Nevil Maskelyne Research Articles

XI. Extract of a letter from the Rev. John Brinkley, D. D. F. R. S. Andrew's Professor of Astronomy in the University of Dublin, to the Rev. Nevil Maskelyne, D. D. F. R. S. Astro­nomer Royal, on the annual Parallax of α Lyræ

I have now had sufficient experience of my eight feet circle, to be highly satisfied with it, and have arrived at one con­clusion, that it is of importance in astronomy. My observations on α, Lyrae for the purpose of discovering an annual parallax now amount to 47 in number, viz. 22 near opposition, and 25 near conjunction, and the mean of these gives a result of 2,"52 as the parallax of the annual orbit for that star, and I have no doubt that it exceeds 2".

X. Observations on atmospherical refraction as it affects astro­nomical observations; in a letter from S. Groombridge, Esq. to the Rev. Nevil Maskelyne, D.D. F. R. S. Astronomer Royal. Communicated by the Astronomer Royal

Dear Sir, The great advantages we derive from the labours and writings of those learned men, who have preceded us ; the profound researches in physical astronomy by the mathema­ticians of the last century; and the improvements in the con­struction of instruments, effected by the ingenuity of our modern artists: these circumstances should stimulate all those who have inclination and opportunity, to the endeavour of contributing to the common stock of knowledge. I beg leave to add my tribute of admiration to the general voice, for the large share you, Sir, have taken in the promotion of science, not only by your learned publications, but also by the liberal encouragement and assistance you have given to those who have been honoured with your acquaintance. I am, therefore, induced to commit to your protection the inclosed paper, ac­knowledging myself indebted to your friendly communications for much useful information. I could have wished the task had been performed at an earlier period ; but as you are well acquainted with the labour required in the reduction of so many observations by one person, it will appear to have been impracticable. I remain, Dear Sir, Your Obliged and very obedient servant, Stephen Groombridge. To the Rev. Dr. Maskelyne, Astronomer Royal, &c. &c. When I had fixed my four feet transit circle, made by Troughton, it was my intention to make observations of a sufficient number of circumpolar stars, at different altitudes, to ascertain the latitude of my observatory with the greater precision; and also to endeavour to settle the true quantity of refraction: especially as my instrument was better adapted for that purpose, both from the construction and convenient size thereof, than those which had been heretofore made. Being fixed on stone piers, it is not so liable to partial expan­sion, as those instruments which are supported on brass frames: and having both sides divided, with two microscopes to each face; the same observation has the advantage of four made with a quadrant. I have also contrived, by means of sliding shutters in the roof, to prevent the rays of the sun from falling on any part, excepting on the object glass. By these means I flatter myself that, the observations having been made with great care and attention, the result will prove both satisfactory and useful.

IX. On a new property of the tangents of three arches trisecting the circumference of a circle, by Nevil Maskelyne, D. D. F. R. S. and Astronomer Royal

Mr. William Garrard having shewn me a curious property of the tangents of the three angles of a plane triangle, or in other words, of the tangents of three arches trisecting a semicircle, in a paper which I have communicated to this Society, I was led to consider whether a similar property might not belong to the tangents of three arches trisecting the whole circumference; and, on examination, found it be so. Let the circumference of a circle be divided any how into three arches A, B, C; that is, let A + B + C be equal to the whole circumference. I say, the square of the radius multiplied into the sum of the tangents of the three arches A, B, C, is equal to the product of the tangents multiplied together. I shall demonstrate this by symbolical calculation, now commonly called (especially by foreign mathematicians) analytic calculation.

XXII. An improved solution of a problem in physical astronomy; by which, swiftly converging series are obtained, which are useful in computing the perturbations of the motions of the Earth, Mars, and Venus, by their mutual attraction. To which is added an appendix, containing an easy method of obtaining the sums of many slowly converging series which arise in taking

Reverend Sir, Such is the subject of the inclosed paper, and such the repu­tation for skill and industry, which the many valuable papers you have communicated to the Royal Society, and your other learned works, have justly procured to you, that it could not with more propriety be submitted to the judgment of any other person than yourself, even if the writer of it were a stranger to you. But there are circumstances which render my presenting it to you, in some measure, a duty. I had the advantage of being, for some years, your Assistant in the Royal Observatory at Greenwich; during which time, you made the important observations on the mountain Schehallien , in Scotland, which afford an ocular demonstration of the attraction of that mountain, and a strong argument for the general attraction of matter, a subject nearly connected with that of the following pages; and it was from you that I received the problem of which you will here find an improved solution.

