WORKS OF CAPTAIN H. E. CLOKE

The Gunner's Examiner.

Third Edition, Revised and Enlarged. 8vo, viii + 206 pages, 109 figures. Cloth, $1.50.

The Enlisted Specialists' Examiner.

8vo, vi + 186 pages, 146 figures. Cloth, $2.00 net.

THE GUNNER'S EXAMINER

PREPARED BY
HAROLD E. CLOKE
Captain Coast Artillery Corps, U. S. A.

THIRD EDITION, REVISED AND ENLARGED.
FIRST THOUSAND

NEW YORK
JOHN WILEY AND SONS
London: CHAPMAN AND HALL, Limited
1908

Copyright, 1905, 1906, 1908,
BY
HAROLD E. CLOKE

The Scientific Press
Robert Drummond and Company
New York

PREFACE.

Owing to the practical impossibility of a student of gunnery obtaining ready access to all the books, pamphlets, circulars, orders, etc., necessary to fit him for the examinations as required by General Orders of the War Department for first- and second-class gunners, and also owing to the extreme difficulty the average enlisted man has in comprehending the technical language in which these books, pamphlets, etc., are couched,—provided he does by some stroke of good fortune come into possession of some of them,—the author has been impelled to compile this work.

Effort has been made to eliminate all subjects that are not included in the requirements of G. O. 141, 1904, yet being particular that it contain all such subjects as an examining board might fairly construe to be within the interest and scope of the order.

As the art of gunnery changes from year to year, and the scope of gunner's examinations changes likewise, it is intended that this book be revised and published accordingly.

The preparation of this book was suggested to the author by the members of his company—the 61st Coast Artillery.

As is well known, the first publication of a text-book is liable to contain a few technical errors. The author will be grateful for any information of such a character concerning this work.

The author is indebted to Brigadier-General William Crozier for supplying him with many pamphlets issued by the Ordnance Department; to First Lieutenant W. K. Moore for correction of proof and other matters; and to Master Electrician C. M. Beer, Artillery Corps, for photographs.

Fort Totten, N. Y., February, 1905.

PREFACE TO THE SECOND EDITION.

In this edition the author has endeavored to make all the corrections which were suggested to him during the past year, and to add to the book descriptions, etc., of the new range-board, the deflection-board, several later types of guns, and a brief discourse on the loading, planting, and care of submarine mines according to the new and adopted system.

The author desires to thank Captain R. P. Davis for his revision of the "torpedo gunnery" contained in the work.

Fort Totten, N. Y., November, 1905.

PREFACE TO THE THIRD EDITION.

As was stated in the preface of the first edition, this book will be revised from year to year as the rules of gunnery change, and this revision is made merely to bring the book up to date.

It is intended in this revision to conform strictly to G. O. 105, 1907, and to add to the book only such matter as will assist enlisted men of the Coast Artillery Corps to pass their examinations for first or second-class gunners.

The chapter on submarine mining is almost completely revised, for the reason that the new system has undergone many more radical changes within the past few years than has gunnery in the Coast Artillery.

Several additions in mortar gunnery have been made in order to keep pace with the rapid and remarkable development of this arm of Coast Artillery.

Fort Totten, New York, March, 1908.

CONTENTS.

CHAPTER I.

EXTRACTS FROM GENERAL ORDERS NO. 105, WAR DEPARTMENT, WASHINGTON, MAY 11, 1907.

144. A candidate to be eligible for qualification as first-class gunner must have previously qualified as second-class gunner, though both qualifications may be made at the same examination.

145. Boards of examination shall be convened annually in each artillery district by the district commander, to meet within one month after the expiration of the indoor instruction period. Separate boards may be convened for the examination of candidates for first and second-class gunners and also for the posts attached to the artillery district. All boards shall consist of three artillery officers, selected with reference to their special qualifications for this duty; provided, that when a member of the board is a company commander he will, during the examination of candidates from his company, be replaced by an officer of another company. Where travel is necessary the selection of an officer for this duty will be made subject to the approval of the authority competent to order the necessary journeys.

146. Each company commander will, previous to the commencement of the examination, submit to the adjutant a duly signed list, in the triplicate, giving the full names, arranged in muster-roll order, of all the men in his company who are to be examined for first or second-class gunners, with the statement that he believes that each man so presented is capable of qualifying in the class designated. These lists will be transmitted to the senior member of the board by the post commander.

147. In determining the qualifications of candidates credit shall be given for practical knowledge of subjects rather than for text-book answers to questions.

Schedules for Examinations for Candidates for Gunners.

148. For candidates in companies assigned to gun defence:

149. The examination of candidates for first-class gunners of organizations assigned exclusively to rapid-fire guns not provided with separate position-finding system shall include the following head in lieu of that given above under (b):

(b) Subcaliber firing 50

150. The examination of candidates for first-class gunners shall be held as far as practicable at such places as the material or equipment pertaining to the subject in hand is located, i.e., at the guns or in the plotting-rooms.

