« AnteriorContinuar »
than the other holy-water. To these more private basins, during the time of libation, the priest might have recourse, and be at liberty to judge by the quantity, colour, motion, and other appearances in the water, of future events, of dubious cases, without danger of contradiction from the people below. This water might serve to mix their misletoe withal, as a general antidote; for, doubtless, those who would not let it touch the ground, would not mix this their divinity (the misletoe) with common water. Oak leaves, without which the druid rites did scarce ever proceed, ritually gathered and infused, might make some very medicinal or incantorial potion. Lastly, libations of water were never to be made to their gods, but when they consisted of this purest of all water, as what was immediately come from the heavens, and partly therefore thither to be returned, before it touched any other water or any other vessel whatsoever, placed on the ground.
“ As logan, or rocking-stones, were some of the pia fraudes of the druids, the basins found on them might be used to promote the juggle; by the motion of the stone the water might be so agitated, as to delude the enquirer by a pretended miracle; might make the criminal confess; satisfy the credulous; bring forth the gold of the rich; and make the injured, rich as well as poor, acquiesce in what the druid thought proper.”
Sorry are we to destroy a web which has been so ingeniously woven by its author; but the interests of truth admit not of compromise. Dr. Macculloch, in an interesting paper, published in the Transactions of the Geological Society, on the decomposition of the granite tors of Cornwall, has justly observed, that the true nature of these rock-basins may be easily traced by inspecting the rocks themselves. On examination, they will always be found to contain distinct grains of quartz, and fragments of the other constituent parts of the granite. A small force is sufficient to detach from the sides of these cavities additional fragments, showing that a process of decomposition is still going on under favourable circumstances. The principal of these circumstances is the presence of water, or rather the alternate action of air and water. If a drop of water can only make an effectual lodgement on a surface of this granite, a small cavity is sure to be sooner or later produced; this will insensibly enlarge as it becomes capable of holding more water; and the sides, as they continue to waste, will necessarily retain an even and rounded cavity, on account of the uniform texture of the rock. This explanation is sufficiently satisfactory; in addition to which, it may be stated, that these very basins not unfrequently occur on the perpendicular sides of rocks, as may be distinctly seen in the granite of Scilly, and in the gritstone rocks in the park of the late Sir Joseph Banks, in the parish of Ashover, in Derbyshire; a fact which at once excludes the idea of their artificial origin.
The other grotesque and whimsical appearances of rocky masses, such as rock idols, logan stones, &c., are to be explained by the tendency which granite possesses of wearing more rapidly on the angles and edges than on the sides; thus, then, upon simple and philosophical principles, are such appearances to be satisfactorily accounted for, and the phantasmagoria of Borlase vanishes as the light penetrates the theatre so long dedicated to its exhibition,
- REFERRED TO BY THE FIGURES IN
Note 1. p. 3.
BEFORE we enter upon the subject to which this note more immediately refers, we are anxious to supply an important omission in the text; and it is not a little extraordinary that Mr. Twaddleton, who was so devoted to every kind of literary research, should have suffered the circumstance to which we allude to have escaped his notice. Every player at marbles well knows that there are two very different descriptions of them, distinguished by the term taw and alley; the former is dark-coloured, while the latter is valued for the purity of its whiteness. We are desirous of communicating to the reader the etymology of these terms, which we have only lately discovered; the taw is an abbreviation for tawny, a word descriptive of the colour of the marble; while alley is abbreviated from alabaster, the stone of which it is composed.
In investigating the effects produced upon bodies by collision, it is necessary to distinguish between elastic and non-elastic substances, since their motions after impact are governed by very different laws.
If two bodies, void of elasticity, move in one right line, either the same or contrary ways, so that one body may strike directly against another, let the sum of their motions before the stroke, if they move the same way, and the difference of their motions, if contrary ways, be divided into two such parts as are proportional to the quantities of matter in the bodies, and each of those parts will respectively exhibit the motion of each body after the stroke: for example, if the quantities of matter in the bodies be as two to one, and their motions before the stroke as five and four, then the sum of their motions is nine, and the difference is one ; and therefore, when they move the same way, the motion of that body, which is as two, will, after the stroke, be six, and the motion of the other, three ; but, if they move in contrary directions, the motion of the greater body after the stroke will be two thirds of one, and of the lesser body one third of one; for, since the bodies are void of elasticity, they will not separate after the stroke, but move together with one and the same velocity; and, consequently, their motions will be proportional to their quantities of matter ; and it follows from the fact of action and reaction being equal, that no motion is either lost or gained by the stroke when the bodies move the same way; because, whatever motion one body imparts to the other, so much must it lose of its own; and, consequently, the sum of their motions before the stroke is neither increased nor diminished by the stroke, but is so divided between the bodies, as that they may move together with one common velocity; that is, it is divided between the bodies in proportion to their quantities of matter : but it is otherwise, where the bodies move in opposite directions, or contrary ways, for then the smaller motion will be destroyed by the stroke, as also an equal quantity of the greater motion, because action and reaction are equal; and the bodies, after the stroke, will move together equally swift, with the difference only of their motions before the stroke; consequently, that difference is, by means of the stroke, divided between them in proportion to their quantities of matter.
The several particular cases, concerning the collision of bodies, may be reduced to four general ones; viz.
1st. It may be, that one body only is in motion at the time of the stroke.
2d. They may both move one and the same way. . 3d. They may move in direct opposition to each other, and that with equal quantities of motion.
4th. They may be carried with unequal motions in directions contrary to each other,
As the bodies may be either equal or unequal, each of these four general cases may be considered as consisting of two branches.
As to the first, if a body in motion strikes another equal body at rest, they will, according to the proposition, move together each of them with one half of the motion that the body had which was in motion before the stroke; and since the quantity of motion in any body is as the product arising from the multiplication of its quantity of matter into its velocity, the common velocity of the two