Pièce GPP/2/3 - Astronomical Journal'

1 volume

Alphabetical index at start, followed by numbering on right-hand pages numbered 1-259.

Index under Z, ‘Citations of my Observations’: citations 1764 to 1771 in Philosophical Transactions, Memoires de l’Academie de Sciences de Paris, Histoire de l’Academie des Sciences de Paris, and Recueil pour les Astronomes ; these refer to eclipses of the sun, the transit of Venus, and meteorological observations at Caen.

SUMMAY AND EXTRACTS:
Page 2, observations and corrections of ‘spring clock by Shelton London at Caen’, September 1764 to February 1765.
Note, ‘placed my astronomical compound pendulum made by Lepaute of Paris in my observatory at the Abbatial at Caen in Normandy November the second 1767’. Observations using this clock taken from 23rd December 1767 to 8th March 1770 continue from page 2 to page 13; pages 3-13 are headed ‘Lepautes clock at Caen’. Note on page 13, ‘Continued Page 116’.

Page 15 is headed ‘Journal 1761’ and ‘Journal 1762’: these pages give details of astronomical reports from Mr Waddington and others from 1761 to 1764, and an observation of the diameter of the sun taken on 31st December 1764. Pages 16-25 are headed ‘Journal’, the year (from 1765 to 1769), and ‘Caen’: these are of astronomical observations including those relating to the comet of 1769 and the transit of Venus of 3rd June 1769 (observations were made by Pigott, his wife, and his son Edward), with reports of the transit from other sources. The last entry in this section is for 26th November 1769. ‘N.B. This Journal Continued Page 117’.

Pages 26-28, ‘Quelques articles utiles Dans La Connaissance des tems publieé tous les ans Par L’academie des Sciences de Paris et dans L’exposition du Calcul astronomique, par Monsr. de La Lande; et dans les memoires de L’academie des Sciences de Paris.’ Index in French of articles 1742 and 1760 to 1771 under headings, ‘Soleil’, ‘Lune’, ‘Etoiles Fixes’, etc.

Pages 29-69 are blank.

Page 70, ‘Observations of Jupiter’s Sattellites at the Refuge of wrowperg [‘Groenendale’ deleted] in Louvain’ taken August 1762 to March 1763 (sample below), with notes of other reports of eclipses of Jupiter’s satellites.

Page 71 blank.

Pages 72-74, ‘Observations of Jupiter’s Satellites at the Abbatiale in Caen’, taken between September 1764 and May 1769; from 1768 these include observations taken by Edward (then 15 years old) using Short’s 18-inch reflector.

Pages 75-113 blank.

Page 114, observations and calculations, : ‘Eclipse of the Moon Novr. 1st 1762 at the Refuge of vrowperg [‘Groenendale’ deleted] at Louvain’, ‘eclipse of the sun august 16th 1765 at the abbatial a caen’, ‘Eclipse of the Sun august 5th 1766 at the abbatial at Caen’, ‘Eclipse of the Sun Jun 3d. 1769 at the abbatial at Caen’. Page 115, comparison of timing of eclipses of 5th August 1766 and 16th August 1765 (a) as observed, (b) as calculated from astronomical tables by M. Desbleds of Caen.

Page 116 blank.

Page 117-244, journal of astronomical observations 1770-1786, including instrument calibration. ‘Continued from P.25’. Commencing in 1770 with observations taken at the Abbatiale in Caen, Normandy, includes reported observations by other astronomers. April 12th, ‘This Day arrived from England my new reflecting Telescope 2½ F: Focal length made by Heath & Wing in the Strand and magnifying as follows: Long or Day Eye Piece with the day or great mettle 220 times / Long or day Eye Piece with small or night mettle 290 Do. / Short or night Eye Piece with day or great mettle 290 Do. / Short or night eye Piece with night or small mettle 360 Do. } See further concerning these magnif: Powers. Page 128’. April 22nd, ‘Em: third Sat: / at 13h..5’..58”,0 by the Clock. Em. Jupiter’s third Sat. Wing’s 2½ Reflector : 5 inches aperture, magnifying 220 times: the weather fine: good observation. / at 13h..5’..27”,0 by Clock. Em. Jupiter’s Third Sat. Short’s 18 Inch Reflector: 4 Inch aperture : mag. 55 times: Exceeding good. Edward’, followed by a calculation to bring this to apparent time.
October 25th, ‘Em. of Jupiter’s Second Sat:
5h..17’..43” by clock. Edward achro: 6 feet.
5h..16’..8” by clock. Mrs. Pigot 18 inch refl. 55 times
5h..16’..42” by clock. Self 2½ reflector 220 times:
The observations Dubious : thin clouds almost always covered Jupiter : the moon on the Horizon : we were none of us quite certain we had seen the Sattellite ; but all of us concurring as to the Situation & other circumstances makes it highly probable we were not mistaken.’, followed by a calculation to convert the times by clock to apparent time.

