Chapter XII: Part IV: Ranges

1. What is meant by the _range_ of a piece of artillery?

The distance from the muzzle to the first graze.

2. How may the range of a projectile be extended?

Either by raising the piece to a higher level, or by giving its axis greater elevation within certain limits.

3. Define _point-blank range_.

The distance from the muzzle of the piece to that point in a shot’s trajectory where it cuts the prolongation of the natural line of sight, a second time.

4. In what does the French definition for point-blank range differ from ours?

It requires that the natural line of sight should be horizontal.

5. What is the British definition for point-blank range?

The distance from the muzzle to the first graze when the axis of the piece is parallel to the plane upon which the carriage stands.

6. Explain by a figure, the position of, and relations existing between the line of sight, the line of fire or axis of the piece, and the trajectory, and also what the point-blank range is.

[Sidenote: 64]]

_ABcF_, the line passing through the highest points of the base ring and swell of the muzzle, or the muzzle-band, is called, _the natural line of sight_. _EPcG_, is the _axis of the piece_ or _line of fire_; the curved line, _PgD_, described by the projectile, is called the _trajectory_, and is entirely below the line of fire, in consequence of the action of the force of gravity giving the projectile a downward tendency. The point D is called the _point-blank_, and its distance from the mouth of the piece, the _point-blank range_.

7. Mention some of the causes which vary the point-blank range.

The form of the cannon; the weight or force of the charge; the diameter and weight of the projectile; and the inclination of the line of sight to the horizon.

8. Why has the form of the cannon an influence on the point-blank range?

Because as the difference between the diameter of the breech and muzzle become greater, the angle of sight, _BcP_ = _GcF_ (see fig.) increases, and the point-blank D is removed farther off; on the contrary, as the diameters approach to an equality, the point-blank approaches the piece. Within a certain angle, or when there is no angle of sight, as is the case with some old howitzers in which the line of sight is parallel to the axis of the bore, there will be no point-blank, as the trajectory will be constantly below the line of sight.

[Sidenote: 65]]

9. What influence has the charge on the point-blank range?

An increase of the charge determines a more distant point-blank; its diminution produces a contrary effect: but beyond a charge equal to one-third the weight of the ball, the increase of range is inconsiderable, and the force of the recoil becomes very great.

10. How do the diameter and weight of the projectile affect the range?

As the ball increases in size and density, it will overcome with more ease the resistance of the air.

11. Does the inclination of the line of sight to the horizon have much effect on the point-blank range?

Only when this inclination is very considerable. For the ordinary inclination, from 0° to 15°, above or below the horizon, the difference may be wholly neglected.

12. What is the effect on the point-blank range of firing upwards under a large angle?

The action of the weight being nearly directly opposed to the impulsive force, the trajectory becomes compressed and the point-blank distance diminishes. The contrary effect obtains in firing downwards under a similar angle, as the weight and the force then act in nearly the same direction.

[Sidenote: 66]]

13. Why may the point-blank be considered constant for the same calibre?

The dimensions, charges, and weights of projectiles, being constant, and the inclination of the natural line of sight, except in a very few cases, being comprised between 0° and 15°, it follows that for the same calibre, the point-blank may be considered constant, and may serve as a point of reference in firing at different distances.

14. What is the extreme range of a piece of artillery?

The distance from the piece to where the projectile finally rests.

15. For a given velocity what effect has an increase of the angle of lire on the range?

It increases with the angle of fire up to a certain limit, beyond which it diminishes.

16. What angle gives the greatest range in _vacuo_?

Forty-five degrees.

17. When will this angle give the maximum range in practice?

Only for feeble charges, and very heavy projectiles.

18. How is the angle of greatest range in practice affected by a change in the velocity and size of the projectile?

It seems to diminish as the velocity is increased, and as the ball is reduced. For the musket the angle of maximum range varies from 28° to 30°; and is nearly 42° for mortars.

