Astronomers From England

"[U]niversally, the Weights which generate all Tones in Strings, are reciprocally as the Squares of the lengths of Strings of equal Tension, producing the same sound in any Musical Instrument."

"Mr Issac Newton in addition to the geometric figure in any orbit of a projectile sought also to find the measure of the (tending to a given centre) of the body borne in that orbit, from whatever cause that force may arise, be it from a deeper mechanical one or from a law imposed by the supreme creator of all things. He inquires geometrically into the law of centripetal force of a body moved in the circumference of a circle with the force tending to a given point either on the circumference or anywhere outside it or inside it, or even infinitely removed. By the same method he seeks the law of centripetal force tending to the centre of a plane nautical spiral (that is one that the radii cut in a given angle) which will drive a body in that spiral. Also the law of centripetal force that would make a body rotate in an ellipse when the centre of the ellipse coincides with the centre of forces. If the ellipse is changed into a hyperbola and the centripetal force into a centrifugal one the same things apply to the hyperbola. Also the resolution of the same problem when the centre of forces coincides with either focus of the ellipse shows that the law of centripetal force is reciprocally in the duplicate ratio of the distance [as the inverse square of the distance]; others had long before shown that this was the one and only law that would satisfy the other phenomenon observed by Kepler in the motion of the planets. These results also apply to the hyperbola and the parabola when the centre of forces is situated in a focus of the conic section."

"Descartes's cosmic system, which he jokingly called his fable of the world, is shown to be a fable indeed."

"David Gregory’s manuscript ‘Isaaci Neutoni methodus fluxionum’ is the first systematic presentation of the method of fluxions written by somebody other than Newton. It was penned in 1694, when Gregory was the Savilian Professor of Astronomy at Oxford. ...[I]t sheds light upon Gregory’s views on how Newton’s mathematical innovations related to... other mathematicians, both British and Continental. This paper... proves that Newton, far from being—as often stated—wholly isolated and reluctant to publish the method of fluxions, belonged to a network of mathematicians who were made aware of his discoveries. Second, it shows that Gregory—very much as other Scottish mathematicians such as George Cheyne and John Craig—received Newton’s fluxional method within a tradition that was independent from England and that, before getting in touch with Newton, had assimilated elements of the calculi developed on the Continent."

"[T]hose persons seem to apply their thoughts but to a very indifferent purpose in the study of Nature, that overlook this part of Astronomy, from whence the principal and most simple Laws of Nature are to be learn'd."

"... He was among the first Europeans to acquire a working knowledge of a North American language—in this case, —and by means of it to understand and record indigenous culture at the time of first contact with Europeans. Outgoing and amiable, he made friends with the people, hunted and feasted with them, learned their methods of agriculture, canoe building, and fishing, and clearly enjoyed much about their way of life. As a general rule, he recorded what he saw with the detachment of a physicist and the engagement of a linguist and ethnologist, describing rather than judging religious practices and cultural ceremonies that were completely alien to him, and observing in context the details of Algonquian life."

"There is an herb which is sowed apart by itself & is called by the inhabitants Uppówoc: In the it has divers names, according to the several places & countries where it grows and is used: The Spaniards generally call it Tobacco. The leaves thereof being dried and brought into powder: they use to take the fume or smoke thereof by sucking it through pipes made of clay into their stomach and head; from whence it purges superfluous & other gross , opens all the pores & passages of the body: by which means the use thereof, not only preserves the body from obstructions; but also if any be, so that they have not been of too long continuance, in short time breaks them: whereby their bodies are notably preserved in health, & know not many grievous diseases wherewithal we in England are oftentimes afflicted."

"By the end of the 16th century with the work of Viète and especially during the first half of the 17th century in the work of Harriot, Fermat, and Descartes, mathematicians began to treat algebra more symbolically, eventually adopting a notation that readily lends itself to making algebraic computations."

"No physicist could tolerate religious dogma or extremism, but I have found that Christianity provides answers to the deeper questions about life and purpose which are beyond the range of science to answer. To me it is nonsense to claim, as some atheists do, that there is nothing worth knowing that is beyond the range of science. Religion is unfashionable in our current materialistic and consumer society, but I have not found Nobel Laureates to be especially atheistic. Accurate statistics are not available, and atheists tend to make more noise, but I know at least 6 examples amongst living physics laureates who are Christians. Being religious means accepting mystery, but so does physics. Things like quantum entanglement, where I can do something to an electron in the lab, and another electron at the edge of the Universe will respond instantly, are not understandable."

