"
NA TURE
Aprils, 1870J
conversely that every possible free motion about its centre of gravity of every such solid admits of being so represented. To revert for an instant to the general question of therepresensentative rolling ellipsoid, I thinl< it must be admitted that the addition of the time element to the theory and the substitution of a second fixed plane in lieu of a fixed centre, considerably enhance the value and give an unexpected roundness and completeness to Poinsot's image of the free motion of rotation of a rigid body, of which so much and not altogether undeservedly has been made. From an idea or shadow Poinsot's representation has now become a corporeal fact and reality, as if, so to say, Ixion's cloud, in the moment of fruition, had substantified into a living Juno. I heard the late Professor Donkin, of revered and ever-to-be-cherished memory, state that when as a referee of the Royal Society he first toolc in hand my paper on rotation, he did so with a conviction that all had already been said that could be said on the subject, and tliat it was a closed question; but that when he laid down the memoir he saw reason I owe my thanks to M. Radau and the to change his opinion. editors of the Annals of the Ecole Normale Superieure for having been at the pains to disentomb the little-known conclusions therein contained from their honourable place of sepulture in the Philosophical Transactions. J. J. Sylvester House, Woolwich Common, April 2
K
familiar to naturalists. natural history, tsayfa
It
is
well
known
that collections of
Herbarium or an Entomological cabinet, will, if left undisturbed for a number of years, and unpoisoned, become infested with animal life, chiefly Acari and larva: of Coleoptera ; and that the surest w^ay of preventing such
Now
attacks is thorough ventilation. if the floating matter in the air settles so readily after only a few days' stillness, as Prof Tyndall's experiments seem to indicate, and does not even enter into an uncorked flask, it is out of tlie question that it can penetrate through the keyholes or chinks of our cabinets. Setting aside the theory of spontaneous generation, A'e are then forced to the conclusion that this life must arise from germs already existing in the specimens wlicn they are presen'cd, or in the very limited amount of atmosphere originally confined in the cabinet. Is either of these expLmations tenal^le ? strong argument against the former alternative seems presented by the fact that, as far as I am aware, the same species of Acarus infests plants in a Herbarium brought from the most widely diverse localities, an inland meadow or the seashore, the plains of England or the Can any of your physiological readers Alps of Switzerland. throw light on this subject? F. L. .S.
A
Catkins of the Hazel
While
The
Principle of the Conservation of Force and
Mr. Mill's System of Logic
Will you permit me briefly to point out, what has not, as far as I am aware, been yet noticed — the very important modifications of the logical theory of induction resulting from the consideration in reference thereto of the physical theory of the
correlation of forces ? As I believe the subject it
58;
is now more was when, some dozen years ago, I
ripe for discussion than began to work out
first
the bearings of the higher results of physical research on the general theory of causation, logical, and metaphysical ; the following questions ^hich, in the course of a correspondence on this subject, I submitted to Mr. Mill so long ago as 1863, may, peiliaps, contain suggestions of thought not unwelcome to some students of N.vruRE. " How then," I wrote, "do our new views of force affect the Now I would rather, if you established tlieory of causation ? will allow me, submit the whole subject interrogatively to you, And, more particuthan give dogmatically my own thoughts. 1st, larly, allow me to submit to you these two questions Whether the physical theory of transformation (and identity) does not necessitate all such logical changes of expression, at least, as may be implied in tire abolition of the conceptions of "permanent causes," and of "kinds," as real and absolute " if, as I have endeavoured to existences ? And, 2ndly, whether show, the inductive facts on which are based the principles of conservation and correlation lead to such a more general principle as may be thus expressed, every existence has a determined and determining eo-existenee^ whether, I say, "we are not justified in enunciating such a principle as the complement of that fundamental axiom of our present logic, ' every effect has a cause ? I believe I am at liberty to say that, though affirmative answers to these questions would necessitate very important changes in the "system of logic, inductive and ratiocinative," Mr. Mill, as to the first, admitted the necessity of certain changes of expression, at least, and generously encouraged me in the prosecution of the researches indicated by the second
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—
—
'
question. Of the results of these researches I shall here only say that, as the axiom, "every effect has a cause," is the foundation of a logic which must be distinguished as a logic of sequence, the new axiom above stated may be shown to be the basis of a logic of co-
which Geometry appears as an example. But as to to the conception of force implied in tliis idea of coexistence, and as to the bearing of this new conception of force existence, of this, as
on the speculations with regard to space of a fourth dimension, perhaps I may have another opportunity of addressing you. J. S. Siu.RT Glennie Athenanim Club, March 30
Dust and Germs of Life Prof. Tyndall's exceedingly interesting article in No. 20 of Nature seems to me to leave unexplained a fact very
looking at some hazel bushes to-day, I noticed that where the red tuft of stigmas was protruded, the male catkins adjacent on the same twig were immature ; while, on the other hand tlie stigmas had fallen, and the fruit was already swelling, where the scales of the male flowers were open to show the stamens. A week or two back (in another locality) I could not find a single female catkin which had not lost its stigmas ; while nearly all the male catkins had opened, and many had shed their pollen. Is this
always the case with the hazel ? If so, it would be a Darwin's aphorism, "Nature abhors per-
striking illustration of
petual self-fertilisation." I ought to add, that my observations are not confirmed by the illustrations in the books to which I have access, namely, Balfour's "Class Book," Lindley's "School Botany," and Lem.aout and Decaisnes' " Traite de Botanique. " In all these, a female catkin with its tuft of stigmas is represented on the same twig as a bunch of fully developed male catkins. Will some one of greater experisnce inform me if I am in Marcus M. Hartog error as to the above facts? University College, London, March 24
ANCIENT BRITISH LONG BARROWS II.
'T^HE chambered
long barrows of North Wilts, Somer•set, and Gloucestershire differ, as a rule, but slightly in external form from the simple or unchambered long barrows of South Wilts and Dorset. They are, however, generally of somewhat smaller dimensions, being from about 1 20 to 200 feet in length and from 30 to 60 feet in breadth. The side ditches characteristic of the unchambered baiTOws are seldom to be met with, but the margin of the grave-mound is, or rather was, usually defined by a low wall, built of loose tile-shaped fragments of oolitic stone. In some cases, as at West Kennct (see fig. i), there is good evidence that the mound was originally surrounded by a series of obelisks of sarsen stone, the intervals being filled up with the usual dry walling just described. Soinetimcs, too, large monoliths or triliths are found at the broad end of the tumulus. As regards orientation, or position in reference to the points of the compass, the direction of east and west commonly observed in the simple barrows prevails in four out of five and as in the former cases with the chambered barrows class of monument the interments were at the eastern end, which is also the higher and broader, so likewise do we find that the stone chambers or cists occupy the same position in the chambered barrows. In internal structure the chambered barrows exhibit many varieties, but three principal types are recognised by Dr. Thurnam, viz. (i) those in which the chamber
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