The Nautical Magazine: A Journal of Papers on Subjects Connected with ...

PERPETUAL LOG FOR SHIPS.

Another valuable contribution to a ship's furniture has been made by the Rev. E. Berthoun of Fareham, in the shape of a perpetual log, which is likely to become not only a favourite, but will hereafter be considered almost an essential to her safety. We propose in an early number to describe it, at present it being before the Royal Society. Unlike Massey's or Walker's it has no machinery to get out of order, or require repair, and being (with the exception of about three inches) all inside of the ship, is free from any external accident. It consists of a small tube in which the pressure of the water occasioned by the way of the ship, acting on a column of mercury, indicates the velocity of sailing. The index, which very much resembles in size and appearance a common thermometer, may be fitted to hang in the captain's cabin, or in any other part of the ship, being at once ornamental and useful. We understand it is being at present fitted in H.M.S. Dauntless, and we fully anticipate every ship afloat, being hereafter supplied with it. It not only indicates the velocity, but also the lee-way should the vessel be sailing by the wind; and is highly creditable both to the judgment and good taste of the inventor.

NEW BOOKS.

THE PRACTICE OF NAVIGATION AND NAUTICAL ASTRONOMY.—By Henry Raper, R.N., Third Edition:-Bate, London,

We took some pains on the first appearance of this work to make it known to our readers: it had peculiar claims to our attention, being the production of a Naval officer who ventured to leave the beaten path of writers on navigation, and with his own experience of the navigator's wants to methodize both the materials and their arrangement in a manner more congenial to them than his predecessors had attempted. How far he has succeeded the Third Edition of the book now before us amply proves. We have, therefore, to notice the new matter, and of this we have abundance: we find it first in the number of examples to illustrate the various methods. and next in the elementary portion of arithmetic and geometry; subjects in which we quite agree with our author navigators cannot be too well grounded.

In the former he is initiated with examples to illustrate proportion, very happily borrowed from the daily occurrences of a sea life, such for instance as the time required for watering a ship by a number of boats, each loading in a certain time, and carrying a different quantity of water; and numerous other well chosen examples of a similar nature. A short course of geometry is also introduced, sufficient to establish three propositions, which the author takes as the limit of the geometrical matter he considers necessary for the navigator; these are the well known 47th of Euclid, the relation of the angles at the centre and circumference, and the analogy of similar triangles which constitute the basis of trigonometry.

We insisted long ago that the theory of the Law of Storms should be familiar to every commander of a ship, and we are glad to find a few pages devoted to it, for even they are sufficient to convey the principle. Already have some of our intelligent correspondents in the command of ships shewn in the

pages of the Nautical, the advantage they have derived foom this little knowledge. The method of ascertaining the position of a ship by means of a variation in latitude, known as "Sumner's Method," forms a very important new feature in this edition.

In the chapter on navigating the ship we find ample evidence in the length of the sections, of the introduction of much that is new. The instructions on Great Circle Sailing are more complete information of a mixed and interesting nature appears under the heads of "obtaining water," "indications of land," "dangers," &c. collected with much care from numerous voyages. In the directions for making a proper report of a newly discovered island or reef, the author quotes the case of the island of Osnaburgh, which on its first discovery by Carteret was described as a small island, but which has since been found to have an extent of fourteen miles. Here is a good instance of the necessity of a careful attention to many particulars which from different causes may have much influence on the appearance, or the description of the same place after the lapse of many years.

We have so many demands on our space that we must conclude our first notice of Mr. Raper's valuable book, with, perhaps the most conspicuous, if not the most important improvement he has introduced. We allude to the Table of Positions of Places extending to 8,800. If anything imparts value to a mass of information of this kind, it is the correctness of the quantities given. The system adopted by the author in discussing these positions (we allude to the longitudes generally determined by chronometer,) is such as to ensure the most accurate one that can be arrived at with existing data, and, therefore. those which should be current among seamen whose calculations depend for making land on them. On this account alone we attach much importance to this table; it is one which has been sadly overlooked by authors, who have taken them as they came to hand and thereby involved themselves in all kinds of inconsistencies. But, with the view of rendering this useful table still more useful, the author has added in a compressed form much information for the seaman.

In the First Edition we found the more prominent information of lights, and also heights introduced by abbreviations; but in the present table we have numerous other particulars respecting the appearance of land, the depths on shoals, the extent or dimensions of islands and dangers; supplies, such as water and refreshments, their quality and degree of quantity, and several other particulars of information useful to the seaman, and the knowledge of which is essential to him. All this information, and much more besides, which has been evidently collected with great pains by the author from a multitude of volumes, would require almost a volume to convey in the usual manner, and desirable as it might be, could not otherwise be introduced in a work of this kind, but by a well digested system of symbols. Indeed we believe it is this very table which has so long delayed the appearance of this edition, but in the utility of which and its consequent appreciation by seamen, the author will eventually find the reward due to him. As we gave a sample of this mode of conveying information in our last volume, we may refer the reader to it, but we are quite of opinion that much information may not only be given in the manner adopted by the author of the "Practice of Navigation;" but that the charts and plans which seamen use, are no less adapted for the employment of these and additional symbols for the conveyance of even more information, such as the prevailing wind, the times and duration of wet and dry seasons, &c. This would form a beginning to which

more would gradually be added as the facility of doing so became apparent. We must now leave a further consideration of the add tional matter in the work before us for another number.