"What we’re finding is that combining human and machine classification gives better results than either on their own – the machines do the bulk of the work, but you still get that human ability to be surprised and to deal with the unexpected. We need to work with our robot colleagues, not see them as competition!"

"I actually wanted to be an astronaut more than an astronomer for a quite a long time. Then I learned this would require I somehow become a US citizen (at the time Brits could not be ESA Astronauts because of the UK’s refusal to fund the human spaceflight part of ESA – although this has recently changed), and I also discovered how much detail I would be required to know about the space shuttle and just how fit I would have to be. I’m not really a detail oriented person, and I’m not that keen on the gym, so I gently switched my goal to becoming an astronomer! This also has the advantage of letting me keep my feet on the ground!"

"I was a big meteor spotting fan, at school, what I really liked to do was meteor counts. So I would lie in the back garden in December for the Geminids or something with a tape recorder and a piece of string, and when a meteor went past I would call out the time on to the tape and hold a piece of string up and measure the length of the meteor and then we’d write all this down and send it off. It was a way of doing science with nothing except eyes, and so I was hooked at that idea that I could do something in the back garden with really simple equipment that could make a contribution to science. If you look at what I do now, where I spend my day job running websites like Galaxy Zoo that get the public involved in doing science with nothing more than a web browser it’s almost full circle, we’ve gone from being in the back garden with a deck chair and piece of string to a web browser but the principle is still the same."

"Bradley, upon his being elected into this professorship, gave up both his livings, and with great joy quitted a situation in which his duty was directly opposite to his inclination. From this time he applied himself wholly to the study of his favourite science, and in the year 1727, he published his theory of the aberration of the fixed stars, which is allowed to be one of the most useful and ingenious discoveries of modern astronomy."

"It had been long observed that the position of the fixed stars were subject to some variations, which in no sort corresponded with the apparent motion of a degree in seventy-two years, which gives the precission of the equinoxes. The late abbe Picard had remarked these variations in the pole star in 1671, but he did not attempt either to reduce them to any settled rule, or to account for them. Dr. Bradley not only verified Picard's observations, but discovered many other variations which had never before been thought of; he found that some stars appeared to have, in the space of about a year, a variation of longitude backward and forward, but without any variation of latitude, that others, varied in latitude, but not in longitude, and others, by far the greater number, appeared to describe, in the space of a year, a small ellipsis, of different degrees of elongation. The period of a year, in which all these motions, so different from each other, were performed, seemed to prove, that they had a connection with the revolution of the earth in its orbit; but the difficulty was to discover in what manner the stars were apparently influenced by that revolution; this was attempted for some time by Mr. Bradley, but without success; at last, however, his sagacity and his diligence surmounted all difficulties, and he found the cause of these seemingly capricious appearances in the successive motion of light co-operating with the motion of the earth round the sun."

"Light had long been supposed to move with a velocity physically infinite, but the late M. Roemer of the Royal Academy of Paris discovered the contrary... But however natural this theory might be, and however well it might be supported, it was then thought too bold, and poor Roemer did not live to see it adopted. It has, however, been since universally a agreed, that the motion of light is successive; and upon this successive motion of light, Mr. Bradley built his explanation of the irregular variations which he had observed in the stars, and which he called their aberation. His theory was this: Let us suppose a series of very small particles, united into a thread, to fall in direction perpendicular to the horizon; and let several of these threads of particles fall at the same time, in he same direction, so as to be parallel to each other, in the same manner as drops of rain in a dead calm. Let us then suppose a tube to be placed in this rain, in a vertical position, and it is manifest that the drop of water which enters the aperture at the upper end of it, will issue at the aperture below, without touching the inside of the tube. But if the tube be moved parallel to itself, though still kept in a position parallel to the direction of the water, it is clear, that this motion of the tube will cause the drop that enters it to touch one of its sides, before it gets to the bottom; and that this contact will happen sooner, in proportion as the motion of the drops is slow, compared with the motion of the tube; and it is easy to demonstrate, that if the motion of the tube, and that of the rain are equal, the drop which falls in the center of the upper aperture of the tube, will come in contact with the inside of the tube, when it has passed down the tube the distance of half its diameter; and, consequently, that the line of its direction will make an angle of five and forty degrees with the axis of the tube: It follows, therefore, that, to prevent the drops of water from touching the inside of the tube, notwithstanding its motion, the tube must be inclined in an angle of five and forty degrees, on the side towards which it moves; and that, if this inclination should be successively made round in the circumference of a circle, the tube would describe round the vertical line, drawn from the centre of its base, a curve, the angle of which would be ninety degrees. But what has been said, with respect to an inclination of the tube necessary to make the drop pass through it... depends upon the proportion between the motion of the tube, and the motion of the drop; and, in proportion as the motion of the drop is greater than that of the tube, the less the tube must be inclined: so that, if the motion of the drop be supposed to be infinite, no inclination at all of the tube would be necessary... In order to apply this theory to the aberration of the fixed stars, we must substitute for the drops of water, uniting into a thread, the rays of light that come from those stars; and, for the tube, which we have supposed to be first at rest, and then in motion, that of the telescope used to determine the position of the stars, which is carried round with the Earth, in its revolution about the Sun; and we must suppose, that the velocity of the ray of light, having a finite relation to the velocity of the Earth's motion, the tube ought to change its inclination, in proportion as that motion changes its direction; whence it follows, that each star must have a series of different positions; or, which is the same thing, an apparent motion in the heavens, which causes it to describe, in the space of a year, ellipses more or less elongated according to its position. From the calculations of this gentleman it follows, that the velocity of light, as fixed by the aberrations of the stars, is the fame with what M Roëmer supposed it to be, and exactly quadrates with the retardation of the eclipses of the first satellite of Jupiter. A new proof of the truth of his hypothesis, if any new proof had been necessary."

