The Project Gutenberg EBook of The Gunner's Examiner, by Harold E. Cloke This eBook is for the use of anyone anywhere at no cost and with almost no restrictions whatsoever. You may copy it, give it away or re-use it under the terms of the Project Gutenberg License included with this eBook or online at www.gutenberg.org/license Title: The Gunner's Examiner Author: Harold E. Cloke Release Date: January 6, 2015 [EBook #47895] Language: English Character set encoding: ISO-8859-1 *** START OF THIS PROJECT GUTENBERG EBOOK THE GUNNER'S EXAMINER *** Produced by Chris Curnow, Moti Ben-Ari and the Online Distributed Proofreading Team at http://www.pgdp.net (This file was produced from images generously made available by The Internet Archive) WORKS OF CAPTAIN H. E. CLOKE PUBLISHED BY JOHN WILEY & SONS 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. SOME RESULTS OF LONG RANGE FIRING IN BOSTON HARBOR. BULLS EYE, 12" B.L.R. HIT ON WATER LINE, 10" B.L.R. [Frontispiece.] 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. [i] [ii] [iii] [iv] 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. PAGE Extracts from G. O. 105, May 11, 1907 1 Schedule of Examination for Gunners 2 Syllabus of Examination for Gunners 3 Second-class Gunners 4 First-class Gunners 6 Torpedo-company Gunners 9 Examination for Second-class Gunners 11 General Information 11 Service of the Piece 11 12-inch B. L. R., Disappearing Carriage 13 12-inch B. L. R., Mounted on Non-disappearing Carriage 26 8-inch Non-disappearing 30 12-inch Mortar, Model 1896 33 6-inch Disappearing 37 Nomenclature and General Description 41 Breech-blocks, Recoil-cylinders, etc. 44 Care of Guns and Carriages 66 Powders, Projectiles, Primers, and Fuses 73 Cordage, Blocks, Tackle, Gins, Shears, etc. 88 Knots and Hitches 91 Splices 95 Rigging-tackles 96 Gins 98 Shears 99 Hydraulic Jacks 102 U. S. Magazine Rifle Description etc. 105 CHAPTER II. Examination of First-class Gunners 111 (a) The Azimuth Instrument and Definitions 111 (b) The Plotting-board 116 The Range-board 123 The Deflection-board 128 The Telescopic Sight 136 Wind Component 145 The Aeroscope 146 Anemometer 149 Electric Stop-watch 149 The Atmosphere-board 150 [v] [vi] [vii] [viii] Special Apparatus for Mortars 151 Battle-ships, Armor, etc. 151 Examination for Torpedo-company Gunners 169 Second-class Gunners 169 Service of the Piece, Nomenclature 169 Duties in the Loading-room 174 Duties on the Water 181 Magazine Rifle, Description, etc. 186 First-class Gunners 186 Care and Preservation of Mine Material 186 Handling High Explosives 189 The Azimuth Instrument and Plotting-board 190 Storage Batteries 190 Generators 190 Searchlights 190 Oil-engines 195 Apparatus and Operation of Casemate Switchboard 198 THE GUNNER'S EXAMINER. 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: For second-class gunners— (a) Service of the piece 25 (b) Guns and carriages 25 (c) Powders, projectiles, primers, and fuses 25 (d) Cordage, gins, shears, jacks 15 (e) U. S. magazine rifle 10 —— 100 For first-class gunners— (a) The azimuth instrument 20 (b) Duties in the plotting-room 50 (c) Aiming and laying guns and mortars 15 (d) Elementary gunnery 5 (e) Warships 10 [1] [2] —— 100 149. 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: For second-class gunners— (a) Ammunition, nomenclature, and service of guns assigned to the company of which the candidate is a member 15 (b) Material of and duties in the loading room (except electrical principles involved) 35 (c) Material for and duties on water 30 (d) Cordage 10 (e) U. S. magazine rifle 10 —— 100 For first-class gunners— (a) Care and preservation of mine material 20 (b) Handling high explosives 20 (c) Knowledge and use of the azimuth instrument and plotting-board 20 (d) Batteries, generators, and searchlights assigned to the company of which candidate is a member 20 (e) Apparatus and operation of switchboard and care and use of telephone 20 —— 100 153. 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. [3] [4] [5] 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. [6] [7] [8] (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 [9] [10] [11] 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. General Information. 1. Gunnery is the science and art of operating and firing guns. 2. A gun is a machine which throws projectiles with great force in a certain direction under the expanding force of powder gas. 3. The army is composed of the following divisions: The line and the staff. The line is composed of Infantry, Cavalry, Artillery, Engineers, etc. The staff of Quartermaster Dept., Commissary Dept., Ordnance Dept., Signal Corps, Pay Dept., etc. 4. The artillery in our army is organized as a corps of Coast Artillery composed of 169 companies and 6 regiments in the Field Artillery. 