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OF THE SCIENTIFIC ADVISERS. Whether it was feared by the party who govern the Royal Society, that its Council would not be sufficiently tractable, or whether the Admiralty determined to render that body completely subservient to them, or whether both these motives concurred, I know not; but, low as has been for years its character for independence, and fallen as the Royal Society is in public estimation, it could scarcely be prepared for this last insult. In order to inform the public and the Society, (for I believe the fact is known to few of the members,) it will be necessary to trace the history of those circumstances which led to the institution of the offices of Scientific Advisers, from the time of the existence of the late Board of Longitude. That body consisted, according to the act of parliament which established it, of certain official members, who usually possessed no knowledge of the subjects it was the duty of the Board to discuss—of certain professors of the two universities, and the Astronomer Royal, who had some knowledge, and who were paid 100L. a year for their attendance;—of three honorary members of the Royal Society, who combined the qualifications of the two preceding classes; and, lastly, of “three other persons,” named Resident Commissioners, who were supposed to be “WELL versed in the sciences of mathematics, astronomy, or navigation,” and who were paid a hundred a year to do the work of the Board. The first three classes were permanent members, but the “three other persons” only held the appointment for one year, and were renewable at the pleasure of the Admiralty. This Board was abolished by another act of parliament, on the ground that it was useless. Shortly after, the Secretary of the Admiralty communicated to the Council of the Royal Society, the copy of an Order in Council: Admiralty office, November 1, 1828. Sir, I am commanded by my Lords Commissioners of the Admiralty, to send herewith, for the information of the President and Council of the Royal Society, a copy of His Majesty’s Order in Council of the 27th of last month; explaining that the salaries heretofore allowed to the Resident Commissioners of the Board of Longitude, and to the Superintendents of the Nautical Almanac, and of Chronometers, shall be continued to them, notwithstanding the abolition of the Board of Longitude. And I am to acquaint you, that the necessary orders have been given to the Navy Board for the payment of the said salaries. I am, Sir, John Barrow. At the court at WINDSOR, Present, Whereas, there was this day read at the Board a Memorial from the Right Honourable the Lords Commissioners of the Admiralty, dated 4th of this instant, in the words following, viz.— Whereas, by an Act of the 58th of his late Majesty’s reign, cap. 20, instituted “An Act for the more effectually discovering the Longitude at sea, and encouraging attempts to find a Northern passage between the Atlantic and Pacific Oceans, and to approach the North Pole,” three persons well versed in the sciences of Mathematics, Astronomy, or Navigation, were appointed as a Resident Committee of the Board of Commissioners for discovery of the Longitude at sea, and a Superintendent of the Nautical Almanac and of Chronometers was also appointed, with such salaries for the execution of those services as his Majesty might, by any Order in Council, be pleased to direct; and, whereas, your Majesty was in consequence, by your Order in Council of the 27th of May, 1828, most graciously pleased to direct, that the three said Resident Commissioners should be paid at the rate of 100L. a year each; and by your further Order in Council, of the 31st October, 1818, that the Superintendent of the Nautical Almanac should be allowed a salary of 300L., and the Superintendent of Chronometers 100L. a year; and, whereas, the act above mentioned has been repealed, and the Board of Longitude abolished; and doubts have therefore arisen, whether the said Orders in Council shall still continue in force; and whereas it is expedient that the said appointments be continued; We beg leave most humbly to submit to your Majesty, that your Majesty may be graciously pleased, by your Order in Council, to direct that the said offices of Superintendent of the Nautical Almanac, and of Superintendent of Chronometers; and also the three persons before-mentioned as a Resident Committee, to advise with the Commissioners for executing the Office of Lord High Admiral, on all questions of discoveries, inventions, calculations, and other scientific subjects, be continued, with the same duties and salaries, and under the same regulations as heretofore; and further beg most humbly to propose, that such three persons to form the Resident Committee, be chosen annually by the Commissioners for executing the office of Lord High Admiral, from among the Council of the Royal Society. His Majesty, having taken the said Memorial into consideration, was pleased, by and with the advice of his Privy Council, to approve thereof and the Right Honourable the Lords Commissioners of the Admiralty are to give the necessary directions herein accordingly. (Signed) James HILLER. Thus, it appeared that the Admiralty were to choose three persons from among the Council of the Royal Society, who were to have a hundred a year each during the pleasure of the Admiralty. Such an open attack on the independence of the Council could not escape the remarks of some of the members, and a kind of mild remonstrance was made, in which the real ground of complaint was omitted. Minute of council of the
