matter or force. Knowing the sequence of events in the formation of a stratum, or the growth of a tree, it can affirm from present appearances certain previous facts, out of which the existing facts have arisen, but it knows nothing of the birth, or the bridal, of matter and force, and speculations on such themes belong to the metaphysician, the poet, or the divine.

Force may be inherited. A large mass of fluid, twirling round with great swiftness, may be broken up into smaller masses, each one inheriting from the parent mass a portion of the motion which belonged to it as a whole. A river falls over the brow of a stupendous cliff; as it descends, it divides and divides again, until, if the descent be long enough, the once-coherent fluid is scattered into myriads of disunited drops of spray, each one of which inherits its share of the family property of motion originally communicated to the river as a whole. The centrifugal motion of planets may have been inherited from movements once belonging to nebular and condensing masses, from which they may have been derived.

No mass, no particle, can approach or recede from another mass or particle without exerting a force, or changing the resistance to an existing force. Every fragment of material we can hold or see is a storehouse of force. In the case of certain compounds like gunpowder, we know how to unlock chemical forces of affinity and cohesion, and to obtain, by a sudden expansion and rearrangement of atoms, a mechanical power that rends the rock or propels the ball; but it is startling to think that the most quietly behaved bodies we find on the globe, the granite frames of mountains, or the very dust particles on the road, are like sleeping lions, full of potential force, which they can give out the moment the balance of their affinities is disturbed.

The amount of force exerted at any given time depends upon the quantity of material in motion, and the energy with which that motion is performed. When heat and light waves are propagated from the sun to the earth, the quantity of matter in the ether between us and our great luminary concerned in transmitting those wave motions, which, beginning in the sun's body or photosphere, reach us with a power sufficient to snatch myriads of tons of water from the ocean, and compel myriads of tons of carbon to arrange themselves in the forms required for vegetable growth, is so small, that our imagination fails to grasp the notion of its tenuity, but the energy of its movements makes up for the smallness of its quantity; and all the men that ever lived upon the earth could not have counted, had they spent their whole existence in the task, more than the minutest fraction of the waves of light

and heat that strike, in the course of a few minutes, upon the humblest plant. No force that we are acquainted with as operating within the system to which we belong at all approaches sun force in its various forms. When it gives light and warmth in different proportions to enormously distant bodies, and causes in all innumerable transpositions of matter, it uses as a medium for the conveyance of its powers that ether fluid, so subtle, that we only experience a pleasant sensation when its waves dash against our cheeks with a velocity so great, that the swiftest mechanical motion beside it seems still. In another paper we must consider the doctrines of the correlation and conservation of force, to which latter Mr. Grove has contributed so much excellent thought and illustration. But if gravitation bears any resemblance to heat force, light force, or electric force, then, astounding as it may appear, it may prove that, through the same impalpable ether, the sun transmits the attraction which keeps his planets around him, and compels remote Neptune to curve his far-off wanderings back to their appointed place.

DECEPTIVE FIGURES.

OUR attention was recently called to an optical delusion with which, we are told, practical masons are familiar, and of which they have to take account in arranging certain ornaments of stucco or stone. We find, however, from experiments made with various persons, that few are acquainted with it, and as it will afford amusement and at the same time illustrate certain principles of vision, we beg to introduce it to our readers.

Two pieces of card should be cut and arranged, as shown in Fig. 1 of the annexed plate. If shown to any one in the position indicated, and the question is asked which of the two is the largest, the answer will be "B, to be sure." A should then be placed under B, still forming the figure as shown in the plate. This will cause it to look longer than B, and the two should then be placed so that one covers the other, and they will be found exactly the same size.

Fig. 2 exhibits a similar optical deception; whichever is uppermost looks the smallest, but C and D like A and B are the same size.

A and B may be placed in the position of C and D, and the upper one will then look the smaller of the two, though this form of the delusion is best shown with the patterns C and D. Reversing the curves changes the effect.

