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"Are not those pin-wheels, which are elevated above the railing?" said Tom.

"Yes; they are pin or Catharine wheels, and if you will look at them, you will perceive that they are of very simple construction; consisting merely of a long paper tube, filled with inflammable matter, and rolled round a small circle of wood, so as to form a helix or spiral line."

"The circle of wood, I suppose, is pierced in the middle for the purpose of receiving a pin, by which the wheel is attached to the post," said Tom.

"Exactly so; and the cause of their revolution is the same as that which produces the flight of the rocket; the impulse of the air forces back the ignited part of the wheel, which generates, as it were, a centrifugal force, while the attachment of the pipe, by preventing its obeying such a force, may be said to represent the centripetal force, and thus is the revolution of the wheel continued, until the whole of the composition is consumed."

"I think you told us, when speaking of the thaumatrope*, it was the rapidity with which * See the present volume, p. 15.

the flame revolved, that occasioned the star-like appearance which is exhibited by this fire-work," observed Louisa.

"Undoubtedly, my dear, it cannot be other

wise."

The party now examined the remaining specimens of the pyrotechnic art. Mr. Seymour informed them that marroons were nothing more than small cubical boxes, filled with a composition proper for making them burst, and thence producing a loud report. He said that they were principally used in combination with other pieces, or to form a battery, in which, by different lengths of quick match, they were made to explode at distinct intervals. Mr. Seymour added, that when the cases were made cylindrical, instead of being cubical, they exchanged the name of marroon for that of saucisson. Louisa enquired the nature of certain cylindrical cases she observed on the stage, and was informed that they were gerbes, a species of fire-work, which throws up a luminous and sparkling jet of fire, and from a supposed resemblance to a water-spout, has derived the appellation of gerbe. Mr. Seymour next pointed out to Tom a row of Roman candles, some of

which were fixed quite perpendicular, others inclining at different angles, so that the balls might be projected to various distances, and thus produce a more varied effect. He observed, that, to his taste, it was by far the most beautiful fire-work ever exhibited.

"I am quite impatient for the exhibition," cried Tom; "pray, papa, what is the hour? I think it was determined to let them off at ten o'clock."

"It is now about eight o'clock; we will, therefore, return to the house: we shall, however, I suspect, have a curious sight to witness in our way through the fair; for by this time. every booth is illuminated."

The scene was indescribably beautiful, and might be said to resemble an enchanted island. The trees were lighted up with an endless profusion of Chinese lanterns, of various colours, and decorated with fantastic transparencies, which produced an effect highly graceful and pleasing. The booths were richly studded with lights; and, near the platform, on which the villagers were enjoying the country dance, was erected a pyramid, which blazed with several hundred variegated lamps.

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At ten o'clock the commencement of the fireworks was announced by a shower of rockets. The music ceased; and the dancers, together with the spectators which had gathered around the platform, hastened to the spot, whither they were summoned by the sound of trumpets, to witness the pyrotechnic entertainment which was to crown the festivities of the day.

The little Seymours had been stationed by their father in the most favourable spot for seeing the exhibition; and highly were the major and his party delighted with the observations which fell from the intelligent children on the

occasion.

"Observe, Louisa, the rocket as it ascends describes a parabola," cried Tom.

"Oh, how extremely beautiful! see the head has burst, and is discharging a number of brilliant stars! What is that red spark which is now falling to the ground, papa?"

"That is the ignited stick of the rocket,” replied his father.

"Take care, Louisa, do not hold your face up," exclaimed Tom; "for as the rocket bursts over our heads, the stick may fall upon us." "I scarcely expected such an observation

from you, Tom," said his father," after the sensible remark you just made respecting the parabolic path of the rocket; do not you remember that when a projectile has reached its greatest altitude it will descend in a curve similar to that in which it ascended."

"True, true," answered Tom, "I see my error; the stick must, of course, fall at a considerable distance from us."

"Look! look!! There goes a courantine : how it ran along the rope!" exclaimed Louisa. "There goes another!" cried Tom, "and see, it is the dragon; and, I declare, there is another running in an opposite direction ;- they meet. Look at the serpents which they discharge from their mouths. Now they return to the extremity of the line with great violence. What an explosion!!!"

In like manner were next exhibited two ships, which, being filled with serpents, were made to pour their broadsides at each other.

"I never saw better courantines in my life," said Mr. Seymour; "the major really conducts the exhibition with great skill; it does him infinite credit as an engineer."

Another shower of rockets succeeded, and the

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