October 22, 1891] 



NATURE 



593 



Travels," stated that some corrections of values given in vol. i. 

 are required in consequence of the identification, made too late 

 for their correction, of the value of Tavernier's carat, but the 

 present discussion as to the Koh-i-Nur is quite independent of 

 that. 



With regard to the mutilated condition of the Koh-i-Nur, I 

 have nothing to add ; the statement as to its condition, quoted by 

 me, and the figures and models of the stone appear to be suffi- 

 cient proof that portions had been removed by cleavage, which 

 would account for the difference between its weight and the 

 Mogul, as described by Tavernier, and I still retain that 

 opinion. 



It is not of the least importance as regards the main question, 

 whether my suggestion should prove correct or not, that if Babar's 

 stone has survived it may be identical with the Darya-i-Nur, to 

 which Malcolm attributed a weight of i86 carats. Prof Maske- 

 iyne, upon a system of calculation which I cannot admit as 

 applicable to the case, as we do not know the thicknesses of the 

 stones which he compares, gives to the Darya-i-Nur an estimated 

 weight of 210 carats. For the present, therefore, I prefer 

 Malcolm's definite statement to Prof Maskelyne's theory about 

 the attributed weight being the "echo associated with the Koh- 

 i-Nur." 



I shall have something to say about the Golconda table dia- 

 mond, and about a great many other diamonds and other precious 

 stones too, on a future occasion. In that work I shall be as careful 

 to give, as I have hitherto been, chapter and verse for every 

 statement of fact quoted, and I shall trust the histories so 

 supported will find acceptance from those who care to in- 

 vestigate the evidence in favour of the conclusions connected 

 therewith. 



I am not quite sure that I appreciate the full force of the phrase 

 " verisimilitude of a true history" — the last words of Prof. Maske- 

 lyne's article — but of this I am certain, that if ever I should see 

 a history of the Koh-i-Nur following the lines of that article, 

 I shall feel bound to make another and special " incursion " into 

 the subject in defence of Tavernier if not of myself. 



Dublin, October 1 2. V. Ball. 



THE NAUTICAL ALMANAC. 



T T has been known for some little time that Dr. John 

 ^ Russell Hind, F.R.S., who for many years past has 

 been responsible for the production of the national ephe- 

 meris, would soon seek that retirement to which his long 

 services and his distinguished career entitle him. At the 

 end of the year, he will relinquish the office of Superin- 

 tendent of the " Nautical Alamanac," and the good wishes 

 and kindly sympathy of the astronomers of many nations 

 will follow him in the retirement he is seeking. 



His successor has been appointed, and in Mr. A. M. 

 W, Downing we have not the slightest doubt that the 

 Admiralty have made a happy selection, and that under 

 his auspices the high character and reputation of the 

 " Nautical Almanac " will be fully maintained. Mr. Down- 

 ing has long been associated with meridian astronomy 

 in its best traditions ; and in his position of greater respon- 

 sibility and greater freedom we entertain the hope that his 

 astronomical reputation will be fully maintained and 

 extended. He may be said to enter on his office 

 at a time when the " Nautical Almanac " is on its trial. 

 The arrangement of the book, and the information it con- 

 veys, were practically settled by a Committee some sixty 

 years since. How efficiently that Committee performed 

 its task is shown by the fact that so little alteration has 

 been needed for so long a period. But the outcry for 

 change has gone forth : new committees are deliberating 

 and reporting, and it will be among Mr. Dovvning's first 

 duties to give shape, alike to the suggestions of irrespon- 

 sible authorities, as well as to incorporate the recommen- 

 dations of recognized committees in a new and improved 

 " Nautical Almanac." 



One great difficulty which has to be encountered, and 

 of which it is not easy to see the proper solution, is due 



NO. II 47, VOL. 44] 



to the fact that the " Nautical Almanac " seeks to supply the 

 wants of two very different classes of persons— namely, 

 astronomers properly so called, and nautical men. The 

 former demand very considerable detail in the exhibition 

 of the several computations, the latter are satisfied with 

 a very few final results. The former class is a small 

 one, and a very moderate edition would satisfy their 

 demands. The latter class is a very large one, and 

 necessitates the printing, it may be, of thirty or forty 

 thousand copies. The first question therefore, it seems, 

 which must claim the attention of any Committee, or of 

 any Superintendent, is, whether it be desirable to sepa- 

 rate the " Nautical Almanac '' into two, or it may be more, 

 sections — one circulating among astronomers, the other 

 among mariners. Private enterprise, anxious to minister to 

 the wants of a rapidly increasing mercantile marine, has 

 long supplemented the "Nautical Almanac" with a smaller 

 and pirated edition, valuable to sailors, but detrimental to 

 the circulation of what may be considered the legitimate 

 ephemeris. Woulditnotbebetter if the Admiralty couldsee 

 their way to publish an ephemeris with other nautical infor- 

 mation, entirely for the use of the marine ? Such a course 

 is followed by the Governments of other countries. The 

 German Government publish at Berlin a compact 

 " Nautisches Jahrbuch," admirably adapted for naval 

 purposes. This example is followed in Austria and in 

 America, and we believe that the sale of our "Almanac" to 

 the naval men of those countries has fallen off in the 

 last years, or at least has not kept pace with the increase 

 of foreign tonnage. 



Such questions are of importance, as concerning not 

 only the financial position of the work, but its influence 

 in our own and foreign navies. There are, however, 

 others touching the scientific and purely astronomical 

 side of the compilation. Such, for instance, is the vexed 

 question of the introduction of empirical terms in the 

 final positions of the moon. Astronomical purists will 

 maintain that the position of the moon should be that 

 assigned by a purely gravitational theory, to facilitate the 

 comparison of that theory with observation. Others 

 demand that the place of the moon should coincide; aa 

 accurately as possible, with observation ; and looking at 

 the large portion of the " Nautical Almanac " devoted to 

 " lunar distances," it would seem (if this section is ever 

 used) that it is desirable that the distances given should 

 represent observed facts. After a naval man has been at 

 the trouble of observing and reducing a lunar distance, to 

 ask him to apply a correction for the error of moon's 

 place seems wanton and irritating. And if the amount of 

 the empirical correction is clearly ascertainable, it can be 

 easily removed before instituting a comparison between 

 observation and that theory from which the moon's place 

 has been computed. But to satisfy the demands of both 

 classes of astronomers will try the tact and ability of the 

 new Superintendent to the utmost. 



The section devoted to the apparent places of the stars 

 has also been submitted to considerable criticism. No 

 doubt here enlargement is needed, and possibly im- 

 proved places of the stars, particularly of circumpolar 

 stars in the southern hemisphere, are much wanted. 

 But on this point the new Superintendent is himself a 

 weighty authority. He has worked much and success- 

 fully in the determination and removal of systematic 

 differences from star catalogues, and their reduction to 

 known and recognized standards. So that, under his 

 influence, we may hope that this section will take and 

 maintain a foremost position. 



Mr. Downing has undertaken a very important duty, of 

 great national importance, at a very critical period. We 

 fully believe that he will grapple with this task success- 

 fully, and that, in his efforts to improve our ephemeris, he 

 will have the assistance and support of all classes of 

 astronomers. 