royal society. Resolved, That in acknowledging the communication of the Lords Commissioners of the Admiralty, made to the Council of the Royal Society, on the 20th of November last, it be represented to them that inconvenience may arise from the plan therein specified, from the circumstance of all the members of the Council being annually elected by the Society at large; and that body being consequently subject to continual changes from year to year. This was answered by the following letter from the Secretary of the Admiralty : Admiralty office, Dec. 30, 1828. Sir, Having submitted to my Lords Commissioners of the Admiralty your Letter of the 18th instant, subjoining an extract from the Minutes of the proceedings of the Council of the Royal Society, arising out of the communication made to them by their Lordships, on the subject of his Majesty’s Order in Council, of the fifth of October last, I have their Lordships’ command to acquaint you, for the information of the President and Council, and with reference to what they have stated as to the inconvenience which may arise from the intended plan of limiting their Lordships’ choice of members of the Resident Committee of Scientific Advice to the Council of the Royal Society, that their Lordships were induced to recommend this plan to his Majesty as a mark of respect to the Society, and as a pledge to the public of the qualification of the persons chosen. Nor did their Lordships apprehend any inconvenience from the circumstance stated in the Minute of the Council, of the Members being annually elected, as the Resident Committee is also annually appointed; and, in point of fact, no practical inconvenience has been felt during the ten years that the Committee has been in existence, as four of the distinguished gentlemen whom their Lordships have successively appointed to this office, have continued during the whole period to be members of the Council; and if any such difficulty or inconvenience should hereafter arise, their Lordships will be ready to take proper measures for remedying it. Their Lordships’ intention therefore is, to propose to Captain Kater and Mr. Herschel, to continue to fill this office; and to Dr.Young, who had resigned it, on receiving the appointment of Secretary to the late Board of Longitude, to be appointed. I am, Sir, Your obedient servant, The representation made by the Council was not calculated to produce much effect; but the Secretary of the Admiralty, who knew well the stuff of which Councils of the Royal Society are composed, might have spared the bitter irony of making their Lordships say, that they recommended this plan “As A mark of respect to the society,” and “As A pledge to the public of the qualifications of the persons chosen,” whilst he delicately hints to them their dependent situation, by observing, that the “Resident committee is also annually appointed.” The Secretary knew that, practically speaking, it had been the custom for years for the President of the Royal Society to nominate the Council, and consequently he knew that every scientific adviser must first be indebted to the President for being qualified to advise, and then to the Admiralty for deriving profit from his counsel. Thus then their Lordships, as a “Mark of respect for the society” confirm the dependence of the Council on the President, by making his nomination a qualification for place, and establish a new dependence of the same Council on themselves, by giving a hundred pounds each year to such three members of that Council as they may select. “The pledge” they offer “To the public, of the qualifications of the persons chosen,” is, that Mr. Davies Gilbert had previously thought they would do for his Council. What the Society, when they are acquainted with it, may think of this mark of respect, or what value the public may put upon this pledge, must be left to themselves to express. In looking over the list of officers and Council of the Royal Society the weakest perhaps (for purposes of science) which was ever made, a consolation arises from the possibility of some of those who were placed there by way of compliment, occasionally attending. In that contracted field Lord Melville’s penetration may not be uselessly employed; and the soldier who presides over our colonies may judge whether