Chapter XXIII: Appendix: B.--No. I

GRADUATION OF SIGHTS AND MEAN RANGES
OF
UNITED STATES NAVAL SMOOTH-BORE GUNS.

(_From Results of Practice, by Admiral_ DAHLGREN, _United States Navy._)

The graduation commences from the bottom of the head of the bar resting on the sight-box.

The aim is supposed to be taken at the water-line of a ship.

---------------------+-------------------------+-----------------------+
| 32-POUNDER OF 27 CWT. | 32-POUNDER OF 33 CWT. |
+-------------------------+-----------------------+
Charge | 4 lbs. | 4-1/2 lbs. |
| | |
Axis of bore above | | |
load-line | 7 feet. | 7-1/2 feet. |
| | |
Distance between | Old Model. | New Model. | |
sights | 29-1/4 | 26-3/4 | |
| inches. | inches. | 31 inches. |
----------+----------+------------+------------+-----------+-----------+
ELEVATION.| RANGE. |GRADUATION. |GRADUATION. | RANGE. |GRADUATION.|
----------+----------+------------+------------+-----------+-----------+
Degrees. | Yards. | Inches. | Inches. | Yards. | Inches. |
Level. | 250 | 0.353 | 0.324 | 287 | 0.350 |
1 deg. | 545 | 0.746 | 0.684 | 581 | 0.792 |
2 deg. | 800 | 1.266 | 1.161 | 857 | 1.343 |
3 deg. | 1,047 | 1.801 | 1.652 | 1,140 | 1.909 |
4 deg. | 1,278 | 2.337 | 2.144 | 1,398 | 2.478 |
5 deg. | 1,469 | 2.870 | 2.633 | 1,598 | 3.044 |
6 deg. | 1,637 | 3.398 | 3.116 | ... | ... |
----------+----------+------------+------------+-----------+-----------+