151. The examination in subjects (a), (b), (c) for second-class gunners and in subjects (a), (b), (c) and (d) for first-class gunners shall be confined to the material of the battery and its accessories to which the company is assigned. If no azimuth instrument is included in the battery equipment, the instrument used in the company instruction shall be used in the examination. If for any cause beyond the power of the battery commander any part of this equipment has been removed from his control and has not been available for instruction for at least two months previous to the examination, such material shall form no part of the examination.

152. For candidates in companies and detachments assigned to mine defence:

153. The qualifying mark for classification as first or second-class gunner shall be in each case not less than an average of 75 per centum. Whenever, during the progress of the examination of a candidate for either grade, the sum of the marks received on subjects in which he has already been examined, increased by the maximum allowed for the remaining subjects, is less than 75, his examination will be discontinued.

154. Instruction in the course for first or second-class gunner will be given to such men as the company commander may consider capable of mastering the prescribed schedules.

155. Men not receiving instruction in the gunners' classes will perform such duties at their batteries or elsewhere during the hours for instruction as their company commander, with the approval of the post commander, may direct.

156. The board shall keep a record of its marks during the examination, but these marks shall not be published in orders. The record of each company shall be sent to the artillery district commander as soon as possible after the completion of the examination, to be published immediately. The report of the board to be published in orders shall contain the names of those who have qualified as first and second-class gunners and recite the date of the report, which will be the date of the completion of the company examination in each case, the names being arranged for each organization in each class in muster-roll order.

Syllabus of Examination for Candidates for Gunners in Companies assigned to Gun Defence.

The following syllabus gives the outline of the scope of the examination of candidates for gunners in companies assigned to gun defense. While the indoor instruction in any subject need not be limited to what is indicated in this syllabus, the examination of candidates for gunners shall be confined thereto.

SECOND-CLASS GUNNERS.

(a) Service of the Piece.

Questions on the service of the piece and nomenclature of the piece to which organization is assigned. If the company is assigned to pieces of different calibers, the candidate will be examined upon the piece of the caliber selected by the company commander. Examining boards are cautioned not to attach too much importance to nomenclature, where a candidate shows a knowledge of the practical use of the part under examination.

(b) Guns and Carriages.

Explain briefly how a breech-block of a heavy gun or mortar is dismantled; having a breech-block completely dismantled (not dismounted), how it is assembled and adjusted for firing; how old packing is removed from recoil-cylinders, and how they are repacked; how recoil-cylinders are filled. Object, care, and use of throttling-valve for guns and by-pass valve for mortars. Parts and surfaces of guns and carriages to be oiled; how much oil to use, and how it is used. Adjustment of grease-cups. In the case of rapid-fire guns explain how to adjust firing mechanism, percussion, and electric (if so equipped).

(c) Powders, Projectiles, Primers, Fuses.

Examination: Name the kind of powder used in the pieces of battery to which organization is assigned; give the weights of service charges and corresponding muzzle velocities of these pieces; also the lowest and highest muzzle velocities of the steel and cast-iron mortars, if assigned to mortar battery. Name the projectiles used in the pieces and give their weights. Tell how to distinguish from the painting of projectiles used, its kind, armor-piercing quality, and nature of bursting charge. Point out the cap, the ogive, the bourrelet, the body, the base, the rotating band, the fuse hole of a projectile.

Name each kind of fuse used in the battery (ring resistance, centrifugal, combination, detonating, see Ordnance Department pamphlet No. 1727); tell how it is inserted to make a tight joint. Name the different kinds of primers used in the battery. Friction, electric, combination (electric-friction), percussion, igniting. Reload a drill primer. (Ordnance Department pamphlet No. 1881.)

(d) Cordage.

How is the size of a rope denoted? How do you serve a rope? Make a square knot; a bowline; rolling hitch; blackwall hitch; round turn and two half hitches; clove hitch. What is a strap or sling, and what is its use? Make a shear lashing. Mouse a hook and explain for what purpose used.

Point out the shell, sheave, pin, strap of a block, and describe the different kinds (single, double, treble, snatch, and tail blocks). Point out the running part; the standing part; the fall of a tackle.

Rig the following: Whip, gun tackle, luff, single burton.

Gins.—Name the different parts of a garrison-gin. Explain briefly how it is assembled and raised (the drill is not required). How can the upper block be placed in position after the gin has been raised?

Sheares.—What do sheares consist of, how are they rigged and raised, and what are they used for? How and when is the tackle made fast? How are sheares held in position after being raised?