the principles which pervade it are open and liberal as his own. The inconvenience to the public service from such an arrangement is, that the number out of which the advisers are selected must, in any case, be very small; and may, from several circumstances, be considerably reduced. In a council fairly selected, to judge of the merits of the various subjects likely to be brought under the consideration of the Society, anatomy, chemistry, and the different branches of natural history, will share with the numerous departments of physical science, in claiming to be represented by persons competently skilled in those subjects. These claims being satisfied, but few places will be left to fill up with mathematicians, astronomers, and persons conversant with nautical astronomy. Let us look at the present Council. Is there a single mathematician amongst them, if we except Mr Barlow, whose deservedly high reputation rests chiefly on his physical and experimental inquiries, and whom the President and the Admiralty have clearly shown they do not look upon as a mathematician, by not appointing him an adviser? Small as the number of those persons on the Council, who are conversant with the three subjects named in the Act of Parliament, must usually be, it may be still further diminished. The President, when he forms his Council, may decline naming those members who are most fit for such situations. Or, on the other hand, some of those members who are best qualified for them, from their knowledge, may decline the honour of being the nominees of Mr. Gilbert, as Vice Presidents, Treasurers, or Councillors, and thus lending their names to support a system of which they disapprove. Whether the first of these causes has ever operated can be best explained by those gentlemen who have been on the Council. The refusals are, notwithstanding the President’s taciturnity on the subject, better known than he is willing that they should be. Having discussed the general policy of the measure, with reference both to the Society and to the public, and without the slightest reference to the individuals who may have refused or accepted those situations, I shall now examine the propriety of the appointments that have been made. Doubtless the gentlemen who now hold those situations either have never considered the influence such a mode of selection would have on the character of the Council; or, having considered it, they must have arrived at a different conclusion from mine. There may, however, be arguments which I have overlooked, and a discussion of them must ultimately lead to truth: but I confess that it appears to me the objections which have been stated rest on principles of human nature, too deeply seated to be easily removed. That I am not singular in the view I have taken of this subject, appears from several circumstances. A question was asked respecting these appointments at the Anniversary before the last; and, from the nature of the answer, many of the members of the Society have been led to believe the objections have been removed. Several Fellows of the Society, who knew these facts, thought it inexpedient ever to vote for placing any gentleman on the Council who had accepted these situations; and, having myself the same view of the case, I applied to the Council to be informed of the names of the present Scientific Advisers. But although they remonstrated against the principle, they replied that they had “No COGNIZANCE” of the fact. The two first members of the Council, Mr. Herschel and Captain Kater, who were so appointed, and who had previously been Resident Commissioners under the Act, immediately refused the situations. Dr. Young became one of the Advisers; and Captain Sabine and Mr. Faraday were appointed by the Admiralty as the two remaining ones. Of Dr. Young, who died shortly after, I shall only observe that he possessed knowledge which qualified him for the situation. Whether those who at present fill these offices can be said to belong to that class of persons which the Order in Council and the Act of Parliament point out, is a matter on which doubt may reasonably be entertained. The Order in Council speaks of these three persons as being the same, and having the “SAME duties” as those mentioned in the Act; and it recites the words of the Act, that they shall be persons “WELL versed in the sciences of mathematics astronomy, and navigation.” Of the fitness of the gentlemen who now hold those situations to pronounce judgment on mathematical questions, the public will be better able to form an opinion when they shall have communicated to the world any of their own mathematical inquiries. Although it is the practice to consider that acceptance of office is alone necessary to qualify a man for a statesman, a similar doctrine has not yet prevailed in the world of science. One of these gentlemen, who has established his reputation as a chemist, stands in the same predicament with respect to the other two