of that body, dated Feb. 10, 1841. Nor must your Committee pass in silence the instructions given, and the instruments supplied by Government, (in duplicate, and with complete instructions for the use of each,)—also on application from the President and Council of the Royal Society,-to the African Expedition, for the purpose of observation in the course of that expedition. From the scientific zeal which distinguishes many of the officers of that expedition, scarcely inferior to that zeal in the cause of humanity which has led them to enter on so perilous a service,—results highly valuable to magnetic science may be expected. The transportable magnetometer being one of their instruments, observations on term-days during some months, corresponding with those in Guiana, will probably be obtained, and thus localities, otherwise of high interest, and remote from any central station, will be bound together.

Mr. Caldecott, Astronomer to His Highness the Rajah of Travancore, whose magnetical observatory, completely furnished in instruments, commenced its operations on the May term-day of the present year, has also declared his intention to undertake the magnetic survey of Southern India; while in the north of that empire we may expect, from the zeal and energy of Capt. Boileau, that no exertions on his part will be wanting to secure a similar advantage in that quarter.

In all such surveys it is highly desirable that a regular and concerted system of observation should be followed, and above all things, that the condition of exact conformity to the hours of simultaneous observation should be adhered to; as well as that, if practicable, all determinations of important points, intended to be made with particular care and exactness, should be performed on the term-days; which object, by the exercise of a certain degree of forethought in laying out the plan of travel, may doubtless be accomplished in the great majority of instances.

Connected with, and of importance to, the practical working of the observatories, your Committee beg leave to call attention to Prof. Lloyd's supplementary paper, "On the Mutual Action of permanent Magnets," in which those conditions of equilibrium are investigated which it is possible to satisfy, independent of the relative forces of the magnets. In this paper, independent of the practical utility of the rules laid down for the disposal of the magnets in fixed observatories, the demonstration of the extreme minuteness of the possible amount of uncompensated error arising from mutual attraction cannot but be regarded as highly satisfactory.

Finally, your Committee have to report on their employment of the grant of 50%., placed at their disposal at the last meeting, which they have expended on the purchase of a transportable magnetometer, by Meyerstein, of Göttingen, for the Guiana survey. Some improvements, not contemplated originally, having been introduced into the construction of this instrument, its total cost, including freight, somewhat exceeded this sum, leaving a balance of 127. 28. against the Committee, for which it is necessary they should pray an indemnity, as well as a continuance of the grant of money placed at their disposal. Signed, on the part of the Committee, J. F. W. HERSCHEL.

Reports of Committees appointed to provide Meteorological Instruments for the use of M. Agassiz and Mr. M'Cord.

WITH reference to the resolutions passed at Glasgow, viz. "That a Committee, consisting of Major Sabine and Sir J. Herschel, be requested to pro

vide two actinometers, for observations on the intensity of Solar Radiation, to be made by Prof. Agassiz, at considerable heights in the Alps, and that the sum of 101. be placed at the disposal of the Committee for that purpose; "That Major Sabine be requested to provide a good mountain barometer and a thermometer, for the assistance of Mr. M'Cord in his meteorological observations the sum of 20%. to be placed at the disposal of Major Sabine for the purpose "-Col. Sabine reported, that M. Agassiz had been supplied with two actinometers, at the cost of 107.; and that a good mountain barometer was forwarded to Mr. M'Cord early in the spring of this year, having been previously compared with the standard barometer of the Royal Society; and that a thermometer was not sent, because Mr. Newman informed Col. Sabine that an excellent standard thermometer had been ordered by Mr. M'Cord himself, and had been forwarded to him. The cost of the mountain barometer was 61. 12s. 6d.

Report of a Committee, consisting of Sir J. HERSCHEL only, to superintend the reduction of Meteorological Observations.-July 1841. DURING the last year several series of observations for the years 1837 and 1838, as well as a few for 1839, have dropped in, and every endeavour has been made to procure copies of such as were still wanting from stations whence there was reason to presume that observations were forwarded but had never come to hand. These endeavours, in several instances, have proved successful, and in consequence the list of stations at which available series, having some degree of consecutiveness and connexion, can be made out, is considerably enlarged. The whole number of series in hand, and under reduction at present, amounts to upwards of three hundred, being the results of observations at about seventy stations.

