Feb. 24, 1870] 
NATURE 
445 
Rylands, T. Wills, and P. Wright. An account was given by 
Prof. Tyndall of his researches on ‘‘ the action of light on gases 
and vapours,” illustrated by a series of beautiful experiments. 
Dr. Tyndall began by remarking that it had, for the last ten 
years, been his endeavour to make radiant heat a means of get- 
ting an insight into the working of the atomic forces, or, in other 
words, into the state which is called chemical combination. 
Whilst pursuing his experiments with luminous waves on matter 
in a finely divided state, he was forced to imagine molecules 
and atoms ; in fact, his belief in the existence of atoms is founded 
more upon those physical evidences than upon the considerations 
which are current in the chemical world. If he had to give up 
the notion of atoms, and to replace that conception by the 
abstract idea of multiple proportions, he would feel; completely 
at a loss how to account for changes in the physical pro- 
perties of matter. After these introductory remarks, the lec- 
turer proceeded to the main subject. The apparatus which 
served to illustrate the statements, consisted of a glass tube 
about 3 feet in length, and 3 inches internal diameter, closed at 
each end by glass discs. This tube, after having been exhausted 
by an air-pump, was partially filled with dry air which had been 
permitted to bubble through the liquid whose vapours were to 
be examined. The condensed beam of an electric lamp was 
caused to pass through the tube from end to end. Since the aim 
of these experiments is to render visible the chemical action of 
light upon vapours, substances have been chosen, one at least of 
whose products of decomposion by light has so high a boiling 
point that as soon as it is formed it is precipitated. Nitrous 
oxide gas, the vapours of Alleylic Iodide, Amylic Nitrite, Ben- 
zole, &c., mixed with some air which had passed through hydric 
nitrate or hydric chloride, were found well suited for this pur- 
pose. In all cases, no matter what the nature of the vapours 
was, if it was only employed in a sufficiently attenuated state, the 
visible action commenced with the formation of a blue cloud, 
which in some instances was of the deepest azure tinge, rivalling 
the colour of the purest Italian sky. When a cell containing 
some of the liquid whose vapours are to be examined was in- 
serted between the lamp and the tube, no clouds were formed 
within the tube ; the luminous waves traversing the liquid had 
been deprived of their acting power. When polarised light was 
sent through the tube the blue cloud was visible only in one 
direction—the direction varying according to the position of the 
Nicol’s prison ; when the short diagonal of the Nicol was verti- 
cal, the blue cloud was seen when the specator’s eye looked 
horizontally upon the tube, not otherwise ; as soon as the prism 
was turned round its axis, the blue cloud was only seen when the 
line of vision fell vertically upon the experimental tube. 
After concluding his account of this highly interesting subject, 
Prof. Tyndall showed some of the experiments bearing on his 
researches upon Dust, quite recently communicated at the Royal 
Institution. 
Anthropological Society, February 15.—Dr. Berthold 
Seemann, V. P., in the chair. C. W. Eddy, Esq., M.A., and 
E. Schiemann, Esq., were elected Fellows. The following 
papers were read :—No. r. ‘‘On the Aborigines of the Chatham 
Islands,” by Dr. Barnard Davis and Mr. E. A. Welch. Mr. Welch, 
after discussing the history and discovery of those islands, 
described their conquest by the Maories and the ultimate fate 
of the Aborigines. Dr. Barnard Davis gave the results of a 
particular examination of the characters presented by the skulls 
and skeletons of many of the inhabitants. In three cases the 
cephalic indices of the skulls were stated to be *74, "74and ‘87. The 
stature of the Moriories, or Chatham Islanders, appeared to indicate 
a race shorter and stouter than the inhabitants of New Zealand. 
‘*On polygamy : its influence in determining the sex of our race 
and its effects on the growth of population.” By Dr. J. Camp- 
bell. The author, who had been many years resident in Siam, 
gave minute details of the relative proportions of female to male 
births in the harems of the King and other important Siamese 
dignitaries. The result seemed to be that the proportions of 
males and females born were, as in the case of Monogamist mar- 
riages, entirely equal.—Mr. Ralph Tate described an inscribed 
rock on the banks of the Iguana, a tributary of the Orinoco. 
This presented an incised marking which the author considered 
to be more ancient than the present inhabitants of the district. 
