Part 109

DETACHED pieces, in fortification, are such out-works as are detached, or at a distance from the body of the place; such as half-moons, ravelines, bastions, &c.

DETACHEMENT, Fr. See DETACHMENT.

DETACHMENT, in military affairs, an uncertain number of men drawn out from several regiments or companies equally, to march or be employed as the general may think proper, whether on an attack, at a siege, or in parties to scour the country. A detachment of 2000 or 3000 men is a command for a general officer; 800 for a colonel, 500 for a lieutenant-colonel, 200 or 300 for a major, 80 or 100 for a captain, 40 for a lieutenant or ensign, 12 for a serjeant, and 6 for a corporal. Detachments are sometimes made of intire squadrons and battalions. One general rule in all military projects that depends upon us alone, should be to omit nothing that can insure the success of our detachment and design; but, in that which depends upon the enemy, to trust something to hazard.

DETAIL, Fr. faire le détail d’une armée, d’une compagnie, ou d’une corps de gens de guerre; is to keep a strict eye upon every part of the service, and to issue out instructions or orders, that every individual belonging to a military profession may discharge his trust with accuracy and fidelity. Faire le détail d’une compagnié, likewise means to make up a company’s report, &c.

DETAIL of duty, in military affairs, is a roster or table for the regular and exact performance of duty, either in the field, garrison, or cantonments. The general detail of duty is the proper care of the majors of brigade, who are guided by the roster of the officers, and by the tables for the men, to be occasionally furnished. The adjutant of a regiment keeps the detail of duty for the officers of his regiment, as does the serjeant-major that for the non-commissioned, and the latter that for the privates.

DEVASTATION, in military history, the act of destroying, laying waste, demolishing, or unpeopling towns, &c.

DEVELOPPER, Fr. to unfold, to unravel; as Se développer sur la tête d’une colonne, to form line on the head of a column.

DEVICE, the emblems on a shield or standard.

DEUIL militaire, Fr. military mourning.

DEVUIDER, in the manege, is applied to a horse that, upon working upon volts, makes his shoulders go too fast for the croupe to follow.

DIABLE. Fr. See CHAT.

DIAGONAL, reaching from one angle to another; so as to divide a parallelogram into equal parts.

DIAGONAL MOVEMENTS. See ECHELLON.

DIAMETER, in both a military and geometrical sense, implies a right line passing through the centre of a circle, and terminated at each side by the circumference thereof. See CIRCLE.

The impossibility of expressing the exact proportion of the diameter of a circle to its circumference, by any received way of notation, and the absolute necessity of having it as near the truth as possible, has put some of the most celebrated men in all ages upon endeavoring to approximate it. The first who attempted it with success, was the celebrated Van Culen, a Dutchman, who by the ancient method, though so very laborious, carried it to 36 decimal places: these he ordered to be engraven on his tomb-stone, thinking he had set bounds to improvements. However, the indefatigable Mr. Abraham Sharp carried it to 75 places in decimals; and since that, the learned Mr. John Machin has carried it to 100 places, which are as follows:

If the diameter of a circle be 1, the circumference will be

3.1415926535,​8979323846,​2643383279,​5028841971,​6939937510,​ 5820974944,​5923078164,​0528620899,​8628034825,​3421170679,​+

of the same parts; which is a degree of exactness far surpassing all imagination.

But the ratios generally used in the practice of military mathematics are these following. The diameter of the circle is to its circumference as 113 is to 355 nearly.--The square of the diameter is to the area of the circle, as 452 to 355. The cube of the diameter is, to the solid content of a sphere, as 678 to 355.--The cubes of the axes are, to the solid contents of equi-altitude cylinders, as 452 to 355.--The solid content of a sphere is, to the circumscribed cylinder, as 2 to 3.

How to find the DIAMETER of shot or shells. For an iron ball, whose diameter is given, supposing a 9-pounder, which is nearly 4 inches, say, the cube root of 2.08 of 9 pounds is, to 4 inches, as the cube root of the given weight is to the diameter sought. Or, if 4 be divided by 2.08, the cube root of 9, the quotient 1.923 will be the diameter of a 1-pound shot; which being continually multiplied by the cube root of the given weight, gives the diameter required.

