Jan. 15, 1874] 



NA TURE 



Science, as the manual and guide of practical astronomy, 

 wherever it may be cultivated." 



But if the English are impartial and generous towards 

 strangers, they could not bear to be for any time inferior 

 in the various services which touch upon their interests. 

 The sub-committee* charged with preparing the plan for 

 reorganising the Nauiicai Aliia)iai\ presented its report 

 to the Society at the meeting of November 19, 1S30, a 

 report which was adopted by the Council and immediately 

 approved by the Admiralty. The results of this beneficial 

 agitation were of immense value to astronomy and navi- 

 gation, and the improvements introduced were such that, 

 even from an astronomical point of view, the Nautical Al- 

 vianac easily surpassed the Jahrhiicli, and from a mari- 

 time stand-point it has not yet been equalled. 



First of all, it should be stated that the Commissioners 

 laid down as an absolute rule, a rule which has ever since 

 been scrupulously followed, that the Nautical Almanac 

 ought to appear four years in advance of the year 

 for which it is calculated. Moreover, the direction ol the 

 Nautical Almanac, W'hWe. continuing under the jurisdic- 

 tion of the Admiralty, was entrusted thenceforth to a 

 single person, the Superintendent of the Nautical Almanac 

 Office. 



The Nautical Almanac has been from that time in 

 reality a special scientific institution, having its offices 

 and its library established in a separate building. The 

 salary of the superintendent was fixed at 500/., and the 

 annual parliamentary allowance was made amply suffi- 

 cient to permit of the employment of calculators nume- 

 rous enough to insure the gi'eatest possible accuracy in 

 the results. The first superintendent of the Nautical 

 Almanac ofSce was Lieut. S. Stratford, well known for 

 the part which he took in the publication of Baily's 

 "Zodiacal Catalogue." 



The first volume of the new almanac, the Nautical 

 Almanac and Astronomical Ephcmeris for the Year 1S34, 

 appeared in July 1833. It embodied all the reforms 

 which we have already mentioned ; it would therefore be 

 useless to indicate its contents in detail. We shall con- 

 tent ourselves with adding, that all the calculations rela- 

 tive to the principal planets were made under the direction 

 of SchuiTiocher of Altona, and those relating to the tele- 

 scopic planets by the celebrated Encke. Moreover, as 

 it is absolutely essential that a single list of stars of the 

 moon should suffice navigators of all nations, the Royal 

 Society came to an understanding with Encke oir this 

 subject. The stars of the moon (" moon's culminating 

 stars ' ), ceased from that time to figure in the Jahrhuch, 

 and the Najttical Almanac obtained the monopoly of this 

 useful publication, a monopoly which it has since pre- 

 served. 



The tables employed were nearly the same in the 

 Jahrbuch and the Nautical Almanac. For the sun 

 there were the new tables of Carlini, with the corrections 

 of Encke and Bessel ; for the moon the tables of Burck- 

 hardt ; for Mercury, Venus, and Mars, the tables of 

 Von Linderau, with the corrections of Schumacher ; for 

 Jupiter, Saturn, and Uranus, the tables of Bouvart ; for 

 the satellites of Jupiter, the new tables of Delambre, witli 

 the corrections of Jenkins and Woolhouse. 



XI. The " Connaissance tics Temps" since 1832. 



While this great work of reform and renovation was 

 being carried on, the Bureau des Longitudes of France did 

 not remain inactive. "The Bureau have recently appointed 

 a commission, chosen from its own members, to examine 

 some modifications which it would be expedient to intro- 

 duce into the Connaissance ties Temps. In considering 

 this object, the commission has not lost sight of the fact 

 that it is dealing with a work specially designed for 

 mariners, with which they have been familiar for many 



* Composed of Sir James South, president, F. Baily, reporter, C. Bab- 

 bage, C.ipt. F. Beaufort, J, F. W. Herscliel, J. Pond, Rev. Dr. Robinson, 

 Lieut. S. Strafford, W. Slruve. 



years, and of which it was, above all, desirable that the 

 price should not be increased."* 



On the one side maritime necessities required that the 

 Connaissance des Temps sliould, like the Nautical Al- 

 manac, appear four years in advance ; although for long 

 it has been published on an average only a year and 

 a half before its date, being a delay of two years and a 

 half On the other side, the ephemeris then published 

 by the Connaissance ties Temps was evidently insufticient 

 for French astronomers ; the following modifications were 

 therefore adopted, and were completely embodied in the 

 Connaissance des Temps for 1835. 



