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ciation lias shown me in their magnificent Meeting. I shall never forget the help afforded to me in so many different ways, and I desire earnestly to put it in immediate contribution towards the advancement of science.
"The Observatory of Coimbra must have in its library, as a memorial, the valuable collection of Transactions of the British Association, and I hope that you may be so kind as to put me in the way of obtaining these volumes.
"I remain, dear Sir,
"J. P. Gassiot, Esq." "Jacistho A. Dk Souza."
The request of this letter has been complied with by the Council of the Association, and a complete set of the Transactions has been dispatched to Coimbra.
The Director of the Lisbon Observatory has since requested the Committee to superintend the construction of a set of self-recording Magnetographs. The Committee, in complying with his request, have made arrangements for the instruments at present exhibited in the International Exhibition, and these will afterwards be mounted at the Kew Observatory for inspection and verification.
A Differential Declinometer for the Government Observatory at Mauritius has been verified and forwarded to Prof. Meldrum, who has received it in Bafety.
Lieut. Rokeby, of the Boyal Marines, already favourably known by a meteorological register very carefully kept at Canton during its occupation by the British troops, has received instruction at Kew in the use of magnetical instruments, and has been furnished with a Dip Circle, a Unifilar, a Bifilar, and a Differential Declinometer, of which the constants have been determined at the Observatory. Lieut. Kokeby proposes to employ these instruments at the Island of Ascension during his term of service at that station. He has also been furnished by Admiral FitzRoy with a complete equipment of the meteorological instruments supplied by the Board of Trade. The importance of Ascension as a magnetical station has long been recognized. Situated very nearly on the line of no magnetic dip, the determination of the periodical variations and of the secular changes of the three magnetic elements cannot fail to possess a high value; and as a meteorological station, a rock in the mid-ocean, within 6° of the Equator, presents an almost unrivalled locality for an exact measure of the amount of the lunar atmospheric tide, and of the variations in direction and force of the trade-wind. The Admiralty, apprised of Lieut. Rokeby's meritorious purposes, have sanctioned the appropriation of the officers' quarter at the summit of the Green Mountain, known as the "Mountain House," as an observatory; and the department of the Board of Trade, under Admiral FitzRoy's superintendence, has authorized the expenditure of £50 in providing the additional accommodation required for the instruments. Lieut. Rokeby has arrived at Ascension with the instruments uninjured, and writes in strong terms of the support he receives from Captain Barnard, the commander of the troops on the island.
On June 19th the Chairman received a letter from the Astronomer Royal, in which he stated that he was very desirous of comparing the Greenwich records of the vertical-force magnet with those at Kew; and that, if agreeable to the Committee, he would request Mr. Glaisher to endeavour to arrange a meeting with Mr. Stewart for that purpose.
The Chairman immediately replied, offering every facility, and Mr. Glaisher has since visited the Observatory, where the comparison has been made.
1862. * c
The usual monthly absolute determinations of the magnetic elements continue to be made, and the self-recording magnetographs are in constant operation under the zealous superintendence of Mr. Chambers, the Magnetical Assistant.
. Major-General Sabine, Pres. R.S., has laid before the Royal Society a paper entitled " Notice of some conclusions derived from the Photographic Records of the Kew Declinometer in the years 1858, 1859, 1860, and 1861."
The exceedingly good definition which the labours of the late Mr. Welsh procured for the magnetic curves, has also enabled the Superintendent, Mr. Stewart, to discuss the disturbance-curves by a peculiar method, depending on such definition; and he has presented a paper to the Royal Society "On the forces which are concerned in producing the larger magnetic disturbances."
The Committee are at present engaged in investigating the best means of multiplying copies of these curves, and exhibit to the Association two prints from such—one kindly taken by Sir Henry James by his process, and the other taken by that of Mr. Paul Pretsch.
The expense incurred by Mr. Pretsch has been defrayed by £25 obtained from the Government Grant through the Royal Society.
The Chairman of the Balloon Committee having applied to the Superintendent for the instruments used by the late Mr. Welsh in his ascents, these were delivered over to Mr. Criswick on the 12th of March last, having been previously verified at the Observatory.
The Meteorological work of the Observatory continues to be performed in a satisfactory manner by Mr. George Whipple, and each Member of the Staff of the Observatory seems much interested in the duties he is called upon to discharge.
