Part 2

=Definition of an Explosion=: An explosion is a chemical reaction which is completed in an exceedingly short period of time with the evolution of a large quantity of gas at a very high temperature. If this reaction occurs in a body which is closely confined, the expansive effect of the highly heated gases produces disruptive effects. If the suddenness of the reaction is very great, disrupted action upon solid objects in contact with the body may be obtained even when it is unconfined, because the cohesion of these objects can be overcome more readily in an instant of time than the inertia of the surrounding air. This has given rise to the popular error that nitro-glycerine and other high explosives act downwards; as a matter of fact they act with equal force in all directions. It is evident, therefore, that the violence of an explosion depends upon three things, namely, the time occupied completing the reaction of the explosive body; the temperature produced by the reaction, upon which directly depends the expansive forces of the resultant gases; and the quantity of gas evolved by the reaction. A fourth consideration--whether the products of the reaction are the result of one set of chemical actions occurring simultaneously; or whether the set of new compounds react upon each other, producing a second set of compounds.

LECTURE III.

STUDY OF A FEW OF THE PRINCIPAL TYPES OF RIFLE AND HAND GRENADES.

=General.= The undermentioned types of grenades, empty, are issued for instruction:--

(a) Grenade, 303-inch, short rifle, No. 3, Mark 1. (J. pattern.) (b) Grenade, hand, No. 1, Mark 1. (c) Grenade, hand, No. 5, Mark 1. (d) Grenades, hand, Nos. 6 and 7, Mark 1.

These grenades were also known as (a) Hales Rifle Grenade; (b) R. L. impact or percussion grenade; (c) Mill’s pattern grenade; (d) R. L. grenades, friction, time.

Of these (a) is for firing from the point .303-inch short rifle. Its range is about 200 yards.

The remainder are intended to be thrown by hand.

Hand grenades can be of two classes, Heavy and Light. Heavy grenades weigh about 2 lbs. and light about 1 lb. It is considered that a man can throw a 2-lb. weight about 30 yards and a pound-weight about 50 yards. Heavy grenades project fragments of some weight a fair distance, while light grenades rely for effect principally on the blast of detonation.

The effective area of a light grenade is mainly local, 6 yards diameter, but when possible it should not be thrown less than 20 yards in the open, as stones, etc., thrown up by the explosion would be dangerous to the thrower.

The danger area of the heavy grenade is about 30 yards in diameter, and, therefore, it should not be thrown less than 25 yards in the open. With both grenades the thrower should cover the eyes at the moment of explosion and protect himself, as small fragments of metal may carry further than the distance mentioned.

The types of hand grenades (b), (c) and (d) differ fundamentally in the means by which ignition is effected; (b) explodes instantaneously on impact (by percussion), while (c) and (d) are fired by time fuse, which is lit in (c) by spring action releasing a trigger at the moment the grenade leaves the thrower’s hand, and in (d) by an independent action on the part of the thrower before throwing the grenade.

In the case of (b) it is necessary that the grenade fall head first. This is done by the backward pull in the air of the streamers attached to the handle. In using this grenade it is, therefore, necessary to see that the streamers are opened out and free--before throwing, and to throw the grenade well upwards.

In the case of (d) the total time of delay is slightly over 5 seconds, so that from 1-1/2 to 2 seconds should be used in throwing. If thrown hastily it may arrive at the mark 3 seconds before exploding and allow it to be returned by the enemy.

When handling detonators for grenades, it should be remembered that the detonator by itself is capable of blowing the hand off, so it must be carefully handled, and if an igniter is accidentally fired it should be thrown a few yards clear of any one in the neighborhood. When the igniters and detonators are in the grenades reasonable care should be taken to avoid rough usage as violent treatment might fire the grenades, even in the safe position.