Royal Microscopical Society, February 9.—Annual meet- 
ing; the Rev. J. B. Reade, president, in the chair. The follow- 
ing gentlemen were elected officers for the ensuring year :— 
President, Rev. J. B. Reade ; Vice-Presidents, Charles Brooke, 
L. S. Beale, James Glaisher, F. H. Wenham; Treasurer, 
Richard Mestayer; Secretaries, H. J. Slack, Jabez Hogg. The 
president read an address and announced his intention of pre- 
senting to the Society a copy of the Philosophical Transactions 
—60 vols. iz extenso, from 1665 to 1812, and the parts from 
1813 to the present time, as issued by the Royal Society.—Mrs. 
Holland presented the silver medal of the Society of Arts, with 
certificates awarded to her late husband for his ‘‘ Microscopic 
Triplet,” 1832. A micrometer ruled on silver by Mr. Barton, 
with some specimens of beads and bead lenses made by the late 
Mr. Holland, &c.—A vote of thanks was given to the president 
and Mrs. Holland for their presents. 
Institution of Civil Engineers, February 1. — Mr. 
Charles B. Vignoles, F.R.S., president, in the chair, ‘‘On 
the statistics of railway expenditure and income, and their 
bearing on future railway policy and management.” Mr. 
John Thornhill Harrison, M. Inst. C.E. From returns now 
made to the Board of Trade supplying definite informa- 
tion on most points of interest, the author had prepared a 
synopsis of this information for twenty of the principal 
railways in England and Scotland, representing about 85 per 
cent. of the entire capital expended in the United Kingdom. 
The original cost of railways, the working expenses, revenue, 
&c., were described, and it was shown that while the National 
Debt, amounting to 750 millions sterling, with a return of 26% 
millions per annum, or 33 per cent., was a burden on the in- 
dustry and capital of the country, the capital expended on rail- 
ways, amounting to 500 millions sterling, gave a return of 20 
millions, or 4 per cent. per annum; whilst a sum nearly equal to 
the interest on the National Debt was annually expended in labour 
and materials. 
PARIS 
Academy of Sciences, February 14.—The greater part of 
the proceedings at this meeting had reference to subjects con- 
nected with mathematics and mechanics. M. de Saint-Venant 
presented a second part of his memoir on the determination of 
the pressure of incoherent soils upon walls; M. Morin an 
elaborate report upon a memoir by M. Tresca on the effects of 
punching and stamping, and on the mechanical theory of the de- 
formation of solid bodies ; M. de Saint-Venant appended to the 
latter a theoretical proof of the equality of the two coefficients of 
resistance to cutting with shears and to extension or compres- 
sion in the continuous movement of deformation of ductile 
solids beyond the limits of their elasticity ; and a report on five 
memoirs by M. F. Lucas, entitled investigations upon the 
mechanics of atoms.—M. C. Jordan communicated a paper on 
a new combination of the twenty-seven right lines of a surface 
of the third order; M. Pellet a note on the functions irre- 
ducible by means of one module, and one modular function, and 
M.A. Ribacoura note on the deformation of surfaces. —An extract 
from a letter or M. De la Rire to M. Jamin was read, referring to 
the observations of M. Tréve on the action of magnetism'upon rare- 
fied gases.—M. Zaliwski read a note on a battery with three 
liquids regarded by him as superior to Bunsen’s battery. The 
battery consists of an inner porous vessel, containing nitric acid 
and a plate of carbon, and an outer porous vessel containing 
sulphuric acid, the whole placed in a vessel containing a solution 
of hydroclorate of ammonia and a plate of zinc.—In a short note 
M. J. M. Séguin communicated some interesting observations on 
the accidental images of white objects.—M. A. Demoget 
described a new electro-magnetic apparatus, which, by an 
increase in the number of coils and alteration in their shape, 
can be made to produce a greater evolution of electricity, 
with less rapid revolution, than Siemens’ apparatus. — 
M. P. Volpicelli communicated a paper containing an account 
of a photographic barometer, and some historical details upon 
lunar radiation. He noticed some modifications which he 
has introduced into the construction of a barometer for the 
Observatory at Rome, and with regard to the second subject, 
after citing several old writers, such as Aristotle, Thomas 
Aquinas, Pico della Mirandola, and Cardan as having admitted 
the production of calorific effects by the lunar radiation, main- 
tains that the first experimental and incontestable demonstra- 
tion of the phenomenon was given by Melloni in 1843.—A 
short note, illustrated with a figure, upon two solar spots now 
visible with the naked eye, by M. Tremeschini, was presented. 
The penumbras of these spots measure 0° 3' 45” and 0° 4! 50” 
in their greatest diameter; one of them contains a nucleus 
measuring O° O' 45”II in its greatest diameter.—M. J. Girard 
presented a note upon double crystals of snow, the formation 