The mean time was the only time used (although astro- 

 nomers needed the equatorial co-ordinates of the sun for 

 true noon) ; the co-ordinates expressed in time were given 

 at o=' 01, and those in arc, o"- i ; the latitude and longi- 

 tude of the moon were given for midnight and noon of 

 each day ; to the lunar distance were added those of the 

 planets Venus, Mars, Jupiter, and Saturn ; lastly were 

 given for every tenth day, the apparent positions of sixty- 

 four fundamental stars (the Nautical Almanac g2.\ii 100). 



On the other hand, as it came to be seen that the solar 

 tables of Delambre were defective, the Bureau invited 

 Savary to amend them, but all he did was to remedy 

 errors here and there by means of the corrections of 

 Bessel. Moreover, Delambre's tables of satellites having 

 been discontinued till 1S40, Damoiseau was ordered to 

 continue them. But all this was so insufticient, that the 

 Connaissance des Temps could not be more serviceable 

 to astronomers. 



Thus, in 1838, the positions of the planets, which were 

 given until then for every tenth day, were calculated to 

 a minute of time and of arc ; every third day for Mer- 

 cury ; every sixth day for Venus and Mars ; every seventh 

 day for Jupiter ; every tenth day for Saturn ; every fif- 

 teenth day for Uranus ; and the value of the radius vector 

 was added to the other elements. This was very far 

 behind the Nautical Almanac, which gave the positions 

 for every day to 0^01 and o"'l. 



In 1849, the number of fundamental stars whose appa- 

 rent positions were given was carried to 115, and the 

 apparent position of a Ursa; Minoris, was given for every 

 day in the year. The Nautical Almanac had given those 

 of a and 8 Ursffi Minoris for 1834. 



In 1854, M. Mathieu was specially appointed to the 

 editorship of the Connaissance ties Temps. Very soon 

 after he entered upon his duties he had to sustain an 

 attack which recalls that already referred to between 

 Young, Baily, and Sir James South. For some years a 

 sharp controversy was maintained between M. Mathieu 

 and M. Leverrier, and at length the Connaissance des 

 Temps oi 1862 published for the first time the positions 

 of the moon for every hour, with the differences for 10 

 minutes. " This innovation," the learned editor said, "is 

 valuable to mariners ; it simplifies the calculations of in- 

 terpolation, and now sailors will be able to make use of 

 the ephemeris of the moon with as much ease as that of 

 the sun." The calculations of the moon are, moreover, 

 made according to the tables of M. Hansen,f which the 

 Nautical Almanac ha-d employed since 1S58. Lastly, in 

 the same year, are given the positions of 6 Urste Minoris 

 for every day. 



In the following year the ephemeris of the planets was 

 improved, and there were given for every day the helio- 

 centric and geocentric positions at mean noon of Mercury, 

 Venus, Mars, Jupiter, and Saturn ; for Uranus and Nep- 

 tune the positions were calculated only for every fourth 

 day. This was in imitation of a modification suggested 

 by Mr. (now Sir G. B.) Airy to the superintendent of the 

 Nautical Almanac, and applied by him from 1857 

 {Almanac for 1861). But, since 1839, besides the pre- 



* Advertisement of the Coitnntssance des Temfis for 1832. 



■t "Taijicsof the moon constructed according to the Newtonian law ol 

 Universal Gravitation," by P. A. Hansen, Director of the Ducal Observatory 

 of Gotha. (Printed at the expense of the British Government, 1857.) 