sciences. It remains then to consider Captain Sabine’s claims, which must rest on his skill in “PRACTICAL astronomy and navigation,”— a claim which can only be allowed when the scientific world are set at rest respecting the extraordinary nature of those observations contained in his work on the Pendulum. That volume, printed under the authority of the Board of Longitude, excited at its appearance considerable attention. The circumstance of the Government providing instruments and means of transport for the purpose of these inquiries, placed at Captain Sabine’s disposal means superior to those which amateurs can generally afford, whilst the industry with which he availed himself of these opportunities, enabled him to bring home multitudes of observations from situations rarely visited with such instruments, and for such purposes. The remarkable agreement with each other, which was found to exist amongst each class of observations, was as unexpected by those most conversant with the respective processes, as it was creditable to one who had devoted but a few years to the subject, and who, in the course of those voyages, used some of the instruments for the first time in his life. This accordance amongst the results was such, that naval officers of the greatest experience, confessed themselves unable to take such lunars; whilst other observers, long versed in the use of the transit instrument, avowed their inability to take such transits. Those who were conversant with pendulums, were at a loss how to make, even under more favourable circumstances, similarly concordant observations. The same opinion prevailed on the continent as well as in England. On whatever subject Captain Sabine touched, the observations he published seemed by their accuracy to leave former observers at a distance. The methods of using the instruments scarcely differed in any important point from those before adopted; and, but for a fortunate discovery, which I shall presently relate, the world must have concluded that Captain Sabine possessed some keenness of vision, or acuteness of touch, which it would be hopeless for any to expect to rival. The Council of the Royal Society spared no pains to stamp the accuracy of these observations with their testimony. They seem to have thrust Captain Sabine’s name perpetually on their minutes, and in a manner which must have been almost distressing: they recommend him in a letter to the Admiralty, then in another to the Ordnance; and several of the same persons, in their other capacity, as members of the Board of Longitude, after voting him a thousand pounds for these observations, are said to have again recommended him to the Master-General of the Ordnance. That an officer, commencing his scientific career, should be misled by such praises, was both natural and pardonable; but that the Council of the Royal Society should adopt their opinion so heedlessly, and maintain it so pertinaciously, was as cruel to the observer as it was injurious to the interests of science. It might have been imagined that such praises, together with the Copley medal, presented to Captain Sabine by the Royal Society, and the medal of Lalande, given to him by the Institute of France, had arisen from such a complete investigation of his observations, as should place them beyond the reach even of criticism. But, alas! the Royal Society may write, and nobody will attend; its medals have lost their lustre; and even the Institute of France may find that theirs cannot confer immortality. That learned body is in the habit of making most interesting and profound reports on any memoirs communicated to it; nothing escapes the penetration of their committees appointed for such purposes. Surely, when they enter on the much more important subject of the award of a medal, unusual pains must be taken with the previous report, and it might, perhaps, be of some advantage to science, and might furnish their admirers with arguments in their defence, if they would publish that on which the decree of their Lalande’s medal to Captain Sabine was founded. It is far from necessary to my present object, to state all that has been written and said respecting these pendulum experiments: I shall confine myself merely to two points; one, the transit observations, I shall allude to, because I may perhaps show the kind of feeling that exists respecting them, and possibly enable Captain Sabine to explain them. The other point, the error in the estimation of the division of the level, I shall discuss, because it is an admitted fact. Some opinion may be formed of transit observations, by taking the difference of times of the passage of any star between the several wires; supposing the distances of those wires equal, the intervals of time occupied by the star in passing from one to the other, ought to be precisely the same. As those times of passing from one wire to another are usually given to seconds and tenths of seconds, it rarely happens