=Grenade .303-inch, Short Rifle, No. 3, Mark 1 (J. pattern). Description=: The grenade consists of a steel body filled with explosive. Down the centre of the explosive is a brass tube into the forward end of which the detonator is inserted. The rearward end of the body is closed by the base piece which carries the needle pellet, two retaining bolts, wind vane and releasing socket with safety pin. To the base piece is fixed a base plug carrying the spring clip and a 10-inch steel rod.

The action of the grenade is that, the safety pin having been removed, on firing the releasing socket sets back from under the wind vane, which is then revolved by the wind pressure as the grenade travels through the air. After a few turns of the vane the retaining bolts are no longer held in position by its inner surface.

On impact the needle pellet sets forward against the creep spring, on the detonator cap, firing the grenade.

The steel body is serrated so as to furnish numerous missiles.

=Package of Grenades=: The wooden box provided carries 20 grenades in protecting tins with screw-off lids, 20 detonators, rifle grenades in four tin boxes with lever lids, and 22 special blank cartridges in a tin box.

=Preparation for Firing=: The grenade is removed from its tin and the ebonite plug in its head is unscrewed by hand. The grenade is held nose down to make sure that the needle pellet is held by the retaining bolts.

If correct, the detonator is inserted and screwed home.

The rod is then gently lowered into the rifle, the clip sprung on the muzzle and a blank cartridge inserted in the chamber.

The safety pin is withdrawn just before firing.

If, after the safety pin has been removed, the grenade is not used, the safety pin may be replaced if the screwed ring has not unscrewed and uncovered the two retaining bolts, but if these are uncovered the grenade is in a dangerously sensitive condition, and if so found should be destroyed. Only the special detonators and cartridges provided should be used.

If by accident a grenade were fired with a bulleted round the rifle would probably burst and injure firer.

This grenade is very safe to handle, as it cannot be fired by knocking or dropping on the ground; it must travel through the air some distance before the retaining bolts fall out.

=Pendulum Dial Sights.= A pendulum dial sight graduated in yards, for direct aim or high elevation, is issued for use with the rifle grenades, and can be easily affixed to the leaf of the back-sight.

Should the sight not fit tightly on the leaf, the spring sides should be slightly pinched in.

=Grenade, Hand, No. 1, Mark 1. Description=: The grenade consists of a brass cylinder encircled by a narrow cast-iron ring serrated to break up into 16 fragments.

The cylinder is mounted on a wood block to which a cane handle, with streamer, is attached.

The brass cylinder or body of the grenade is filled with explosive, and has its upper end closed by the detonator holder, fixed by three screws. This holder carries two pins for securing the detonator. The body has fitted above the serrated ring two knobs and two indicating stops.

The firing needle is carried in the removable cap, which has two grooves formed on it in which slide the knobs on the body. The cap is centrally pierced for the safety pin.

On the outer surface of the cap are stamped the words “Remove,” “Travel” and “Fire.” When the knobs are in the groove “Remove,” as indicated by the stops, the cap can be removed and replaced; the central position, marked “Travel,” is to be adhered to normally; while in the position “Fire” the cap, after removal of the safety pin, is held in position by friction only, and can be pressed inwards to fire the grenade.

The action of the grenade is simply that the cap is forced in on impact, carrying the needle on to the detonator, the cap having been turned into the position “Fire” and the safety pin having been removed before the throwing.

=Packing=: The grenades are packed six in a wooden box. Cylinders containing 10 detonators, No. 1 Hand Grenade, Marks I. or II., are issued separately.

=Preparation=: The cap is removed, a detonator is inserted in the recess, the grooves in the detonator being placed opposite the pins on the body, and the detonator is then pressed home and turned to the left (its flange being under the heads of the two pins) until the spring on the detonator flange is released thus locking it in position.

The cap is then replaced and turned into the position “Travel.”

The safety pin must on no account be withdrawn during these operations.

The cap from one grenade will not invariably fit another grenade well, and steps should be taken to prevent caps and grenades being interchanged.