Hydraulic Jacks.—For what is a hydraulic jack used? What liquids are used in the jack? How is it filled and emptied? How is the jack cared for when not in use? Show how to use the jack when lifting a heavy weight; in lowering a heavy weight; use of the claw in connection with the jack.

(e) U. S. Magazine Rifle.—Nomenclature of the piece, kind and weight of powder used, description and weight of projectile, muzzle velocity. Setting of sight for range and deflection.

FIRST-CLASS GUNNERS.

(a) Azimuth Instrument (pattern in use by the company for instruction), definition of angles, horizontal angles, vertical angle, angle measured by the instrument, leveling and orientation; focussing the telescope. Graduation of the instrument: Set up the instrument over a given point and orient it from sufficient data; direct the telescope successively on a series of points and read their azimuths with accuracy.

(b) The Plotting-room (for guns).

1. Plotting-board.—Point out the following: Primary and secondary stations, directing gun, displacement, gun-arm, travel-scale, azimuth-correction scale, tally dials, range-correction scale.

Lay off a distance of so many yards on the board; conversely, tell the distance in yards between two given points on the board.

The azimuths of a fixed target from the primary and secondary station being given, locate the corresponding point on the board, and give its azimuths and range, from the directing gun or directing point.

The azimuths of a fixed target from the primary and secondary stations being given, locate the corresponding point on the board and determine its range and azimuth from the directing gun or point.

2. Range Board.—Show how to make the range corrections for atmosphere, wind, tide, muzzle velocity, travel, and how this range correction is applied to the range-correction scale.

3. Deflection Board.—Show how to make deflection correction for wind, drift, and travel. Show how to make azimuth correction in Case 3 for wind, drift, travel, and how this correction is applied to azimuth correction scale.

What data are sent to the guns in Case 1, Case 2, and Case 3?

The plotting-room (for mortars).

1. Plotting-board.—Point out the following: Primary and secondary stations, directing point, gun-arm, gun-arm azimuth circle, displacement, powder zones, elevation, times of flight.

Lay off a distance of so many yards on the board; conversely tell the distance between two given points on the board.

The range and azimuth of a fixed point (from primary station) being given, locate the corresponding point on the board. Tell the zone, elevation for firing at this point, and its azimuth from the directing point. The azimuth of a fixed target from the primary and secondary stations being given, locate the corresponding point on the board and determine its range and azimuth from the directing point.

2. Show how a target is tracked, how to get travel, how the time of flight is used, how to get predicted point, how to get set-forward point. What is the predicted point used for? What is the set-forward point used for? What data are sent to the pit and what to the B. C. station? Show how range corrections are made.

3. Drift Device (for deflection board if issued).—Show how to make arbitrary and drift corrections.

(c) Aiming and Laying Guns or Mortars.

1. For Rapid-fire Guns.—Set and read the sight for given elevations and deflections; aim the gun at some object; show how elevating and traversing hand-wheels are used; explain the use of the deflection scale for firing right and firing left. What is Case 1?

2. For Mortars.—Use of the gunner's quadrant, setting and reading the instrument, when and how placed when used with mortars. With the data received from the plotting room lay the piece. What is Case 3?

3. For Heavy Guns.—(Heavy guns refer to 8-inch, 10-inch, and 12-inch rifles and other guns which are provided with a system of vertical and horizontal position finders.) Name the principal parts of the telescopic sight (one used for instruction purposes); show how it is used. Its readings for elevation and deflection, east count of its scales. Place it on the Hagood tripod mount, level it; set it for given elevation and deflection.

4. Use of Difference Chart.—An example like the following will be given: Range 4500 yards, azimuth 210. Put down the corrected range and azimuth.

Examination in the foregoing subject (c) to be confined to the authorized systems in use by the company during the year and to the complete equipment of the battery to which the company is assigned.

(d) Elementary Gunnery.—Axis of the bore; line of departure; line of sight; drift; muzzle velocity; quadrant elevation; sight elevation; angle of fall; jump; trajectory; time of flight.

(e) General Features of Warships.—General features of battleships (broad beam compared to length, low freeboard, general massive appearance, large turrets fore and aft, heavy guns, heavy armor, generally moderate speed).

Armored cruisers: (High freeboard, narrow beam compared to length, medium armor, medium turrets, medium guns, high speed).

Protected cruisers: (Fine lines, moderate size, no armor, medium guns usually with shields, protective deck).

Torpedo-boat destroyers: (High bow, generally great speed, light guns, no armor).

Torpedo boats: (Small size, high speed, no armor).

The following head will take the place of subject (b) in the examination of candidates for first-class gunners of organizations assigned exclusively to rapid-fire guns:

(b) Subcaliber Firing.—The 15-pounder gun and subcaliber attachment will be used. The target will be Target X, miniature target, page 25, Small-arms Firing Regulations, 1906, pasted on a screen of sufficient size to catch all the shots, preferably the screen used for small-arms Target A; range about 95 feet, where six minutes on the scale is equal to 2 inches at the target; method of scoring as prescribed for small-arms practice.

