Signs of approach. First, a long heavy swell, a slight rise followed by a continuous fall of the barometer; second, strong gusty wind from some northerly point (northeast, north, or northwest), blowing with increasing force; and, third, a rough, increasing sea. If one or more of these signs be wanting there is little cause for anticipating a hurricane.

The approach of a hurricane is usually indicated by a long heavy swell, propagated to a great distance two or three days in advance, where there is no intervening land to interrupt it, and which comes from the direction in which the storm is approaching.

One of the earliest signs of a hurricane are high cirrus clouds which converge toward a point on the horizon that indicates the direction of the center of the storm. The snow-white fibrous mare's tails appear when the center of the storm is about 300 or 400 miles distant.

As the storm center approaches the barometer continues to fall, the velocity of the wind increases and blows in heavy squalls, and the changes in its direction becomes more rapid. Rain in showers accompanies the squalls, and when closer to the center the rain is continuous and attended by furious gusts of wind; the air is frequently thick with rain and spume drift, making objects invisible at a short distance. A vessel on a line of the hurricane's advance will experience the above disturbances, except that as the center approaches the wind will remain from the same direction, or nearly so, until the vessel is close to or in the center.

Distance from center. The distance from the center of a hurricane can only be estimated from a consideration of the height of the barometer and the rapidity of its fall, and the velocity of the wind and rapidity of its change in direction. If the barometer falls slowly and the wind increases gradually it may be reasonably supposed that the center is distant; with a rapidly falling barometer and increasing winds the center may be supposed to be approaching dangerously

near.

Practical rules.-When there are indications of a hurricane vessels should remain in port or seek one if possible, carefully observing and recording the changes in barometer and wind and taking every precaution to avert damage by striking light spars, strengthening moorings, and if a steamer preparing steam to assist the moorings. In the ports of the Southern States hurricanes are generally accompanied by very high tides, and vessels may be endangered by overriding the wharf where lying if the position is at all exposed.

Vessels in the Straits of Florida may not have the sea room to maneuver so as to avoid the storm track and should use every endeavor to make a harbor or stand out of the straits to obtain sea room. Vessels unable to reach port and having sea room to maneuver should observe the following rules:

When there are indications of a hurricane near, sailing vessels should heave to on the starboard tack and steamers remain stationary and carefully observe and record the changes in wind and barometer so as to find the bearing of the center and ascertain by the shift of wind in which semicircle the vessel is situated. Much will often depend on heaving to in time.

Bearings of center.-Facing the wind, the storm center will be 8 to 12 points to the right; when the storm is distant it will be from 10

to 12 points, and when the barometer has fallen five or six tenths it will be about 8 points.

A line drawn through the center of a hurricane in the direction in which it is moving is called the axis or line of progression, and looking in the direction in which it is traveling the semcircle on either side of the axis is called, respectively, the right hand or dangerous semicircle and the left hand or navigable semicircle.

To find in which simicircle the vessel is situated: If the wind shifts to the right, the vessel will be in the right hand or dangerous semicircle with regard to the direction in which the storm is traveling, in which case the vessel should be kept on the starboard tack and increase her distance from the center.

If the wind shifts to the left, the vessel will be in the left or safe semicircle. The helm should be put up and the vessel run with the wind on the starboard quarter, preserving the compass course, if possible, until the barometer rises, when the vessel may be hove to. on the port tack, or if there is not sea room to run the vessel can be put on the port tack at once.

Should the wind remain steady and the barometer continue to fall, the vessel is in the path of the storm and should run with the wind on the starboard quarter into the safe semicircle.

In all cases act so as to increase as soon as possible the distance from the center, bearing in mind that the whole storm field is advancing.

In receding from the center of a hurricane the barometer will rise and the wind and sea subside.

RADIO SERVICE.

The United States naval coast wise radio stations and all ships of the United States Navy equipped with radio apparatus are open for commercial business. Information concerning regulations, rates, and the commercial work of the stations may be obtained by addressing the Director of Naval Communications, Radio, Va. Hydrographic information, weather reports, storm warnings, and time signals are sent out from the stations for the benefit of shipping.