=Throwing the Grenade=: When it is required to use the grenades, all on the belt should be turned to “Fire,” and the whipcord beckets and leather strips should be removed from the safety pins.

When a grenade is taken from the belt, the streamer is unwound and allowed to hang free, and the safety pin is withdrawn immediately before throwing.

The grenade is grasped by the end of the handle and thrown in the required direction, care being taken that the streamer does not get entangled with the thrower.

To insure the grenade firing on impact, it should be thrown well upwards, at an angle of not less than 35 degrees.

Should the grenade not be used the cap should be turned back to “Travel” and the safety pin replaced and secured by passing the whipcord becket over the cap and threading the leather strip through the slot in the end of the safety pin.

=Grenade, Hand, No. 5, Mark 1. Description=: The body of the grenade is of cast-iron, serrated to provide numerous missiles on detonation. Into one end is screwed a centre piece, with separate recesses for the striker and detonator.

The striker is kept cocked against its spring by its head catching on the end of the striker lever when the latter lies against the body of the grenade, pivoted on its fulcrum pin.

The lever is retained in its position by the safety pin.

The detonator is a separate unit, consisting of cap, cap chamber, safety fuse, and detonator.

The action of the grenade is that, after the safety pin is withdrawn, on throwing the grenade the lever swings outward under the pull of the striker pin spring, thus releasing the striker, which fires the cap. The safety fuse burns less than five seconds and then fires the detonator.

=Packing=: The grenades are packed 12 in a wooden box, together with a cylinder containing 12 detonators and lengths of safety fuse attached.

=Preparation and Use of the Grenade=: Unscrew the base plug, insert the detonator, etc., into the recesses provided and replace the plug.

The grenade is then held in the throwing hand in such a manner that the striker lever is held securely against the body of the grenade by some part of the hand.

The safety pin is pulled out by the other hand just before the grenade is thrown.

If not thrown the safety pin should be replaced.

=Grenades, Hand, Nos. 6 and 7, Mark 1. Description=: The grenades consist of tin vessels filled with high explosives and are packed 40 in each packing case, with four haversacks.

The “HEAVY GRENADE,” weight about 1 lb. 13 oz., contains an outer layer of scrap iron. The igniter socket is closed by a wooden plug for transit, and covered by a papier mache cap.

The “LIGHT GRENADE” is entirely filled with explosive. Weight slightly over 1 lb.

The IGNITERS and DETONATORS, packed 10 in a tin and 40 in each packing case, consist of a friction igniter, a length of safety-fuse and a service detonator. The friction igniter consists of the holder to which is fixed a flange with two notches and two springs. It also has two horns, which form a grip for turning the igniter into the locked position. The friction bar is fixed to a button through which the firing loop passes.

The HAVERSACK is intended to be carried similarly to be ordinary service haversack, but the sling is shorter to cause the grenades to rest above the hip and as far as possible clear of other equipment.

The loose strings should be tied round the waist to prevent the pockets sagging and the grenades knocking against one another.

=Preparation of Grenade=: Remove papier mache cap and the wooden plug from the igniter socket. Tear the strip from the tin box containing the ten igniters, insert an igniter in the socket so that the notches in the flange pass over the brass studs on the grenade. Turn the igniter in either direction until it is locked by the springs on the flange and one of the studs which is then held between the two springs. If it is required to remove an igniter, one of the springs must be kept pressed down while the igniter is turned till the spring is clear of the stud. Replace the papier mache cap and place the grenade in a pocket of the haversack with the cap uppermost.

=Firing the Grenade=: Remove the papier mache cap.

Hold the grenade in the right (or throwing) hand so that the igniter is towards the wrist, the forefinger over the bottom of the grenade. Pass the forefinger of the other hand through the firing loop and, when ready to throw, pull with a sharp jerk. If a second’s time is taken and the grenade bowled or thrown it should explode soon after reaching the mark.

LECTURE IV.

BOMBERS’ TRAINING--PART I.