Or by logarithms much shorter, thus: If the logarithm of 1.923, which is .283979, be constantly added to the third part of the logarithm of the weight, the sum will be the logarithm of the diameter. Suppose a shot to weigh 24 pounds: add the given logarithm .283979 to the third part of .460070 of the logarithm 1.3802112 of 24, the sum .7440494 will be the logarithm of the diameter oi a shot weighing 24 pounds, which is 5.5468 inches.

If the weight should be expressed by a fraction, the rule is still the same: for instance, the diameter of a 1¹⁄₂ pound ball, or ³⁄₂, is found by adding the logarithm .2839793, found above, to .0586971 ¹⁄₃ of the logarithm of ²⁄₃, the sum .3426764 will be the logarithm of the diameter required, i. e. 2.2013 inches.

As the diameter of the bore, or the calibre of the piece, is made ¹⁄₂₀ part larger than that of the shot, according to the present practice, the following table is computed for this proportion.

DIAMETERS of the shots and calibres of English guns.

+---+-----+-----+-----+-----+-----+-----+ |lb.| 0 | 1 | 2 | 3 | 4 | 5 | +---+-----+-----+-----+-----+-----+-----+ | | 0 |1.923|2.423|2.775|3·053|3.288| | 0 +-----+-----+-----+-----+-----+-----+ | | 0 |2.019|2.544|2.913|3.204|3.568| +---+-----+-----+-----+-----+-----+-----+ | |4.143|4.277|4.403|4.522|4.635|4.743| | 1 +-----+-----+-----+-----+-----+-----+ | |4.349|4.490|4.623|4.748|4.866|4.981| +---+-----+-----+-----+-----+-----+-----+ | |5.220|5.305|5.388|5.409|5.547|5.623| | 2 +-----+-----+-----+-----+-----+-----+ | |5.480|5.579|5.661|5.742|5.824|5.893| +---+-----+-----+-----+-----+-----+-----+ | |5.975|6.041|6.105|6.168|6.230|6.290| | 3 +-----+-----+-----+-----+-----+-----+ | |6.275|6.343|6.410|6.475|6.?41|6.604| +---+-----+-----+-----+-----+-----+-----+ | |6.576|6.631|6.684|6.737|6.789|6.640| | 4 +-----+-----+-----+-----+-----+-----+ | |6.904|6.962|7.018|7.076|7.128|7.182| +---+-----+-----+-----+-----+-----+-----+

+---+-----+-----+-----+-----+------+ |lb.| 6 | 7 | 8 | 9 | | +---+-----+-----+-----+-----+------+ | |3.498|3.679|3.846|4.000|diam. | | 0 +-----+-----+-----+-----+------+ | |3.668|3.861|4.038|4.200|calib.| +---+-----+-----+-----+-----+------+ | |4.846|4.945|5.040|5.131|diam. | | 1 +-----+-----+-----+-----+------+ | |5.088|5.192|5.292|5.368|calib.| +---+-----+-----+-----+-----+------+ | |5.697|5.769|5.839|5.908|diam. | | 2 +-----+-----+-----+-----+------+ | |5.982|6.057|6.129|6.203|calib.| +---+-----+-----+-----+-----+------+ | |6.350|6.408|6.465|6.521|diam. | | 3 +-----+-----+-----+-----+------+ | |6.666|6.707|6.788|6.846|calib.| +---+-----+-----+-----+-----+------+ | |6.890|6.940|6.989|7.037|diam. | | 4 +-----+-----+-----+-----+------+ | |7.234|7.287|7.338|7.383|calib.| +---+-----+-----+-----+-----+------+

EXPLANATION.

The numbers in the first line of the table are units, and those in the first column of the left side of the table tens; the other numbers, under the one, and opposite to the others, are the respective diameters of shot and calibres. Thus, to find the diameter of the shot, and the calibre of a 24 pr. look for the number 2 on the left-hand side, and for 4 at top; then the number 5.547, under 4, and opposite 2, will be the diameter of the shot in inches and decimals, and the number 5.824, under the first, the calibre of a 24-pounder &c.