"For common purposes we may without sensible error suppose the earth's motion equable and neglect the corrections, and then the rule for the parallax of will be this: Sine lat. : rad. : : cotang. A : cotang. C, or rad : sine lat. : : tang. A : tang. C; then long. star \mp C = long. of λ. Cosine C : cosine A : : semi transverse axis : z. And cosine decl. cosine (ʘ - λ) :: z : x = parallax of right ascension."

"Hitherto we have considered the apparent motion of the star about its true place, as made only in a plane parallel to the ecliptic, in which case it appears to describe a circle in that plane; but since, when we judge of the place and motion of a star, we conceive it to be in the surface of a sphere, whose centre is our eye, 'twill be necessary to reduce the motion in that plane to what it would really appear on the surface of such a sphere, or (which will be equivalent) to what it would appear on a plane touching such a sphere in the star's true place. Now in the present case, where we conceive the eye at an indefinite distance, this will be done by letting fall perpendiculars from each point of the circle on such a plane, which from the nature of the orthographic projection will form an ellipsis, whose greater axis will be equal to the diameter of that circle, and the lesser axis to the greater as the sine of the star's latitude to the radius, for this latter plane being perpendicular to a line drawn from the centre of the sphere through the star's true place, which line is inclined to the ecliptic in an angle equal to the star's latitude; the touching plane will be inclined to the plane of the ecliptic in an angle equal to the complement of the latitude. But it is a known proposition in the orthographic projection of the sphere, that any circle inclined to the plane of the projection, to which lines drawn from the eye, supposed at an infinite distance, are at right angles, is projected into an ellipsis, having its longer axis equal to its diameter, and its shorter to twice the cosine of the inclination to the plane of the projection, half the longer axis or diameter being the radius. Such an ellipse will be formed in our present case..."

"The invention of the telescope, the application of the pendulum to clocks, the invention of the micrometer, the combination of the telescope with the divided arc of a circle, invention of the transit circle by Roemer, with many improvements in minor apparatus, distinctly stamp the [17th] century as a remarkable period of preparation for achievements of the next century. From the standpoint of the modern mechanician the instruments at the Greenwich Observatory in Bradley's time were very imperfect in design and construction, and yet on the observations obtained by his skill and perseverance depends the whole structure of modern fundamental astronomy. The use the quadrant reached its highest excellence under Bradley's management. ... Bradley's observations furnish the data for Bessel's "Fundamenta Astronomiae," and many astronomers have since attempted by reductions to obtain improved positions for Bradley's stars. The value of these observations in the development of modern astronomy can hardly be exaggerated. Their importance in the determination of stellar s increases with the lapse of time, and yet the accuracy of the original observations was far inferior to that obtained in ordinary routine work with modern methods and improved instruments."

"When Bradley's observations of γ Draconis were corrected for abberation, they showed, according to himself, that the parallax of that star could not be as much as 1".0 or that the star was more than 200,000 times as distant from the earth as the sun."

"His friends intended him for the church, and his studies were regulated with that view; and as soon as he was of sufficient age to receive holy orders, the bishop of Hereford, who had conceived a great esteem for him, gave him the living of Bridstow, and soon after he was inducted to that of Welfrie in Pembrokeshire. But, notwithstanding these advantages, from which he might promise himself still farther advancement in the church, he at length resigned his livings that he might be wholly at liberty to pursue his favourite study, the mathematics and particularly astronomy."

