That this would not be a sufficient excuse for the defective cx planation given in the N.A., appears evident from the fact that in the treatises on Navigation by Norie, Raper, and others, the same mistake is made when the passage happens a.m. at ship. Although the N.A. condescends to give rules for such simple operations as converting civil time into astronomical time, and vice versa, also ship time into Greenwich time; all of which are given in every treatise on navigation, there is not the least intimation given in the directions for finding the meridian passage of the moon or a planet to guard the calculator against making the mistake above referred to. And if such men as Norie, Raper, and others, have been misled, what can be expected of practical men ! 4th.-Notation of Time. In reckoning time we have civil, astronomical, and nautical time. It might therefore have been presumed that mathematicians would have devised and the Nautical Almanac explained some notation whereby each particular mode of reckoning would at once be recognized, or at least confusion prevented. Instead of which we have the following various ways of expressing such instant of time as 4 o'clock in the morning of the first of January, 1861 1st.-1161 at 4h. a.m. Civil. 2nd. Jan. 1, 1861, at 4h. a.m. Astronomical. 6th.-1860, Dec. 31st, at 16h. 7th.-16h. on Dec. 31st, 1860. 8th.-1860, Dec. 31d. 16h, 9th.-16h. after mean noon of Dec. 31st, 1860. 10th.-1860, Dec. 31 st. 16. In the Nautical Almanac nearly all the above notations are used. The last expression certainly is not used, and it happens to be the only correct one for the astronomical time as explained in the N.A. If Horace's painter painted a horse so badly that he thought it necessary to write under his picture-" This is a horse," surely the calculator who uses such notations as the above ought to write after each "This is civil time," or "This is astronomical time," as the case may be. 5th.-Date of an Observation. In the N.A. questions are given for civil time, for astronomical time, and for time which may be taken either as civil or astronomical. Nautical men always note an observation as on the proper civil date. It is therefore improper to tell a nautical man that an observation was taken on Jan. 15th, (at same time meaning the astronomical date, without saying so,) when such observation was actually taken on Jan. 16th, a.m., civil time. Such vagueness in expression leads to inex tricable confusion. 6th.-Correcting the Sun's Declination. N.A. p. 512,-The sun's declination is here directed to be corrected for Greenwich time by means of the change in 24 hours: it is surprising that no reference is made as to the use of the diff. for 1 hour. Although the example is given for South declination, the rule for applying the correction is with propriety given the same as for North declination. The explanation is therefore intelligible to nautical men, but what follows is not. 7th.-Correcting the Derlination of a Planet or Fixed Star. N.A. pp, 528, 529.-If the explanation has been written by a Scotsman, we must infer that he is fond of "hotch potch," for we have here a jumbled mixture of algebraical notation and arithmetical language. For the planets, algebraical notation is used; for the fixed stars, the explanation is expressed in a compound of algebraical notation and arithmetical language: being an attempt to speak at the same time to mathematicians or astronomers and arithmeticians or nautical men. The writer of this explanation should have recollected that a practical man uses for ada and for subtract; but when he is told that + denotes subtract and ddd, he looks upon this with much the same surprise as if he were told that he must take black as white and white as black. 8th. Variation for 1 Hour of Longitude. N.A. p. 528.-The explanation directs for the example which is given for East longitude to take 22"-4 as the variation of the declination for Nov. 23: this should have been the mean of the variations for Nov. 23 and Nov. 21, or 20"7. Again, for Nov. 24 the variation is stated to be 24"-O, whereas it should have been taken for Nov. 23 or 22"-4. Opposite any given day the diff. for 1 hour in the case of the sun, and the var. of declin. in 1 hour of long. in the case of a planet, are given as from that day towards the following day. Consequently, as in correcting for East longitude, the Greenwich time is between the given day and yesterday, we must take the hourly diff. or var. opposite yesterday. If a young man passing his examination as Second Mate at the Marine Board used the above method as given in the Nautical Almanac, for working a meridian altitude of the sun observed in East longitude, he would almost to a certainty be rejected. Notation of Time. Having shown that great confusion arises from not properly noting time according to the different modes of reckoning; we trust that the Astronomer Royal, as our first mathematician and astronomer, will condescend to give the subject his consideration, and will establish some notation which will effectually remove all ambiguity. In the mean time we beg to offer the following suggestions :— Take for example the instant of time which is called 4 o'clock in the afternoon of the first of January, we would propose to note it as 1st.-Jan. 1st 4h. p.m., civil time. 2nd.—Jan. 1, 4h., astronomical time. 3rd.-Jan. 1d. 4h., nautical time, or the time which should always be used in nautical calculations. The 1st notation to be used in practical questions for nantical men. The 2nd when using the Nautical Almanac. The 3rd when calculating with time in nautical problems. English astronomers would certainly be obliged to note it as Od. 4h. To remove this anomaly M. Bessel proposed to make the epoch of the astronomical tables, instead of noon of Jan. 1st, civil time, noon of Dec. 31st (last year); that is, the commencement of the year according to nautical reckoning. So that Jan. 1 astronomical reckoning would be really Jan. 1d. (January 1 day complete), the same as it is in nautical time. By M. Bessel's proposal, the astronomical and nautical days would be assimilated. But whether astronomers choose to change or retain the epoch of their tables, we trust they will not perplex nautical men in their Nautical Almanac by saying that Jan. I is Jan. 1d. astronomical time, when it is Jan. 1st or Od. astronomical time, but Jan. 1d. nautical time. We may be allowed here to remark that Mr. Bell, the nautical examiner London Marine Board, has with great propriety adopted a notation similar to what we suggest, so that no one can be in any doubt whether he