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5.-- Define range, trajectory, line of sight, line of fire, angle of departure and descent.
6.—Compare the dangerous spaces when firing a 9-in. M. L. R. gi at an object 15 feet
high and the distance 2,000 yards.
Charge.

Elevation.
Battering ..

.3° 17'
Full....

.40 30' The angle of descent is about greater than the angle of elevation. 7.—The initial velocity of the projectile of the 10-in 18-ton gun is 1,364 f. s.; what

will be its velocity at 1,500 yards?

Weight of shot, 400 lbs.; diameter of bore, 10 inches. 8.-Explain and describe the action of the crusher-gauge.

Did it register the best results with pebble powder or R. L. G. and why?
9.-Compare the perforating powers of the following projectiles:
Diameter.
Weight.

Velocity.
9.92 inches.....

400 lbs

..1,118 f. s. 8.92 inches.....

250 lbs

.1,236 f. s. 10.—Explain with a diagram the general distribution of the armor of the Triumph.

SUB-LIEUTENANTS.

(June, 1878.) 1.-In what plane is the director placed with reference to the racers and to the ship! 2.-Calculate the vertical and horizontal corrections for the starboard director. Distance above center gun

20 feet. Distance abaft center gun

80 feet. Speed of ship ...

10 knots. Distance of target.

800 yards. Time of flight....

1.8" Correction of rifling ...

5' 3.—The charge of the Bacchaute's guns has been altered from 14 lbs. to 22 lbs. ; why

does that alter the correction table ? 4.-What metals are used in the construction of the Woolwich guns? Why are the

Woolwich guns preferred to Krupp's ? 5.—Give a short account of the manufacture of a 10-inch gun, giving a diagram. 6.—Define “angle of elevation,” “line of sight,” trajectory, and deviation.

The ship is heeling 10° to port and you are in charge of the bow gun, firing at an

object right ahead, distant 1,000 yards; what error is introduced by the heel,

and how would you correct it! 7.-Describe the armor and offensive powers of the Glatton. Is she different from the

Hecate, and in what respects? 8.-Explain the meanings of the terms “tenacity,” “ elastic limit,” “tensilestrength,"

and how are they respectively measured as applied to metals? 9,-Give a description of the process by which cast iron is obtained from the ore.

How may the cast iron so obtained be converted into steel? 10.--Explain by a diagram what is meant by a theoretically perfect gun.

SUB-LIEUTENANTS.

(July, 1878.) 1.-Explain what marks are placed on the racer and how it is done. 2.-How do you practically test whether the director is in adjustment with the guns? 3.-Work out the correction tables for a director 30 feet above and 60 feet to left of midsbir gun. Correction for ritling..

5 Speed of ship.....

15 knots. Distance of object.

500 yards. Time of flight...

21

4.- Detine "line of fire,” “line of sight,” “angle of departure," "jump,” and “tra

jectory." What forces act on the projectile after it leaves the gun? 5.-Describe how a double coil is made and give a diagram of the 10-inch gun. 6.-What is a vent like? 7.-Describe the armor and armament of the Belleisle. 6.-- Define the terms “elastic limit,” “ malleability,” “durability," and“ tenacity,"

as applied to metals. 9.–What are the properties of "wrought iron," "steel,” and “cast iron”! Give a

definition of the term "steel." Why is this metal used for the inner tubes of our heavy guns? 10. —How are the muzzle velocities of the projectiles of our service guns ascertained ?

The muzzle velocity of the 9-inch 12-ton yun is 1,420 f. s.; find the energy per inch of shot circumference at 1,000 yards : Diameter of shot

8.92 inches. Weight of shot..

250 lbs. l'sing Bashforth's tables.

GUNNERY LIEUTEXAXTS.

(July, 1876.)

FIRST PAPER.

1.-What is the difference between a statical and a dynamical strain ?