"About the fame time the chair of at Oxford became vacant, by the death of the celebrated Dr. Keil; and Mr. Bradley was elected to succeed him on the 31st of October 1721, being then just nine and twenty years old; and his colleague was Mr. Halley, who was professor of Geometry on the same foundation."

"Such is the ingenious Theory of the Aberration, which Mr. Bradley published in the year 1727, and which was received by the whole learned world with the applause that it merited. M. Clairaut, of the acedemy of sciences at Paris, afterwards made this discovery the subject of a Memoir, which he printed in 1737: In this Memoir, he examines the principles on which the Theory of the Aberration is founded, and gives the necessary rules for putting it in practice."

"But before I proceed farther it may be proper to take notice, that since the time when I gave their lordships an account of the near agreement of Mr. Professor Mayer's lunar tables with the observations that had been then made at the Royal Observatory, I have compared several others, which concurred to prove that the difference between the observed and computed places nowhere amounted to more than about one minute and a half; and I find that the difference (small as it is) may yet be diminished by making alterations in some of the equations, whose true quantity could not be determined without proper observations; after making the needful corrections it appeared, by the comparison of above eleven hundred observations taken here since the new instruments were fixed up, that the difference did nowhere amount to more than a minute: it may therefore be reasonably concluded, that so far as it will depend upon the lunar tables the true longitude of a ship at sea may in all cases be found within about half a degree, and generally much nearer."

"Sir, Having long deferred to make any report relating to the observations that were taken at sea by captain Campbell, in the year 1757, which you transmitted to me by order of the lords of the admiralty, I think it necessary to acquaint you, that, upon examining those observations, I perceived that they were not in all respects accompanied with such circumstances as are requisite for forming a right judgment of the accuracy and certainty with which observations proper for finding the longitude at sea by the moon can in fact be taken; for which reason I delayed giving my opinion upon this point till I could have an opportunity of comparing a greater variety of observations, made at different times, and with different instruments: such an opportunity having lately been given me by captain Campbell, who has favoured me with a copy of several observations that were made by him in 1758 and 1759, I now beg leave to lay before their lordships the result of the comparisons which I have made."

"This fundamental and most important article being established upon such full evidence, it remained to be examined within what limits the errors arising from observations actually taken at sea could be contained. In order to determine this point, I computed the ship's longitude from each of the observations made by captain Campbell, and, upon comparing the results of several that were taken near the same time and under the like circumstances, it appeared that in general the observer was not liable to err more than one minute in judging of the apparent contact of the moon's limb and the object with which it was compared. Now this being nearly the same error that would be found to obtain, if the like observations were to be made with the same instruments on land, it may hence be inferred, that in moderate weather the motion of the ship is no otherwise an impediment in this sort of observations, than as it renders the repetition of them more tedious and troublesome to the observer, which yet ought by no means to be omitted; because if each single observation be liable to an error of a minute only, by taking the mean of five or six, the error on this head may be so far diminished as to be of small moment."

"When the year was completed, I began to examine and compare my observations, and having pretty well satisfied myself as to the general laws of the phenomena, I then endeavored to find out the cause of them. I was already convinced that the apparent motion of the stars was not owing to the of the earth's axis. The next thing that offered itself was an alteration in the direction of the plumb-line with which the instrument was constantly rectified; but this upon trial proved insufficient. Then I considered what refraction might do, but here also nothing satisfactory occurred. At length I conjectured that all the phenomena hitherto mentioned, proceeded from the progressive motion of light and the earth's annual motion in its orbit. For I perceived that, if light was propagated in time, the apparent place of a fixed object would not be the same when the eye is at rest, as when it is moving in any other direction than that of the line passing through the eye and the object; and that, when the eye is moving in different directions, the apparent place of the object would be different."

"My Instrument being fixed, I immediately began to observe such Stars as I judged most proper to give me light into the Cause of the Motion... There was Variety enough of small ones; and not less than twelve, that I could observe through all the Seasons of the Year; they being bright enough to be seen in the Day-time, when nearest the Sun. I had not been long observing, before I perceived, that the Notion we had before entertained of the Stars being farthest North and South, when the Sun was about the Equinoxes, was only true of those that were near the solstitial Colure: And after I had continued my Observations a few Months, I discovered what I then apprehended to be a general Law, observed by all the Stars, viz. That each of them became stationary, or was farthest North or South, when they passed over my Zenith at six of the Clock, either in the Morning or Evening. I perceived likewise, that whatever Situation the Stars were in with respect to the cardinal Points of the Ecliptick, the apparent Motion of every one tended the same Way, when they passed my Instrument about the same Hour of the Day or Night; for they all moved Southward, while they passed in the Day, and Northward in the Night; so that each was farthest North, when it came about Six of the Clock in the Evening, and farthest South when it came about Six in the Morning."