The rationale of the deception shows it to arise from the tendency of the eye to be guided by simple decided lines, and to follow the direction they indicate. The right and left boundary lines of C would cut through D if they were prolonged, and the same boundary lines of D would include C if prolonged; therefore the eye or brain is misled, and we fancy C smaller than D.

In estimating by the eye the length of circular curves, we ought to commence our reckoning from a point in the centre. If this rule is applied to A and B, it immediately becomes evident that the same perpendicular line cannot pass through their centres, and thus the mind realizes the fact that A does not extend to the right as far as B, because it is just as much out of centre as it looks shorter than B.

In estimating C and D the eye must be made to avoid following their slanting boundary lines, and to follow, instead, imaginary perpendiculars uniting the upper and lower corners. As soon as this is done the delusion disappears.

Some of our readers may like to amuse themselves by inventing analogous means of deception, and with trying what action this curious effect of leading or misleading lines may be made to have in ornamental designs, or what allowance must in some cases be made for it.

POWELL AND LEALAND'S NEW BINOCULAR.

MESSRS. POWELL AND LEALAND have just introduced a new mode of obtaining binocular vision, especially adapted to high powers. It consists of a flat of glass interposed in a slanting position, and so as to catch the entire cone of rays coming from the object-glass. A portion of this cone is reflected as in their form of condenser recently described, and then suffers a second reflection from a prism, which forwards it up one tube of the instrument to the eye. The rest of the cone of rays is transmitted through the glass flat, and passes straight onward to the other eye. As different portions of the cone of rays strike the glass flat at different angles, some are reflected more than others, and some are transmitted more than others. Thus, one image will be formed by a larger portion of central, and the other by a larger proportion of peripheral rays, and this appears to give as much difference as is requisite to produce a stereoscopic effect with high powers, for which the apparatus is specially devised. The circulation of the valisneria is beautifully shown by this method with ath, and with the same

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power we have seen the two sets of lines in that most difficult object, the Amician test, finely displayed.

When lower powers are employed, Messrs. Powell and Lealand remove their peculiar arrangement of the field, and substitute Mr. Wenham's prism. Their plan is, therefore, a valuable addition to that of Mr. Wenham, and not a substitute for it. The separation of the cone of rays into two halves by the new plan is quite free from any action of diffraction, as no solid body like Mr. Wenham's prism is introduced into the cone, and made the means of its division.

With the two arrangements of Mr. Wenham and Messrs. Powell and Lealand both elegantly arranged in the same slide, microscopists seem provided with all that they can desire, and no severer test could be tried than the Amician diatom, whose markings we have alluded to as well displayed. The new plan can be adapted to any good binocular instrument.

ARCHEOLOGIA.

A VERY singular DISCOVERY OF HUMAN SKELETONS was made in the earlier part of the last month, and deserves recording. Milcote, or Millcott, is a hamlet belonging to the parish of Weston-on-Avon, in the county of Gloucester, although it is enclosed in the adjoining county of Warwick. It occupies an angle of land formed by the confluence of the Stour and the Avon, and is between two and three miles from Stratford-on-Avon. In this hamlet there is a grass-field of about four acres, at a place named Clifford Chambers, in which from time to time human bones have accidentally been dug up, and this circumstance had given rise to a story that it had been the scene of a battle with the Danes. This has been for some ages a common way of explaining the discovery of remains of the dead under such circumstances. The sub-soil of this grassfield is gravel. At the period mentioned above, the farmer who occupies the land was in want of gravel, and, knowing that he would find abundance of it under the grass-field, began digging there. At a depth of about eighteen inches beneath the surface, the workmen came upon human skeletons lying regularly arranged In a space of forty-four feet by eighteen, no less than thirty-nine perfect skeletons were found; and if, as is supposed, the skeletons extend over the whole field, or even over one half of it, the number of interments would amount to several thousands. The bodies appear to have been carefully laid in regular rows, rather close to each other, the bodies lying in a direction east and west, on their backs, with the arms generally crossed over the pelvis. Medical men who have seen these skeletons pronounce them to be those of males in the vigour of age, and some of the skulls are said to

in rows.