Taking into account these two properties, which it was necessary to state technically, but which are matters of common experience, all the mysteries of the motion of the boomerang immediately vanish. A boomerang is a thin, flat body of any shape, except round; the usual form is like

a horse shoe. A more convenient one perhaps would be that which will describe an orbit very like the former. Let us first consider the motion of the figure we have excluded;

a flat circle-if

+

this be placed in a horizontal position, and projected in the direction A C it will of course condense the air before it, while it rarefies that behind as a ship raises the water about her bows, but leaves a comparative vacuum behind. The effect of this is, that the front of the circle C is less affected by gravity than the rear A; and that tendency to a rotatory motion is produced round a horizontal axis BD; now if the circle had originally a rotatory motion round an axis perpendicular to its plane, the result will, by our first principle, be a rotation about an axis A between the two, that is, if the original rotation was from D to C,

B

Ө

D

C

the axis will move towards D, and by the second of our principles, the axis of figure will go with it, so the side D of the card will go down until the plane becomes actually vertical; the contrary will be the case if the rotation be from D to A; in each case, instead of the front rising, and the binder part descending, (as would appear at first sight,) one side ascends and the other descends; this is a fact well known to all who have studied mechanics theoretically,* and others may easily prove it by experiment. This, then, will not be a boomerang, for though the plane will change, there is nothing to change the direction of motion. But suppose the case of the cross, D moving in the direction of E F, and revolving from A to B. It is evident that the side A B moves faster than A B the side D C, therefore, the air is more condensed at that side; and the point

E

C

F

of greatest condensation will no longer be the front, but more towards the point B; it will, in fact, be a variable point, but will always lie between F and H. This, then, will give a tendency to rotatory motion, about an axis nearly in the direction of A C, which, combined with the original motion, will cause the axis of rotation to move towards A, and as before, the axis of figure will go with it. So the point A will go down; the plane of boomerang will revolve about the line B D ; and the line E F will no longer be in that plane; therefore, the boomerang must move iu some other direction, in the same manner that the direction of a ship's motion is changed by bringing round her head. This, then, is the principle of its change of direction. So long as the direction of motion continued in the plane of the boomerang, there was no reason for its changing that direction; but in this case the plane is so changed, that it contains that line no longer, therefore, it must move in some other direction. The same applies to the common horse-shoe shape. The details of its motion easily follow :Suppose the plane to be originally nearly vertical, but a little inclined to the right, (rotation being from right to left,) the axis, as before, will move towards A, the plane will therefore both turn gradually to the left, and become more inclined to the vertical, and the direction of motion will be changed from E F to the projection of that line on the new position of the plane-this projection, as is evident, will lie above and to the left of E F. Thus, then, the course of the boomerang is changed upwards and to the left-the upward motion is of course, more or less counteracted by gravity, but the result is, that the plane of boomerang becomes gradually more horizontal, but as long as it continues clined to the horizon, the right hand side being uppermost, the direction of motion is changed to the left and upward; the leftward tendency diminishing, and the upward tendency increasing as it becomes more horizontal, until at last, when it passes the horizontal position, the tendency is changed from the left to the right, so that the boomerang begins to describe the other branch of the figure 8; but it is generally exhausted before it has time to complete it. The action of gravity of course modifies the motion; as, if it

in

is thrown rather downwards, the upward tendency will prevent its touching the ground. It will nearly graze the surface of the earth, then ascend, (as the upward tendency is always increasing,) until, at length, it will be moving upwards at an angle of, say 40°. The force of gravity will then act against its progressive motion, and combined with the tendency to the left, will bring it down a plane equally inclined as fast as it went up this. Meanwhile, the plane of boomerang is becoming more and more horizontal, and the great art of an accomplished thrower is to manage so as that when it comes a second time almost to the ground, the plane shall be perfectly horizontal; then the upward tendency has reached its maximum, the boomerang seems a second time to have derived new energy from its approach to the earth; and again it rises even more speedily than before; ; but this time it has no tendency to the left, and as the point A descends still farther, the inclination becomes actually contrary to what it was at first and the future deviation is to the right; but this deviation continually increases, and the upward tendency having passed its maximum, diminishes; so that, on its third descent, it is left devoid of all resource, and can never rise again. This, then, is the entire mystery: the investigation of the precise figure is, of course, difficult, depending, as it does, on the law of the air's resistance. But the cause of the change of direction is evident; and if the weight and difference of pressures be properly proportioned, there seems to be no reason why a boomerang, perfectly plane on both sides, whether in the form of a cross, a horse shoe, or any other more convenient form, should not describe the entire orbit. This, however, is not usually the shape. The boomerang is generally made with one side plane,