"I give all my printed books to Samuel Peach, son of Samuel Peach, in my Will named, and desire that this may be a codicil to my last Will and Testament, and taken as part thereof, as witness my hand, this third day of December. in the year of our Lord 1761."

"I would by no means attempt to infer from hence, that the longitude found by observations of this sort may in all cases be depended upon within one degree; but I beg leave to observe, that whatever extraordinary circumstances may have concurred to produce so near an agreement in this particular case, the event is such as may give reason to hope, however great the difficulties of finding the longitude by this method seem to be, that they are not insuperable, or such as ought to deter those whom it most nearly concerns from attempting to remove them."

"He was nephew to Mr. Pound, a gentleman who is well known in the learned world by many excellent observations, and who would have enriched it with more, if the journals of his voyages had not been burnt at Pulo Condor, when the place was set on fire, and the English who were settled there cruelly massacred... With this gentleman, Mr. Bradley passed all the time that he could spare from the duties of his function; and perhaps he sometimes trespassed upon them; he was then sufficiently acquainted with the mathematics to improve by Mr. Pound's conversation, yet it does not appear that in this study, he had any preceptor but his genius, or any assistant but his labour."

"If we suppose the distance of the fixed stars from the sun to be so great that the diameter of the earth's orbit viewed from them would not subtend a sensible angle, or which amounts to the same, that their annual is quite insensible; it will then follow that a line drawn from the earth in any part of its orbit to a fixed star, will always, as to sense, make the same angle with the plane of the ecliptic, and the place of the star, as seen from the earth, would be the same as seen from the sun placed in the focus of the ellipsis described by the earth in its annual revolution, which place may therefore be called its true or real place. But if we further suppose that the velocity of the earth in its orbit bears any sensible proportion to the velocity with which light is propagated, it will thence follow that the fixed stars (though removed too far off to be subject to a parallax on account of distance) will nevertheless be liable to an aberration, or a kind of parallax, on account of the relative velocity between light and the earth in its annual motion. For if we conceive, as before, the true place of any star to be that in which it would appear viewed from the sun, the visible place to a spectator moving along with the earth, will be always different from its true, the star perpetually appearing out of its true place more or less, according as the velocity of the earth in its orbit is greater or less; so that when the earth is in its perihelion, the star will appear farthest distant from its true place, and nearest to it when the earth is in its aphelion; and the apparent distance in the former case will be to that in the latter in the reciprocal proportion of the distances of the earth in its perihelion and its aphelion. When the earth is in any other part of its orbit, its velocity being always in the reciprocal proportion of the perpendicular let fall from the sun to the tangent of the ellipse at that point where the earth is, or in the direct proportion of the perpendicular let fall upon the same tangent from the other focus, it thence follows that the apparent distance of a star from its true place, will be always as the perpendicular let fall from the upper focus upon the tangent of the ellipse. And hence it will be found likewise, that (supposing a plane passing through the star parallel to the earth's orbit) the locus or visible place of the star on that plane will always be in the circumference of a circle, its true place being in that diameter of it which is parallel to the shorter axis of the earth's orbit, in a point that divides that diameter into two parts, bearing the same proportion to each other, as the greatest and least distances of the earth from the sun."

"Three years after this discovery, by which Mr. Bradley acquired very great reputation, he was appointed Lecturer in Astronomy and Physic, at the Museum at Oxford. He pursued his studies with equal application and delight; and in the course of his observations... he discovered that the inclination of the Earth's axis, upon the plane of the , was not always the same, but that it varied backwards and forwards some seconds, and that the period of these variations was nine years. This period seemed altogether unaccountable, as it could not be supposed to have any thing in common with the revolution of the Earth, which is performed in one year. Mr. Bradley, however, discovered the cause of this phenomenon in the Newtonian system of attraction. The first principle of that system is known to be, that all bodies mutually attract each other in the direct ratio of their masses, and in the inverse ratio of the squares of their distances. From this mutual attraction, combined with motion in a right line, Newton deduces the figure of the orbits of the planets, and particularly that of the Earth. If this orbit was a circle, and if the terrestrial globe was a perfect sphere, the attraction of the Sun would have no other effect than to keep it in its orbit, and would cause no irregularity in the position of its axis; but neither is the Earth's orbit a circle, nor its body a sphere; for the Earth is sensibly protuberant towards the equator, and its orbit is an ellipsis, which has the Sun in its focus. When the position of the Earth is such, that the plane of its equator passes thro' the centre of the Sun, the attractive power of the Sun acts only so as to draw the Earth towards it, still parallel to itself, and without changing the position of its axis, and this happens at the equinoxes. In proportion as the Earth recedes from those points, the Sun also goes out of the plane of the equator, and approaches that of one or other of the tropics; the semidiameter of the Earth, which is then exposed to the Sun, being no longer equal, the equator is more powerfully attracted than the rest of the globe, which causes some alteration in its position, and its inclination upon the plane of the ecliptic; and as that part of the orbit, which is comprized between the autumnal and vernal equinox, is less than that which is comprized between the vernal and the autumnal, it follows, that the irregularity caused by the Sun, during his passage through the northern signs, is not entirely compensated by that which he causes during his passage through the southern signs; and that the parallelism of the terrestrial axis, and its inclination with the ecliptic, will be a little changed. But though the irregularity is now accounted for, we are still at a loss for the cause of its happening in a period of nine years. This difficulty, however, will immediately disappear."

