Autobiography of Sir George Biddell Airy Part 21

Of private history: There was the usual visit to Playford in January: also a short visit in May: and a third visit at Christmas.--There was a short run in June, of about a week, to Coniston, with one of his daughters.--And there was a trip to Weymouth, &c., for about 10 days, with one of his daughters, in the beginning of August--On his return from the last-mentioned trip, Airy found a letter from the Secretary of the Swedish Legation, enclosing the Warrant under the Royal Sign Manual of His Majesty (Oscar), the King of Sweden and Norway, by which he was nominated as a First Cla.s.s Commander of the Order of the North Star, and accompanying the Decorations of that Order.

1874

"In this year Mr Glaisher resigned his appointment: I placed his Department (Magnetical and Meteorological) under Mr Ellis.--A balance of peculiar construction has been made by Mr Oertling, from my instructions, and fixed near the public barometer at the Entrance Gate. This instrument enables the public to test any ordinary pound weight, shewing on a scale the number of grains by which it is too heavy or too light.--Fresh counterpoises have been attached to the Great Equatoreal to balance the additional weight of the new Spectroscope, which was finally received from Mr Browning's hands on May 2nd of the present year. The Spectroscope is specifically adapted to sweeping round the Sun's limb, with a view to mapping out the prominences, and is also available for work on Stars and Nebulae, the dispersive power being very readily varied. An induction-coil, capable of giving a six-inch spark, has been made for this instrument by Mr Browning.--Some new cla.s.ses of reductions of the meteorological observations from 1848 to 1868 have been undertaken and completed in the past year. The general state of this work is as follows: The diurnal changes of the dry-bulb thermometer, as depending on the month, on the temperature waves, on the barometric waves, on the overcast and cloudless states of the sky, and on the direction of the wind, have been computed and examined for the whole period; and the exhibition of the results is ready for press. The similar reductions for the wet-bulb thermometer are rapidly approaching completion.

--Regarding the preparations for the Transit of Venus Expeditions.

Originally five stations were selected and fully equipped with equatoreals, transits, altazimuths, photoheliographs, and clocks; but I have since thought it desirable to supplement these by two branch stations in the Sandwich Islands and one in Kerguelen's Island; and the additional instruments thus required have been borrowed from various sources, so that there is now an abundant supply of instrumental means.... There will thus be available for observation of the Transit of Venus 23 telescopes, nine of which will be provided with double-image-micrometers; and five photoheliographs; and for determination of local time, and lat.i.tude and longitude, there will be nine transits and six altazimuths.... All the observers have undergone a course of training in photography; first, under a professional photographer, Mr Reynolds, and subsequently under Capt. Abney, R.E., whose new dry-plate process is to be adopted at all the British Stations.... A Janssen slide, capable of taking 50 photographs of Venus and the neighbouring part of the Sun's limb at intervals of one second, has been made by Mr Dallmeyer for each of the five photoheliographs."--Attached to the Report to the Visitors is a copy of the Instructions to Observers engaged in the Transit of Venus Expeditions, prepared with great care and in remarkable detail.--"In the past spring I published in the Monthly Notices of the Royal Astronomical Society a statement of the fundamental points in a new treatment of the Lunar Theory, by which, availing myself of all that has been done in the best algebraical investigations of that theory, I trust to be able by numerical operations only to give greater accuracy to final results. Considerable progress has been made in the extensive numerical developments, the work being done, at my private expense, entirely by a junior computer; and I hope, at any rate, to put it in such a state that there will be no liability to its entire loss. When this was reported to the Board of Visitors, it was resolved on the motion of Prof. Stokes, that this work, as a public expense, ought to be borne by the Government; and this was forwarded to the Admiralty. On June 24th I wrote to the Secretary of the Admiralty, asking for _100_ for the present year, which after the usual enquiries and explanations was sanctioned on Aug. 29th."

Of private history: There were short visits to Playford in January, June, and October, but only for a few days in each case.--In March there was a run of two or three days to Newnham (on the Severn) to see the Bore on the Severn, and to Malvern.--In July he went to Newcastle to observe with Mr Newall's great telescope, but the weather was unfavourable: he then went on to Barrow House near Keswick, and spent a few days there, with excursions among the mountains.--On Aug. 13th he went with his daughter Christabel to the Isle of Arran, and then by Glasgow to the Trosachs, where he made several excursions to verify the localities mentioned in the "Lady of the Lake."--While in Scotland he heard of the death of his brother, the Rev. William Airy, and travelled to Keysoe in Bedfordshire to attend the funeral; and returned to Greenwich on Aug. 24th.