XXVI. An account of an appearance of light, like a star, seen in the dark part of the moon, on Friday the 7th of March, 1794, by William Wilkins, Esq at Norwich. In extracts of a letter to the Rev. Samuel Vince, F. R. S. and of three letters to the Rev. Nevil Maskelyne, D. D. F. R. S. and

Letter I. Reverend Sir, Norwich, 17th April, 1794. I received your letter yesterday ; and I am extremely happy in giving you the best description in my power respecting the phenomenon I saw in the moon, on Friday the 7th of March, a few minutes before eight o'clock in the evening. I was in hopes, as it was a bright evening, that some astronomer might observe it, who would have described it in a more scientific manner than I can. The few observations I made were merely to compare with some account I expected and wished to meet in some periodical publication. My friend Mr. Beckwith having the day before told me that I might see Mercury soon after sun-set, I had been looking for that planet from the Castle-hill in Norwich, but was disappointed by a clouded horizon. I mention this merely as the reason of my being led to a more particular notice of the moon also in this evening, having lost the first object of that evening's attention.

XXVII. An account of an appearance of light, like a star, seen lately in the dark part of the moon, by Thomas Stretton, in St. John's Square, Clerkenwell, London; with remarks upon this observation, and Mr. Wilkins's. Drawn up, and communicated by the Rev. Nevil Maskelyne, D.D. F. R. S. and Astronomer Royal

Mr. Vince, Fellow of this Society, having acquainted me by letter, early in April last, that a gentleman at Norwich had a month before seen a bright spot upon the dark part of the moon, and had made a little drawing of it in his pocket-book, which he promised to send to him, I immediately wrote a letter in answer to Mr. Vince, to desire him to request the gentleman to send the drawing he had promised, and a full account of the phenomenon. Mr. Vince accordingly wrote to the gentleman immediately, Mr. William Wilkins, archi­tect at Norwich, which produced the first of the foregoing letters, and addressed by Mr. Wilkins to him, giving a par­ticular account of his observation, with a drawing of the ap­pearance. Soon after, my relation Sir George Booth, Bart, with his lady, being on a visit at the Royal Observatory, upon my men­tioning Mr. Wilkins's observation, Lady Booth said their servant, who is curious for a person in his situation, and fond of looking at the stars, had some time before seen something extraordinary in the moon. Upon this I took occasion, on the 28th of April, to question the man about it, taking care at the same time to direct my inquiries so as to give him no hint of what had been seen by Mr. Wilkins. I immediately minuted down the information he gave me, which was as follows. “Some time ago, about six in the evening, the moon “not being a quarter old, he saw a light like a star, and as “large as a middle sized star, but not so bright, in the dark“ part of the moon. He continued looking at it for a minute “or more, during which time it kept the same light, and he “then lost sight of it by going into the house. He said he “thought it was not the present moon, viz. that which is now “almost gone, and that it was not above seven weeks ago. “He was not, however, certain whether it was three weeks or “seven weeks ago.” I made a drawing of the moon before him, and desired him to direct me about forming the size of the crescent, and laying down the place of the star-like ap­pearance in the dark part of the moon, which sketch I have subjoined to this account. (See Tab. XXI. fig. 3.)

VI. Extracts of two letters from the Rev. Edward Gregory, M.A. Rector of Langar, Nottinghamshire, to the Rev. Nevil Maskelyne, D.D. F. R. S. Astronomer Royal; containing an account of the discovery of a comet, with observations thereon

Extract of the first letter, dated Langar, near Nottingham. January 10th, 1793. I trouble you with this letter to communicate to you such observations as I have made of a comet, which I saw on the 8th instant. The evening of the 8th being very clear, I was employed in my observatory, in taking differences of right ascension and declination between the planet Venus and Aquarii, when, happening to look towards the north-west part of the hemisphere, I saw a star of a hazy appearance, and about the size of a star of the second magnitude, in the space between the flexure of the Dragon and the foot of Hercules, larger and brighter than I had before remarked in that part of the heavens; which excited my attention so much, as to induce me to direct such a telescope to it as lets in much light, and is generally used at sea to see objects in the night. This star seemed to have a hazy and indistinct appearance in the telescope, which immediately led me to suspect it might be a comet; but the twilight yet remaining, I was not quite certain of it. When the night was completely come on, it became evident it was a comet, the coma being of a white light, hazy, and ill defined. I could perceive no nucleus, nor as yet any appearance of a tail. I waited for, and was fortunate enough to obtain, an ob­servation of its passage over the meridian under the pole, at 4 h 8' 30" by Earnshaw's clock, or 4 h 6' 43" sidereal time; its zenith-distance, by Bird's quadrant, being 75° 16' 16". The observation of the passage over the meridian was taken by guessing when a hazy dim appearance, about the shape and size of a hen's egg, was in the centre of the field of the transit instrument; any light, however weak, effacing all the light of the comet.