5. A battery of coast artillery consists of two or more guns or two or more pits of mortars. 6. A fire command is composed of two batteries or more whose fire sweeps the same area or adjoining areas; this fire is controlled by one man, called the fire commander. 7. A battle command is two or more fire or mine commands sweeping the same or adjacent areas; this commanded by one man— the battle commander. 8. A mine command is a portion of submarine defenses and rapid-fire guns, all commanded by one man—the mine commander. 9. The number of men required for a fire, battle, or mine command depends on the number and caliber of the guns or mortars or the size of the mine command. 10. The number of men in a coast artillery company is 109; in a troop of cavalry 65, in a company of infantry 60. EXTRACTS FROM G. O., 9, W. D. 1908. IV. Seacoast Artillery Table of Annual Allowances of Ammunition for Target Practice and Instruction per Battery in Commission. Entries of the first column: A = 15 pdr. R. F. (all models) B = 4-inch and 4·72-inch R. F. C = 5-inch R. F., models of 1897 and 1900 D = 6-inch Ordnance Department R. F., models of 1897, 1900, 1903, and 1905 E = 8-inch rifle F = 10-inch rifle, models of 1888, 1895, and 1900 G = 12-inch rifle, models of 1888, 1895, and 1900 [12] [13] [14] H = 12-inch mortar, models of 1886 and 1890: H1 = At batteries to which only one company is assigned H2 = At batteries to which two companies are assigned Full Service Charges. Additional Primers for Drill. Guns, Caliber Trial Shots. Record Shots. Sub- Service Drill and Model. caliber. Primers. Primers. 1st 2d 1st 2d Pract. Pract. Pract. Pract. A 3 3 10 10 3000 160 800 B 3 — 10 — 900 225 225 C 3 — 10 — 900 60 400 D 3 3 10 10 900 60 400 E 3 3 6 4 600 60 400 F 3 3 6 4 600 60 400 G 3 3 6 4 600 60 400 H H1 3 3 16 16 150 100 400 H2 3 3 16 16 300 200 800 Note.—All projectiles will be service weight and form, cast iron only, or such projectiles as are specially designated for target practice. Companies which cannot have subcaliber practice at home station have only one-half the annual subcaliber allowance. 12-inch Mortars.—The number of zones, muzzle velocities corresponding thereto, zone limits, width of zones and overlaps for the 12-inch mortar, cast-iron, steel-hooped, and the 12-inch mortar, steel, have been rearranged and are now as shown by the following table: Column headings: A = Number of Zone. B = Muzzle Velocity. C = Weight of Projectile. D = Zone Limits. E = Width of Zone. F = Overlaps. 12-inch Mortar, Cast-iron, Steel-hooped. 12-inch Mortar, Steel. A B C D E F B C D E F F. S. Lbs. Yds. Yds. Yds. F. S. Lbs. Yds. Yds. Yds. 1 560 1046 2225-3000 775 400 550 1046 2210-2970 760 370 2 610 1046 2600-3480 880 480 600 1046 2600-3431 831 361 3 670 1046 3080-4110 1030 400 660 1046 3070-4030 960 399 4 743 1046 3710-5000 1290 400 725 1046 3631-4800 1169 371 5 837 1046 4600-6240 1640 400 810 1046 4429-5940 1511 420 6 910 1046 5840-7319 1479 594 915 1046 5520-7476 1956 449 7 1050 824 —— —— —— 1050 1046 7027-9250 2223 492 8 —— —— —— —— —— 1300 824 Note.—Each smokeless powder cartridge to have 10-ounce igniter (black rifle powder) at each end in addition to above charges. All smokeless-powder charges for mortars will be issued made up, ready for use, as the charges vary with each lot of powder. They will be distinctly marked to indicate the zone number. (a) SERVICE OF THE PIECE. Q. Give the general duties of a gun commander. A. The gun commander repeats the commands "Commence firing" and "Cease firing," announces the kind of projectile to be used, the order to fire, the method of pointing, and in restricted fire the number of shots and the firing interval, all in accordance with the [15] orders of a battery commander. The gun commander is responsible to the battery commander for the condition of the material and the efficiency of the personnel of his command. Q. Give the general duties of a chief of detachment. A. Each chief commands his own subdivision whenever it acts separately; is responsible for its drill efficiency and for the condition of the material to which it is assigned. He will especially see that the gas-check seat is clean and kept free from injury; that the projectile is rammed fully home; that the chamber is sponged properly after each firing; that the vent is properly served; that