means of a simple assumption as to the law of 
variation of density in a stratum of air near the earth’s surface, 
a complete explanation could be given of the very curious erect, 
inverted, and again erect images which were observed by Vince 
towards the end of last century, and formed the subject of the 
Bakerian Lecture of 1799. The necessary geometric conditions 
fulfilled by contiguous rays so as to give either an erect or an 
inveited image are well known; but no attempt had been made 
to imagine a simple state of affairs which would give do/h images 
at once. If the refractive index of a portion of a medium is 
given by the equation n*=a*+y*, where y is the distance of the 
portion considered from a given plane—the plane, namely, of 
minimum density, then it can be easily shown by Hamilton’s 
general method that the path of any ray which is deflected with- 
out touching the plane of minimum density is a distorted inverted 
catenary, and is obviously symmetrical with respect to a vertical 
line through its vertex. Whatever the law of density, the upper 
of two such contiguous rays emanating from a given point 
must in general have its vertex either a little behind or a little 
in front of that of the hiwerray. In the former case the rays 
cross before they return to the same level from which they 
started, and an inverted image is the consequence; in the latter 
case they do not cross, and the result is an erect image. Hence 
the mere inspection of the locus of vertices of all possible rays 
coming from a given point is enough to tell the kind of image 
seen by any given pencil of rays belonging to the system. Also 
all rays that pass between any two given points on the same level 
must have their vertices on the vertical line half way between 
these points. If then the locus of vertices is such that it can be 
cut in three distinct points by a vertical straight line, evidently 
three images will be possible, two direct and one inverted, pre- 
cisely as seen by Vince. ‘That under certain circumstances the 
locus is of this nature can easily be demonstrated. It is not 
essential that the alteration of refractive index should extend 
through a large stratum of air; indeed the supposition that it 
holds only through a limited stratum, and that below the air 
may be of practically uniform density, gives results much more 
in accordance with what has been observed in nature. 
CONTENTS Pace 
ArcTIc SUCCESS'AND' DISASTER... .. < 3 sss « © woes ROO 
Cuartes Lygtt, II. By Prof. Joun W. Jupp, F.R.S. . . 2. . . 170 
Our Book SHELF :— 
Ross’s ‘‘ Treatise on the Diseases of the Nervous System” . . . 172 
LETTEKS TO THE EpIroR :— 
The Function of the Ears, or the Perception of Direction.— 
ANTOINE D°ABBADIE« cs 3 is) aie) ss (gl, 6 epee oe 
Dante and the Southern Cross. —J. J. Watker; Dr. Samver 
WHERE” f.225. ve Sela wig ol pA wee bi by ON eee a as ‘27S 
Helophyton Williamsonis,—Prof. Wm. C. Wittiamson, F.R.S. . 173 
A Smokeless London.—Epmunp McCLurzk . . . . s+ + « 373 
Meteors.—E. E. BARNARD; HOWARTH. . - . 2 ime 
Herbaceous Stem on a Palzolithic Implement.—WorTHINGTON 
GFSRRUR YE Bee eae i epee fey me sy, sie ee 
Awned Carpels of Erodium.—Prof. G. Mactoskime. . . . « 74 
The Song of the Lizard.—Capt. S. P. Oriver, R.A. 174 
A Double Egg,—E. HowakTH ...... «4 ee 174 
Srr Antonio Brapy. By Dr. Henry Woopwarp, F.R.S. . 174 
BriGHTON HEALTH CONGRESS 2. 5 2s sss us 8 ey of ow 995 
ANcIENT Tipat ACTION AND PLANES OF MARINE DenupaTion By 
Prof. EDWARDUELGLE, EiRiS.,.0 2 6 le ee en ee ee 
TELEGRAPASIIN|CRINA§ 0 oe ss 6 te we we wt «ZO 
Tue VovaGe or THE “Vaca” (With Illustrations) . . . + « + 179 
NOTES's bp. secs e) Ses © 6 we 6, We sheen a iietin en oes 
Our ASTRONOMICAL COLUMN :— 
A Variable of the Algol Type . . . 2. 2. - © © © 186 
A: Probable'Variable Star. . 2. « + 8 wie «8 « » 186 
The Binary Star 7 Cassiopeim . . . » + s « =» 4» « © « . 186 
Sotar Purysics, IJ. By Capt. Asney, R.E., F.R.S. (With 
Diego a ewe a ive De, Geen aes MAM ane Shien San 
UNIVERSITY AND EDUCATIONAL INTELLIGENCE 191 
SocleTIES AND ACADEMIES . . . + + + @ « 192 