During the test one member of the board will be at the target and will personally superintend the marking.

The preliminary shots will be fired under direction of the examining board until three hits have been obtained with the same elevation and deflection. The center of impact of these three shots will be referred to the horizontal and vertical axes through the bulls'-eye of the target and its coordinates carefully measured. This center of impact will not be on the miniature target and may be changed by the board as often as they deem necessary during the examination. These measurements, with the elevation and deflection used, will be given to the candidate, who will be required to make corrections corresponding to the distance of the center of impact from the bull's-eye. Each candidate will fire five shots, the piece being thrown off the target between shots. Each shot will be marked as fired, the candidate making such changes in elevation and deflection as he may deem necessary before firing the next shot. The ratio of the candidates' score to the maximum score possible will determine the credit, the maximum credit being 20.

After this test the candidate will fire at the fixed subcaliber target anchored at about 500 yards, without knowing the exact distance, five rounds under service conditions in one minute and thirty seconds. Three sighting shots will be allowed each candidate preceding the latter test. Each hit on the material target counts 6.

Syllabus of Examination for Candidates for Gunners in Companies and Detachments assigned to Mine Defense.

The following syllabus gives the outline of the scope of the examination of candidates for gunner in companies and detachments assigned to mine defense. It is not intended that the theoretical instruction in any subject shall be limited to what is indicated in this syllabus, but the examination for candidates for gunners will be closely confined thereto.

SECOND-CLASS GUNNERS.

(a) Ammunition, Nomenclature, and Service of Guns assigned to the Company of which the Candidate is a Member.

Duties of the cannoneer and nomenclature of the piece to which assigned. (Note: If not assigned to a piece, or if the company is assigned to different pieces of different calibers, the candidate will be examined upon the piece of the caliber selected by the company commander.)

Describe the ammunition and name all the projectiles used for the piece upon which examined.

(b) Material of and Duties in the Loading Room (except electrical principles involved).

What apparatus is used in making a Turk's head? A telegraph joint? A joint to be used under water? Name all the parts of an assembled mine. Name all the parts of a compound plug and explain how to load one. What is a cut-out plug? Explain how to prepare a cut-out plug and box. What apparatus is used in preparing a compound plug? How are mines numbered? How are mooring pipes prepared, and what are the rules for lengths of mine cables and of mooring ropes?

(c) Material for and Duties on the Water.

What apparatus is taken out in the grand-junction box-boat? How and in what way are the cores of cable numbered? How is a mine, together with its attachments, arranged on a boat for planting? Name the apparatus on the boat used in planting and raising mines. What are the duties in the triple-junction box-boat in planting and in raising mines, and what precaution is taken so that cables may be distinguished when box is raised? Explain how soundings for a triple group are made.

(d) Cordage.

Name the important knots used in mine work and explain how to make four of them. The mooring rope of a heavy weight cannot pass over the winch, but lifting must be done with the fall; explain the method of proceeding.

(e) U. S. Magazine Rifle.—Nomenclature of the piece, kind and weight of powder used, description and weight of projectile, muzzle velocity. Setting of sight for range and deflection.

FIRST-CLASS GUNNERS.

(a) Care and Preservation of Mine Material.

Name the supplies necessary for cleaning mine material. Name those used in preserving it, stating for what each is used, and how certain ones (to be selected by the examiner) are applied.

(b) Handling High Explosives.

What high explosives are used in mines? What are the important precautions to be taken in loading mines? How is frozen dynamite thawed? Where is the main supply of explosive kept, and how much is taken out at one time to the explosive house near the loading-room?

(c) Knowledge and Use of Azimuth Instrument and Plotting Board.

Names of important parts. Set up the instrument with given data. Read angles from instrument. Act as observer. Act as reader.

Describe a plotting board. Explain the method of computing the time from any plotted point to a mine. Act as plotter.

(d) Batteries, Generators, and Searchlights assigned to the Company of which the Candidate is a Member.

Name the batteries used in mine work. Describe the casemate battery. What precautions are necessary in keeping it in order? What is used as the signal battery in mine work? Describe a searchlight. Describe parts of generators and important points to be observed in caring for them.

(e) Apparatus and Operation of Casemate Switchboard and Care and Use of Telephone.

Name the apparatus of the switchboard. Explain how to fire a mine by judgment, and how to start the motor generator. Explain how to test mine and cable ends. How are boat telephones operated? Name the parts of fire-control telephones used in mine-commander stations, and give the principal points to be observed in operating them.

SECOND-CLASS GUNNERS.