Radio compass bearings are furnished to vessels upon request by the naval shore compass stations.

To obtain bearings the compass station should be called in the usual manner, using the 800-meter wave length, the call to be followed by the signal "QTE?," meaning " What is my true bearing?" When told by the compass station to "K" (go ahead) the ship's radio operator should follow the procedure outlined below:

(a) Transmit the ship's radio call for 30 seconds.

(b) Make dashes, each dash 5 seconds long, for one minute, with the ship's radio call after each dash.

(c) Terminate with the signal "K" (go ahead).

If satisfactory bearings are obtained the operator at the compass station will call the vessel in the usual manner and reply "QTE," followed by the true bearing in degrees (0 to 359) spelled out in words, and the name of the radio compass station from which the bearing was obtained; otherwise a repetition of the test will be requested.

The ship's operator should acknowledge receipt of the bearings by answering the compass station in the usual manner and repeat, in numerals, the bearings received. This procedure enables all stations concerned to check the bearings.

All United States naval shore radio compass stations keep watch and transmit on 800 meters for merchant vessels, and this wave length must be used for calling and answering and carrying on all communications with these stations.

Attention is invited to the fact that when a single bearing is furnished there is a possibility of an error of 180 degrees, as the operator at the compass station can not always determine on which side of his station the vessel lies; in such cases the decision is left to the commander of the vessel. (See page 15.)

Time signals. In connection with the service over the land telegraph lines, time signals by radio are sent daily, Sundays and holidays excepted, from certain United States naval coastwise radio stations at noon of the seventy-fifth meridian time on the Atlantic coast and at noon of the one hundred and twentieth meridian time on the Pacific coast. The signals begin at 11.55 and continue for 5 minutes. During this interval every tick of the clock is transmitted, except the twenty-ninth second of each minute, the last 5 seconds of each of the first 4 minutes, and finally the last 10 seconds of the last minute. The noon signal is a longer contact after this long break. Similar time signals are also sent at 10 p. m. from some of the stations.

The supervision of radio communication in the United States is controlled by the Bureau of Navigation, Department of Commerce. A list of the radio stations of the United States, including shore stations, merchant vessels, Coast Guard cutters, vessels of the United States Navy, and amateurs, and the radio laws and regulations of the United States are published by that bureau, and either publication can be obtained from the superintendent of documents, Government Printing Office, Washington, D. C.; price, 15 cents each. Changes or additions to the stations and to the laws and regulations are published in bulletins issued monthly; price, 5 cents per copy, or 25 cents per year.

The International List of Radio Stations of the World includes the stations of the United States, excepting amateurs, and contains additional information, such as geographical location, normal range in nautical miles, radio system, and rates. Persons desiring this list should communicate direct with the International Bureau of the Telegraphic Union (Radiotelegraphic Service), Berre, Switzerland. The price is 60 cents per copy, not including postage. The rates of postage are: One copy, 24 cents; two copies, 36 cents; three copies,

48 cents.

Standard time. The standard time of Porto Rico and the Virgin Islands is sixtieth meridian (west longitude) time.

TIDES AND CURRENTS.

The periodic tides in this locality are very small, the average mean rise and fall being approximately one foot. The actual fluctuations in the water level will therefore depend largely upon the winds and other meteorological conditions. Off the northern and western coasts

of Porto Rico the tide is chiefly semidiurnal, with high water occurring about 8 hours after the moon's upper or lower meridian passage. Along the coast of Porto Rico that borders the Caribbean Sea the tide is more or less diurnal and high water occurs from 10 to 102 hours after the moon's upper meridian passage. At the Virgin Islands the tides are chiefly diurnal, the high-water interval referred to the upper transit of the moon being approximately 72 hours.