the cylinders are properly filled and the throttling-valve properly set before firing; that the mushroom head and gas-check are properly adjusted; that the kind of projectile designated by the battery commander is used, and that the breech detail observe great care and caution in sponging out and wiping breech mechanism and recess free from powder residue, dirt, etc., after each round fired. Q. Describe how to signal elevate or depress. A. Elevate: Raise either hand to the height of the head, fingers pointing upward. Depress: Raise either hand to the height of the head, fingers pointing downward. Q. Describe how you would signal traverse right or traverse left. A. Motion with either hand, fingers pointing in the required direction. Q. Give the signals for the following: Clamp or Halt; Ready. A. Clamp or Halt: Raise either arm to a horizontal position, fingers closed. Ready: Raise either arm vertically to its full extent, fingers extended. Q. How would you signal stand fast with the whistle at a rapid-fire gun? A. One blast signifies stand fast, the pause being of sufficient duration to enable orders to be correctly given and received; to resume operations the command "Go on!" will be given. Other signals may also be used. 12-INCH B. L. R. DISAPPEARING CARRIAGE. (CHAIN HOIST ON LEFT SIDE.) Q. What composes a gun section? A. A gun commander, a gun detachment, an ammunition detachment, and a reserve. Q. How many men in a gun detachment? A. One chief, one gunner, one range-keeper, and eighteen privates. Q. Name the details into which a detachment is divided, and give posts of each. A. Details. Posts. Chief of detachment Two yards in rear of the breech, facing it (sergeant). or wherever presence is necessary. Gunner (duly qualified Sighting-platform or wherever presence is non-commissioned necessary. officer or private). Range-keeper (non- Near the elevation-scale, on the right or commissioned officer left of the carriage. or private). Breech detail (Nos. Nos. 1 and 2 in line immediately in rear of 1, 2, and 3). the breech, facing it, No. 1 on the right; No. 3 on the right of the piece, two feet from and facing it, opposite the elevating-band. Rammer detail At the platform rail facing the carriage, No. (Nos. 4, 13, and 14). 4 opposite the rammer, four feet from its head, Nos. 13 and 14 four paces to his right and left respectively. Elevating detail At the elevating hand-wheels, facing them, (Nos. 5 and 6). No. 5 on the right of the carriage, No. 6 on the left. Traversing detail In front of the traversing-cranks, facing (Nos. 7 and 8). from the parapet, No. 7 on the right of the carriage, No. 8 on the left. Tripping detail At the tripping-levers, facing the carriage, (Nos. 9 and 10). No. 9 on the right of the carriage, No. 10 on the left. Truck detail Near the hoist, in rear of a loaded truck, (Nos. 11 and 12). No. 11 on the right, No. 12 on the left, both facing the truck. Telautograph detail At the telautograph. (No. 15). Hoist detail (Nos. At the delivery-table and facing it. 16, 17, and 18). Q. Name the equipments or implements which each member procures and places in proper position at the command "Posts!" on first arriving at the gun. [16] [17] [18] A. Gunner: Sight and difference-chart. Range-keeper: Stop-watch and prediction-scale. No. 1: Translating roller or crank, can with sponge and oil, and a silk wiper. No. 2: Loading-tray and a silk wiper. No. 3: Primer-pouch, bag for empty primers, scabbard containing punch, gimlet, and reamer, and a lanyard. No. 4, assisted by No. 13: Rammer. No. 9: Wrench, funnel, and measure with oil. No. 10: Chamber-sponge and wrench. No. 11: Dummy-cartridge extractor. No. 12: Shot-trucks. No. 13: Same as No. 4 (Rammer). No. 13 assists No. 4. Q. State in brief what each member of the gun detachment inspects and tests at the command "Examine gun!" A. Chief inspects gun and carriage throughout. Gunner inspects and tests sight, sight-standard, azimuth subscale, traversing-gear, and firing-key. Range-keeper inspects elevating gear. No. 1 removes breech-cover and inspects breech mechanism, and assists in sponging bore when necessary. No. 2 examines bore, chamber, gas-check seat, and breech-recess, cleans them when necessary, and oils breech-recess. No. 3 cleans vent and primer-seat, hangs lanyard on elevating-arm. No. 4 brings sponges and assists Nos. 1 and 2 when necessary and replaces sponges. Nos. 5 and 6 test elevating-gear with range-keeper. Nos. 7 and 8 test traversing-gear with gunner. Nos. 9 and 10 examine recoil-cylinders to see that they are properly