1875

"In October of this year I wrote to the Admiralty that I had grounds for asking for an increase of my salary: because the pension which had been settled on my wife, and which I had practically recognized as part of my salary, had been terminated by her death; so that my salary now stood lower by _200_ than that of the Director of Studies of the Royal Naval College. The Admiralty reply favourably, and on Nov. 27th the Treasury raise my salary to _1_,200.--For the service of the Clock Movement of the Great Equatoreal, a water-cistern has been established in the highest part of the Ball-Turret, the necessity for which arose from the following circ.u.mstance: The Water Clock was supplied by a small pipe, about 80 feet in length, connected with the 3-inch Observatory main (which pa.s.ses through the Park), at a distance of about 250 feet from any other branch pipe. In spite of this distance I have seen that, on stopping the water-tap in the Battery-Bas.e.m.e.nt under the North-East Turret, the pressure in the gauge of the Water Clock has been instantly increased by more than 40 lbs. per square inch. The consequent derangement of the Water Clock in its now incessant daily use became intolerable. Since the independent supply was provided, its performance has been most satisfactory.--With the Spectroscope the solar prominences have been mapped on 28 days only; but the weather of the past winter was exceptionally unfavourable for this cla.s.s of observation. After mapping the prominences, as seen on the C line, the other lines, especially F and b, have been regularly examined, whenever practicable. Great care has been taken in determining the position, angle, and heights of the prominences in all cases. The spectrum of Coggia's Comet was examined at every available opportunity last July, and compared directly with that of carbon dioxide, the bands of the two spectra being sensibly coincident. Fifty-four measures of the displacement of lines in the spectra of 10 stars, as compared with the corresponding lines in the spectra of terrestrial elements (chiefly hydrogen), have been made, but some of these appear to be affected by a constant error depending on faulty adjustment of the Spectroscope.--Photographs of the Sun have been taken with the Kew Photoheliograph on 186 days; and of these 377 have been selected for preservation. The Moon, Jupiter, Saturn, and several stars (including the Pleiades and some double stars) have been photographed with the Great Equatoreal, with fairly satisfactory results, though further practice is required in this cla.s.s of work.--I would mention a supplemental mechanism which I have myself introduced into some chronometers. I have long remarked that, in ordinary good chronometers, the freedom from irregularities depending on mechanical causes is most remarkable; but that, after all the efforts of the most judicious makers, there is in nearly every case a perceptible defect of thermal compensation. There is great difficulty in correcting the residual fault, not only because an inconceivably small movement of the weights on the balance-curve is required, but also because it endangers the equilibrium of the balance. The mechanism adopted to remedy the defect is described in a Paper in the Horological Journal of July 1875 by Mr W. Ellis, and has received the approval of some able chronometer-makers.--With respect to the Transit of Venus Expeditions: The parties from Egypt and Rodriguez are returned. I am in continual expectation of the arrival of the other parties. I believe the eye-observations and the ordinary photographs to be quite successful; I doubt the advantage of the Janssen; one of the double-image-micrometers seems to have failed; and the Zenith-telescope gives some trouble. At three stations at Rodriguez, and three at Kerguelen, the observations appear to have been most successful. At the Sandwich Islands, two of the stations appear to have been perfectly successful (except that I fear that the Janssen has failed), and a rich series of lunar observations for longitude is obtained. At New Zealand, I grieve to say, the observations were totally lost, entirely in consequence of bad weather. There has been little annoyance from the dreaded 'black drop.' Greater inconvenience and doubt have been caused by the unexpected luminous ring round Venus.--With regard to the progress of my proposed New Lunar Theory: Three computers are now steadily employed on the work. It will be remembered that the detail and ma.s.s of this work are purely numerical; every numerical coefficient being accompanied with a symbolical correction whose value will sometimes depend on the time, but in every case is ultimately to be obtained in a numerical form. Of these coefficients, extracted (for convenience) from Delaunay's results, there are 100 for parallax, 182 for longitude, 142 for lat.i.tude; the arguments being preserved in the usual form."--After reviewing the changes that had taken place at the Observatory during the past forty years, the Report to the Board of Visitors concludes thus: "I much desire to see the system of time-signals extended, by clocks or daily signals, to various parts of our great cities and our dockyards, and above all by hourly signals on the Start Point, which I believe would be the greatest of all benefits to nautical chronometry. Should any extension of our scientific work ever be contemplated, I would remark that the Observatory is not the place for new physical investigations.