=Discipline.= Soldiers do not receive any training in bombing until they have passed the recruit stage, in which special attention is given that a very high degree of discipline is attained. In bomb fighting and trench warfare a higher degree of discipline is demanded. In addition to the discipline which enables a unit to go on parade and carry out the different movements as one man, it is necessary that every man be taught in such a way that, should circumstances arise, that he should be cut off from his comrades he can carry on intelligently as a little unit by himself, doing the right thing at the right time. It is only by training that enables him to do this in the absence of commanders that the necessary degree of efficiency can be attained.

=Organization.= The use of bombs was adopted by the British War Office early in the summer of 1915. The organization put into effect in England was as follows: In each brigade was formed what was known as the Brigade Bombers’ Company. Men were detailed from each of the units forming the brigade for their initial training, which lasted over a period of six days. During the first of the training periods at least one subaltern per battalion should be attached to the Brigade Company for training, so that the battalion is provided with an officer qualified to superintend the training of the battalion bombers’ section. This officer and others should return to the brigade company for short periods of training from time to time as it has been found that new technical as well as tactical ideas are continually being introduced into this important branch of work.

One sergeant, two corporals and 32 rank and file are detailed from each battalion. The company is commanded by a selected officer, who will be assisted by an additional N.C.O., who acts in the capacity of C.S.M. and C.Q.M.S. The Company is kept up to strength by a system of relays, so that at the end of each three days half the men of the Company are returned to their units for duty, their place being taken by others detailed for that purpose. It will be seen that by this method in a short time the entire brigade will have received their preliminary training in this subject. It must not be considered that their training in bombing is complete at the end of six days, further periods for practices being arranged for in their weekly training syllabus. The preliminary training having been completed, there is formed what was known as a permanent Brigade Bombers’ Company.

=The Battalion Bombers’ Section.= The Battalion Bombers’ Section, when complete, should consist of about 40 trained men, including N.C.O.’s, but the training of all men should be proceeded with so that ultimately every man in the battalion is qualified. When trained a thrower should be able, when standing in a trench behind one traverse, to place 75 per cent. of his bombs in a bay on the farther side of a traverse 30 yards away. To be an expert bomber, one must be fit. It is therefore necessary to take a certain amount of physical exercise each day while in training and when on active service. In this respect the grenadiers are especially cared for. They are given special privileges, given the best of billets and shorter hours in the trenches, which gives them plenty of time for exercise, and their favorite games, which keeps them in good condition. Drinking is not prohibited, but if a man expects to be able to keep cool and think and act quickly it is better to be temperate. A bombers’ duties in the trenches are looked upon as most interesting and lack monotony. If he understands his work and the grenades, that is, when they are safe, he has nothing to fear, although he will find that some of his more ignorant pals may shun him when he goes about with his full complement, in fact, they will make way wherever he goes. When our First Canadian Division went into the trenches, as also have many other reinforcing battalions, without a sufficient knowledge of bombs, the result was that many accidents occurred through carelessness and ignorance and lack of training in this important branch of work.

=Practice in Making and Throwing of Dummy Bombs.= In order that the men may become proficient in the matter of throwing live bombs it is necessary to have dummies which represent as nearly as possible in size, shape and weight the live manufactured types which are used in active service. The men are accordingly taught to make these by hand. There are four types of these, as follows:--

(a) =The Jam-Tin Dummy=, which is made with an empty jam tin, three-quarters filled with clay, the top being drawn together and sewn with wire. This type contains no explosives.

(b) A jam-tin made in the same manner but in the centre of the tin is placed half a cartridge of monobel with fuse and cap. These two types of bombs are made to weigh from one to two and a quarter pounds, and may be thrown from thirty to fifty yards.

