The Historical Instruments of Armagh Observatory

John McFarland

Armagh Observatory, College Hill, Armagh,
Northern Ireland BT61 9DG, U.K.

Further information on the history of Armagh Observatory.

1. Introduction

Armagh Observatory and Museum was founded in 1789 by Richard Robinson (1708 - 1794), Lord Archbishop of Armagh and Primate of All Ireland (1765 - 1794). Primate Robinson also founded and endowed other establishments in Armagh such as the Public Library in 1771. The building of an Observatory in Armagh may have been to the Primate a step towards the formation of a University in Ulster, as he had been interested in such an institute (Dreyer 1883a). However, the University did not materialise at that time.

2. Instrumentation

The first Astronomer of the Observatory, Revd. Dr. J. A. Hamilton, was appointed in July 1790, and as an endowment for the Astronomer, Primate Robinson gave twenty acres of land and the estate of Derrynaught. Several instruments, including a Ramsden transit instrument and meridian circle, a Troughton equatorial telescope and three clocks, were ordered at the Primate's expense. However, owing to the Primate's death before receipt of all the instruments, the two Ramsden instruments never came to Armagh (Robinson 1829, p.i). The Troughton equatorial and the three clocks (including Thomas Earnshaw's first two) did arrive. One of these clocks has been described as unusually good (Dreyer 1883b). The then Astronomer Royal, Revd. N. Maskelyne, advised that the clock case should be made as air-tight as possible. Earnshaw, being somewhat apprehensive about constructing a clock (he was a chronometer maker), made his now famous quotation in reply to Maskelyne's request for a clock for Primate Robinson: "I told him [Maskelyne] I had never made a clock, and did not know how many wheels were in one; and asked him, if I were to make one, how near he expected it to go. He [Maskelyne] said, he should not allow more than half a second per day error; I replied, that if the great clock makers, Graham, Harrison, Shelton, Kendal and Arnold, could not make a clock go to half a second per day, what hope had he that I could do it who had never yet made one". However, Earnshaw took Maskelyne's advice and constructed the clock. It was sent for trial to the Royal Observatory in February 1792 (Earnshaw 1808).

The Troughton equatorial, with an aperture of 2.5 inches, was erected in 1795. With it, the declinations of thirty seven standard stars were measured and the results published in the Philosophical Transactions of the Royal Society (Pond 1806).

Compensating for the non-arrival of the Ramsden transit instrument, an Armagh watchmaker, Mr James Waugh, constructed one, and observations with it commenced in July 1793 (Stuart 1819). Some results with this instrument were published in the Transactions of the Royal Irish Academy (Hamilton 1810).

During the season 1794-95, Hamilton employed a 42-inch Dollond refractor to make observations of the Sun's apparent diameter in order to test the relative accuracy of a wire- micrometer and an object-glass micrometer, both by Dollond, with a 10-inch sextant by Troughton (Hamilton 1806).

Dr Hamilton held office until 1815, when he was succeeded by Revd. Dr. W. Davenport. During Davenport's occupation, his assistant, Revd. R. Hogg, continued to use the locally-made transit instrument. Davenport died in 1823 and he in turn was succeeded by Revd. Dr. J. T. R. Robinson, who held office until 1882.

At the commencement of Robinson's term, the Observatory's instrumentation was virtually the same as in 1795. Since there were severe limitations in the use to which the Troughton equatorial and the transit instrument could be put, the then Primate, Lord John George Beresford, ordered a new transit instrument and a mural circle from Thomas Jones of London. The transit instrument was erected in 1827 and the mural circle arrived in 1831. After some improvements were made to the mural circle, and with the aid of an electric chronograph, Robinson commenced measuring the places of certain stars selected from those observed by Lalande (Robinson 1879, Dreyer 1886). With these instruments, Robinson carried out the observations which lead to the publication of the catalogue: "Places of 5,345 Stars observed from 1828 to 1854 at the Armagh Observatorv" (Robinson 1859). In this work, Robinson gives details of the instruments.