Page 128, comparison of the magnifying powers of his telescope as it appears ‘to Mrs Pigot, my son Edward and to me’.
In 1771 there is a series of observations with the quadrant.
‘Having at the Request of the Gouvernment at Bruxelles Consented to observe for the Long. and Lat. of Some of the Towns in Flanders’ (page 136), Pigott began by checking his instruments. On the 22nd August he measured the difference of heights of the telescope of his Bird’s 12-inch quadrant in an upright and an inverted position, on the 25th he checked for the error of the line of collimation (in the park, using markers at 600 feet), and on the 26th he set out with Edward and Mr. Needham (John Needham F.R.S., Director of the Academy of Science at Brussels) for Namur.
His instruments are described, ‘1. a Gridiron Pendulum made by Lepaute at Paris. 2. an astronomical Quadrant made by Bird one foot Radius with which all the merd. altitudes were taken. 3. an astro: Quadrant 18 inches rad. with which the Equal altitudes were taken. 4. Two portable Barometers made by Ramsden divided into Inches, 10ths of inches, 5/100 of inches with a vernier dividing ye 5/100 of inches into 50 Parts […] on the face of these instrumts. is adapted a Fahrenheits Thermometer […]. 5. a Portable Barometer made by Wing divided into inches, tenths with a vernier dividing the inch into a hundred parts ; & a thermometer on Fahrenheit’s Scale. 6. a three feet and a half Reflector the focal distance of which is 2 ½ feet made by Wing : the aperture 5 inches & mag. from 150 to 260 times. N.B. the observat: of [Jupiter]’s Sat. by me are made with this Telescope if not otherwise mentioned. 7. a Two feet Reflector the focal distance of Which is 18 inches made by Short : the aperture 4 inches & magnifies from 55 to 200 times. N.B. the observat: of [Jupiter]’s Sat. by Edward are made with this Telescope, if not otherwise mentioned. 8. a Six feet achro: refractor with a Double object glass magnifying 80 times : the Diameter of the object glass 2 4/10 inches made by Dollond to which is adapted a micrometer. the instrument is steadily fixed & has a Polar axis with rackwork to make the wire more parallel to the Equator. 9. a Stout Mahogany Table 2 feet Square which has Strong Screws fastening it to a Strong oak bar which being let into the Stone or brick Sides of the walls of a window has no Communication with the floor & on the first trial at namur was so Steady that Several persons at the Same time Coming to & going from it, did not make the difference on the plumet line or Spirit Level of the Quadrant.’
They set out in August 1772 and took observations in Namur, Luxembourg, Hogstraeten, Ostend, and Tournai, before returning to Brussels in January 1773. There are frequent barometer and thermometer readings; although the thermometers mentioned are in Fahrenheit, the temperature is usually expressed as ‘French .. Therm.’ and appears to be in degrees Reaumur. Mr Needham is not mentioned, except as measuring the distance from the church at Hogstraeten to the house where the observations were being taken. On March 23rd 1773 a set of observations and a calculation are marked ‘N.B. the above by Edwd. I have some doubt about the precision of them’ (p.169). At Louvain on May 29th, ‘Having Settled the observatory at Monsr. De Beriot’s house Called Refuge de vrouwperck rue des Dominicaines I this day took the following altitudes […]’.

Observations then made in Louvain and Brussels. At the end of August 1773 there is a note, ‘N.B. the following observations at Louvain till Oct. 25th by Edward alone ; I being absent.’ In October, ‘all the observations at Bruxelles were made in my house near the Court unless when another place is mentioned.’ April 11th 1775, ‘having Communicated to the R. Acad. of Sciences at Paris the observ. I made in the Low Countries in 1772 and 1773 I this day received a Certificate from the Sd. Acad. by which it appears that having appointed Monsr. Le Monnier et M. Jeaurat to examine the Sd. observ. on their report the Acad. has ordered the obs. to be printed in their Mem. des savants etrangers.’ The following page has an account of an experiment on the line of collimation of a quadrant (page 195), observing stars near the zenith with the face of the quadrant turned alternately to the east and the west. Observations cease in August 1775.

