PART VII. WINDAGE.
Reading edition
1. What is meant by windage?
The difference between the diameter of the projectile and that of the bore.
2. Is it absolutely necessary to allow windage?
Yes, in order to make an allowance for a piece becoming foul, the expansion of shot by heat, the incrustation of rust, and for the tin straps of fixed ammunition.
3. What advantages are derived from reducing the windage?
An increase in the accuracy of fire; a more extensive range, or an equal range with a smaller charge, as there is less loss of gas; and less injury to the surface of the bore.
4. Why should the bore suffer less injury by a diminution of the windage?
Because in proportion to the decrease of windage there will be less space for the reflections of the shot along the bore, and consequently less injurious power exercised upon it.
5. What is the loss of velocity by a given windage proportional to?
It is directly as the windage, and inversely as the diameter of the bore very nearly.
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6. What is the loss of velocity by the windage of the ball?
KIND OF GUN. Charge of powder. Initial velocity of ball. Loss of velocity by windage of 1-40th diam.
Without windage. With windage of 1-40th diam.
lbs. feet. feet. feet. per cent.
32-pdr. Sea-Coast, 4 1444 1271 173 12
24-pdr. Siege, 4 1600 1433 167 10
6 1890 1723 167 9
12-pdr. 25 calibres, 2 1617 1444 173 11
3 1915 1742 173 9
4 2124 1951 173 8
12-pdr. Field, 16 calibres, 2 1528 1370 158 10
3 1793 1635 158 9
4 1992 1834 158 8
6-pdr. Field, 1.5 1734 1560 174 10
7. What windage is allowed to guns?
IRON. BRASS.
Sea-Coast. Siege and Garrison. Field.
42 32 24 18 12 12 6
inches. inches. inches. inches. inches. inches. inches.
0.16 0.15 0.14 0.13 0.10 0.10 0.09
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8. What windage is allowed to columbiads and howitzers?
Columbiads. Howitzers.
Iron. Iron. Brass.
Sea-Coast. Siege and Garrison. Field. Mountain.
10-in. 8-in. 10-in. 8-in. 8-in. 24-pdr. 32-pdr. 24-pdr. 12-pdr. 12-pdr.
in. in. in. in. in. in. in. in. in. in.
0.12 0.12 0.12 0.13 0.13 0.14 0.15 0.14 0.10 0.10
9. What amount of windage is allowed to mortars?
IRON. BRASS. IRON.
Heavy. Light. Stone Mortar. Coehorn 24-pdr. Eprouvette.
inches. inches. inches. inches. inches. inches. inches.
0.13 0.13 0.13 0.13 — 0.14 0.025
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