A COMPLETE AND UNIVERSAL DICTIONARY OF SIGNALS for the boats of Her Majesty's Fleet, &c.—By Arthur Parry Eardly Wilmot.-London, Cleaver. A very comprehensive little pocket volume well adapted for its intended purpose. A good set of boat signals was much wanted, and we have no doubt Capt. Wilmot's will be a favorite in the hands of our signal officers, both from its compactness and its general application. We observe a modification of the Homograph of former days introduced, and signals by balls, oars, the semaphore, &c., in which different ways much may be done. We perceive in the title page that the author addresses his work to the commanders of yachts, merchant ships, &c., and no doubt a work that will be so extensively used, in the Royal Navy as this, cannot bring stronger claims for such extensive patronage; the advantage of making a book like this general in both services are evident. It is very properly dedicated to the First Lord of the Admiralty.

PROBLEMS IN ASTRONOMY, SURVEYING AND NAVIGATION, with their Solutions By H. W. Jeans, F.R.A.S.-Wilson, Leadenhall Street.

Self instruction appears to be the object of the author in this little volume, which is accordingly well stored with problems and examples in the above subjects. It may, however, be considered more as a mentor of the principles and rules of those subjects than as adapted for a beginner, and would be still more acceptable with a good index. The concise method of the author as well as the compact form he has adopted will always recommend it.

NEW CHARTS.

Charts and Books Published by the Hydrographic Office, Admiralty and Sold by R. B. Bate, 21, Poultry, in Dec. 1849.

s. d.

ARCHIPELAGO, sheet 5, Capt. Graves, R.N.
NORTH AMERICA, EAST COAST, Corrected to 1849, sheets 5, 6, 7, each
TIDE TABLES for 1850.

price

2 0

1 6

EX-MERIDIAN ALTITUDE TABLES, Mr. J. T. Towson, 1849.

E. DUNSTERVILLE, Master B.N.

Hydrographic Office, Dec. 19th 1849.

EXAMINATION OF MASTERS, AND SECOND MASTERS.

Admiralty, December 17th, 1849.

THE Lords Commissioners of the Admiralty having had under their consideration, the present Regulations for the Examination of Masters, and Second

Masters, of her Majesty's Fleet, as defined by Art. 21, Chap. 2, p. 22, and Art, 25, Chap. 2, page 25, of the printed Instructions; have been pleased to direct. that on, and after, the 1st of January next, the following Regulations shall be adopted, viz :

All Officers passing for the rank of 2nd Master, (or Officers from the Merchant Service who are Candidates for the rank of Master, under the Queen's Regulations, Art. 6, Chap. 3, page 21,) shall be examined in Seamanship, either at home, or abroad, by one Captain or Commander, and three Masters; and after having received a Certificate of having passed such Examination, they shall undergo their Examination in Navigation, at the Royal Naval College, (instead of the Trinity House.) under the same regulations, and at the same period, as Midshipmen passing for Lieutenants; but the Examination for Pilotage is to be conducted at the Trinity House, under the rules and regulations at present in force, but subsequent to the above mentioned examinations. Having completed the above Examinations they will be considered eligible for the rank of Master in the Royal Navy, provided they shall have served the time required by the Queen's Regulations.

The seniority of Second Masters (or of Candidates for the rank of Master) is in future to reckon from the date of their passing in Seamanship for that rank, provided they shall subsequently pass in Navigation at the Royal Naval College, on the first or second Examination day following, either of which days, they are at liberty to select ; or, in the event of an Officer having previously passed abroad in Seamanship, he is at liberty, after his arrival in England, to select either the first or second Examination day at the Royal Naval College; or if belonging to a ship under orders to be paid off, on the first or second Examination day after having been so paid off, when, if he shall succeed in passing, he will be allowed Seniority from the date of his havfng passed abroad. But no Second Master (or Candidate for the rank of Master) will be allowed such Seniority, who shall fail in passing at the Royal Naval College, at the first trial, or who shall not pass at the Trinity House within a month after his having passed in Navigation.

Officers appearing before the Trinity Board for the purpose of passing in Pilotage must be qualified to take charge as Pilot of any of her Majesty's Frigates for the coast and ports for which Masters have hitherto been examined; and when they shall have served three years at least in Frigates or Sloops, they may be further examined as to their Qualifications to take charge of Line of Battle Ships, but in this examination it will be required that they pass for the largest description of first Rates. In the event of an Officer serving abroad as Acting Master of a Line of Battle Ship, the time so served may reckon as part of the aforesaid three years.

The Class of Ship, of which Officers are capable of taking charge as Pilots, will be stated in the Certificate granted to them by the Trinity House.

All Officers desirous of being examined in Pilotage at the Trinity House, either for the rank of Second Master, or as to their qualifications to serve as Masters of Frigates, or of Line of Battle Ships, should present themselves at the Admiralty, bringing with them a Certificate of their birth, and also their original Certificates for the entire period they have been employed in her Majesty's Service, or in Merchant Ships, in each of which Certificates, the word Sobriety must be included. Similar Certificates must be produced by Officers presenting themselves to pass in Navigation at the Royal Naval College.

By command of their Lordships,

To all Flag Officers, Captains, and Commanding Officers,

of Her Majesty's Ships and Vessels.

J. PARKER.

METEOROLOGICAL REGISTER.

Kept at Croom's Hill, Greenwich, by Mr. W. Rogerson, Royal Observatory. From the 21st of November, to the 20th of December, 1849.