During the past year 184 Barometers and 282 Thermometers have been verified; and, to give an idea of the amount of this kind of work which has been accomplished since first the subject was commenced in the year 1854, it may be Btated that no fewer than 1185 Barometers and 6429 Thermometers have been verified up to this date.
Rear-Admiral FitzRoy having been informed of the existence at the Observatory of a Barograph invented and used by Mr. Ronalds, the following letter was addressed by him to the Chairman:—
"Board of Trade (and Admiralty) Meteorological Department, 2 Parliament Street, London, S.W., 7th April, 1862.
"Sir,—I have the honour to address you as Chairman of the Kew Committee of the British Association for the Advancement of Science, on behalf of this branch department of the Board of Trade and the Admiralty.
"I am authorized to request that you will allow us to endeavour to benefit by your regular photographic self-registration of the Barometer at the Kew Meteorological and Magnetical Observatory during at least one complete year of continuous record, by causing this office to be furnished with copies of photographic tracings, or their results, in full detail.
"The objects specially in view here, are:—
"Such accurate and indisputable continuous delineation of atmospheric pressure, or (rather) tension, as can only be obtained by perfectly reliable means; and
"Such details of occasional oscillations, or pulsations (so to speak), as can best be obtained photographically.
"For practical daily purposes, a self-registering Barometer, on the Milne principlo, may be sufficient; but for elaborate analysis of atmospherical conditions and changes, in connexion with the numerous influences operating, some occasionally, some frequently, others always, in the air and its everrestless currents, such an apparatus as that now available at Kew would appear to be indispensable.
"Besides ordinary meteorological peculiarities, the direction of magnetic earth-currents, the occurrence of magnetic storms, the differing electrical conditions of various currents of air, the phenomena of earthquakes, and their 'lightnings' *, seem to be more or less in certain relations to atmospheric tension, and therefore to require a close and unbroken barometrical registration. Towards some additional expense incurred by the Kew Observatory in complying with this request, I am authorized to say that this department will contribute, on principle similar to that of verification of instruments.
"I have the honour to be,
"Tour obedient Servant,
(Signed) "Kobebt Fitzkoy, R. Adm."
"P.S. Probably two scales of tracing, analogous to 'Sailing Charts ' and 1 Particular Plans,' would be convenient."
"John Peter Gassiot, Esq., F.R.S., Chairman of the Kew Committee of the British Association."
To which the Chairman shortly afterwards replied in the following terms:—
"Kew Observatory, 23rd April, 1862. "Sir,—I have the honour to acknowledge receipt of your letter of 7th inst., addressed to me as Chairman of the Kew Committee of the British Association.
"On behalf of this Committee, I may state in reply that it will afford us much satisfaction to furnish your department with Photographic Selfregistrations of the state of the Barometer at Kew Observatory.
"I am informed by Mr. Stewart, our Superintendent, that we have in our possession an instrument well calculated, with some slight alterations, to produce the results you desire.
"It possesses a compensation for temperature; besides which, it will be placed, when finally in action, in a room where the daily range of temperature is not more than half a degree Fahrenheit.
"This instrument is not yet, however, in working order, and two months may perhaps elapse before it is quite ready. As you seem to think it desirable to obtain occasionally curves on an enlarged scale, it will be matter for our consideration whether this can be managed, and how. You will be duly informed of our resolution; but, in the mean time, I may state that it would be somewhat more than two months before such additional curves could be ready. In conclusion, without binding ourselves to any specified time (which, indeed, would not be desirable in a matter of this nature), I beg to assure you that we shall do all in our power to hasten the desired result; and, as we hope to have things ready in the course of two or three months,
* Secchi and Palmieri, 1862.
we shall then also be prepared to reply to you with respect to remuneration for the additional work which the Observatory would thus undertake. "I have the honour to be, "Sir,
"Your obedient Servant,
(Signed) "J. P. Gassiot."
"Bear-Admiral FitzRoy, F.R.S., t(c"
The Mechanical Assistant being engaged at the Exhibition, it was found impossible to complete the alterations alluded to quite so soon as anticipated; but a curve was procured about the middle of August, which was sent to Admiral FitzRoy, and approved of by him.
The Barograph has since received some further alterations, with a view to increase its stability and general efficiency. These are now completed, and the instrument will be henceforth kept in constant operation. One of the curves from this instrument is presented to the Association.