that the accordance is perfect. The transit instrument used by Captain Sabine was thirty inches in length, and the wires are stated to be equi-distant. Out of about 370 transits, there are eighty-seven, or nearly one-fourth, which have the intervals between all the wires agreeing to the same, the tenth of a second. At Sierra Leone, nineteen out of seventy-two have the same accordance; and of the moon culminating stars, p. 409, twelve out of twenty-four are equally exact. With larger instruments, and in great observatories, this is not always the case. Captain Kater has given, in the Philosophical Transactions, 1819, p. 427, a series of transits, with a three and a half foot transit, in which about one-eleventh part of them only have this degree of accuracy; and it should be observed that not merely the instrument, but the stars selected, have, in this instance, an advantage over Captain Sabine’s. The transit of M. Bessel is five feet in length, made by Frauenhofer, and the magnifying power employed is 182; yet, out of some observations of his in January, 1826, only one-eleventh have this degree of accordance. In thirty-three of the Greenwich observations of January, 1828, fifteen have this agreement, or five-elevenths; but this is with a ten-feet transit. Now in none of these instances do the times agree within a tenth of a second between all the wires; but I have accounted those as agreeing in all the wires in which there is not more than four-tenths of a second between the greatest and least. This superior accuracy of the small instrument requires some explanation. One which has been suggested is, that Captain Sabine employs a chronometer to observe transits with; and that since it beats five times in two seconds, each beat will give four-tenths of a second; and this being the smallest quantity registered, the agreement becomes more probable than if tenths were the smallest quantities noticed. In general, the larger the lowest unity employed the greater will be the apparent agreement amongst the differences. Thus, if, in the transit of stars near the pole, the times of passing the wires were only registered to the nearest minute, the intervals would almost certainly be equal. There is another circumstance, about which there is some difficulty. It is understood that the same instrument,—the thirty-inch transit, was employed by Lieutenant Foster; and it has not been stated that the wires were changed, although this has most probably been the case. Now, in the transits which the later observer has given, he has found it necessary to correct for a considerable inequality between the first and second wires (See Phil. Trans. 1827). If an erroneous impression has gone abroad on this subject, it is doing a service to science to insure its correction, by drawing attention to it. Should these observations be confirmed by other observers, it would seem to follow that the use of a chronometer renders a transit more exact, and therefore that it ought to be used in observatories. Among the instruments employed by Captain Sabine, was a repeating circle of six inches diameter, made by order of the Board of Longitude, for the express purpose of ascertaining how far repeating instruments might be diminished in size:—a most important subject, on which the Board seem to have entertained a very commendable degree of anxiety. The following extract from the “Pendulum Experiments” is important: “The repeating circle was made by the direction, and at the expense of the Board of Longitude, for the purpose of exemplifying the principle of repetition when applied to a circle of so small a diameter as six inches, carrying a telescope of seven inches focal length, and one inch aperture; and of practically ascertaining the degree of accuracy which might be retained, whilst the portability of the instrument should be increased, by a reduction in the size to half the amount which had been previously regarded by the most eminent artists as the extreme limit of diminution to which repeating circles, designed for astronomical purposes, ought to be carried. “The practical value of the six-inch repeating circle may be estimated, by comparing the differences of the partial results from the mean at each station, with the correspondence of any similar collection of observations made with a circle, on the original construction, and of large dimensions; such, for instance, as the latitudes of the stations of the French are, recorded in the Base du Systeme Metrique: when, if due allowance be made for the extensive experience and great skill of the distinguished persons who conducted the French observations, the comparison will scarcely appear to the disadvantage of the smaller circle, even if extended generally through all the stations of the present volume; but if it be particularly directed to Maranham and Spitzbergen,—at which stations the partial results were more numerous than elsewhere, and obtained with especial regard to