A Herschel reflector of ten feet focal length which had been housed under the East dome was replaced by a Grubb reflector of 15 inches aperture in 1835. This equatorially mounted reflector had a clock movement and the first ever three-point floating suspension speculum mirror cell (Grubb 1932). The mounting was constructed as an experimental model of Cooper's equatorial, calculated to bear a 10-foot Newtonian of Sir William Herschel, but was capable of carrying the 15-inch reflector (Robinson 1842).

In 1841, Armagh Observatory was honoured by the gracious presentation by Her Majesty Queen Victoria of part of the King George III Collection of Scientific Instruments, formerly housed at the King's private Observatory at Kew, Surrey. The items sent, and the scenario relating to their journey to Armagh were described by Dr. E. M. Lindsay, a former Director of Armagh Observatory (Lindsay 1969), and include four refracting telescopes, two reflecting telescopes, a Herschel mirror, six clocks, a transit instrument, a brass quadrant, a telescope stand, an equatorial sector, an equal altitude instrument, and a zenith sector.

Following the death of Robinson, Dr. J. L. E. Dreyer, a Dane, assumed the directorship. Dreyer initiated a memorial fund for the purchase of a refracting telescope in memory of Dr. Robinson. This fund reached the sum of 100 pounds and, together with a contribution of 2000 pounds from the Treasury, it became possible to order a refractor of 10 inches aperture from Howard Grubb of Dublin, and have a dome for it constructed. The 10- inch refractor came into operation in 1885 and was used by Dreyer to examine certain nebulae suspected of change (Dreyer 1887, 1891). Also, some objects of uncertain nature were examined during the compilation of "A New General Catalogue of Nebulae and Clusters of Stars" (Dreyer 1888), the catalogue prepared by Dreyer at the suggestion of the Royal Astronomical Society, and which is still universally referred to. Between the years 1888 and 1893, the refractor was used to make micrometer measures of nebulae and adjacent stars (Dreyer 1894). From 1893, observations of double stars, and investigations of systematic errors in transit observations were made (Dreyer 1896a,b).

A Troughton and Simms micrometer-microscope was purchased by a grant from the Royal Society and arrived at the Observatory in 1899 (Dreyer 1910). With this instrument, Dreyer carried out a survey of the stars and nebulae in the galaxy Messier 33, utilizing photographic plates exposed by Isaac Roberts (Dreyer 1904).

In 1919, the then Director, Revd. W. F. A. Ellison, presented an 18-inch Calver reflector to the Observatory. Ellison had acquired this instrument from John Pierce of the Wexford Engineering Works. Studies of stellar spectra were carried out with this reflector. With a grant from the Royal Society, the optical parts of this instrument were converted into a 12"/18" Schmidt camera in 1950 by the firm of Cox, Hargreaves and Thomson, who also provided an electronic synchronised drive. The mounting of the Calver reflector was retained.

Ellison completed a 6-inch refractor in 1921 and mounted it on the equatorial of the 15" Grubb reflector in the East dome. This refractor also employed the clock drive of the 15-inch Grubb reflector.

Under an international agreement involving Armagh, Dunsink and Harvard Observatories, a large southern hemisphere Baker- Schmidt telescope manufactured by Perkin-Elmer came into operation in 1950. The instrument was designed by Professor James Baker of Harvard University and became known as the ADH telescope. The world's then largest objective prism of 33 inches diameter was provided for the telescope through funds from Harvard and The Queen's University of Belfast. The ADH telescope (32"/35.6", f/3.75) was mounted on the Fecker mounting of the 24" Bruce telescope situated at the Boyden station of the Harvard Observatory in Bloemfontein, South Africa. Photographs exposed with this instrument have been used in the study of globular clusters, cluster Cepheids, and the nearby galaxies, the Magellanic Clouds.

