Pièce GPP/3/3 - Edward Pigott's Astronomical Journal'

1 volume

372 numbered pages, with alphabetical index on pp.3-6. Title has been written on the outside cover of the volume on the wrong side.

SUMMARY AND EXTRACTS:
After the index the book is blank to p.19.

Page 20 has a table headed ‘Interval of the Wires for every Degree of Declination to the 45th’; this gives the difference in seconds between the cross-wires of the transit instrument.

On pp.21-22 is a ‘Description of the Observatory, Instruments and Observations’;
‘Observatory it is situated at the end of our garden, about 200+- yards from the Street ; consists of two Octagon rooms over each other, 14+- feet diameter ; in the upper one is placed all the instruments ; the plan of the building is nearly like that of Mr. Aubert’s, having 4 windows, a Slit in the ceiling for the Transit and two others to the North & South for the Quadrant, which open & shut with the greatest facility – the whole was completed in May 1781.

Pillars
The two Pillars which support the Transit & Quadrant are about 12 feet high 12 inches thick & 20 broad; each of them is composed only of two stones ; they were erected in September 1780 on a most solid foundation, made according to the directions from London, with mortar, bricks, soot &c the floors surrounded them without being in contact, so that the instruments did not appear to be affected by any motion, as jumpping or by carriages passing in the Street.

Transit Instrument, it was made by Sisson in 1777, the axis is two feet & the Telescope three, being a double achromatic, the object glass of which is 2,0 inches, made by Dollond ; magnifys about 50+- times ; the whole is of Brass – in the focus are placed one horizontal & 5 perpendicular wires parallel to each other, and distant about 13” of time at the Equator (see Page 20) ; by means of a moveable eye piece the wires may always be made to appear in the center ; the instrument was ajusted by a good spirit level ; and the Altitude of objects shewn by a semi-circle & vernier which divides a degree into two minutes ; but a much greater exactness maybe obtained by taking stars on the same parallel & attending to the intermediate divisions ; at the end of the Telescope, was a kind of a diaphragm for when the Sun was Observed ; the plates that support the axis are fixed by the means of 4 screws, & the knobs which receive these screws were bored into the Pillars and melted lead poured round them ; the whole is perfectly tight & strong ; the instrument was always kept clean, screen’d from the Sun, & a little oil frequently put on its axis.’

There are further notes on the meridian mark for the transit instrument (on an iron plate attached to the wall of a house 400 yards away), the adjustment of the transit instrument and manner of observing; ‘the manner I observed was thus; I took the second of the Clock & continued reckoning them by hearing the beats, & could in the same time observe & write down the instant of the Star’s crossing each wire, & afterwards look’d at the Clock to see if I was still right ; it hardly ever happened there was a mistake, but if so it was punctually noted down, as also every circumstance, Strictly, without making the least alteration ’.

‘Clock it is a Gridiron Pendulum made by Le Paute at Paris, about the year 1767 ; it was very steadily fixed against the wall ; the following journal & that at Frampton shew its rate of going ; it seems to have had no sudden change, tho’ once or twice it altered its rate by two or three seconds in a few days, which is immaterial where there is a Transit Instrument. {all these memorandums are made in 1786.’ Observations begin on p.23, at York on September 21st 1781.

10th January 1785, against observations of Delta and Rho Gemini, ‘I was disturbed by Fop’s barking violently at a Cat; nevertheless have not the least doubt but the Observations are very exact.’

In July 1785, ‘my Father having left open at night, the upper Slits, a heavy shower of rain completely soused both Transit and Quadrant – but did not I believe get into the Telescope so as to touch the glasses or wires.’(p.73)

In 1786, ‘as we propose staying abroad about two years; the instruments were all taken down, well cleaned, packed up and put in a dry Garret’ (p.76). ‘Returned to York Jany: 5th 1792 after an absence of six years and … months’ (p.77) and between May and August some observations were made to verify the instrument.

In August Edward’s mother died. ‘Since the above observations, I had the misfortune to lose the best of friends and the best of mothers, which took away the pleasure I ever had in Astronomical pursuits until revived again accidentally seeing a Comet’. Observations were made of the comet from the 15th to 22nd of January 1793. ‘… here concludes the Observations made in our Observatory at York; where for the future I do not mean to reside : besides my Father has parted with the lease of his House & consequently removed all his Instruments’.

‘Septr:16-1793 came to Bath […] where the following Obserns: were made with a portable Transit Instt: made by Sisson, that I lately purchased of Sir W. Musgrave. the length of its axis is 8½ Inches ; resting on a frame, supported by a Steel pivot, all of brass well constructed & strongly put together. its telescope, a double achromt. focal length 18 Inches & the diameter of the Object Glass 1 7/8 Inches’ (p.79). The description of the instrument is continued on p.88. Transit observations are from November 1793 (p.80) to June 1796 (p.121). There is a memorandum that preceding meridian marks were too much to the West, due to friction of the index on the circle of altitude (pp.115-116).

Pages 122-372 are blank.

3 slips of paper bearing observations dated 1795 are inserted after p.120.

Summary and extracts have been provided by a volunteer.

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