It is well adapted for following out any which, originating with private investigators, have been reduced to laws susceptible of verification by daily observation. The National Observatory will, I trust, always remain on the site where it was first planted, and which early acquired the name of 'Flamsteed Hill.'

There are some inconveniences in the position, arising princ.i.p.ally from the limited extent of the hill, but they are, in my opinion, very far overbalanced by its advantages."--In a letter on the subject of the Smith's Prizes Examination at Cambridge, which was always a matter of the greatest interest to him, Airy renewed his objections to the preponderance in the Papers of a cla.s.s of Pure Mathematics, which he considered was never likely under any circ.u.mstances to give the slightest a.s.sistance to Physics. And, as before, these remarks called forth a rejoinder from Prof. Cayley, who was responsible for many of the questions of the cla.s.s referred to.--In this year Airy completed his "Notes on the Earlier Hebrew Scriptures," which were shortly afterwards published as a book by Messrs Longmans, Green, & Co. In his letter to the publishers introducing the subject, he says, "For many years past I have at times put together a few sentences explanatory as I conceive of the geographical and historical circ.u.mstances connected with the princ.i.p.al events recorded in the Hebrew Scriptures. The view which I take is free, but I trust not irreverent. They terminate with a brief review of Colenso's great work. The collection now amounts to a small book." From the references already given in previous years to his Papers and correspondence on the geography of Exodus, his correspondence with Colenso, &c. &c., it will be seen that he took a great interest in the early history of the Israelites.--On August 10th, 1875, Airy celebrated the Bicentenary of the Royal Observatory by a dinner in the Octagon Room, which was attended by the Presidents of the Royal Society and the R. Astr. Society, and by a large number of Scientific gentlemen interested in Astronomy.--In February he was revising his Treatise on "Probabilities."

Of private history: up to Jan. 16th Airy was at Playford as usual.--For about a week in April he was in the Isle of Man with his daughter Christabel.--In June there was a short trip to Salisbury, Blandford, and Wimborne.--On August 12th he started with his daughter Annot for a holiday in c.u.mberland, but on the next day he was recalled by a telegram with the intelligence that a change for the worse had come over his wife's health. Lady Airy died on August 13th, 1875. For the last five years of her life she had been very helpless from the effects of a paralytic stroke--a very sad ending to a bright and happy life--and had been continually nursed throughout this time by her two unmarried daughters with the greatest self-denial and devotion. Her husband had been unremitting in his care and attention. Nothing was wanting that the most thoughtful kindness could supply. And in all his trips and excursions his constant and kind letters shewed how anxious he was that she should partic.i.p.ate in all his interests and amus.e.m.e.nts. From the nature of the case it could hardly be said that her death was unexpected, and he received the shock with the manly steadiness which belonged to him. Lady Airy was buried in Playford churchyard.--From Sept. 22nd to Oct. 4 he made a short expedition to Wales (Capel Curig, &c.).--On Dec. 15th he attended the Commemoration at Trinity College, Cambridge.--On Dec. 22nd he went as usual to Playford.

In this year Airy received the high honour of the Freedom of the City of London, in the following communication:

STONE, Mayor.--A Common Council holden in the Chamber of the Guildhall of the City of London, on Thursday the 29th day of April 1875.

Resolved Unanimously

That the Freedom of this City in a Gold Box of the value of One hundred guineas be presented to Sir George Biddell Airy, K.C.B., D.C.L., LL.D. &c., Astronomer Royal, as a recognition of his indefatigable labours in Astronomy, and of his eminent services in the advancement of practical science, whereby he has so materially benefited the cause of Commerce and Civilization.

MONCKTON.

This Resolution was forwarded with a letter from Benjamin Scott, the Chamberlain. Airy's reply was as follows:

ROYAL OBSERVATORY, GREENWICH, S.E.

_1875, May 1_.

DEAR SIR,

I have the honour to acknowledge your letter of April 30, accompanied with Copy of the Resolution of the Common Council of the City of London pa.s.sed at their Meeting of April 29, under signature of the Town Clerk, That the Freedom of the City of London in a valuable Box be presented to me, in recognition of works stated in the Resolution. And I am requested by you to inform you whether it is my intention to accept the compliment proposed by the Corporation.