19. Under what angle is a mortar usually fired?

Under the constant angle of 45°, and the charge is varied according to the range required.

20. What are the advantages of this practice?

Economy of ammunition; the recoil being inconsiderable, the mortar and its bed receive but little strain; the ranges are more uniform, and the effect of a slight error in the angle of fire is less than with any other.

[Sidenote: 67]]

21. Is the mortar ever fired at any other angle than 45°?

Yes; sometimes at 60°.

22. When is the mortar fired under an angle of 60°?

When the battery is situated very near the object assailed, and it is desired that the shells may fall upon the magazines of the besieged. It is evident that projectiles the higher they are thrown up acquire more velocity in falling, besides striking the object more directly and with increased violence.

23. Under what angle are stone-mortars usually fired?

Under an angle of 60°, and sometimes of 75°, that in falling from a great height, the stones may have the maximum force of percussion.

24. Under what angle should grenades be thrown from stone-mortars?

About 33°; otherwise they will be buried in the earth, and their fragments will not be sufficiently destructive.

25. When a gun or howitzer is aimed with the line of metal horizontal, what is the elevation equal to?

The natural angle of sight or dispart.

26. How is the time of flight for siege mortars at an elevation of 45° determined?

It is nearly equal to the square root of the range in feet divided by four.

[Sidenote: 68]]

RANGES OF FIELD GUNS AND HOWITZERS.

====================================================================
KIND OF PIECE. |Powder.| Ball. |Elevation|Range| Remarks.
----------------+-------+---------+---------+-----+-----------------
| lbs. | | deg. min| yds.|
6-Pounder Field| 1.25 | Shot | 0 | 318 |
Gun. | | “ | 1 | 647 |P. B. Range
| | “ | 2 | 867 |
| | “ | 3 |1138 |
| | “ | 4 |1256 |
| | “ | 5 |1523 |
+-------+---------+---------+-----+-----------------
| 1. |Sph. case| 2 | 650 |Time of flight 2“
| | “ | 2 30 | 840 | do. 3“
| | “ | 3 |1050 | do. 4“
----------------+-------+---------+---------+-----+-----------------
12-Pounder Field| 2.5 | Shot | 0 | 347 |
Gun. | | “ | 1 | 662 |P. B. Range.
| | “ | 1 30 | 785 |
| | “ | 2 | 909 |
| | “ | 3 |1269 |
| | “ | 4 |1455 |
| | “ | 5 |1663 |
+-------+---------+---------+-----+-----------------
| 1.5 |Sph. case| 1 | 670 |Time 2 seconds.
| | “ | 1 45 | 950 | “ 3 “
| | “ | 2 30 |1250 | “ 4 “
----------------+-------+---------+---------+-----+-----------------
12-Pounder Field| 1. | Shell | 0 | 195 |
Howitzer. | | “ | 1 | 539 |
| | “ | 2 | 640 |
| | “ | 3 | 847 |
| | “ | 4 | 975 |
| | “ | 5 |1072 |
+-------+---------+---------+-----+-----------------
| 0.75 |Sph. case| 2 15 | 485 |Time 2 seconds.
| | “ | 3 15 | 715 | “ 3 “
| | “ | 3 45 |1050 | “ 4 “
----------------+-------+---------+---------+-----+-----------------
24-Pounder Field| 2. | Shell | 0 | 295 |
Howitzer. | | “ | 1 | 516 |
| | “ | 2 | 793 |
| | “ | 3 | 976 |
| | “ | 4 |1272 |
| | “ | 5 |1322 |
+-------+---------+---------+-----+-----------------
| 1.75 |Sph. case| 2 | 600 |Time 2 seconds.
| | “ | 3 | 800 | “ 3 “
| | “ | 5 30 |1050 | “ 4 “
| 2. | “ | 3 30 | 880 | “ 3 “
----------------+-------+---------+---------+-----+-----------------
32-Pounder Field| 2.5 | Shell | 0 | 290 |
Howitzer. | | “ | 1 | 531 |
| | “ | 2 | 779 |
| | “ | 3 |1029 |
| | “ | 4 |1203 |
| | “ | 5 |1504 |
+-------+---------+---------+-----+-----------------
| 2.5 |Sph. case| 3 | 800 |Time 2¾ sec’ds.
----------------+-------+---------+---------+-----+-----------------
Mountain | 0.5 | Shell | 0 | 170 |
Howitzer. | | “ | 1 | 300 |
| | “ | 2 | 392 |
| | “ | 2 30 | 500 | Time 2 seconds.
| | “ | 3 | 637 |
| | “ | 4 | 785 | Time 3 seconds.
| | “ | 5 |1005 |
+-------+---------+---------+-----+-----------------
| 0.5 |Sph. case| 0 | 150 |
| | “ | 2 30 | 450 | Time 2 seconds.
| | “ | 3 | 500 |
| | “ | 4 | 700 | Time 2¾ sec’ds.
| | “ | 4 30 | 800 | Time 3 seconds.
+-------+---------+---------+-----+-----------------
| 0.5 | Canister| 4 to 5°| 250 |
----------------+-------+---------+---------+-----+-----------------