every circumstance by which their accuracy might be affected, the performance of the six-inch circle will appear fully equal to that of circles of the larger dimension. The comparison with the two stations, at which a more than usual attention was bestowed, is the more appropriate, because it was essential to the purposes for which the latitudes of the French stations were required, that the observations should always be conducted with the utmost possible regard to accuracy. “It would appear, therefore, that in a repeating circle of six inches, the disadvantages of a smaller image enabling a less precise contact or bisection, and of an arch of less radius admitting of a less minute subdivision, may be compensated by the principle of repetition.” Captain Sabine has pointed out Maranham and Spitzbergen as places most favourable to the comparison. Let us take the former of these places, and compare the observations made there with the small repeating instrument of six inches diameter, with those made by the French astronomers at Formentera, with a repeating circle of forty-one centi-metres, or about sixteen inches in diameter, made by Fortin. It is singular that this instrument was directed, by the French Board of Longitude, to be made expressly for this survey, and the French astronomers paid particular attention to it, from the circumstance of some doubts having been entertained respecting the value of the principle of repetition. The following series of observations were made with the two instruments. [I have chosen the inferior meridian altitude of Polaris, merely because the number of sets of observations are rather fewer. The difference between the extremes of the altitude of Polaris, deduced from sets taken above the pole by the same observers, amounts to seven seconds and a half.] Latitude deduced from Polaris, with a repeating circle, 16 inches diameter.—Base du Systeme Metrique, tom. iv. p. 376. 1807. Number of Latitude Names of Observers.  Observations. of Formentera. deg. min. sec. 64 38 39 55.3 Biot 100 54.7 Arago 10 56.2 Biot 88 56.9 Biot 120 56.7 Arago 84 54.9 Biot 100 56.5 Arago 102 57.1 Arago 80 54.5 Biot 88 53.3 Arago 90 53.6 Arago 88 53.8 Arago 92 53.7 Arago 42 55.6 Chaix 90 54.1 Chaix 80 53.9 Arago Mean of 1318 Observations, 38deg. 39min. 54.93sec. * Sets of Observations made with a six-inch repeating circle, at Maranham. Star. Number of Latitude
Observer. deg. min. sec. alpha Lyrae 8 2 31 42.4 Capt.  Sabine alpha Lyrae 12 43.8 Ditto alpha Pavonis 10 44.5 Ditto alpha Lyrae 12 44.6 Ditto alpha Cygni 12 42.1 Ditto alpha Gruris 12 42.2 Ditto Mean latitude deduced from 66 observations 2deg. 31min 43.3sec. In comparing these results, although the French observations were more than twenty times as numerous as the English, yet the deviations of the individual sets from the mean are greater. One second and three-tenths is the greatest deviation from the mean of the Maranham observations; whilst the greatest deviation of those of Formentera, is two seconds and two-tenths. If this mode of comparison should be thought unfair, on account of the greater number of the sets in the French observations, let any six, in succession, of those sets be taken, and compared with the six English sets; and it will be found that in no one instance is the greatest deviation from the mean of the whole of the observations less than in those of Maranham. It must also be borne in mind, that by the latitude deduced by the mean of 1250 superior culminations of Polaris by the same observers, the latitude of Formentera was found to be 38deg. 39min 57.07sec., a result differing by 2.14sec. from the mean of the 1318 inferior culminations given above. [This difference cannot be accounted for by any difference in the tables of refraction, as neither the employment of those of Bradley, of Piazzi, of the French, of Groombridge, of Young, of Ivory, of Bessel, or of Carlini, would make a difference of two-tenths of a second.] These facts alone ought to have awakened the attention of Captain Sabine, and of those who examined and officially pronounced on the merits of his observations; for, supposing the skill of the observers equal, it seems a necessary consequence that “the performance of the six-inch circle is” not merely “fully equal to that of circles of larger dimensions,” but that it is decidedly superior to one of sixteen inches in diameter. This opinion did indeed gain ground for a time; but, fortunately for astronomy, long after these observations were made, published, and rewarded, Captain Kater, having borrowed the same instrument, discovered that the divisions of its level, which Captain Sabine had considered to be equal to one second each, were, in fact, more nearly equal to eleven seconds, each one being 10.9sec. This circumstance rendered necessary a recalculation of all the observations made with that instrument: a re-calculation which I am not aware Captain Sabine has ever thought it necessary to