56 
Mr. Pascoe.—‘ A Catalogue of British Neuroptera,”” compiled 
for the society by Mr. McLachlan, and published by the society, 
was on the table. 
Ethnological Society, May 10.—Special meeting held at 
the Museum of Practical Geology, by permission of Sir R. I. 
Murchison, Bart. Prof. Huxley, LL.D., F.R.S., in the chair, 
Dr. O'Callaghan was announced as a new member.—Col. Lane 
Fox read a letter from Lieut. Oliver, R.A., relative to the de- 
struction of the fine menhir of Le Quesnel, in Jersey, described 
in the last number of the Society's Journal.—Sir J. Lubbock, 
Bart., and Mr, J. S. Mackie made remarks on the importance 
of the labours of the society in obtaining reports on the present 
condition of our megalithic monuments.—Prof. Huxley then de- 
livered an address on the Ethnology of Britain. He showed that 
the early accounts of the inhabitants of these islands, such as that 
given by Tacitus, prove the existence of two types of people 
physically distinct—the one being tall, fair, yellow-haired, and 
blue-eyed, whilst the other was short and dark, with dark hair 
and black eyes. This dark type, as exemplified in the ancient 
Silures, closely resembled the people of Aquitania and Iberia, 
whilst the fair type of south-east Britain was physically related 
to the Belgz of north-east France and what is now Belgium ; and 
these again resembled the old Germani, who dwelt on the east bank 
of the Rhine. In this country both the fair and the dark people 
spoke Celtic—probably Cymric in Britain and Gaelic in Ireland. 
But on the Continent the dark type spoke a Euskarian or Basque 
tongue, while the ancient Gauls spoke Celtic and the Germani 
Teutonic. The Celtic and Teutonic languages both belong to 
the Aryan family, but the Euskarian appears to have no affinity 
to any other Eur-asiatic language. None of the invasions to 
which Britain has been subjected has introduced any new race- 
element. It is doubtful whether the Romans strengthened the 
fair or the dark type of the pre-existing population, but it is 
certain that the invasion of the Low Dutch from the shores of 
North Germany bordering on the Baltic and the North Sea 
strengthened the fair element, as also did the incursions of the 
Danes. ‘The effect of the Norman conquest would be shown by 
Dr. Nicholas. —The Rev. Dr. Nicholas then read a paper “On 
the Influence of the Norman Conquest on the Ethnology of 
Britain.” He first inquired what race-elements were present in 
Britain prior to the Conquest, and concluded that the blood pre- 
ponderated considerably in favour of the ancient British race—a 
race which he did not hold to be purely Celtic. He then sought 
to determine what were the elements in William the Bastard’s 
so-called ‘* Norman” army, and showed that they were mainly 
Gaelic and Cymric. Hence the conclusion that the effect of this 
conquest was in the gross greatly gainful to the old British or 
Gallo-Celtic population. 
MANCHESTER 
Literary and Philosophical Society, March 22.—The fol- 
lowing extract of a letter, dated March 21, 1870, from Sir 
William Thomson, D.C.L., F.R.S., hon. member of the Society, 
was read :— 5 
“‘T have now at last got into good working order measure- 
ments of electrostatic capacity (which, perhaps, you may re- 
member I was working on the first time you ever came to see 
me, and more or less almost ever since). I have two students 
of last year, junior assistants in my laboratory, measuring elec- 
trostatic capacities of condensers, and variations of specific induc- 
tive capacities of resistance, with sensibility of 34; per cent., and 
with constancy in spite of accidental variations, generally within 
Zor} percent. My occupation on the Kinetic theory of gases 
has led me at last to come to definite terms as to the size of 
molecules. Ever since about the first year of my professorship 
I have taught my students that Cauchy’s theory of Dispersion 
proves heterogeneousness, or molecular structure, to become sen- 
sible in contiguous portions of glass or water, of dimensions 
moderately small in comparison with the wave-lengths of or- 
dinary light. I have spoken to you also, I think, of the argu- 
ment deducible from the contact electricity of metals. This, I 
now find, proves a limit to the dimensions of the molecules in 
metals quite corresponding to that established for transparent 
solids and liquids by the dynamics of dispersion. In experiments 
made about ten years ago, of which a slight sketch is published 
n the Proceedings of the Literary and Philosophical Society of 
Manchester, I found that a plate of zinc and a; plate of copper 
kept in metallic connection with one another (by a fine wire or 
otherwise) act electrically upon electrified bodies in their neigh- 
NATURE 
| May 19, 1870 
bourhood, and upon one another, as they would if they were of 
the same metal and kept at a difference of potentials equal to 
about three-quarters of that produced by asingle cell of Daniell’s, 
Hence, and from my measurement of the electrostatic effects of 
a Daniell’s battery, published in the Proceedings of the Royal 
Society, for February and April, 1860, I find that plates of zinc 
and copper held parallel to one another at any distance, D, 
apart which is a small fraction of the linear dimensions of their 
opposed surfaces, and kept in metallic communication with one 
another, exercise a mutual attraction equal to 
axzo7 W) x A grammes weight. 
Db? 
Hence, if they were allowed to approach from any greater dis- 
tance, D’, to the distance D, the work done by their mutual at- 
traction is 
A(D'—D) 
2 10m tox —‘centimetre grammes ; 
D'D 
which, if D is very small in comparison with D’, is very approxi- 
mately equal to 
A 
oe it Ns 
D 
Now suppose a pile to be made ofa great number (N + 1) of very 
thin plates alternately of zinc and copper, kept in metallic con- 
nection while they are brought towards one another. Let their 
positions in the pile be parallel, with narrow spaces intervening. 
For simplicity let the thickness of each metal plate and inter- 
vening space be D. The whole work done will be 
5 7A 
2X TO wal oe Ne 
D 
The whole mass of the pile (if we neglect that of one of the end 
plates) is 
NADp, 
where p denotes the mean of the densities of zinc and copper. 
Hence, if # be the height to which the whole mass must be raised 
against a constant force equal to its weight at the earth’s surface, 
to do the same amount of work, we have 
NADph=2x10- x N4 
D 
which gives f 
pee 
pD 
or, as p=8, nearly enough for the present rough estimate, 
I 
f= ey 
(200000D)? 
Hence, if 
D=zpobhoo centimetre, 
A=1 centimetre. 
The amount ot energy thus calculated is not so great as to afford 
any argument against the conclusion which general knowledge of 
divisibility, electric conductivity, and other properties of matter 
ndicates as probable: that, down to thicknesses of spppop Of 
a centimetre for the metal plates and intervening spaces, the con- 
tact electrification, and the attraction due to it, follow with but 
little if any sensible deviation the laws proved by experiment for 
plates of measurable thickness with measurable intervals between 
them. But let D be a two-hundred-millionth of a centimetre. 
If the preceding formulz were applicable to plates and spaces of 
this degree of thinness we should have 
A= 1,000,000 centimetres or 10 kilometres. 
The thermal equivalent of the work thus represented is about 
248 times the quantity of heat required to warm the whole mass 
(composed of equal masses of zinc and copper) by 1° Cent. This 
is probably much more than the whole heat of combination of 
equal masses of zinc and copper melted together. For it is not 
probable that the compound metal when dissolved in an acid would 
show anything approaching to so great a deficiency in the heat 
evolved below that evolved when the metallic constituents are 
separately dissolved, and their solutions mixed ; but the experiment 
should be made. Without any such experiment, however, we 
may safely say that the fourfold amount of energy indicated by 
the preceding formula, fora value of D yet twice as small, 1s 