They resume (page 199) in February and March 1777 at Wickhill, near Stow-on-the-Wold (Gloucestershire); observations were made ‘with 2 feet treble object glass achrom. telescope and a Compound Pendulum by Magellan. the Corresponding alt. with my theodolite four inches diameter.’

From August 1777 they are at Frampton House, near Cowbridge (Glamorganshire). ‘The Meridian Zenith Distances there were all taken with my quadrant of one foot & a half Rad. made by Bird as also the Equal altitudes and by Le Paute’s Gridiron Clock’ (p.201). Temperatures now usually expressed as Reaumur. ‘Supplement 1777’ gives timing of 4 immersions in October and November; underneath, ‘Note. for the reduction of the times, see Edward’s Journal. My books not being arrived at Frampton, the obs. in above Supplement were written down in another book and forgot to be inserted in their place’. 27th October 1779, ‘Sent an acct of 3 Double Stars, discovered in the summer, to Dr Maskelyne for R.S.’.

In 1780 the journal is headed ‘York’ (p.229). In May 1781:
‘May / Observatory / it being nearly finished and the transit instrument fixed, I began to observe – the observatory is an octagon of 14 feet; on the ground floor are two Stone pillars each of one Stone, on the most Solid foundation free from all Communication whatever either of the floor or walls of the building ; across these pillars is placed a horizontal large Stone, which receives the two pillars between which is fixed, in the room above, the transit instrument ; these pillars and the Stone above
them are Supposed to weigh above seven Ton. Slits opening both to the North and South from the Zenith to the Horizon are also provided with Meridian Marks firmly fixed on walls in both directions: the Telescope of the Transit Instrument, the axis being two feet, is an achromatic of three feet with an object Glass about four inches aperture made by Dollond – this excellent instrument was made by Sisson – to the pillars is fixed an excellent Quadrant made by Bird of 18 inches Rad. with Telescopes of 2 feet, which can be easily moved from one pillar to the other, a well contrived apparatus of Mr. Smeaton’s invention being adapted to each pillar.’

From this point the temperature, given as ‘Therm.’ uses the Fahrenheit scale. 20th October 1782, ‘Sir Harry Englefield was here : we compared his Barometer Lately adjusted by Ramsden to mine in the observatory marked A made also by Ramsden agree to abt. 2/100 of an inch. Nov. Monday 18 / in Consequence of the above Compared my three Barom. Ramsden’s in the observatory marked A – Ramsden’s in my room marked B and Wing’s in Mrs. Pigott’s room by two observations at an hour’s interval :
A …. 29,956 …. 29,946
B …. 29,904 …. 29,900 Diff. .049
W…. 29,850 …. 29,840 Diff. .106
See Page 222’.

The next entry is for July 1783. Then on 18th August, ‘Obs’d. a Curious Meteor : See the account of it in my letter to Dr. Maskelyne dated 19th Augt. 1783’: on September 23rd he ‘went to Hewit Common to the Spot, where I saw the meteor of 18th Augt. and with the Theodolite took the azimuths, altitude &c. and on the 26th sent Dr. Maskelyne the results and a Scheme of the Same for the R.S. See Calc. among my papers.’

September 28th 1783, ‘ Mr John Goodricke acquainted me that he had deduced the Long. of Brussels from the occultations of Aldebaran made at Brussels and Greenwich Nov. 1st 1773 that it came out east of Paris 8m 15” and by my observ. of [Jupiter]’s Sat. See Phils. trans. 8’7”’. For 1784 the only observations are of temperature for 16th to 24th May (page 238), followed by a note of publications in Philosophical Transactions, volumes 57 to 74. Observations from York resume in January 1785 and continue until 31st July 1785 (page 244).

This is followed by a single side headed ‘Journal 1786 Louvain’. ‘Wednesday 3 May / Transit of Mercury over [Sun] / this observation was made at Le College Royale Rue de Heverle, which may be 1/3 of a Second in time West of Vrouw-park : Monsr. Thysbaert the president supplied me with a Geg. Teles. of 21 inches of length and 4½ which seemed to magnify about 70 or 80 times ; a compound pendulum clock beating dead Second and 18 inches astron. Quadrant ; for the times, which were gotten by Equal alt. of the Sun, for which and other particulars, see my papers of transit of [Mercury]
app. time
H. M. S.

20. 45. 41 internal contact : perhaps a few seconds later
21. 47. 26 Emers. of Centre by estimation
22. 49. 16 external contact
23. 49. 41 [Mercury] certainly clear of [Sun]’

Pages 245 on are blank.

Summary and extracts have been provided by a volunteer.

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