In the preceding chapters we have been dealing with displays of fireworks, that is to say; fireworks in the mass. We will now turn our attention to the firework units composing those displays, and endeavour to trace their gradual evolution from the crude originals. Fireworks may be divided into two classes, simple and compound. The first of these include fireworks which are a complete item in themselves, as the rocket, shell, or Roman candle; also the units which, fitted on a framework, go to compose the set pieces and devices of a display, and the small shop goods not used in displays. We will consider this class first. The two oldest forms of fireworks known are undoubtedly the cracker and the rocket. As we have already noted, both of these—or at least primitive forms—are mentioned by Marcus Graecus, Albertus, and Roger Bacon. The description by the former is sufficiently clear to leave no doubt in our minds that he is describing a rocket; although the description of a cracker is not so explicit as to enable us to say that he is actually describing a jumping cracker, yet his mention of folding and tying would certainly give colour to that belief. In fact, some writers have endeavoured to find a connection between the words “Graecus” and “Cracker.” Greene, in “Orlando Furioso” (1599), uses the words, “Yes, yes, with squibs and crackers brauly.” John Bate, in his book previously mentioned, under the somewhat misleading heading, “How to make Crackers,” says: “It is well knowne that every boy can make these, therefore I think it will be but labor lost, to bestow time to describe their making.” He also describes a kind of kite which he designates a “Fire Drake,” to the tail of which he fastens “divers crackers” which are shown in the illustration to be exactly like the jumping crackers of the present day. Babington illustrates a cracker fixed to the top of a rocket. Pepys makes the following entry in his diary for November 5th, 1661: “Seeing the boys in the streets flying their crackers.” The only practical difference between the cracker of 1635 and that of to-day is in the difference of methods of manufacture, the early practice being to fold the gunpowder in the paper, the modern, to roll a paper case and fill the powder in through a funnel, afterwards flattening it through a roller mill. [Illustration: Cracker Making] Curiously enough, although the cracker has been in use for centuries in England, there appears to be no early reference to it on the Continent, the word “petard” meaning a cracker in French, but more often being applied to a firework with a single report, such as a maroon or cannon. The _Dictionnaire National_ of 1852, however, describes the true cracker as one of the meanings of “petard.” The rocket is equal to the cracker in its claim to antiquity, and it is extraordinary that these two fireworks should have changed so little in form and composition.