“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,[[82]] it was the rapidity with which the flame revolved, that occasioned the star-like appearance which is exhibited by this fire-work,” observed Louisa.
“Undoubtedly, my dear; it cannot be otherwise.”
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.
At ten o’clock the commencement of the fire-works was announced by a shower of rockets. The music ceased; and the dancers, together with the spectators who 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.