sender's feet. An oil lantern may more conveniently be swung outward and upward. It is important to obtain a good background and to select a flag the colors of which present the most marked contrast with the background.

527. The prescribed calls may be supplemented by flag-hoist calls as in semaphore. The procedure prescribed for semaphore shall be followed.

528. While slower than semaphore, the rate of transmission being 10 words per minute, a large wigwag flag against a good background may be read at a greater distance than semaphore.

SOUND.

529. Sound signaling is prescribed for use in thick weather under circumstances where the use of radio is inadvisable and when such signals will not be confusing to strangers in connection with the "Rules of the Road" or confusing to our own ships in connection with "Rules of the Road" or emergency signals. Sound may be made on the whistle, foghorn, or similar sound-producing apparatus. The Morse Alphabet and special signs are used. In using the steam whistle, see that the condensed steam is blown clear before starting. A short blast of the whistle or single stroke of a bell represents a "dot," a longer blast or two short strokes in quick succession represents a "dash." Care must be taken in the spacing or interval between strokes. While a signal or dispatch is being sent by whistle by a vessel, the sounding of the whistle by other vessels within hearing distance should be limited to sounding it for strictly navigation purposes in accordance with the "Rules of the Road." Two or more ships within hearing of each other should never attempt sound signaling at the same time, when by so doing they cause interference with one another.

530. The following procedure is prescribed for signals by sound: 531. When signaling to one ship direct

532. Due to the abberration of sound, when signaling to more than one ship the repeating of signals by each ship is necessary to insure its receipt.

533. When signaling to more than one ship, or when signaling to one ship when conditions are such that the signal has to be relayed or repeated by an intervening ship, the procedure for the commander in chief is the same as given above except that the executive signal is not made, the commander in chief stopping after the finale" sign following the signal. The call is answered only by the nearest or next adjacent ship included in the call, and that ship becomes the receiving ship.

534. When the next adjacent ship has received the signal she becomes the transmitting ship pro tem, and the next adjacent ship in a direction away from the commander in chief becomes the receiving unit, and so on down the formation; that is, the commander in chief transmits to ship "A," ship "A" transmits to ship "B," etc. The transmission of the signal by ship "A" to ship "B" insures the originating ship that the signal has been received by ship "A," and whether or not the reception was correct.

535. When the ship farthest from the original transmitting ship has received and understands the signal she shall sound "R (..), which shall be repeated back to the commander in chief in the reverse order in which the signal was sent.

536. When the commander in chief has received the "R" repeated back to him he is assured that all ships are ready for the signal of execution. The signal of execution is a 10-second blast preceded by the sign IX IX. The signal of execution is repeated

(a) In simple formation, by the guides of the divisions. (b) In compound formation, by the unit leaders.

537. The sign I should be repeated several times.

538. Care should be taken to allow an interval for the repeating ships to complete their repetitions of the preliminary sign I before sounding the 10-second blast.

539. The signal is to be executed on the completion of the 10second blast.

540. Should a ship miss a word or group made by the ship next before her she is immediately to make the "repeat" sign, when the transmitting ship is to repeat the word or group missed and continue the signal.

541. Should a ship hear her next following ship repeating the signal incorrectly she is at once to make the "erase" sign. Upon hearing the " erase" sign the next ship will immediately stop signaling and wait until the word or group which she transmitted incorrectly has been made again to her.

542. When the commander in chief is not at the end of the column or line, the signals are to be repeated, first by the ships ahead or to starboard of him, the ships astern or to port of him commencing the repetition when the signal has gone sufficiently far from them to avoid confusion.

543. When in more than one column, the signal is to be relayed through the leading ships of columns, who are then responsible for passing it down their own column, using a procedure similar to the above, except that in addition to receiving the "R" from her own column each leading ship is to pass "R" in from her own colu:n to the commander in chief through intermediate leading ships.

544. Care must be taken to allow the signal to go sufficiently far down the commander in chief's column before the leading ships of other columns commence sounding their repetitions.

545. Should a ship fail to repeat any signal within half a minute of her proper turn, the next in succession is to take up the signal without further delay.

DISPATCHES BY SOUND.

546. The procedure prescribed for the transmission of dispatches by flashing light shall be followed for the transmission of dispatches by sound.

547. Should the transmitting ship fail to receive the acknowledging blast after a reasonable wait the word, group, or sign last made shall be repeated until acknowledged. This procedure insures the receipt of a dispatch part by part and reduces not only the probability of a complete repetition, but saves the time required in making the requests for repetitions.

548. After the transmission of the dispatch, the receiving unit may request a repetition of any part or all of the dispatch by using th "repeat" sign

VERY'S LIGHTS.

549. Very stars are used primarily as recognition signals, night emergency signals, special signals for exercises, etc. The detailed instructions for their use under these conditions and the special significations or meanings assigned is given in the publications directing their use.

550. The Very system, while prescribed, is little used for ordinary signals. It may become of great importance when other means of signaling are not available. The signals are transmitted by projecting red stars and green stars into the air from a specially constructed pistol, supplemented by rockets.

551. For general signals, the code used is the International Morse, the red star representing the dot, the green the dash. The procedure follows the procedure for flashing lights as near as practicable. For brevity, the following conventional signs are prescribed:

553. Ships at anchor shall in thick weather sound the ship's bell in accordance with the International Rules for Preventing Collisions. When boats are away from the ship and are expected to return, the ship's call may be sounded at intervals for their guidance, provided such call is not the same as that of any neighboring permanent fog bell on the shore or on board a light-vessel.

1 Stars are fired simultaneously. Great care shall be taken to fire stars at the same time and in approximately the same direction.

SHAPE SIGNALS.

554. Shape signals are primarily long-distance signals. Shape signals may become of importance when it is inadvisable to use radio and when a ship is not fitted with or can not use searchlights and when atmospheric or light conditions make it impossible to distinguish the colors of flags.

555. Long-distance visual signaling between men-of-war will usually be transmitted by searchlight. However, naval ships should be prepared to communicate by shape signals.

556. To prevent confusion, no special naval shape-signal code is provided. Detailed instructions for the use of shape signals and a shape-signal code sufficient for general use is prescribed in the International Signal Book and again in the Allied Fleet Signal Book. As there is no distinguishing signal to indicate when the Allied Fleet Signal Book Code is used, a previous understanding is necessary to prevent confusion.

557. The commander in chief may prescribe when shape signals are to be used, and he may assign temporary or special meanings to shape signals should circumstances require.