"Some persons in Europe carry their notions about cruelty to animals so far as not to allow themselves to eat animal food. Many very intelligent men have, at different times of their lives, abstained wholly from flesh; and this too with very considerable advantage to their health. … The most attentive research which I have been able to make into the health of all these persons induces me to believe that vegetable food is the natural diet of man; I tried it once with very considerable advantage: my strength became greater, my intellect clearer, my power of continued exertion protracted, and my spirits much higher than they were when I lived on a mixed diet. I am inclined to think that the inconvenience which some persons experience from vegetable food is only temporary; a few repeated trials would soon render it not only safe but agreeable, and a disgust to the taste of flesh, under any disguise, would be the result of the experiment. The Carmelites and other religious orders, who subsist only on the productions of the vegetable world, live to a greater age than those who feed on meat, and in general herbivorous persons are milder in their dispositions than other people. The same quantity of ground has been proved to be capable of sustaining a larger and stronger population on a vegetable than on a meat diet; and experience has shewn that the juices of the body are more pure and the viscera much more free from disease in those who live in this simple way. All these facts, taken collectively, point to a period, in the progress of civilization, when men will cease to slay their fellow mortals in the animal world for food, and will tend thereby to realize the fictions of antiquity and the Sybilline oracles respecting the millennium or golden age."

"The issue [of the Nautical Almanac] for 1774 first introduces Mason's improvements of Mayer's Lunar Tables. The preface written by Maskelyne on July 2, 1772, states: To this Ephemeris are annexed 1220 Longitudes and Latitudes of the Moon deduced from the late Dr. Bradley's Observations. ...The greater part of these calculations were made during Dr. Bradley's Lifetime by himself and his Assistant Mr. Charles Mason; and what was left unfinished has been completed by Mr. Mason since, at the Instance and at the Expense of the Board of Longitude. A Series of Observations this for Number and Exactness far excelling anything of the kind which the World ever saw before... Accordingly the Board of Longitude have thought proper to employ Mr. Mason farther in making the necessary calculations for improving Mayer's printed Tables under my Direction..."

"The last quarter of 's life was spent on projects that grew out of his earlier work at Greenwich Observatory as assistant observer to Astronomer Royal Bradley. From studies of Bradley's records Mason prepared tables for and he was able to improve Mayer's Tables of the Moon by comparing them with the Greenwich records. was established by in 1767, immediately after his appointment as Astronomer Royal, and it has appeared annually ever since. In the first issue the latitude and longitude of are given as found by Mason and Dixon in 1761. The comment follows that "it is probable that the Situation of few Places is better determined." To the Almanac for 1773 Mason contributed a catalogue of stars. The preface, written by Maskelyne, states: To this are annexed... a Catalogue of 387 fixed Stars.... adapted to the beginning of the year 1760... calculated from the late Dr. Bradley's Observations by Mr. Charles Mason, formerly his Assistant. ...After the Catalogue follow some Memoranda... communicated by the same Mr. Mason."

"James Bradley had not published his Greenwich observations. In law they proved to be his personal property, and after his death they were claimed successfully by his only child, a daughter, and her husband, the Reverend Samuel Peach. They in turn gave the records to Oxford University where Bradley had studied and had held the Savilian professorship of Astronomy. The first of Bradley's records to be published was the catalogue of stars that Mason prepared for the Nautical Almanac of 1773. The Clarendon Press of Oxford University undertook the publication of all the records. The first volume appeared in 1798 under the editorship of Professor . It includes Mason's star catalogue. Mason and Hornsby carried on an extensive correspondence about the Greenwich records that undoubtedly aided in preparing them for the press. The second volume, edited by Dr. Abram Robertson, appeared in 1805. Finally in 1832 there was published The Miscellaneous Works and Correspondence of Reverend James Bradley under the editorship of Professor S. P. Rigaud."