and the other convex. It is then thrown in the same manner as before, but taking care that the convex side shall be turned to the left, and a little upwards. The effect of this is, that the boomerang cleaves the air like a wedge; and the resistance acts in the direction of the line bisecting the angle of the wedge; whence it has always a tendency to turn to the round side, as a boat with one side flat, and the other curved, will always veer to the curved side. Thus, then, there is an additional leftward and upward tendency, produced, and the whole effect is doubled. Of course, if the boomerang was reversed, the two forces would counteract one another, and it would move straightforward; or, if the convexity was too great, it would turn down to the ground at once. The latter is usually the case, and ought to be avoided, if one really wishes to use the boomerang as a missile; for it is clear that it cannot be made use of in this way with much effect, unless it goes straight forward. In this case, it will be of nearly as much use as a stone. The patrons of the instrument, indeed, speak of the great advantage of its always returning to the thrower; but to us, the only advantage appears to be, that a man has a much greater certainty of wounding himself or his friends than his foes. He has, however, the comfortable reflection, that it moves so slowly that no man with his eyes open, would let himself be hit. The rotatory motion is so rapid, that if it did strike it would give a pretty hard blow, particularly if the end was the part that struck, so that the only practical effect that seems likely to result from its use is the maiming of some of her Majesty's peaceable subjects, who are not sufficiently initiated in all the vagaries of its motion, to know how to keep out of its way.

Of these interesting volumes our notice has been too long delayed. The readers of the correspondence of Pope and Swift probably remember Gay with more affection than the greater names of that period of our literature. He seems to have been loved by every one of his distinguished friends, more than they loved each other. The re

collection which we have of him is connected with what was most pleasant in the life of each. His talents were not such as to suggest any of those notions of rivalry which interrupted the friendships of some of the greater men of our Augustan era. He sympathised with all. His playful humour was his own. His satire, always lively, was always free from the bitter personalities which have immortalized the names of the enemies of greater men. We are not disposed to pursue, as far as we might, the parallel with the life of Gay, which is suggested by the contemplation of that of Lamb; but in both cases it will be for ever impossible to dissociate from any account of the lives of the great poets of the periods, with which they are respectively conneeted, the recollection of Gay and of Lamb.

Lamb's was, on the whole, a happy life. The best records of it are his own, in his various communications to the "London" and other magazines. The characters in the Essays of " Elia" were in general drawn from his own relatives, and the associates of his early life, and the family pictures form an amusing groupe. His father was clerk to Mr. Salt, one of the benchers of the Inner Temple, an old widower, to whom John Lamb became "his clerk, his good servant, his dresser, his friend, his flapper, his guide, his stop-watch, auditor, treasurer." "He was a man, says his son," of incorrigible and losing honesty." "He had a face as gay as Garrick's, whom he was said greatly to resemble; possessed a fine turn for humorous poetry, next to Swift and Prior;" "made punch better than any man of his degree in England; had the merriest griefs and conceits, aud was altogether as brimful of rogueries and inventions as you could desire. He

19

was a brother of the angle, moreover ; and just such a free, hearty, honest, companion as Mr. Isaac Walton would have chosen to go a fishing with." Lamb's father wrote convivial songs for some benefit society, to which he belonged, and was encouraged by his brother members to publish "Poetical Pieces on several occasions." The biographer of his son praises some of the poems.

Lamb's mother is still recollected as a woman of matronly and commanding appearance, and "she might be taken for a sister of Mrs. Siddons."

"On the 9th of October, 1782, when Charles Lamb had attained the age of seven, he was presented to the school of Christ's Hsopital, by Timothy Yeates, Esq., Governor, as the son of John Lamb, scrivener, and Elizabeth his wife,' and remained a scholar of that noble establishment till he had entered into his fifteenth year. Small of stature, delicate of frame, and constitutionally nervous and timid, he would seem unfitted to encounter the discipline of a school formed to restrain some hundreds of lads in the heart of the metropolis, or to fight his way among them. But the sweetness of his disposition won him favour from all; and although the antique peculiarities of the school tinged his opening imagination, they did not sadden his childhood. One of his school-fellows, of whose genial qualities he has made affectionate mention in his Recollections of Christ's Hospital,' Charles V. Le Grice, now of Treriefe, near Penzance, has supplied me with some particulars of his school-days, for which friends of a later date will be grateful. 'Lamb,' says Mr. Le Grice, was an amiable gentle boy, very sensible and keenly oband by his master on account of his inserving, indulged by his schoolfellows firmity of speech. His countenance was mild; his complexion clear brown, with an expression which might lead you to think that he was of Jewish descent. His eyes were not each of the same colour, one was hazel, the other had specks of grey in the iris, mingled as we see red spots in the blood-stone. His step was plantigrade, which made his walk slow and peculiar, adding to the staid appearance of his figure. I never