In reply, I beg you to convey to the Right Honorable the Lord Mayor and the Corporation that I accept with the greatest pride and pleasure the honour which they propose to offer to me. The Freedom of our Great City, conferred by the spontaneous act of its Munic.i.p.al Governors, is in my estimation the highest honour which it is possible to receive; and its presentation at this time is peculiarly grateful to me.

I have the honour to be, Sir, Your very obedient servant, G.B. AIRY.

_Benjamin Scott, Esq., &c. &c. &c.

Chamberlain of the Corporation of the City of London._

As it was technically necessary that a Freeman of the City of London should belong to one or other of the City Companies, the Worshipful Company of Spectacle Makers through their clerk (with very great appropriateness) enquired whether it would be agreeable that that Company should have the privilege of conferring their Honorary Freedom on him, and added: "In soliciting your acquiescence to the proposal I am directed to call attention to the fact that this Guild is permitted to claim all manufacturers of Mathematical and Astronomical Instruments within the City of London, which is now pleaded as an apology for the wish that one so distinguished as yourself in the use of such Instruments should be enrolled as a Member of this Craft." In his reply, accepting the Freedom of the Company, Airy wrote thus: "I shall much value the a.s.sociation with a body whose ostensible t.i.tle bears so close a relation to the official engagements which have long occupied me. I have had extensive experience both in arranging and in using optical and mathematical instruments, and feel that my own pursuits are closely connected with the original employments of the Company." The Freedom of the Company was duly presented, and the occasion was celebrated by a banquet at the Albion Tavern on Tuesday, July 6th.

The Freedom of the City of London was conferred at a Court of Common Council held at the Guildhall on Thursday the 4th of November. In presenting the gold box containing the Freedom, the Chamberlain, in an eloquent speech, first referred to the fact that this was the first occasion on which the Freedom had been conferred on a person whose name was a.s.sociated with the sciences other than those of war and statecraft. He then referred to the solid character of his work, in that, while others had turned their attention to the more attractive fields of exploration, the discovery of new worlds or of novel celestial phenomena, he had incessantly devoted himself to the less interesting, less obtrusive, but more valuable walks of practical astronomy. And he instanced as the special grounds of the honour conferred, the compilation of nautical tables of extraordinary accuracy, the improvement of chronometers, the correction of the compa.s.ses of iron ships, the restoration of the standards of length and weight, and the Transit of Venus Expeditions. In his reply Airy stated that he regarded the honour just conferred upon him as the greatest and proudest ever received by him. He referred to the fact that the same honour had been previously conferred on the valued friend of his youth, Thomas Clarkson, and said that the circ.u.mstance of his succeeding such a man was to himself a great honour and pleasure. He alluded to his having received a small exhibition from one of the London Companies, when he was a poor undergraduate at Cambridge, and acknowledged the great a.s.sistance that it had been to him. With regard to his occupation, he said that he had followed it in a great measure because of its practical use, and thought it fortunate that from the first he was connected with an inst.i.tution in which utility was combined with science. The occasion of this presentation was celebrated by a Banquet at the Mansion House on Sat.u.r.day July 3rd, 1875, to Sir George Airy (Astronomer Royal) and the Representatives of Learned Societies.

There is no doubt that Airy was extremely gratified by the honour that he had received. It was to him the crowning honour of his life, and coming last of all it threw all his other honours into the shade. To his independent and liberal spirit there was something peculiarly touching in the unsolicited approbation and act of so powerful and disinterested a body as the Corporation of the City of London.

CHAPTER IX.

AT GREENWICH OBSERVATORY FROM JANUARY 1ST, 1876, TO HIS RESIGNATION OF OFFICE ON AUGUST 15TH, 1881.