Arrangements were made for recording photographically, by means of the Heliograph, the transit of Mercury which took place on the 12th of November last, but the weather proved unfavourable. This instrument was also in readiness for the partial eclipse of the sun which took place on the 31st of December last; but, owing to the unfavourable state of tho sky, only two imperfect pictures were obtained. A very good series of sun-pictures was obtained by Mr. Beckley during the months of November and December.
The Heliograph was sent from Kew at the beginning of January to Mr. De la Rue's Observatory, and Mr. Beckley attended at Cranford to assist in erecting and adjusting it to focus; but the weather was so unfavourable during the remainder of that month that no pictures of the sun could be obtained. It had somewhat improved about tho 7th of February, when the first photograph was taken, and since then others have been obtained by Mr. Reynolds (Mr. De la Rue's assistant) on every day on which this has been possible. Altogether, up to the 12th of September inclusive, 177 photographs have been taken on 124 days, namely :—
Number of Number of pho
In the Month of working days. tographs procured.
February 7 13
March 10 17
April 17 31
May: 17 26
June 23 28
July 20 27
August 21 26
Up to September 12 . 9 9
From February 7th to September 12th inclusive there are 218 days; so that on the average one photograph was procured for 1-77 day. Nearly half of the pictures have been obtained by taking advantage of breaks in the clouds, and many have been taken through haze. In several of the photographs, owing to the unpropitious state of the atmosphere, there is a want of that beauty and perfection which the Heliograph is capable of affording; but all the pictures are sufficiently perfect for measurement by means of Mr. De la Rue's Micrometer. Many of these are extremely perfect, and all would have been so had the state of the atmosphere permitted.
During the month of August Dr. Sablcr, Director of the Observatory of Wilna in Russia, resided at Cranford, and received instruction in Astronomical Photography. A Photoheliograph is being constructed for him under Mr. De la Rue's superintendence by Mr. Dallmeyer, and a Micrometer by the Messrs. Simms. This Heliograph -will embody all the optical and mechanical improvements suggested by the experiments -with the Kew instrument; and it is expected that the Wilna apparatus will be in operation in the spring of 1863. In the event of the Kew Heliograph being worked continuously, Sir John Herschel's suggestion that daily records of tho sun should be taken by means of photography will therefore be carried out both in England and Russia; if this were done in one or two other localities, a considerable amount of information would be obtained respecting physical changes continually occurring on the sun's surface.
The experience obtained during tho past year has been such as to lead Mr. De la Rue to recommend that photographic records should be continued for a series of years at some public Observatory. The Committeo have had in consideration whether this could be done at Kew without interfering with the other work, and have come to the conclusion that the Heliograph might be worked at an annual expense of £200, which sum would cover the cost of an additional Assistant, who might at the same time do the other photographic work of the Observatory.
The old dome formerly used for the Heliograph is so inconveniently situated as to be quite unfit for such work, and it will be necessary to make some addition to one of the present out-buildings in order to contain the instrument. The cost of this structure is estimated at £100.
The Committee strongly recommend that the General Committee of the Association take such steps as they may consider advisable for carrying this desirable object into practical effect.
The self-recording Electrometer of Prof. W. Thomson continues in constant operation.
Mr. Francis Galton having made arrangements in the Observatory Park for testing sextants, the Observatory is now prepared to receive such instruments for examination, and to issue certificates to such as may fulfil the conditions of any of the following classes :—
A. Sextants of the highest order of workmanship for lunar observations and general service, on shore as well as at sea.
B. Sextants for naval surveys and for the determination of altitudes with as much precision as is available at sea.
C. Quadrants or sextants to be used without telescopes, for the determination of altitudes with an exactness equal to the requirements of general navigation.
The charges for examination under classes A and B will be 5s., under class C, Is.; and the minute constant errors of instruments under class A will be determined, when desired, at an additional charge of 5s.
Eight sextants have been verified at Kew since the last Meeting of the British Association.
The Observatory has been honoured with a visit from the following distinguished men of science, who had visited this country in consequence of the International Exhibition:—
Professors Dove, Magnus, and Quincke, of Berlin; Professor Fb'rchhammer, of Copenhagen; Professors Bunsen, Kirchhoff, and Eisenlohr, of Heidelberg; Professors Kraft and Pislio, of Vienna; Professor Govi, of Turin; Professor Donati, of Florence; Professor Bolzani, of Kasan; Professor Lapschine, of