Explain the terms “malleability” and “weldability.”
Give a full explanation of the terms “elasticity" and "ductility”; and by means

of a diagram show that of two metals, having equal “limits of fracture,” that which possesses the greater ductility will absorb the larger amount of work

before rupture. 2.-Distinguish between cast iron, wrought iron, and steel. Why is the classification which has reference to the proportion of carbon no

longer admissible! State and explain the general effect of quick cooling on an iron casting. 3.-What are the general properties possessed by wrought iron ?

How is its structure affected by rolling into bars ?

Why is it unsuited for the inner barrel ?
4.-For what material is the term “steel” now usually reserved ?

Give the leading points in the Bessemer process.
What is the object of cooling in oil?

State the arguments for and against steel for the exterior of guns. 5. What are the principal strains to which a gun is subjected ?

Give an investigation of the ratio in which the tangential strain is transmitted. Explain that system of increasing the circumferential strength which is known

under the name of the system of varying elasticity. 6. —Draw diagrams of the latest pattern 7" and 10'' M. L. R. guns, distinguishing

between the welded, coiled, and steel portions. Also draw a diagram of and explain the Woolwich groove.

What is meant by the term “clearance”? 1.-Explain, with diagram, the form of chamber:

1. In the earlier Woolwich guns.

2. In the Fraser guns. What is the reason for the difference? What alteration in this respect is now being tried in the 81-ton gun? Fully explain the object aimed at in the experiment, also any possible disadvan

tages which may arise. --Describe the different kinds of vent bushes.

Of what material are they made !

How are vents examined ?

And when would a gun be condemned for reventing? 9.--A 10'' M. L. R. gun was laid, with the sight close down, for the center of a target,

of which the dimensions were 7 ft. 6 in, wide by 3 ft. 3 in. deep, the distance

being 120 feet: How far below the target did the shot pass ! Also how should the gun be laid in order that the shot may strike the center of the plate ?

Initial velocity 1,200 feet per second.

Tip of center fore-sight to axis of gun 25 inches. 10.- What considerations determine the proof to which a gun should be subjected ?

How are heavy guns proved ?
What are the objections against-

1. A very heavy charge and service projectile?

2. A very heavy projectile and service charge? 11.–Give a brief outline of the phenomenon of explosion of gunpowder.

What is, according to Noble, the pressure when the powder entirely fills a closed

vessel? When fired from heavy guns, what is the limit laid down by the gunpowder con

mittee! 12.–To which products of combustion is the work done on the projectile attributed ? 13.-Give an outline of the methods adopted by the gunpowder committee to deter

mine the action of gunpowder when fired from heavy guns.

Why were two descriptions of instruments necessary? Questions set one month before the examination, and on which papers should now behanded in.

Give your opinion (supporting it, if possible, by the results of actual practice) on

the following points : The distance at which it would be desirable to engage, and the description of fire

which it would be desirable to use, in single actions between unarmored ships. Can you suggest any modifications in, or additions to, the descriptions of fire

already laid down? Or any alterations in the mode of carrying out the quarterly practice! Could any experiments be usefully carried out to throw light on the question ?

If so, what?

GUNNERY LIEUTENANTS.

(July, 1876.)

SECOND PAPER. 1.-Define the following terms:

Line of fire.
Line of sight.
Trajectory.

Range. 2.–To what principal motions is an lougated projectile subjected in its passage

through the air ? Explain the effect of the resistance of the air on elongated projectiles of the seri

ice form. 3.-Explain, with a figure, the great advantage of a flat trajectory.

What other advantages necessarily follow ?

What points have to be considered in order to attain it? 4.-Investigate the following expression for the angle of descent:

Tan. 0 =

R Tan. (6-0)

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And calculate the length of the dangerous” space or error which can be allowed in estimating the distance, when

R

range 1,500 yards. R' = R + 100 yards.

angle of elevation due to R 20 17'

6 = angle of elevation due to R' = 20 281 5.–What is the effect of the following projectiles on the unarmored side of a ship of the Shannon class ?

.65-inch Gatling bullet. 61-pdr, common shell. 64-pdr. shrapnell.

9-inch case. 6. — How are the perforating powers of guns compared in this country!

In what ratio do the resisting powers of armor plates vary when fired at direct ! 7.-What properties are most desirable in the iron for armor plates ?