filled. No. 9 does the filling with oil when necessary. Wrenches, funnel, and measure are passed back and replaced, filling-plugs replaced, and Nos. 9 and 10 take posts two paces on right and left, respectively, of No. 4. No. 11 receives and disposes of muzzle-cover, passes up and replaces funnel and oil-measure when necessary, then takes post near No. 12 at the trucks. No. 12 removes muzzle-cover, examines trucks. No. 13 inspects and tests telautograph. If a telephone is used, he puts on head receiver and wears it until dismissed. Q. Explain briefly how to open a breech mechanism, Model 1888. A. Figure 1 shows breech in normal position—closed. No. 2 turns rotating crank-catch 90° to left and turns rotating-crank in the direction of the arrow till it stops (Fig. 2). No. 1 turns translating-roller to left till, at the end, the shock releases the block (Fig. 3), then swings block free to right of gun till it engages securing-latch (Fig. 4). Mechanism 1895 is opened by No. 3 turning crank continuously till motion stops, being careful that crank does not catch safety-lanyard. Q. Give duties of each member of the detachment at the command "Load!" A. Chief commands: (1) "With shot!" (shell or dummy projectile); (2) "Load!" Gunner gives direction to piece according to the system used, and either fires electrically or signals to No. 3 to fire. (Except in Case 3.) [19] [20] Fig. 1. Range-keeper calls off range, using predicting-scale, and corrects same for gun difference; signals or calls out "Elevation-set!" No. 1 assists in opening and closing breech. Examines for dirt, etc., the breech-block and gas-check. Oils same. When necessary, assists in ramming. Places third section of cartridge on shot-tray. [21] Fig. 2. No. 2 assists in opening and closing breech, examines for dirt, etc., and oils gas-check seat and threads of breech-recess. He commands: (1) "Home!"; (2) "Ram!" Observes scale on rammer, places second section of cartridge on front part of shot-tray, pushes fourth section into chamber, such that its base will almost clear the gas-check seat. If necessary, inserts loading-tray and sponges, assisted by No. 10. [22] Fig. 3. No. 3 inserts a primer. At command "Trip!" steps to rear and slightly to right of piece. Fires at gunner's signal. Coils lanyard. Removes old primer and places it in a bag. No. 4 brings up rammer and places it against base of projectile, assisted by Nos. 9 and 13. Assists in ramming projectile and sections of cartridge. Replaces rammer on its support. Nos. 5 and 6 set the elevation-scale for given range. Nos. 7 and 8 traverse, at the command of the gunner. Nos. 9 and 10 assist in ramming. Trip the piece. After firing No. 10 brings up chamber-sponge. [23] Fig. 4. Nos. 11 and 12 bring loaded truck and place it in position, adjusting height of shot-tray to that of the breech. No. 11 steps to right, and No. 12 to left, of truck. If there be a brake, No. 12 sets it; if not, No. 11 chocks the front wheels. No. 12 places first section of cartridge on tray, No. 11 the fourth. Both remove truck to delivery-table and take posts at a loaded truck. Nos. 13 and 14 assist in ramming projectile and sections of cartridge. Assist 9 and 10 at pinch-bars when piece will not trip. No. 13 assists No. 4 in bringing up and replacing rammer. No. 15 calls out and posts ranges and deflections or azimuths received. No. 16 notifies chief of ammunition detachment kind of projectile required, also when to start and stop the hoist. Nos. 16, 17, and 18 load the trucks. Q. Give the positions of the ramming detail. A. Nos. 1, 4, 9, and 13 on right. Nos. 2, 10, and 14 on left. All face rammer and grasp it with both hands. Q. Explain the method of ramming. A. Nos. 13 and 14 take hold near the end of the rammer, rammer-head being on base of projectile. At the command "Ram!", all rush forward, carrying projectile to its seat with force. Nos. 1 and 2 quit the rammer when near the truck. First three sections of cartridge are rammed without command. Q. Explain how to unload a dummy charge. A. The chief commands "Unload!" Breech is opened and truck brought up as for loading. No. 4 brings up extractor and pulls out sections. No. 1 puts two sections on right of truck, No. 2 puts others on left. Nos. 1, 2, 3, and 4 withdraw projectile to truck. Truck is removed and extractor replaced. Q. Explain how to retract a gun. A. Chief commands (1) "From battery!", (2) "Heave!", (3) "Halt!" At the first command Nos. 7 and 8 go to the retraction-cranks. No. 7 operates the retaining-pawl and speed-crank to permit the [24]