"laid the foundation of his career at Greenwich where he worked from 1756 to 1760 as assistant observer to the Reverend James Bradley, Astronomer Royal. Bradley was then near the end of his career... As a young man he had discovered the aberration of light and the nutation of the axis of the Earth and had founded a new era of precise observations. He had enlarged the Greenwich Observatory and equipped it with new instruments. Mason acquired some of the spirit and the ideals of his preceptor and learned from him the use of instruments of precision and the art of observing. At Greenwich Mason made the acquaintance of the Reverend , a young astronomer who was assisting the Astronomer Royal in a study of atmospheric refraction. This association of Mason and Maskelyne continued as long as Mason lived."

"The observations made with the zenith sector at Kew and Wanstead, by the intercomparison of which Bradley was conducted to the discovery of aberration, were at one time supposed to be lost; but having been found among the papers of the late Dr. Hornsby, they were published by Professor Rigaud, in 1832, at the expense of the University, of which the immortal author of the discovery forms one of the brightest ornaments."

"And at Greenwich Mason first learned to know Mayer's Tables of the Moon. ...Bradley first reported on Mayer's Tables on February 10, 1756, and finally on April 14, 1760. With the assistance of Charles Mason, Bradley had compared positions of the Moon as predicted in the Tables with positions as observed at Greenwich. Eleven hundred comparisons led to the comment: So far as it will depend upon the lunar tables the true longitude of a ship at sea may in all cases be found within about half a degree and generally much nearer. It remained to be examined within what limits the errors arising from observations actually taken at sea could be contained. This test was carried out for Bradley by Captain Campbell, of H.M.S. Royal George, on cruises near Ushant in 1758 and 1759. A sextant was made especially for the trials by John Bird, instrument maker for Greenwich Observatory. Bradley's final comment reads: However great the difficulties of finding the longitude by this method seem to be, they are not insuperable, or such as ought to deter those whom it most nearly concerns from attempting to remove them. James Bradley was now nearing the end of his days. His hand was faltering. Nevil Maskelyne and Charles Mason received the torch he had carried. They made the development of the method of lunar distances for finding the longitude at sea a major concern of the rest of their lives."

"He continued... to fulfill the duties [of holy orders]... though at this time he had made such observations as laid the foundation those discoveries which afterwards distinguished him as one of the greatest astronomers of his age. Though these observations were made as it were by stealth, they gained him first the notice, and then the friendship of lord chancellor Macclessield, Mr. Newton, afterwards Sir Issac, and Mr. Halley, and many other members of the royal society, into which he was soon elected a member."

"Seventy years have nearly elapsed since the death of Bradley and the generation of those who knew him has passed away some little however might be expected to remain in traditionary remembrance The rapid course of time would soon have swept away that little and have impaired some of the means which are still in our power for understanding what may exist in written documents It seemed desirable therefore to try what might yet be collected and though it proved to be far short of what could be wished I indulge the hope of its being authentic and accurate."

"The vast mass of observations made by Bradley... two volumes... continued inapplicable to any useful purpose, in consequence of their not being reduced, until... Bessel undertook to execute this task... The results of his labours were published in 1818, at Königsberg, in one folio volume, entitled Fundamenta Astronomiæ pro anno 1755, deducta ea Observationibus viri incomparabilis James Bradley, in specula Astronomica Grenovicensi per annos 1750 1762 institutis. In this work Bessel has determined, by a series of elaborate investigations, the quantity and laws of refraction, the maximum value of aberration, and other fundamental points of astronomy, as deducible from Bradley s observations."

"James Bradley's successor as Astronomer Royal was , who lived only two years after his appointment. Maskelyne succeeded him early in 1765 and thus became the fifth Astronomer Royal at Greenwich."

"Bradley being new in possession of instruments of unequalled perfection, proceeded to execute a series of preliminary observations for the purpose of ascertaining with greater accuracy the latitude of his observatory, the place of the equinox, the quantity and laws of refraction, and other fundamental points of astronomy. In pursuance of this design the brass quadrant was... employed in making observations of s. ...From them Bradley deduced the latitude of the observatory to be 51° 28′ 38½″. He also succeeded by means of them in constructing the elegant rule, so long used by astronomers, for finding the quantity of corresponding to any assigned zenith distance, and any observed readings of the barometer and thermometer. He determined the absolute right ascensions of a few of the principal stars, by means of observations made near the equinoxes, according to the method of Flamsteed."