What is the use of an iron skin?

Explain the peculiarity of the Palliser armor bolt. 8.-Explain, with diagrams, the general distribution of the armor in the Dreadnought,

Intlexible, and Nelson. 9.- In what plane is it necessary to lay the deck on which a turret revolves ?

Give reasons for your answer.

Explain the method of marking a turret in degrees. 10.-Show how to calculate a correction table for concentrating slide guns.

Investigate, in terms of (d) and (), an expression for the error arising from using the table when trained before or abaft the beam (d being the distance from the

center gun and the angle of training).

Of what use are converging plates ? 11.-Investigate an expression for the error in direction due to the sights being in

clined, in terms of (0) the inclination of the sights and (a) the angle of eleva

tion. 12. –What adjustments are necessary when placing the director in position :

Explain fully how to test their accuracy.
13. – Investigate the horizon method of determining the distance of an object.

Are there any objections to its use?
If so, what?

GUNNERY LIEUTENANTS.

(February, 1877.)

FIRST PAPER.

1.—Explain the meaning of the terms “stress,” “ultimate tensile strength," and

"limit of elasticity.” 2. – Distinguish between cast iron and wrought iron.

Give a brief description of a method of obtaining wrought iron. 3. -Define the term "steel.”

Distinguish as clearly and fully as time permits between wrought iron and steel.

What have been hitherto the chief obstacles to an extended use of the latter? 4.-No possible thickness can enable a cylinder to bear a pressure from within greater

on each sqnare inch than the nltimate tensile strength of the material; prove

this. 5,-Explain, with diagram, the principal parts of a 9' M. L. R. gun with two double

coils. Describe the bushes with whiclı giins are vented. How are vents examined ?

6.-With the uniform twist compare the pressure required to produce rotation with

that necessary to give translation.
Distinguish between uniform and increasing twist.

Which absorbs the most work?
7.-Describe the elevating gear proposed for the gums of the Inflexible.

What are its advantages?

Point out the disadvantages of the capstan-lead olevating gear. 8.-Explain, with a figure, the forces which act on the discharge of a gun mounted

on a carriage and slide; also point out the advantage of a low carriage. 9.—When a charge of powder is exploded, what are the proportions by weight of

gases and solid products ?

Give an outline of the method by which the volume of gas was determined. 10.-Establish a relation between the pressure and density when a charge of powder

is exploded in a closed vessel. 11.-Calculate the velocity of a projectile whose weight is 180 lbs. when fired from an

81 M. L. R. gun: Given length of bore

14.8 calibers. Charge

35 lbs. Gravimetric density of powder...

1 Factor of effect...

78.4 Number of volumes of expansion.

Total work in foot tons that the powder is

capable of realizing per lb. burned, 5.0000

83.53 5.8824

89.35 6.2500

91.46 6.6667

93.64 12.- What is the meaning of the term “factor of effect”? Explain fully the object of “air-spacing” the charge, and of chambering the gun.

Fourteen days allowed for this question.
Give your opinion about the mounting, working, and use of machine guns-

1. On board the ship.
2. In the boats.
3. In landing operations.

GUXXERY LIEUTENANTS.

(April, 1877.)

FIRST PAPER.

1.-Explain the meaning of the terms elasticity and elastic limit, as applied to metals.

How are they respectively measured ? 2.-Summarize the properties of wrought iron. 3.-Explain the meaning of the term steel. 4.-In cylinders of metal, the power exerted to resist pressure from within by the

different parts varies inversely as the square of the distance of the parts from

the axis; prove this. 5.—The angular velocity imparted to a projectilo depends upon the length of twist

and the muzzle velocity of translation ; prove this. 6.-Explain, with diagram, the principal parts of a 64-pdr. Mark III gun.

What considerations determine the length of the bore of a gun? 7.-Calculate the angle of deflection corresponding to a speed of 14 knots, when firing

at an object distant 1,000 yards, time of flight 2.5 seconds. Does the amount of deflection required to counteract the effect of the wind vary

with the distance ? Explain your answer.

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