publish. [Above two hundred sets of observations with this instrument are given in the work alluded to. It can never be esteemed satisfactory merely to state the mean results of the corrections arising from this error: for the confidence to be attached to that mean will depend on the nature of the deviations from it.] This is the more to be regretted, as it bears upon a point of considerable importance to navigation; and if it should have caused any alteration in his opinion as to the comparative merits of great and small instruments, it might have been expected from a gentleman, who was expressly directed by the Board of Longitude, to try the question with an instrument constructed for that especial purpose. Finding that this has not been done by the person best qualified for the task, perhaps a few remarks from one who has no pretensions to familiarity with the instrument, may tend towards elucidating this interesting question. The following table gives the latitudes as corrected for the error of level: Station. Star Latitude
Latitude Diffe- deg.min.sec. deg.min.sec. sec.  Sierra Leone Sirius 8 29 27.9 8 29 34.7 6.8 Ascension Alph.Centuri 7 55 46.7 7 55 40.1 6.6 Bahia Alph.Lyrae 12 59 19.4 12
59 21.4 2.0 Maranham Alph.Lyrae 2 31 42.4 2
31 22 20.4 Trinidad Achernar 10 38 56.1 10
38 58.2 2.1 Jamaica Polaris 17 56 8.6 17
56 4.6 4.0 New York Sun 40 42 40.1 40
42 44.6 4.5 Hammerfest Sun 70 40 5.3 70 40 7.2 1.9 Spitzbergen Sun 79 49 56.1 79
49 58.6 2.5 Greenland Sun 74 32 19.9 74
32 32.4 12.4 Drontheim Sun 63 25 51.3 63
26 6.1 14.8 This presents a very different view of the latitudes as determined by the small repeating circle, from that in Captain Sabine’s book; and confining ourselves still to Maranham, where the latitudes “Were obtained, with especial regard to every circumstance by which their accuracy might be affected,” and where “A more than usual attention was bestowed,” it appears, that if we take Captain Sabine’s own test, namely, “the differences of the partial results from the mean at each station,” the deviations become nearly ten times as large as they were before; a circumstance which might be expected to have some influence in the decision of the question. There is, however, another light in which it is impossible to avoid looking at this singular oversight. The second column of the table of latitudes must now be considered the true one, as that which really resulted from the observations. Now, on examining the column of true latitudes, the differences between the different sets of observations is so considerable as naturally to excite some fear of latent error, more especially as nearly the greatest discordance arises from the same star, Alph.Lyrae, observed after an interval of only three days. It becomes interesting to every person engaged in making astronomical observations, to know what is the probability of his being exposed to an error so little to be guarded against, and so calculated to lull the suspicions of the unfortunate astronomer to whom it may happen. In fact, the question resolves itself into this: the true latitude of a place being determined by sets of observations as in the first of the following columns— Latitudes
as deg.min.sec. deg.min.sec.  Alph.Lyrae, 28th Aug. . . . 2 31 22.0 2 31 42.4 Alph.Lyrae, 29th Aug. . . . 31.8 43.8 Alph.Pavonis, 29th Aug. . . 44,0 44.5 Alph.Lyrae, 31st Aug. . . . 42.6 44.6 Alph.Cygni, 31st Aug. . . . 39.2 42.0 Alph.Gruris, 2d Sept. . . . 27.4 42.2 what are the chances that, by one error all the latitudes in the first column should be brought so nearly to an agreement as they are in the second column? The circumstance of the number of divisions of the level being almost arbitrary within limits, might perhaps be alleged as diminishing this extraordinary improbability: but let any one consider, if he choose the error of each set, as independent of the others, still he will find the odds against it enormous. When it is considered that an error, almost arbitrary in its law, has thus had the effect of bringing discordant observations into an almost unprecedented accordance, as at Maranham; and not merely so, but that at eight of the nine stations it has uniformly tended to diminish the differences between the partial results, and that at the ninth station it only increased it by a small fraction of a second, I cannot help feeling that it is more probable even that Captain Kater, with all his admitted skill, and that Captain Sabine himself, should have been both mistaken in their measures of the divisions of the level, than that so singular an effect should have been produced by one error; and I cannot bring myself to believe that such an anticipation is entirely without foundation. Whatever may be the result of a re-examination, it was a singular oversight not to measure the divisions of a level intended to be used for determining so important a question; more particularly as, in the very work to which reference was made by Captain Sabine