manoeuvres. Full speed is a designated speed greater than standard; half speed is a desig nated speed less than standard ; and slow speed is still less. Tactical diameter. The perpen In performing evolutions there are two prin cipal methods, by rectangular movements and by dieular distance between the course at the be ginning of a turn of ISO degrees and the course after the completion of the turn. Transfer. Dis tanee gained to the right or left (i.e. toward the flank) in turning. Turn. A turn is a change of direct or oblique movements. Certain evolutions also admit of movement by isodrome and others by conversion or wheel. The ease of movement attainable with bodies of men is not possible with ships. There can be no turning with fixed pivots, because ships must continue in motion or they cannot be kept under control; nor are sudden halts possible. for a heavy ship moving at high speed cannot be stopped in a less distance than several times her length. Tbese and other considerations have led to the general acceptance of certain rules.
First.—Movements during battle should be as simple as possible.
The accompanying figures show the various formations commonly used and the method of passing from one to the other. With the excep tions of Figs. 1, 2, 6, and 7, the plans show the movements of a squadron of eight ships; the evolutions would be similar for a fleet of sixteen ships.
Second.—Changes in speed, particularly dur ing evolutions, should be avoided as far as pos sible.
Third.—Evolutions should be performed by the method which requires the least time and the least space.
Fourth.—Ships of like characteristics should be separately grouped as far as possible; this is particularly true as regards speed and hardly less so as regards power and arrangement of battery and armor.
Fifth.—When approaching the enemy and until in position to deliver attack the fleet must be kept concentrated and in condition to assume any desired formation.
BIBLIOGRAPHY. For further information in reBibliography. For further information in re- gard to naval tactics and strategy, see: Captain W. B. 'Toff, U. S. N., Examples, Conclusions, and Maxims of Modern Naval Tactics (Washington, 1884) ; Captain F. A. Parker. U. S. N., Steam. Fleet Tactics (New York, 1863) ; Admiral Sir G. Elliot, R. N., A Treatise on Future Nava/ Bat tles, etc. (London, 1885) ; Saint Farret, French Navy, Etudes comparatives de tactique navale (Paris, 1883) ; also numerous articles in the Proceedings of the United States N'aral Institute, and in the Proceedings of the Royal United Ser vice Institution (London).