In the year elapsed, Mr. Birt has been employed intabulating, reducing, projecting, and comparing the barometric curves, a process which has been completed for the whole of the American group (which is by far the most numerous and consecutive) for the years 1835, 1836, 1837, and for March 1838, comprising eighty-eight series, made at the following twenty-eight stations, viz.— St. Catherine's Island. Magnetic Island. Gulf of Guayaquil. Realejo. Conchagua. San Blas.

Quebec.
Montreal.

Gardiner.

Burlington.

William's College.

Western Reserve College.
Flushing.

New York.

Baltimore.

Cincinnati.

Albany.

Natchez.

One term also has been reduced and projected (June 1836) for each of the other groups, comprising seventeen series, at the same number of sta tions, viz.

The tabulated results of these reductions, and their projected curves, accompany this Report for the inspection of the Meeting. The curves are purposely projected on a large scale (too large for publication) to afford room for a minute examination and analysis of their several inequalities, with a view to the possibility of tracing the progress of subordinate undulations or of cross waves; and each has been made by Mr. Birt the subject of particular and careful discussion, the results of which he has embodied in the form of notes on the several terms. Many of these contain remarks of much interest, especially that on the December term of 1836, which fortunately comprises the ascending branches of the barometer curves during a remarkable storm, as well as others, which however must be reserved for the final report of your Committee, which it may be confidently stated will be ready for presenting at the next Meeting.

Meanwhile the annexed letters from Mr. Birt will serve to give the Meeting somewhat more than a general idea of the direction which the inquiry is taking, and contain some suggestions relative to a system of concerted observation excellently well adapted to the tracing of atmospheric waves across a tract of country, to which, as well as to his offer to undertake the necessary correspondence, your Committee desires to direct the especial attention of the Meeting. (Signed) J. F. W. HERSCHEL.

66

Metropolitan Literary and Scientific Institution, June 1, 1841. "DEAR SIR,-I exceedingly regret that I have been unable to forward you the packet containing the projections, &c. of the American observations until so long after the time mentioned in my last. I was extremely anxious not to omit any point that suggested itself in carefully looking over the projections and tables, and having completed this, I hope the packet will reach you in sufficient time to enable you to draw up the report for the Meeting without inconvenience.

"The remarks I have to offer I have thrown in the form of notes to each sheet of the projections. In these notes I have taken very little, if any, notice of the curves south of the United States, the Bahamas, &c. I may however remark here, that the curves at the Bahamas generally differ from those of the United States; and as they are situated near the northern border of the torrid zone this difference is remarkable and interesting, as it indicates different systems of oscillation peculiar to the zones. Numerous observations from the Bahamas, and the West India islands generally, would be highly interesting.

"One point which I have glanced at in the notes appears to me interesting and worthy of attention in future observations and discussions of this kind, namely, the appearance of the diurnal oscillation when the extent of oscillation at the station is small, for instance under 0.1 inches. Generally as the oscillation increases the diurnal oscillation becomes obscured.

"With respect to the tables and projections, I have very carefully examined them, and I am not conscious of any errors existing; the reductions I have carefully verified in every instance, and the amount of error in the projections is not greater than 0005 in the readings of the barometric altitudes; this amount of error arises from hygrometric causes.

"With respect to the increase of oscillation, as mentioned in the concluding remarks to the notes on the projections, it appears that the stations from which observations have hitherto been obtained are too few to derive correct conclusions relative to it. Probably, on one or two occasions that may be fixed on for future observations, a number of gentlemen may undertake a series of observations of the barometer, having especially this object in view,

once or twice, who might not wish to continue such observations at stated periods. Our universities and academies, and most of, if not all, our provincial institutions, would probably join in this object, and by appointing a day sufficiently remote, many gentlemen who would thus engage in the work would have an opportunity of communicating with their friends, and thus a sufficient number of stations well scattered in different and suitable parts of the country might be obtained. It appears, however, that in order effectually to obtain the object in view, it would be desirable to modify in some degree the observations as they have hitherto been conducted; for, in order to obtain the whole extent of oscillation at any station, it would be necessary to obtain a complete depression and elevation of the barometric curve. Thus a time would be fixed on for a simultaneous commencement of the observations at all the stations, say 6 A.M.; but the termination of the observations would depend on the attainment of the elevation or depression of the curve, as the case might be; so that if the barometer was falling at the commencement of the observations, they would terminate when the greatest altitude had been obtained; three or four hours' observation after this point had been observed, would probably be sufficient to indicate the change in the character of the curve. By thus conducting the observations the extent of oscillation at each station would be distinctly obtained, as the lowest and highest points of the barometer would have been observed. Perhaps you will have the kindness to give this subject your consideration, and should it appear to you worth the trouble, I shall be most happy to undertake the management of a correspondence relative to it. "I have the honour to be, dear Sir, "Yours very respectfully, "W. R. BIRT."

