The fourth is of stars arranged in beds of grain powder; the interstices being filled with a mixture of mealed powder and charcoal. The fifth of “light balls,” and for the sixth he describes “the manner of making figures and various shapes in fire appear in the air.” These letters are made on a frame covered with composition, and are consequently limited to a size to the internal diameter of the shell, that is, less than eight inches. It seems improbable that they could be distinguished satisfactorily at the height of a shell’s trajectory, besides which the difficulties involved, as he himself explains, are very great, which no doubt explains the fact that this idea is now obsolete. Under the heading “Double and Triple Balloons,” this writer describes the method of placing shell of smaller size inside a larger. The bursting of the first shell lights the short-time fuse of the contained shell, which falls some distance and bursts. With the triple shell this action is repeated. Jones (1765) divides shell into four kinds, namely, “illuminated balloons” filled with stars; “balloons of serpents,” “balloons of reports, marrons and crackers,” and “compound balloons.” The last description is misleading, as the balloon is not compound but the contents are varied, as for example, the contents of one specified ten crackers of six reports, twenty golden rains, sixteen two-ounce cases charged half-inch with star composition and bounced, two ounces each of brilliant, blue, coloured tailed, large string and rolled stars. It is hard to believe that this writer had ever seen a shell fired in this manner, the result would have been mere confusion. The star compositions of that date were very rudimentary, the colours when seen from the distance of a bursting shell were indistinguishable. One interesting detail in Jones’s work is the classification of sizes. The smallest shell mentioned by him is the “Coehorn Balloon”; he does not give the size, but it is given in the “Military Encyclopedia” as 4⅔ inches. This corresponds to the 4½-inch of to-day. The name was apparently derived from a Dutch military engineer of that name. The next size is the royal 5½-inch, and above that 8-inch and 10-inch. Ruggieri (1821) is the first writer on the subject to have the shell and lifting charge in a unit as is the practice to-day, which indicates constructionally a great advance over his predecessors, although the fillings show little progress. The modern shell is arranged with a “lighter” of quickmatch, long enough to reach from the top of the shell when in position in the mortar to a sufficient distance outside the mouth to enable it to be ignited without danger. The lighter fires the time-fuse in the top of the shell, and at the same time two pieces of quickmatch which run round the shell in grooves worked in the paper shell case, and ignites the lifting charge, which is contained in a flannel bag, or in the case of small shell, a paper cone.