VII. Observations of the comet of 1793, made by the Rev. Nevil Maskelyne, D.D. F. R. S. Astronomer Royal, and other observers. Communicated by the Astronomer Royal

These places of the comet may admit of some little change, when the stars with which it was compared have been settled by observations with the meridian instruments.

XXXIII. Account of an observation of the right ascension and declination of Mercury out of the Meridian, near his greatest elongation, Sept. 1786, made by Mr. John Smeaton, F. R. S. with an equatorial micrometer, of his own invention and workmanship; accompanied with an investigation of a method of allowing for refraction in such kind of observations; communicated to the

M. de la Lande having announced to some of my astronomical friends the utility of accurate observations of Mercury, at his two elongations the last year, in August and September; I tried to get observations of that planet in crossing the meridian, for some days before and after the greatest elongation in August; and though the state of the atmosphere about that time was not very favourable to the purpose, yet there was one day that I thought unexceptionable, but could not perceive the least appearance of Mercury; at which i was the rather surprised, as I had formerly seen that planet in the like situation, with the same instrument, with perfect perspicuity: and as i did not hear of any one else having succeeded in this observation, I thought it might be very possible for the same disappointment again to happen, with respect to the approaching elongation in September.

XXIII. The latitude and longitude of York determined from a variety of astronomical observations; together with a recommendation of the method of determining the longitude of places by observations of the moon's transit over the meridian. Contained in a letter from Edward Pigott, Esq. to Nevil Maskelyne, D.D. F. R. S. and Astronomer Royal

Sir, The greatest number and variety of observations I have made for determining the longitude and latitude of York will, I believe, settle those points very accurately: I therefore wish to have them presented to the Royal Society, and beg the favour of you to be at that trouble. The instruments I used were a good gridiron pendulum clock, a 2 ½ feet reflector, an eighteen-inch quadrant by Bird, and a transit instrument made by Sisson. The difference of meridians between Greenwich and York was found by the following methods.

II. A series of observations on, and a discovery of, the period of the variation of the light of the star marked δ by Bayer, near the head of Cepheus. In a letter from John Goodricke, Esq. to Nevil Maskelyne, D.D. F. R. S

Sir, The improvements which of late years have been introduced into astronomy, should be attributed not only to the diligence and accuracy wherewith astronomers prosecute their observations and discoveries, but in part also to your exertions, and especially to that kind encouragement which you have, on many occasions, afforded those who make this science their chief study; and I am happy to have this opportunity of acknowledging myself one of those who are much indebted to you in this respect. Under these impressions I thought I could not do better than to address to you the following account of a periodical variation in the star δ Cephei, which I lately discovered. This account will, I presume, be a considerable addition to the few discoveries that have but very lately been made respecting the same subject.

XXI. Observation of the late transit of Mercury over the sun, observed by Edward Pigott, Esq. at Louvain in the Netherlands; communicated by him in a letter to Nevil Maskelyne, D.D. F. R. S. and Astronomer Royal

Sir, We have been fortunate here in seeing Mercury's egress. I observed it thus: Apparent time, May 3. H. M. S. 20 45 25 Mercury's limb in contact with the sun's limb; uncertain.

XXXVI. Observations of the comet of 1783. In a letter from Edward Pigott, Esq. to the Rev. Nevil Maskelyne, D.D. F.R.S. and Astronomer Royal.

Reverend Sir, Having compleated my observations of the comet I discovered on the 19th of November last, I take the liberty of desiring you to present them to the Royal Society. The faintness of the comet's light, and the unfavourable sky you have had in the south, induce me to believe, that few observations of it have been made besides the following.

