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of this privilege; promotion would be more rapid, and a Naval Reserve Would be formed upon which the Government could in case of emergency rely for service afloat or for torpedo duty ashore. For want of other employment, warrant officers are frequently detailed for duty on board vessels already too cramped for the proper acComodation of their crews. From causes too obvious to mention, the man-of-war of the present age is so different from that of last century, that the necessity for the retention in the service of the grades of boatswain, sailmaker, and carpenter, no longer exists. These grades should, then, be allowed to lapse by not making any appointments to fill vacancies. The care of the battery and Small arms of a vessel alone being of sufficient importance to require the services of a warrant officer, the grade of gunner should be retained, and all applicants for the position should be required to pass a thorough examination to prove that they have sufficient intelligence and capacity to understand the mechanism, and to take the proper care for the preservation of the improved weapons now in use. By thus dispensing with the services of these One hundred and forty two superfluous officers, a sum sufficient for the pay and maintenance of over six hundred men would annually be gained. The difficulty of obtaining seamen to man our vessels, during the late war, was seriously felt. We cannot rely upon merchant seamen, for the class has through so many causes become so deteriorated as to be generally worthless ; and so large a proportion are foreigners that they cannot be depended upon to fight for the country that employs them. While the raw recruit may in a comparatively short time be converted into the disciplined soldier, the sailor is made only from the boy. The number of training ships should be increased and twenty five hundred boys, at least, enlisted in addition to the regular complement of the Navy. Each man-of-war going into commission should take a certain proportion of her crew from the boys on board the training ships who have shown most aptitude for a sea life. In this way a reserve of seamen would gradually be formed, for although these boys after the first cruise might not remain in the Navy, in case of war they would naturally gravitate to the service in which they were educated. During time of peace, the navy yards might with advantage be reduced to four ; three, New York, Norfolk, and Pensacola, on the Atlantic coast, and one, Mare Island, on the Pacific ; with a fresh water basin for iron vessels. But, as the extent of our territory would render the yards closed very valuable in time of war, sufficient money should be

annually appropriated to keep them from deterioration. In this connection, I would recommend that the complete control of the navy yards, even to the exclusion of local politicians, should be by law given to the naval officers in charge. The officers might then be held strictly accountable for the work done, and the spectacle of a large increase of the working force prior to elections and the discharge immediately after, happily not visible during the present administration, but so common in former days, would be avoided.

With these few suggestions I bring my remarks to an end. I have shown that the United States does not possess a navy commensurate with its wants, and I have pointed out what I believe to be the best way of properly developing our naval strength. But, after all, it is Congress which decides the naval policy of the country, and it is to Congress therefore, that we must look for the means to accomplish our end. The recommendations I have made apply equally well, in event of the continuation of the present economical policy towards the navy, or should Congress determine that the time had come to again strive to be foremost in the struggle for the commercial supremacy of the world. Sooner or later the day will come when the nation will again enter the arena ; let us then endeavor to be so prepared that in the heat of the strife we may not be disheartened by a discovery of fatal weakness in our trusted weapons.

December, 1879.

PROFESSIONAL NOTES.

These Articles have not been read before the Institute, but are inserted by direction of the Executive Committee.

TO DETERMINE BY THE AID OF AZIMUTH TABLES THE EFFECT UPON THE LONGITUDE OF A CHANGE IN THE LATITUDE USED IN Works NG A TIME SIGHT.

PROPOSITION. The departure due to a change of one minute in the latitude used in working a time sight is the tangent of the difference between 90° and the azimuth of the body observed.

Let P be the position whose longitude has been computed with the assumed latitude. NS is the meridian through P. M is the body o R observed, and NPM is its azimuth. PPP” * is the line of position perpendicular to PM. P\—Q The angle NPP” is the difference between 90° KP and the azimuth. Let P be a point on the line 2^ of position whose latitude is one minute greater than that of P. The departure due to this

S change of latitude is PQ. The tangent of

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NPP” is §–QP , since QP is, by hypothesis, equal to one. There

fore QP", or the departure due to a change of one minute in the latitude, is the tangent of the difference between 90° and the azimuth.

Suppose P" to be a point on the line whose latitude is a minutes greater than that of P. Then RP” = QP × 4, or the departure for any change of latitude is equal to the departure for one minute multiplied by the number of minutes.

The error due to the assumption that RPP" is a plane triangle is not appreciable for ordinary purposes.

The annexed table is formed by changing the natural tangents from decimals of a minute into seconds.

To MAKE USE OF THE METHOD,

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The time sight being worked out, enter the azimuth table with the latitude and declination used and the apparent time, or hour angle, computed, and take out the azimuth corresponding. With the difference between this and 90° enter the table given and take out the departure for With this de

parture and the latitude enter the traverse table

one minute in seconds of arc.

and take out the corresponding difference of longitude. Multiply this by the number of minutes of change in latitude, and the result is the required difference of longitude. The sign of application of this correction to the longitude computed, may be readily determined by a con

sideration of the direction of the line of position.

ExAMPLE.

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. M. T. 12 34 59 —11*. 4

12 –11 4 P.D. 113 27 00 Eq. T. 1". 47°.— 1°. 2 H.D. 14 —11 4 2 01 13 2 5

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Entering the azimuth table with Lat. 16° N., Dec. 23°, 27° S. App. T. 8.* 33", we find the azimuth to be N. 127° E. Entering the given table with 37° the departure corresponding, for one minute of latitude, is 45." Erom traverse table, with Lat. 16°, the corresponding D Long. is 47." The sign of application is evident from sketch of line of position. The position at 8.30 A.M., carried forward to noon, gave 15° 35' N. 119° 09' 45"E, but observation at noon determined latitude to be 15° 45' N; therefore true longitude at noon was 119°09', 45" E + 47" × 10 – 119° 17' 35" E. The method has the advantage of enabling the Navigator to correct his position at noon instantly for any difference between the latitude by observation and dead reckoning, the error for one minute having been determined at the time of working the morning sight. It also enables the second point of the Summer line to be readily determined for the sun or any other body whose declination falls within the limits for which the azimuth tables have been computed. The use of the method gives the Navigator a clear idea of the value of a sight without the necessity of plotting the line of position, and suggests the ease with which he may, when uncertain of his latitude, find from the tables the time of crossing the prime vertical, and take his sight at, or near, that time.

C. S. SPERRY, Lieut. U. S. N.

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