[Sidenote: 69]]

RANGES OF HEAVY ARTILLERY.

================================================================
KIND OF PIECE. |Powder.| Ball. |Elevation|Range| Remarks.
----------------+-------+---------+---------+-----+-------------
| lbs. | | deg. min| yds.|
18-Pdr. Siege | 4.5 | Shot | 1 | 641 |
and Garrison | | “ | 1 30 | 800 | Point-Blank.
Gun on | | “ | 2 | 950 |
Barbette | | “ | 3 |1256 |
Carriage. | | “ | 4 |1450 |
| | “ | 5 |1592 |
----------------+-------+---------+---------+-----+-------------
24-Pdr. Siege | 6. | Shot | 0 | 412 |
and Garrison | | “ | 1 | 842 |
Gun on Siege.| | “ | 1 30 | 953 | Point-Blank.
Carriage | | “ | 2 |1147 |
| | “ | 3 |1417 |
| | “ | 4 |1666 |
| | “ | 5 |1901 |
| 8. | “ | 1 | 883 |
| | “ | 2 |1170 |
| | “ | 3 |1454 |
| | “ | 4 |1639 |
| | “ | 5 |1834 |
-----------------+-------+---------+---------+-----+-------------
32-Pdr. Sea-Coast| 6. | Shot | 1 45 | 900 |
Gun on | 8. | “ | 1 | 713 |
Barbette | | “ | 1 30 | 800 |
Carriage. | | “ | 1 35 | 900 |
| | “ | 2 |1100 |
| | “ | 3 |1433 |
| | “ | 4 |1684 |
| | “ | 5 |1922 |
| 10.67 | “ | 1 | 780 |
| | “ | 2 |1155 |
| | “ | 3 |1517 |

[Sidenote: 70] ]

================================================================
KIND OF PIECE. |Powder.| Ball. |Elevation|Range| Remarks.
----------------+-------+---------+---------+-----+-------------
42-Pdr. Sea-Coast| 10.5 | Shot | 1 | 775 |
Gun on | | “ | 1 30 | 860 |
Barbette | | “ | 2 |1010 |
Carriage. | | “ | 3 |1300 |
| | “ | 4 |1600 |
| | “ | 5 |1955 |
| 14. | “ | 1 | 770 |
| | “ | 2 |1128 |
| | “ | 3 |1380 |
| | “ | 4 |1687 |
| | “ | 5 |1915 |
----------------+-------+---------+---------+-----+----------------
| 4. | 45-lb. | | |
8-in. Siege | | Shell | 0 | 251 | Time ⅔ sec’ds.
Howitzer on | | “ | 1 | 435 | “ 1⅓ “
Siege | | “ | 2 | 618 | “ 2 “
Carriage. | | “ | 3 | 720 | “ 3 “
| | “ | 4 | 992 | “ 4 “
| | “ | 5 |1241 | “ 5 “
| | “ | 12 30 |2280 |
----------------+-------+---------+---------+-----+----------------
| 2. | 17-lb. | | |
24-Pdr. Iron | | Shell | 0 | 295 |
Howitzer on | | “ | 1 | 516 |
a Flank | | “ | 5 |1322 |
Casemate | 1¾ |Sph. case| 2 | 600 | Time 2 seconds.
Carriage. | | “ | 5 30 |1050 | “ 4 “
| 2. | “ | 3 30 | 880 | “ 3 “
----------------+-------+---------+---------+-----+----------------
| 4. | 45-lb. | | |
8-in. Sea-Coast | | Shell | 1 | 405 |
Howitzer on | | “ | 2 | 652 |
a Barbette | | “ | 3 | 875 |
Carriage. | | “ | 4 |1110 |
| | “ | 5 |1300 |
| 6. | “ | 1 | 572 |
| | “ | 2 | 828 |
| | “ | 3 | 947 |
| | “ | 4 |1168 |
| | “ | 5 |1463 |
| 8. | “ | 1 | 646 |
| | “ | 2 | 909 |
| | “ | 3 |1190 |
| | “ | 4 |1532 |
| | “ | 5 |1800 |
----------------+-------+---------+---------+-----+----------------
| 12. | 90-lb. | | |
10-in. Sea-Coast| | Shell | 1 | 580 |
Howitzer on | | “ | 2 | 891 | Time 3 sec’ds.
Barbette | | “ | 3 |1185 | “ 4 “
Carriage. | | “ | 3 30 |1300 |
| | “ | 4 |1426 | “ 5¼ “
| | “ | 5 |1650 | “ 6 “
----------------+-------+---------+---------+-----+----------------

[Sidenote: 71] ]

================================================================
KIND OF PIECE. |Powder.| Ball. |Elevation|Range| Remarks.
----------------+-------+---------+---------+-----+-------------
| 10. | 65-lb. | | |
8-in Columbiad | | Shot | 1 | 932 | Axis of gun 16
on Barbette | | “ | 2 |1116 | feet above
Carriage. | | “ | 3 |1402 | the water.
| | “ | 4 |1608 |
| | “ | 5 |1847 |
| | “ | 6 |2010 |
| | “ | 8 |2397 | Shot ceased to
| | “ | 10 |2834 | ricochet on
| | “ | 15 |3583 | the water.
| | “ | 20 |4322 |
| | “ | 25 |4875 |
| | “ | 27 |4481 |
| 15. | “ | 27 30 |4812 |
| 10. | 50-lb. | | |
| | Shell | 1 | 919 |
| | “ | 2 |1209 |
| | “ | 3 |1409 |
| | “ | 4 |1697 |
| | “ | 5 |1813 |
| | “ | 6 |1985 |
| | “ | 8 |2203 |
| | “ | 10 |2657 |
| | “ | 15 |3556 |
| | “ | 20 |3716 |
| | “ | 25 |4387 |
| | “ | 27 |4171 |
| 15. | “ | 27 30 |4468 |
----------------+-------+---------+---------+-----+----------------

[Sidenote: 72] ]

================================================================
KIND OF PIECE. |Powder.| Ball. |Elevation|Range| Remarks.
----------------+-------+---------+---------+-----+-------------
| 18. | 128-lb. | | |
10-in. Columbiad| | Shot | 0 | 394 | Axis of gun 16
on Barbette | | “ | 1 | 752 | feet above
Carriage. | | “ | 2 |1002 | the water.
| | “ | 3 |1230 |
| | “ | 4 |1570 |
| | “ | 5 |1814 |
| | “ | 6 |2037 | Shot ceased to
| | “ | 8 |2519 | ricochet on
| | “ | 10 |2777 | the water.
| | “ | 15 |3525 |
| | “ | 20 |4020 |
| | “ | 25 |4304 |
| | “ | 30 |4761 |
| | “ | 35 |5433 |
| 20. | “ | 39 15 |5654 |
----------------+-------+---------+---------+-----+----------------
| 12. | 100-lb. | | |
| | Shell | 1 | 800 |
| | “ | 2 |1012 |
| | “ | 3 |1184 |
| | “ | 4 |1443 |
| | “ | 5 |1604 |
| 18. | “ | 0 | 448 |
----------------+-------+---------+---------+-----+----------------
| 18. | 100-lb. | 1 | 747 |
| | Shell | | |
| | “ | 2 |1100 |
| | “ | 3 |1239 |
| | “ | 4 |1611 |
| | “ | 5 |1865 |
| | “ | 6 |2209 |
| | “ | 8 |2489 |
| | “ | 10 |2848 |
| | “ | 15 |3200 |
| | “ | 20 |3885 |
| | “ | 25 |4150 |
| | “ | 30 |4651 |
| | “ | 35 |4828 | Time 35 sec’s.
----------------+-------+---------+---------+-----+----------------
13-in. Sea-Coast| 20. | 200-lb. | 45 |4325 | Time 40 sec’s.
Mortar. | | Shell | | |
----------------+-------+---------+---------+-----+----------------
10-in. Sea-Coast| 10. | 98-lb. | 45 |4250 | Time 36 sec’s.
Mortar | | Shell | | |
----------------+-------+---------+---------+-----+----------------
10-in. Siege | 1. | 90-lb. | 45 | 300 | Time 6.5 sec’s.
Mortar. | 1.5 | Shell | “ | 700 | “ 12. “
| 2. | “ | “ |1000 | “ 14. “
| 2.5 | “ | “ |1300 | “ 16. “
| 3. | “ | “ |1600 | “ 18. “
| 3.5 | “ | “ |1800 | “ 19. “
| 4. | “ | “ |2100 | “ 21. “
----------------+-------+---------+---------+-----+----------------
| lbs oz| 45-lb. | | |
8-in. Siege | 0 8 | Shell | 45 | 209 |Time 6.75 sec’s.
Mortar. | 0 12 | “ | “ | 376 | “ 9. “
| 1 0 | “ | “ | 650 | “ 11.5 “
| 1 4 | “ | “ | 943 | “ 14. “
| 1 8 | “ | “ |1318 | “ 16.5 “
| 1 12 | “ | “ |1522 | “ 18.5 “
| 2 0 | “ | “ |1837 | “ 20.5 “
----------------+-------+---------+---------+-----+----------------
| oz | 17-lb. | | |
24-Pounder | 0.5 | Shell | 45 | 25 |
Coehorn | 1. | “ | “ | 68 |
Mortar. | 1.5 | “ | “ | 104 |
| 1.75 | “ | “ | 143 |
| 2. | “ | “ | 165 |
| 2.75 | “ | “ | 260 |
| 4. | “ | “ | 422 |
| 6. | “ | “ | 900 |
| 8. | “ | “ |1200 |
----------------+-------+---------+---------+-----+----------------
| lbs | Stones | | |
Stone Mortar. | 1.5 | 120 lbs.| 60 |{150 |
| | | |{ to |
| | | |{250 |
| 1 |{15 6-pdr| 33 |50 to| Fuze 15 sec’s.
| |{ shells | | 150 |
----------------+-------+---------+---------+-----+----------------

=NOTE.=—Fire-balls, according to their size, are fired
from mortars of corresponding calibres. With a charge
of ONE TWENTY-FIFTH its weight, the ball is thrown
600 to 700 yards.

[Sidenote: 73]]