In general, the German signal cartridges included four distinct types. The first of these had a non-removable charge, giving a white light; the second, a removable charge, burning with a yellow light; the third, a non-removable charge, having a red illumination with stars; the fourth, a removable charge, having a red light.

In every instance there was a cartridge case of either brass or galvanized iron, which merged into a cylinder case of stout cardboard, colored on the outside according to the fire to be given off. The cartridge contained a primer and a charge of black granulated powder. A zinc tube was inserted into the cardboard case and allowed to project, or it was maintained solidly in position by crimping the cardboard on the inside of the case. The former method was used in connection with the removable charge, while the latter was used for the non-removable. This zinc tube contained a charge of black powder that ignited at the moment of discharge. It thus acted as a relay, and kindled the illuminating mixture. These cartridge cases were 31-millimeter caliber at the base, and 26.5 millimeters at the orifice, while the cardboard cases were 26 millimeters.

The length of the cartridge varied according to the type, from 104 millimeters for the red removable, to 75 millimeters for white non-removable. But the cardboard case was always very short, varying from 8.5 millimeters to 11 millimeters.

A special pistol was required for firing such cartridges.

The various mixtures used were as follows:

Non-Removable White Firing Charge (0.800 Grams Black Powder)

Nitrate of potash ..................................

75

Charcoal....................................

15

Sulphur .................................

10

Powder Relay (6 Grams Black Compressed Powder)

Nitrate of potash.......................

69

Charcoal..................................

19

Sulphur................................

12

Illuminating Charge

Compressed compounded baryta nitrate....................

61.5

Aluminum powder................................

20

Sulphur.....................................

18.5

This mixture burned excellently with a dazzling white flare.

Yellow Removable Illuminating Charge

Firing charge 2 grams black powder, of the same composition as the preceding. Powder relay (9.5 crams mixed powder)

Nitrate of potash..........................

65.9

Sulphur......................

8.5

Powdered aluminum.......................

5.1

Charcoal................................

_ 16

Agglomerating material........................

3.5

Humidity........................

1

The illuminating charge was composed of four small cylinders formed from slightly agglomerated substances. The total weight of the cylinders was 10.8 grams. They were placed one on top of another. The composition was as follows:

Magnesium...........................

67.9

Chlorate of potash............................

2.6

Oxalate of soda ..............................

17.4

Powdered aluminum...........................

2

Sawdust .................................

9.6

Gum-lac....................................

.5

This mixture burned readily with a yellow flame. In the other two types the illuminating charges were as follows:

Bed With Stars (Weight 13.4 Grams)

Chlorate of potash...........................

66.9

Carbonate of strontium...........................

8.7

Gum.............................

16.4

Bitumen............................

8

This burned with a beautiful red flame.

Violet Red With Stars (Weight 14.S)

Chlorate of potash.............................

55

Aluminum scales...........................

23

Carbonate of strontium.......................

10

Bitumen ...........................

10

The color of this also was brilliant.

The use of small scales of aluminum, instead of the powder, caused the mixture to burn more readily. It is to be noted, also, that carbonate of strontium was substituted for the oxalate generally employed.

A special perforated luminous ball cartridge was devised by the Germans for use with aeroplane machine guns. This cartridge contained two charges, one above the other, for driving and for illuminating, respectively. The composition was as follows:

Igniting Charge

Permanganate of potash......................

54.9

Iron ....................................

45.1

Illuminating Charge

Magnesium.....................

64.68

Strontium nitrate .......................

19.29

Hydrated lime...........................

11.74

Resinous organic matter.......................

4.29

An interesting revival of an ancient form of war rockets was made by the Germans, who fashioned cases of iron for a signal rocket of large size.

This rocket, carrying stars, consisted of a cylindrical iron tube, fitted also with an iron head containing the garniture of stars, over which was set a conical cap. The base of the tube was equipped with a cone-shaped tail, which was hollow, but with no orifice at the point.

The tube was fashioned out of sheet iron, with a brazed longitudinal single-riveted lap-joint. In the lower end of the tube, a brass plate was brazed and riveted, with an internally screwed boss projecting 9.5 millimeters from its center. This brass plate was also pierced with six holes, each 16 millimeters in diameter, which were arranged in a circle around the projecting boss.

Five of these holes were covered with paper and painted linen cloth. The sixth hole contained a wooden plug, pierced centrally to receive the igniting device.1

The tubular case of iron was loaded with a rocket composition. A cylindrical cavity of 24 millimeters diameter reached from the bottom of the charge almost to the top. Immediately above the rocket composition was a copper plate, from which a brass tube, filled with the igniting powder, led into the rocket head. Over the upper surface of this plate was a layer of cast sulphur, 60 millimeters deep.

The conical tail was of sheet iron, brazed at the joint end to a solid screw plug by which it was made fast in the base plate of the rocket tube.

The head was a canister of thin tin sheet iron. The connection with the rocket case was by means of a short tube of sheet iron fastened to the base of the canister by four lugs. These were contiguous to the short tube, and were set at right angles to it. Four cup-head screw bolts, with square nuts, attached the tube to the rocket case. The head itself was lined with brown paper, and contained the stars. Loose meal powder was poured in with the lower layers of stars, and a double strand of quick match, 780 to 790 millimeters in length, was placed within the head. A paper tube, containing two strands of quick match, extended upward to the center of the head from the small tube set in sulphur within the rocket case.

1 Compare description of Hale's war rocket in Appendix A.

The stars for this rocket were of two sizes, arranged in layers. The large stars were placed in an outer ring of nine, and the small stars in an inner ring of four. This disposition was followed for the lower five layers of large stars, and for seven layers of the small stars. But in the top outer ring, the sixth, two of the large stars were replaced by two small stars. Finally, above these layers, the space within the conical cover was occupied by two small stars and one large. A mass of coarsely felted crude wool was placed over the stars.

The conical cap itself was of thin tin sheet iron. It was held to the head by two bayonet joints, and painted linen tape covered the junction of head and cap.

In a consideration of bombs used for purposes of illumination, the war has emphasized the importance of a construction such that the projectile may be sent up without leaving a trail of light, which would give warning to the enemy and prevent surprise. For this reason, special care has been given to the ignition device for such bombs. It has been found best that they should be ignited from both ends, so as to burn rapidly. Meal powder is used for the ignition, so that the smoke trail may be avoided, while the kindling of the bomb is both quick and certain. Thus, for example, the dark ignition cartridge, fired from a Very pistol at an elevation of 60°, reaches the height of its flight at a distance of about 100 yards, when the bomb is ignited. Another form of this cartridge for the large Very gun has a parachute attachment, and it may be employed either for illumination or for signaling.

Ground flares giving lights of various colors have been found extremely useful. The latest form is remarkably compact, the material being contained in a small cylinder about 1 1/2 inches long. This is water tight, but the covering. is easily broken off at the end, where it may be ignited by the disclosed tape and cap. Such flares, when placed in a trench or shell hole, are distinctly visible from aeroplanes even in the daytime, while they are hidden from the enemy. Their worth in military operations of various sorts is obvious. It is of such flares that the British forces have been using ten millions monthly.