1876

"At the door from the Front Court to the staircase of the Octagon Room (the original entrance to the Observatory as erected by Sir Christopher Wren), a small porch-shelter has been often desired. I proposed to fix there a fan-roof of quadrantal form, covering the upper flat stone of the external steps.--On a critical examination of the micrometer-screws of the Transit Circle it was found that the corrections, which range from -138" to +076", indicate considerable wear in the screws; and it was found that as much as one-hundreth part of an inch had been worn away from some of the threads. The old screws were consequently discarded, and new ones were made by Mr Simms.--The adjustment of the Spectroscope has occupied a great deal of attention. There was astigmatism of the prisms; and false light reflected from the base of the prisms, causing loss both of light and of definition. The latter defect was corrected by altering the angles, and then astigmatism was corrected by a cylindrical lens near the slit. The definition in both planes was then found to be perfect.--The number of small planets has now become so great, and the interest of establishing the elements of all their orbits so small,--while at the same time the light of all those lately discovered is very faint, and the difficulty and doubt of observation greatly increased,--that I have begun to think seriously of limiting future observations to a small number of these objects.--All observations with the Spectroscope have been completely reduced; the measures of lines in the spectra of elements being converted into corresponding wave-lengths, and the observations of displacement of lines in the spectra of stars being reduced so as to exhibit the concluded motion in miles per second, after applying a correction for the earth's motion. Sixteen measures of the F line in the spectrum of the Moon as compared with hydrogen give a displacement corresponding to a motion of less than two miles a second, which seems to shew that the method of comparison now adopted is free from systematic error; and this is supported by the manner in which motions of approach and recession are distributed among the stars examined on each night of observation. The results recently obtained appear to be on the whole as consistent as can be expected in such delicate observations, and they support in a remarkable manner the conclusions of Dr Huggins, with regard to the motions of those stars which he examined.--Photographs of the sun have been taken with the photoheliograph on 182 days. On one of the photographs, which was accidentally exposed while the drop slit was being drawn up, there appears to be a faint image of a cloud-like prominence close to the sun's limb, though the exposure probably only amounted to a fraction of a second. A prominence of unusual brilliancy was seen with the Spectroscope about the same time and in the same position with reference to the Sun's limb. All groups of Sun-spots and faculae have been numbered, and the dates of their first and last appearances entered up to the present time. Areas of spots have been measured, and the measures have been reduced to millionths of the Sun's visible hemisphere.--The examination of the readings of the deep-sunk thermometers from 1846 to 1873 has exhibited some laws which had been sufficiently established before this time, and some which were less known. Among the former were the successive r.e.t.a.r.dations of seasons in successive descents, amounting to about four months at the depth of 25 feet; and the successive diminutions of the annual range of temperature. Among the latter is the character of the changes from year to year, which the great length of this series of observations brings well to light. It is found that from year to year the mean temperature of the surface for the year, varying by three or four degrees of Fahrenheit, follows in its changes the mean temperature of the atmosphere for the year, and that the changes of annual temperature are propagated downwards, r.e.t.a.r.ded in phase and diminishing in amount of change, in the same manner (though probably not following the same law) as the season changes. The inference from this is, that changes of temperature come entirely from the exterior and in no discoverable degree from the interior; an inference which may be important in regard both to solar action and to geology.

--Referring to the Transit of Venus observations: In the astronomical part of the reductions, there has been great labour and difficulty in the determination of local sidereal times; some books of observations required extensive transcription; some instrumental errors are still uncertain; the latter determinations have perplexed us so much that we are inclined to believe that, in spite of the great facilities of reduction given by the transit instrument, it would be better to rely on the altazimuth for time-determinations.... In the photographic part, I have confined my attention entirely to measures of the distance between the centres of the Sun and Planet, a troublesome and complex operation.--Referring to the progress of the Numerical Lunar Theory: With a repet.i.tion of grant from the Treasury, I have usually maintained four junior computers on this work. The progress, though considerable, has not been so great as I had hoped, by reason of the excessive personal pressure upon me during the whole year.--I wrote a letter of congratulation to Le Verrier on the completion of his great work of Planetary Tables.--On May 13th the Queen was at South Kensington, and I attended to explain the astronomical instruments, and shewed Her Majesty one of the Transit of Venus photographs."

Of private history: He returned from his Playford visit on the 18th of January.--In April there was a two-day trip to Colchester.--From June 13th to July 12th he was travelling in the North of Scotland and the Orkneys with his daughters, staying for a short time with Mr Webster, M.P., at Aberdeen, and with Mr Newall at Newcastle.--In September there was a week's run to Birkenhead and Keswick.--In November a week's run to Playford.--From the 13th to 15th of December he was at Cambridge, and on the 28th he went to Playford for the usual winter stay there.