"Metropolitan Literary and Scientific Institution, July 14, 1841. "DEAR SIR, I have very carefully examined the curves obtained in the British Isles, also those in Europe, and have embodied the results of this examination in the accompanying notes and tables.

"The striking difference between the atmospheric affections in the British Isles and those of Europe, is highly interesting; also the difference in the lengths of the undulations observed at the European stations, the western stations exhibiting the longest. On this point, however, I apprehend the observations are not sufficiently numerous to allow of the slightest conjecture being entertained, with the exception that there might have existed several centres of oscillation, the entire systems extending over comparatively small areas, similar to those indicated by the American observations, I believe, of September 1837. "I remain, dear Sir, yours very respectfully,

"W. R. BIRT."

Report of a Committee, consisting of Sir J. HERSCHEL, Mr. WHEWELL, and Mr. BAILY, for revising the Nomenclature of the Stars. As regards the collection of synonyms, the detection of errors originating in mistakes of entry, copying, printing, or calculation, and their rectification, and the restriction within their just boundaries of the existing constellations, the work of your Committee has been progressive. Owing, however, to the unfortunate accident which has recently befallen one of its members, by whom this department of the work had been especially taken in hand, no precise report at this time can be made of the progress made.

As regards the revision and redistribution of the southern constellations, a catalogue has in the first place been prepared of all stars within the circle of

70° S.P.D. down to the fifth magnitude, with their present actual magnitudes as determined by a series of observations made expressly for that purpose; which catalogue is now in course of printing and publication by the Royal Astronomical Society. With the magnitudes of this catalogue a chart has been constructed, of which several copies have been made. These have been employed for the purpose of grouping the stars in various ways (without regard to existing constellations), and with reference only to forming among themselves the most compact and striking groups which their distribution in the heavens admits, and which the correctness obtained in the magnitudes has now for the first time rendered practicable. After trying many systems, and arranging the groups in a great variety of ways, your Committee have at length agreed on adopting, as the boundaries of the new regions into which they propose distributing the southern stars, only arcs of meridians and parallels of declination for a given epoch; thus including each region within a quadrilateral rectangular figure, whose angular points being tabulated in right ascension and declination, may be treated as artificial stars, and thus brought up by the usual tables of precession to any other epoch, their situation among the stars being unchanged. Thus it will become a mere matter of inspection of a catalogue arranged for the original epoch (which they propose to be that of the Royal Astronomical Society's forthcoming new Catalogue), which region any given star shall belong to.

Proceeding then to assign more particularly the limits of the several regions, they have succeeded in forming an arrangement in which (subject to such revision and modifications as may arise between this and their final report) they feel disposed to rest. Meanwhile, however, as it is of great importance that whatever system they may finally adopt should have the sanction of the astronomical world in general, it has been thought advisable in the first instance to lay before the public an outline of the general plan, together with a reduced sketch of the proposed regions (subject to such revision), with a view to making more generally known its principles, and assembling around it, in the event of its approval, that body of support and assent, of which, as an innovation, it must stand in need. This has accordingly been done in a paper read by one of the members of your Committee to the Astronomical Society, and (with the catalogue above-mentioned) now in course of publication. This being largely distributed among astronomers by the printing an extra number of copies, will, it is expected, lead to the final maturation and reception of the plan. [It was hoped that the printing of this paper, and the accompanying engraving, would be far enough advanced to have enabled copies to be distributed at the present Meeting of the Association; but this not being the case, proof-sheets of the paper and of the reduced skeleton chart are, at all events, annexed to this Report for inspection and perusal by such members as may wish it.]

As respects the nomenclature of the new regions, the Committee are at present engaged in considering it; but some principles, which will probably influence their recommendation when the subject is sufficiently advanced for that step, are stated in the paper already alluded to, which will appear in the forthcoming volume of the Transactions of the Royal Astronomical Society. But the same necessity (grounded on the incorrectness of magnitudes as laid down in all existing charts) exists for a revision of the northern as well as southern stars in this respect. It therefore becomes worthy of consideration whether a similar plan may not advantageously be carried into execution in both hemispheres; and as, at all events, the actual state of the celestial charts in both is such as to admit of great improvement from an assemblage of more correct photometric data, a general review of all the stars down to