XXXV. An account of an observation of the meteor of August 18, 1783, made on Hewit Common near York. In a letter from Nathaniel Pigott, Esq. F. R. S to the Reverend Nevil Maskelyne, D.D. F. R. S. and Astronomer Royal

Reverend sir, On the 19th of last August I communicated to you an account of the remarkable fine meteor, which I had seen under circumstances peculiarly favourable the preceding night. I was then preparing myself for a journey into the East Riding; and, on that account, obliged to postpone the verifications, mentioned hereafter till my return. On the 18th of August, about ten o'clock P.P. after a hot day, the weather a little hazy, but not so as to obliterate the stars, and no wind, being on horseback, in company with two other gentlemen, on Hewit Common, about three miles from York, my attention was attracted towards the W.N.W by several faint slashes of lightning, such as are often seen near the horizon, or which may be still better compared to flashes of an aurora borealis.

XXIII. Extract of a letter from the Rev. James Augustus Hamilton, M. A. to the Rev. Nevil Maskelyne, D. D. F. R. S. giving an account of his observations of the transit of Mercury over the Sun, of Nov. 12, 1782, observed at Cook's-Town, near Dungannon, in Ireland

Sir, From the very indulgent eye with which you regarded my astronomical wishes, when I had the pleasure of seeing you at Greenwich, I make no doubt of your pardon for offering my imperfect efforts towards observing the late transit of Mercury.

XXVI. Farther experiments on cold, made at the Macfarlane observatory belonging to Glasgow College. In a letter from Patrick Wilson, M. A. to the Rev. Nevil Maskelyne, D. D. F. R. S. and Astronomer Royal

Dear Sir, Some days of very cold weather, which we had lately in this country, having afforded an opportunity of prosecuting a little farther the experiments and observations begun in the course of last year, I now do myself the pleasure of communicating to you the following particulars, which perhaps may be considered as not unworthy of notice.

XXVI. An account of a most extraordinary degree of cold at Glasgow in January last; together with some new experiments and observations on the comparative temperature of hoar-frost and the air near to it, made at the MacFarlane Observatory belonging to the college. In a letter from Patrick Wilson, M.A. to the Rev. Nevil Maskelyne, D.D. F.R.S. and Astronomer Royal

Sir, The observations and experiments related in the sequel were made here during the great frost in the course of last month. I shall be extremely happy if they contribute any thing to your entertainment, being induced to send you the account in consequence of you having on a former occasion so politely invited me to a further correspondence. If the paper shall appear to you deserving the notice of the Royal Society, you will please to consider it as entirely at your own disposal.

I. Calculations to determine at what point in the side of a hill its attraction will be the greatest, &c. By Charles Hutton, LL.D and F.R.S. in a letter to Nevil Maskelyne, D.D. F. R. S. and Astronomer Royal

Dear Sir, As the experiment of determining the universal attraction of matter, which you lately conducted with so much accuracy and success, is of so great importance and curiosity, that it may probably be hereafter repeated by the learned in other countries, and in other situations; and as the utmost precision is desirable in so nice an experiment; I have composed the inclosed paper to determine the best part of a hill for making the observations, so as to obtain the greatest quantity of attraction.

XXXIII. An account of the calculations made from the survey and measures taken at Schehallien, in order to ascertain the mean density of the Earth.

The survey from which these calculations have been made was taken at and about the hill Schehallien in Perthshire, in the years 1774, 1775, and 1776, by the direction, and partly under the inspection, of the Rev. Nevil Maskelyne, D. D. F. R. S. and Astronomer Royal, by whom the manner of making the survey has already been fully explained in the Philosophical Transaction for 1775.

XI. Astronomical observations made int he Austrian Netherlands in 1772 and 1773. By Nathaniel Pigott, Esquire, F. R. S. Foreign Member of the Academies of Brussels and Caen. In a letter to the Reverend Nevil Maskelyne, Astronomer Royal, F. R. S

Rev. Sir, I received, about a month ago, the favour of your letter, and return you many thanks for the Greenwich observations, which you were so obliging to send me. I wait, with impatience, the publication of your journey into Scotland, which must be very curious and interesting. I beg of you, Sir, to present by respects to the Royal Society, with the inclosed astronomical observations, which I have contracted as much as I well could, consistently with a view of affording means to verify them, or rectify any mistake which, by inadvertency, may have crept in. I shall only add a short account of the instruments I used, and the elements I employed in the calculations, that a proper judgement may be formed, how far these observations may be depended upon.