1877

"In April of this year I was much engaged on the subject of Mr Gill's expedition to Ascension to observe for the determination of the parallax of Mars at the approaching opposition of that planet.--A large Direct-vision Spectroscope has been quite recently made by Mr Hilger under Mr Christie's direction on a new plan, in which either great dispersion or great purity of spectrum is obtained by the use of 'Half-prisms,' according as the incident pencil falls first on the perpendicular or on the oblique face. In this Spectroscope either one or two half prisms can be used at pleasure, according to the dispersion required, and there is facility for increasing the train to three or four half-prisms, though the dispersion with two only is nearly double of that given by the large ten-prism Spectroscope. The definition in this form of Spectroscope appears to be very fine.--At the end of May 1876, spectroscopic determinations of the Sun's rotation were made by observations of the relative displacement of the Fraunhofer lines at the east and west limbs respectively. The results are in close agreement with the value of the rotation found from observations of Sun-spots. A similar determination has also been made in the case of Jupiter, with equally satisfactory results.--An Electrometer on Sir William Thomson's plan, for continuous photographic registration of atmospheric electricity has been received from Mr White of Glasgow. It was mounted in December.--The computation of the photographic records of the barometer from 1854 to 1873 has so far advanced that we can a.s.sert positively that there is no trace of lunar tide in the atmosphere; but that there is a strongly marked semi-diurnal solar tide, accompanied with a smaller diurnal tide. We are at present engaged in comparing the barometric measures with the directions of the wind.--Regarding the distribution of the printed observations: There is no extensive wish for separate magnetic observations, but general magnetic results are in great demand, especially for mining operations, and to meet this a map of magnetic declination is furnished in the newspaper called the 'Colliery Guardian.'--As regards the operations for the Transit of Venus: The computing staff has by degrees been reduced to two junior computers within the Observatory; and one or two computers external to the Observatory, who are employed on large groups of systematic calculations. The princ.i.p.al part of the calculations remaining at the date of the last Report was that applying to the determination of the geographical longitudes of fundamental stations. At the moment of my writing, the last of these (the longitude of Observatory Bay, Kerguelen) is not absolutely finished:... The method of determining the geographical longitude of the princ.i.p.al station in each group by vertical transits of the Moon has been found very successful at Honolulu and Rodriguez. For stations in high south lat.i.tude, horizontal transits are preferable.--As regards the Numerical Lunar Theory: With the view of preserving, against the ordinary chances of destruction or abandonment, a work which is already one of considerable magnitude, I have prepared and have printed as Appendix to the Greenwich Observations (with additional copies as for a separate work) the ordinary Equations of Lunar Disturbance, the novel theory of Symbolical Variations, and the Numerical Developments of the quant.i.ties on the first side of the Equations.--At various times from February to May I was engaged on the reduction of Malta Tides, and on a Paper concerning the same.--In July I was awarded the Albert Medal for my Compa.s.s corrections, and received the same from the Prince of Wales.--In February, Campbell's instrument for the registration of sunshine was introduced: it was mounted in July."

Of private history: "I was at Playford until Jan. 19th, in close correspondence as usual with Mr Christie at the Observatory, and attending to my Numerical Lunar Theory.--From Mar. 29th to Apr. 2nd I went on a short trip to Hereford, Worcester, &c.--From June 8th to 20th I was at Playford.--From Aug. 13th to Sept. 8th Airy was on an expedition in Ireland, chiefly in the North and West, with his daughters. When at Dublin he visited Grubb's instrument factory. On the return journey he stayed for some time in the Lake District of c.u.mberland, and took soundings in the neighbourhood of the place of the 'floating island' in Derwent.w.a.ter."

Airy took the greatest interest in antiquarian matters, whether military or ecclesiastical, and his feelings on such matters is well ill.u.s.trated by the following letter:

ROYAL OBSERVATORY, GREENWICH, S.E.

_1877, February 27_.

DEAR SIR,

I venture to ask if you can a.s.sist me in the following matter.

In the Parish Church of Playford, near Ipswich, Suffolk, was a splendid bra.s.s tombstone to Sir Thomas Felbrigg. By an act of folly and barbarism, almost unequalled in the history of the world, the Inc.u.mbent and Curate nearly destroyed the bra.s.s inscription surrounding the image of the Knight.

This tombstone is figured in Gough's Sepulchral Antiquities, which, I presume, is to be found in the British Museum.