In the catalogue we have listed the instruments in approximate chronological order of the date of manufacture. Section A contains the instruments still at the Observatory; Section B contains a list of the instruments no longer at the Observatory for one reason or another, that is, sold, lost or on loan; and Section C contains a listing of instruments not positively identified at present. We have given a brief description of each instrument with maker's name, date and serial number, wherever possible. The King George III Collection of Scientific Instruments has, however, been given fully in Section A (IA1.1-.19) even though several items have been sold or are on loan. M numbers refer to the archives of Armagh Observatory as published by Butler and Hoskin (1987). An asterisk beside the catalogue number means that there is an illustration of the item.

Acknowledgments

This catalogue has been compiled from various Observatory reports, published articles, and manuscripts. Without the dedication and faithful recording of many people throughout the Observatory's history, this catalogue could not have been collated. The Armagh Observatory is financed by the Department of Education for Northern Ireland. I wish to express my gratitude to the Department for the opportunity to carry out this work.

References

Butler, J. & Hoskin, M. 1987. "The Archives of Armagh Observatory",
        Journal for the History of Astronomy, 18, 295.

Dreyer, J.L.E. 1883a. "An Historical Account of the Armagh Observatory", p.3. 1883b. ibid., p.6.

Dreyer, J.L.E. 1886. Second Armagh Catalogue of 3,300 Stars for
	the Epoch 1875, deduced from observations made
	at the Armagh Observatory during the years 1859
	to 1883, under the direction of the late T.R.
	Robinson, DD, FRS, and prepared for publication
	by his successor, J.L.E. Dreyer, PhD, FRAS,
	Dublin, xv, 159pp.
      
	1887. "On some nebulae suspected of variability
	or proper motion", Mon. Not. Roy. astr. Soc.,
	47, 412; "Note on some apparently variable
	nebulae", ibid. 52, 100.
  	     
	1888. "A New General Catalogue of Nebulae and Clusters of Stars",
        Mem. Roy. astr. Soc., 49, p.1 
        (See also "Index Catalogue of Nebulae").
	    
	ibid., 51, p.185 and "Second Index Catalogue of
	Nebulae and Clusters of Stars", ibid., 59,p.105).
  	     
	1891. "Note on some apparently variable
	nebulae", Mon. Not. Roy. astr. Soc., 52,100.
  		   
	1894. Trans. Roy. Irish Acad., 30, pt.13.
  	     
	1896a. Mon. Not. Roy. astr. Soc., 57, 44.
  	     
	1896b. Report of the Astronomer of the Armagh
	Observatory for the years 1883 to 1896, p.5.
	     
	1904. Proc. Roy. Irish Acad., 25A, 3.
	     
	1910. Report of the Astronomer of the Armagh
	Observatory for the years 1897 to 1910, p.3.
 
Earnshaw, T. 1808. "An Appeal to the Public", London.
 
Grubb, H. 1932. Obituary Notice: Proc. Roy. Soc., Ser.A, 135, No.A828, p.iv.

Hamilton, J.A. 1806. Trans. Roy. Irish Acad., 10, 109-117.
       
	1810.	  ibid. 11, 25-44.
       
Lindsay, E.M. 1969. Irish Astron. Journ., 9, 57.
       
Pond, J. 1806. Phil. Trans. Roy. Soc., 453-454.
      
Robinson, T.R. 1829. "Astronomical Observations made at the
	Armagh Observatory", Vol.I, Pt.I.

	1830. "Astronomical Observations made at the
	Armagh Observatory", Vol.I, Pt.II.

	1835. Mem. Roy. astr. Soc., 9, 17.

	1842. Report made at the Annual Visitation of
	the Armagh Observatory, p.5.
	    
	1859, "Places of 5,345 Stars observed from 1828
	to 1854 at the Armagh Observatory", Dublin.
	
	1879. "Places of one thousand Stars observed at
	the Armagh Observatory",Trans. Roy. Dublin Soc.,
	1, Ser.2, 101.
	  
Stuart, J. 1819. "Historical Memoirs of the City of Armagh", 523-527.