The currents along the north and south coasts of Porto Rico are, as a rule, greatly influenced by the direction and strength of the trade winds. In general, there is a westerly drift, due to the prevailing easterly trade winds, the velocity of which is greatest near the island; a decided westerly set has been noticed near the 100-fathom curve on the south coast from Muertos Island to Cape Rojo. With variable winds or light trade winds it is probable that tidal currents are felt at times along the north and south coasts of Porto Rico. There are little or no currents in the passage northward of Muertos and Berberia Islands.

In Mona Passage and the various passages from the east coast of Porto Rico to Virgin Passage the tidal currents under normal conditions set each way about 6 hours, turning from south to north from 1 to 2 hours after the moon's meridian passage and from north to south from 1 to 2 hours after moonrise or moonset.

In Mona Passage on the northwest end of the bank, about 13 miles westward of Point Guanajibo, there is a velocity of about 1 knot at strength for both flood and ebb, and in the Guanajibo Channel, 1 mile westward of Fanduca Cay, a velocity of about 14 knots at strength. The current turns from southward to northward about 1 hour after the moon's meridian passage.

In Vieques Sound there are considerable tidal currents over the shoals in the western part and around Cabeza de Perro. In Fajardo Harbor a northerly current with a greatest velocity of nearly 1 knot has been observed. In San Juan and Cucaracha Passages tidal currents with an estimated greatest velocity of about 2 knots at strength have been reported. In the wider passages between Icacos Cay and Southwest Cay it is estimated that the greatest velocity of the currents does not exceed 1 knot. From Culebra Island the flood current sets toward East Point, Vieques Island, around which the tidal currents set with considerable velocity.

In Canal de Luis Pena the flood current from northwestward is deflected northward of Target Bay and thence sets toward the south end of Southwest Cay; there is little current off the entrance to Seine Bay on the flood. The ebb current sets northwestward directly through the canal. The velocity of the tidal currents is about 2 knots at strength.

In Vieques Passage the velocity at strength is about 1 knot for both flood and ebb and the current turns from southward to northward about 2 hours after the moon's meridian passage.

For more detailed information concerning the tides in this locality, the Tide Tables, which are published by the U. S. Coast and Geodetic Survey, should be consulted. The complete tide tables for the world are for sale at 75 cents per copy, but a reprint covering the Atlantic coast of North America may be obtained for 15 cents per copy. These tables may be purchased either directly from the office of the

Coast and Geodetic Survey, Washington, D. C., or from any of its agencies.

It contains a table of full daily predictions of the times and heights of high and low waters for certain standard or principal ports along the coast; full explanations for the use of this table are given on page 8. The use of Table 2 of the Tide Tables should be known to every navigator. By means of this table the predictions given for the standard ports are extended so as to enable one to obtain complete tidal data for each day for stations only a few miles apart for the greater part of the coast, and with almost the same accuracy as though full predictions were given for all of these points.

Instead of using the height differences of Table 2, however, a more accurate method is that of multiplying both high and low water heights at the standard port by the ratio of ranges for the given port to obtain the heights of the corresponding high and low waters. The ratio of ranges is given in Table 2 of the Tide Tables. The minus sign before the predicted heights in the Tide Tables indicates that the water is below the plane of reference, which is mean lower low water.

The time of high or low water at any given port in Table 2 is found by taking the time of the corresponding tide for that day from the standard port for reference and applying to it the time difference for the given port from the third column of Table 2, adding it if the sign is plus and subtracting if minus.

Caution. In using the Tide Tables, slack water should not be confounded with high or low water. For ocean stations there is usually but little difference between the time of high or low water and the beginning of ebb or flood current; but for places in narrow channels, landlocked harbors, or on tidal rivers the time of slack current may differ by two or three hours from the time of high or low water stand, and local knowledge is required to enable one to make the proper allowance for this delay in the condition of tidal currents.

The figures given in Tables 1 and 2 of the Tide Tables are the times of high and low water, and these times are not necessarily the times of slack water.

VARIATION OF THE COMPASS.

The magnetic variations for 1922, and annual increase at points mentioned, are as follows: