Table for the Length and Proportion of Rods.

The last business in the manufacturing of a Rocket is that of fixing it to its rod, which we shall now describe, as much nicety being required in it as in any of the past operations.

The rod should be made of a clean piece of fir, perfectly straight, and its dimensions regulated by the size of the Rocket, in such manner, that when suspended on the edge of a knife or wire, about an inch from the choak, the rod and Rocket shall be in equilibrium. The following Table has been computed for the lengths and proportions of the rod, and may be relied on:—

Weight of the Rockets.		[12]Length of the Rods.		Thickness and Width at top.			Square at Bottom.
lb.	oz.	Feet.	Inches.	Inches.			Inches.
6	0	14	2	1½	by	1⅞	0	¾
5	0	13	8	1¼	—	1¾	0	⅜
4	0	12	9	1¼	—	1½	0	⅝
3	0	10	8	1¹/₇	—	1⅛	0	½
2	0	9	3	1⅛	—	1	0	½
1	0	7	10	¾	—	⅞	0	⅜
0	8	6	6	½	—	¾	0	¼
0	4	5	2	⅜	—	⅝	0	¼
0	2	4	1	³/₁₀	—	½	0	³/₁₆
0	1	3	5	¼	—	⅜	0	³/₁₆
0	½	2	3	³/₁₆	—	¼	0	⅛
0	¼	1	10	⅛	—	³/₁₆	0	⅛

By the above Table we find that a Rocket of six pounds will require a rod 14 feet 2 inches long, which being properly planed to the other dimensions, is to be hollowed out on the side next the Rocket; and on the side opposite, two notches must be made, one about an inch from the end, (the rod going up to the under side of the head,) and the other opposite the choak of the Rocket, in order to admit the string with which it is tied, and that it may be more firmly attached to the rod. Although the foregoing Table has been carefully computed, and that from experiment, yet it will not be well to depend entirely upon it, but rather to produce an equilibrium between the rod and Rocket, (by means of a lighter or heavier rod,) when suspended as before. It is of consequence that this is attended to; for without a proper equilibrium, the Rocket will ascend in an oblique direction, and fall to the ground long before its composition is consumed.

In firing these Rockets, two fixed rings must be screwed fast into an upright post, and exactly opposite to each other, the upper one near the top of the post, and the other about two-thirds the length of the rod downwards; the rod must be passed down them, and the mouth resting lightly on the upper one, the Rocket must be quite free from the post. When thus fixed and a lighted port-fire is applied to its mouth, it will (if properly made,) immediately ascend with a prodigious velocity, and having attained its greatest height will there burst and discharge its luminous beauties in the atmosphere. A Rocket with its head and rod complete is represented at [fig. 22].