means civil or astronomical time (or rather nautical time). But as candidates for examination at the Marine Board have been for years studying the Nautical Almanac and the usual epitomes on navigation, they cannot be expected at once to adopt a correct mode of notation: consequently, many hundreds of candidates for certificates of competency have been rejected entirely from being misled by the defective explanations given in the standard works referred to. Transits. The errors committed in taking out the time of transits arises from the calculator using the Greenwich instead of the ship's astronomical date, being led to do so by what is said in the Nautical Almanac. The same remark applies to the time of high water. Planets and Fixed Stars. The remedy for the defects complained of is easily seen from our remarks. We trust that sufficient has been said to induce the Astronomer Royal to lend his powerful assistance towards having the explanation in the Nautical Almanac completely remodelled, and then epitomes on navigation would follow the example of such high authority. A great benefit would then be conferred on practical men as I have known many nautical men who have neglected planetary observations owing to their being perplexed by the mixture of algebraical notation and arithmetical language used in the N.A. IRON SHIPS AND THEIR DOCKS. Whatever may be the result of experiments at present going forward as to the adoption of wood or iron, or a combination of both, for the construction of our ships of war, one effect of them is before us in the appearance of the Warrior and Black Prince ;-vessels of such enormous dimensions as far to surpass in size any previously built for war purposes, and requiring docks and basins for their equipment which as yet are not prepared. It is well known that at the present time the subject of wooden and iron ships is dividing our attention with that of the Armstrong and other guns to be used in and against them. That the ships of the old school are fast becoming only a type of our men-of-war is no longer a matter of doubt; and it is no less certain that a class of huge iron floating-batteries is coming forward to take their place in the navies of Europe. It is not, however, our present purpose to discuss the question of wood or iron for the construction of ships, or the convertability of those already afloat by such alterations as they are now undergoing, and of which they may be quite capable. The dock and basin accommodation for the iron ships that we already have and are to have is the subject before us, and it certainly is one of very grave importance. We are not at all indifferent to the necessity of cautiously abstaining from unseemly criticism of official action; and are equally aware that a flippant discussion of such subjects may not only prove extremely embarrassing to the government, but may have a mischievous tendency of unnecessarily directing attention to weak points, which are better provided against by a watchful executive. In the present instance, however, we are released in a great measure from the possibility of a charge of indiscretion, inasmuch as a committee is already formed which must take the whole question into its consideration in a public manner We allude to the committee on the improvement and extension of Chatham Dockyard. Considering, therefore that this journal is specially adapted, from its unpolitical character, to discuss this matter with the professional world, we shall at once proceed with the few observations which we have to make on this great nautical question. Perhaps the best mode of illustrating the paramount necessity of considering the resources of Great Britain in dock and basin accommodation for an iron fleet, is to assume that we are suddenly plunged into a war, and as suddenly brought in contact with an enemy's fleet on their way to our own shores. We may justly presume, when we look around us and perceive the gigantic efforts that are being made by a powerful neighbour, that in any future maritime war he will not be far behind us in naval strength, that in any collision which may take place, force will be pretty equally balanced,-that the conflict will be short and sharp,and that the advantage must remain with that side the ships of which can the most readily and most efficiently re-appear in a prepared condition for a renewal of the combat! If we desire to view this great national problem dispassionately and without prejudice or over-confidence, it is obvious that we must not overlook the important fact that we have entered on a new era in naval affairs, that a complete revolution has taken place in the great art of naval architecture, affecting thereby the main source of England's strength-her navy. Now, whatever mistakes we may have made in this oft disputed subject, however ill-formed may have been our models of former years, however we may have borrowed, copied, converted, and even followed wholesale the productions of our neighbours on all sides to make up for any deficiencies in our specimens of naval architecture,— our seamen have managed to find pre-eminence. With their superior nautical skill they have fought the battles of their country in every sea; and the result of those battles we all know has contributed to place England in her present exalted position among the nations of the world. Her senators have followed up the principles which have been the springs of her maritime power,-they prepared and gradually completed her naval arsenals for that navy in which they well knew their safety consisted, because with that power predominant no enemy could land on her shores. But the scene is changed. Another and more formidable class of ship has appeared, for which those mag. nificent arsenals are totally unfitted. They answered well enough for our Victorys, Caledonias, and Temeraires of old, but for an iron Warrior or Black Prince not only are they unfit, but our principal arsenals of Portsmouth and Devonport cannot give them dock room; nor can such ships as these even enter them at all times. England, then, is now in this extraordinary and novel position, viz., that of having no dock or basin for her ships which are already afloat and are hereafter to form the principal models of her navy-the main sinews, indeed, of her maritime strength. Now, what is the duty of England in this state of things. Is it not to look at the fact in its fullest extent, to see the evil which will assuredly arise from it, and to set to work and repair it effectually at once at any cost? Or is she to shut her eyes to it, to let things alone, |