(c) =Powder Puffs=: A powder puff is representative of a hair brush bomb and consists of a piece of wood 1” x 5” x 17”, 7” at one end being left full size, the remainder being cut away on each edge to form a handle. On the broad part of this is placed another piece of wood 2” x 4” x 6” with a hole 1-3/8” in diameter bored through the centre. This piece of 2” x 4” is attached by wire nails to the 1” x 5”; the centre space is filled with gunpowder and covered with a small piece of 1-inch board, the fuse being inserted through a 3/8-inch hole, which is bored through the 1” x 5”. The explosive used in the hair brush, which this dummy represents is a slab of wet gun-cotton, 1-3/4” x 3” x 6” with a 1-3/8” cone-shaped hole in the centre to receive a dry gun-cotton primer which has a 3/8” hole in its centre to receive the detonator, which in turn receives the fuse. The weight of slab 15 ounces; the weight of primer 1 ounce.

=Hand Grenade, No. 1, Mark 1, Dummy.=

(d) A piece of 2” x 2” wood, 17” long, one end shaped for a handle, the other end made partially round, a 1-3/4” gas pipe union being put over the handle end and driven tightly on to the large end of the stick. A groove is cut around the stick about 8” from the handle end, to which is wired three pieces of cotton about 1-1/2” x 24” long. These act as streamers and tend to keep the business end of the bomb forward in its flight.

=Note=: The idea of the explosive being used in the dummy bombs is to accustom the men to handling explosives, the lighting of fuses and gauging of the time required per inch for a service fuse to burn, at the same time not sacrificing distance and accuracy in throwing. It has been noticed that men in their eagerness to get rid of the live bomb lose sight of the main object for which they are being trained, namely, accuracy and range.

=Throwing Position.= The correct position for throwing is as follows:--Spread the feet slightly and brace them firmly on the ground, the shoulder opposite the throwing hand being in the direction to which you are throwing. Bring the other hand containing the bomb upwards with a straight arm and circular motion, releasing the bomb when the hand is above the head. It is impossible in a narrow trench to move from a standing position when throwing. The men in throwing practices should therefore be made to maintain a standing position.

=Sandbags.= It is necessary that all men engaged in trench fighting should be specially taught in the uses of sandbags and the methods of filling, tying and passing them in the trench. The method of passing sandbags in a trench is as follows: The men place themselves from two to three paces apart with their backs in the direction to which they are passing the sandbags and pass them between their legs from one to another. This method has the double advantage of enabling them to pass them very quickly and keep their heads down out of danger from rifle and M. G. fire at the same time. The men should receive further practice in the manner of building them up to form blockades and breast works, etc., in order that they may acquire speed in this matter. In the absence of a full supply of sandbags, grain sacks or flour sacks may be used.

=Training in the Use of Digging and Cutting Tools.= Frequent practices should be carried out in order that the men are efficiently trained in this work. It is very necessary that the men should be taught the use of these tools in the different positions, that is, standing, kneeling and lying. This can only be accomplished by frequent practices.

=Training in Reconstruction and Repair Work.= This can be carried out with success in the dummy trenches which we use for practices in bomb throwing and by changing the front of these trenches and wrecking them it is possible for the men to get practice in the use of the different materials employed in reconstruction and repair work, such as earth, sandbags, sods, timber, brushwood, bale wire and material obtained from old packing cases.

=Means of Egress from Trench.= On taking up a position in a trench men should be taught to provide means of egress therefrom at their first opportunity. This is done by cutting steps in the walls of the trench, just sufficiently large enough to enable them to get a foot-hold; the bottom part of this being reinforced with a small piece of board to keep the earth from breaking away. A hand hold is provided at the top by means of a stake driven into the ground or a small piece of wood secured by bale wire to a “dead man” buried in the parapet. By these means the whole line is enabled to go forward at the same time should occasion demand it.

=Passing of Orders and Information in the Trenches.= Men should be taught the art of passing of orders and information correctly, by word of mouth. This is a very important part of the soldiers’ training, and should always be practised when the trench practices are being carried out; a sender of messages being placed at one end of the line and a receiver at the other to keep a record of messages, etc.