And I take the liberty to ask if you would kindly look at the engraving, and give me any suggestion as to the way in which some copies of it could be made, in a fairly durable form. I am connected with the parish of Playford, and am anxious to preserve for it this memorial of a family of high rank formerly resident there.

I am, dear Sir, Very faithfully yours, G.B. AIRY.

_T. Winter Jones, Esq._

To this request Mr Winter Jones immediately acceded, and the engraving was duly photographed, and copies were circulated with a historical notice of Sir George (not Sir Thomas) Felbrigg and a history of the Monument. Sir George Felbrigg was Esquire-at-Arms to Edward III., and Lord of the Manor of Playford: he died in 1400, and was buried in the North wall of Playford Church.

1878

The Report to the Board of Visitors has this paragraph: "I continue to remark the approaching necessity for Library extension. Without having absolutely decided on a site, I may suggest that I should wish to erect a brick building, about 50 feet by 20, consisting of two very low stories (or rather of one story with a gallery running round its walls), so low that books can be moved by hand without necessity for a ladder.--In the month of December, 1877, the azim.u.t.h.al error of the Transit Circle had increased to 10". A skilful workman, instructed by Mr Simms, easily reduced the error to about 2".5 (which would leave its mean error nearly 0), the western Y being moved to the north so far as to reduce the reading of the transit micrometer, when pointed to the south, from 35r.500 to 35r.000. The level error was not sensibly affected.--The Sidereal Standard Clock preserves a rate approaching to perfection, so long as it is left without disturbance of the galvanic-contact springs (touched by its pendulum), which transmit signals at every second of time to sympathetic clocks and the chronograph. A readjustment of these springs usually disturbs the rate.--To facilitate the observations of stars, a new working catalogue has been prepared, in which are included all stars down to the third magnitude, stars down to the fifth magnitude which have not been observed in the last two catalogues, and a list of 258 stars of about the sixth magnitude of which the places are required for the United States Coast Survey. The whole number of stars in our new working list is about 2500. It may be here mentioned that an extensive series of observations was made, during the autumn, of about 70 stars, at the request of Mr Gill, for comparison with Mars, Ariadne, and Melpomene.--On Apr. 10th last, a very heavy fall of rain took place. Between Apr. 10d. 5h. and Apr. 11d. 2h., 2.824 inch. was recorded, and 75 per cent. of this, or 2.12 inch., fell in the eight hours between 13-1/2h. and 21-1/2h.; and on May 7, 1 inch of rain fell in 50 minutes, of which 1/2 inch fell in 15 minutes.--The supplementary compensation continues to be applied with success to Government chronometers which offer facilities for its introduction, and a marked improvement in the performance of chronometers returned after repair by the makers appears to have resulted from the increased attention now given to the compensation. Of the 29 compet.i.tive chronometers, 25 have the supplementary compensation."--With regard to the reduction of the observations of the Transit of Venus: After reference to the difficulties arising from the errors and the interpretation of the language used by some of the observers, the Report continues thus: "Finally a Report was made to the Government on July 5th, giving as the mean result for Mean Solar Parallax 8".76; the results from ingress and from egress, however, differing to the extent of 0".11.... After further examination and consideration, the result for parallax has been increased to 8".82 or 8".83. The results from photography have disappointed me much. The failure has arisen, perhaps sometimes from irregularity of limb, or from atmospheric distortion, but more frequently from faintness and from want of clear definition. Many photographs, which to the eye appeared good, lost all strength and sharpness when placed under the measuring microscope. A final result 8".17 was obtained from Mr Burton's measures, and 8".08 from Capt. Tupman's.--With regard to the Numerical Lunar Theory: A cursory collection of the terms relating to the Areas (in the Ecliptic) led me to suppose that there might be some error in the computations of the Annual Equation and related terms. A most jealous re-examination has however detected nothing, and has confirmed my belief in the general accuracy of the numerical computations. I dare not yet venture to a.s.sume an error in Delaunay's theory; but I remember that the Annual Equation gave great trouble to the late Sir John Lubbock, and that he more than once changed his conclusions as to its true value.--In February I was engaged on the drawings and preparations for my intended Lecture at c.o.c.kermouth on the probable condition of the interior of the Earth. The Lecture was delivered in April.--At different times in the autumn I was engaged on diagrams to ill.u.s.trate the pa.s.sage of rays through eye-pieces and double-image micrometers.--The miscellaneous scientific correspondence, which was always going on, was in this year unusually varied and heavy."