for the purpose of comparing the observations, it was the very first circumstance which occupied the French philosophers, and several pages [See pages 265 to 275 of the RECUEIL D’OBSERVATIONS GEODESIQUES, &c. PAR MM. Biot et Arago, which forms the fourth volume of the Base du Systeme Metrique.] are filled with the details relative to the determination of the value of the divisions of the level. It would also have been satisfactory, with such an important object in view, to have read off some of the sets after each pair of observations, in order to see how far the system of repetition made the results gradually converge to a limit, and in order to know how many repetitions were sufficient. Such a course would almost certainly have led to a knowledge of the true value of the divisions of the level; for the differences in the altitude of the same star, after a few minutes of time, must, in many instances, have been far too great to have arisen from the change of its altitude: and had these been noticed, they must have been referred to some error in the instrument, which could scarcely, in such circumstances, have escaped detection. I have now mentioned a few of the difficulties which attend Captain Sabine’s book on the pendulum, difficulties which I am far from saying are inexplicable. He would be bold indeed who, after so wonderful an instance of the effect of chance as I have been just discussing, should venture to pronounce another such accident impossible; but I think enough has been said to show, that the feeling which so generally prevails relative to it, is neither captious nor unreasonable. Enough also has appeared to prove, that the conduct of the Admiralty in appointing that gentleman one of their scientific advisers, was, under the peculiar circumstances, at least, unadvised. They have thus lent, as far as they could, the weight of their authority to support observations which are now found to be erroneous. They have thus held up for imitation observations which may induce hundreds of meritorious officers to throw aside their instruments, in the despair of ever approaching a standard which is since admitted to be imaginary; and they have ratified the doctrine, for I am not aware their official adviser has ever even modified it, that diminutive instruments are equal almost to the largest. To what extent this doctrine is correct, may perhaps yet admit of doubt. It cannot, however, admit of a doubt, that it is unwise to crown it with official authority, and thus expose the officers of their service to depend on means which may be quite insufficient for their purpose. How the Board of Longitude, after expressly DIRECTING this instrument to be made and tried, could come to the decision at which they arrived, appears inexplicable. The known difference of opinion amongst the best observers respecting the repeating principle, ought to have rendered them peculiarly cautious, nor ought the opinion of a Troughton, that instruments of less than one foot in diameter may be considered, “For astronomy, as little better than PLAYTHINGS,” [Memoirs of the Astronomical Society, Vol.I. p.53.] to have been rejected without the most carefully detailed experiments. There were amongst that body, persons who must have examined minutely the work on the Pendulum. Captain Kater must have felt those difficulties in the perusal of it which other observers have experienced; and he who was placed in the Board of Longitude especially for his knowledge of instruments, might, in a few hours, have arrived at more decisive facts. But perhaps I am unjust. Captain Kater’s knowledge rendered it impossible for him to have been ignorant of the difficulties, and his candour would have prevented him from concealing them: he must, therefore, after examining the subject, have been outvoted by his lay-brethren who had dispensed with that preliminary. It would be unjust, before quitting this subject, not to mention with respect the acknowledgment made by an officer of the naval service of the errors into which he also fell from this same level. Lieutenant Foster, aware of the many occasions on which Captain Sabine had employed this instrument, and knowing that he considered each division as equal to one second, never thought that a doubt could exist on the subject, and made all his calculations accordingly. When Captain Kater made him acquainted with the mistake, Lieutenant Foster immediately communicated a paper [The paper of Lieutenant Foster is printed in the Philosophical Transactions, 1827, p.122, and is worth consulting.] to the Royal Society, in which he states the circumstance most fully, and recomputed all the observations in which that instrument was used. Unfortunately, from the original observations of Mr. Ross being left on board the Fury at the time of her loss, the transcripts of his results could not be recomputed like the rest, and were consequently useless.
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