"The iron quadrant of Graham continued to be attached to the eastern face of the wall erected for its support in 1725, and was employed both by Halley and Bradley in observing the celestial bodies which passed the meridian to the south of the . Bradley however was desirous of extending the plan of his observations and... presented a memorial to the Government in the year 1740, soliciting another quadrant, by means of which the stars that passed the meridian to the north of the zenith might be observed. The Government... at once acceded... and in the following year the observatory was furnished with a magnificent brass quadrant of eight feet radius constructed by Bird, who now took the place of Graham, as the most skilful divider of instruments in his day. ...these were finally subdivided by the micrometer screw to every 1″. The Government at the same time furnished the observatory with a new transit telescope by Bird, eight feet long, besides an excellent clock by Shelton...They also purchased of Bradley the famous zenith sector with which he discovered the phenomena of aberration and nutation, and appropriated it to the use of the observatory. This noble instrument was designed by Bradley to be henceforward employed in determining the errors of collimation of the quadrants, by making observations with it when its face was turned alternately east and west."

"As soon as Bradley had established these fundamental points he removed the brass quadrant from the western face of the meridian wall, and permanently attached it to the eastern face, where it was afterwards employed in observing the stars that passed the meridian to the south of the zenith. At the same time the iron quadrant was removed from the eastern face of the wall, and, after being re-divided by Bird, was attached to the western face, for the purpose of making observations with the telescope turned towards the north. Bradley now commenced the series of admirable observations which have formed the groundwork of so much valuable research to future enquirers, and which would have assured to him an immortal reputation, even independently of those great discoveries with which his name is inseparably associated. The sun, moon, and principal stars, and the planets when situate in favourable positions, were regularly observed with the transit instrument and the mural quadrants. Moreover, a multitude of small stars, chiefly those of Flamsteed's catalogue were included in the plan of observation. From the year 1750 may be dated the commencement of a series of observations which in point of accuracy may bear a comparison with those of modern times. Henceforward the records of Greenwich Observatory embody a collection of materials, which have almost exclusively formed the groundwork of every investigation undertaken in modern times, for the purpose of improving the solar, lunar, or planetary tables."

"James Bradley, the third Astronomer Royal of Greenwich, was born at Sherbourn, in Gloucestershire, in the year 1692. In 1711 he entered Baliol College, Oxford, where he completed his education. Having qualified himself for the church, he was presented to a living in the year 1719. His predilection for astronomical pursuits, which evinced itself at an early age, was fostered by his uncle, the Rev. . with whom he resided for several years at Wanstead, in Essex. In 1721 he was appointed to the Savilian chair of astronomy in the University of Oxford, which had then become vacant by the death of Keill. His nomination by the Government, as successor to Halley in the Observatory of Greenwich, is dated February 2, 1742. His reputation as an astronomer was already well established in Europe by observations of a miscellaneous nature, and more especially by his immortal discovery of the Aberration of Light, and at the time of his appointment he was actually engaged in those researches which resulted in his discovery of the Nutation of the Earth's axis."

"Mr. Rigaud... imparted his discovery to astronomers in a work, containing much valuable information relating to Bradley, published at Oxford in 1832, under the title of "Miscellaneous Works and Correspondence of the reverend James Bradley." This work contains not only the observations made by Bradley at Wansted, but those also which had been instituted at an earlier period by Molyneux at Kew, and continued there by Molyneux and Bradley conjointly. It contains likewise all the data requisite for a complete investigation of the constants of both elements resulting from Bradley's observations."

"Bradley's first object after his removal to Greenwich was to repair the instruments, and carefully to adjust their positions. Halley had confined himself to the use of the mural quadrant soon after its erection in 1725. Bradley, however, resolved to employ both the quadrant and the transit instrument in his observations. The former of these instruments was repaired by Graham, and the latter by Sisson, several important improvements being at the same time effected in their construction. Bradley's first observation with the quadrant was made on the 15th of June, 1742. His earliest transit observation is dated the 20th of July in the same year."

"Bradley, aided by only one assistant, continued with indefatigable assiduity to prosecute his labours at the Royal Observatory, until at length, in the autumn of 1761, he was compelled by the increasing frailties of old age, to retire from the duties of active life. ...he shortly afterwards withdrew to Chalford, in Gloucestershire, where he continued to reside among his wife's relations till his death, which took place on the 13th of July, 1762, having attained the age of 70 years."