Section A

IA1 His Majesty King George III Collection of Scientific
    Instruments presented to Armagh Observatory by Her 
    Majesty Queen Victoria:

.1 8-foot Achromatic Telescope by Peter Dollond of the
   mural circle by Sisson. At the request of Dr Whipple of
   the Kew Observatory Committee this telescope was
   returned to Kew by Dreyer in 1889 - the mural circle
   was in the Science and Art Department of Kew
   Observatory and the telescope completed the instrument.
   It is believed to have been recently moved to the
   Science Museum, London.

.2 Small Journeyman Clock by Shelton. On the advice of
   Professor H H Turner, Savilian Professor of Astronomy
   at Oxford, this clock and items IA.3,.4,.5 were sold
   for 25 pounds to Mr W A F Wetherfield in 1918. Wetherfield's
   collection was sold in 1928 and the two Shelton
   journeyman clocks probably went to the USA.

.3 Large Journeyman Clock by Shelton. Sold to
   Mr Wetherfield in 1918.

.4 Journeyman Clock by Graham. Sold to Mr Wetherfield in
   1918.

.5 Small Clock by Vulliamy. Sold to Mr Wetherfield in
   1918.

.6* Transit Instrument by Adams with its reversing
    apparatus and observing chair. The Adams transit,
    minus its object glass, reversing apparatus and
    observing chair, was loaned to Queen's, Belfast c.1851
    - no trace can now be found of the Adams transit.

.7 Large Astronomical Night Glass - a small short-focus
   telescope for use at night. Loaned to Queen's, Belfast
   c.1851. No trace can now be found of it.

.8* Astronomical Clock by Recordon. c.1762.

.9* 3.9-inch Achromatic Telescope on stand in case.
    Loaned to Queen's, Belfast c.1851, returned to
    Observatory minus its object glass and eyepieces.

.10* Mean Time Astronomical Clock by Shelton. Used by His
     Majesty King George III to obtain the exact time of the
     transit of Venus in 1769.

.11* 6-inch Reflector by Thomas Short, London. 1745.
     2/1371 = 24, 2 feet focal length.
     Includes 5 eyepieces, 1 slide filter, and angled
     mirrors. Used by His Majesty King George III to
     observe the 1769 transit of Venus. This telescope
     could be adapted to Newtonian, Cassegrain and Gregorian
     systems. M92.2 contains an old page of
     instructions for using the telescope, possibly by 
     Short.
	 
.12* 2-foot Gregorian Reflector.

.13* Brass Quadrant by J. Sisson, London. 20-inches radius.
     Has diagonal divisions, a telescope and a plumb-line.
	     
.14* Herschel Newtonian Mirror. 9-inches aperture, 10-feet
     focal length. Reputed to have been made with peculiar
     care for His Majesty King George III.

.15* 8-foot Achromatic Telescope by Peter Dollond? with
     eyepiece, but no objective.

.16* Trial Telescope Stand.

.17 Equatorial Sector by Adams.

.18* Equal Altitude Instrument by Sisson.

.19 Zenith Sector by Sisson. 4.25 inch objective by Peter
    Dollond, 12-feet focal length.

IA2* Brass Astrolabe (Ring dial)

IA3* Astronomical Clock by Mudge and Dutton, c.1785.
     This is the so-called Buchanan clock.
     This clock had been placed in the West dome of the
     Observatory. Loaned to the Dean and Chapter of the
     Church of Ireland Cathedral, Armagh. A clock by J. Crosthwaite
     was substituted for the Mudge and Dutton clock.
     (Observatory Minute Book 3/9/1844, p.38).

IA4* Astronomical Clock by J. Crosthwaite, Dublin. c.1780s.
     The clock was constructed for Dr Ussher of Dunsink
     Observatory. On Ussher's death it was purchased for
     Armagh Observatory for 40 guineas. The clock has rubied
     pallets, an eight-day movement, and rated at mean solar
     time. This clock was attached to a stone pillar in the
     passage to the transit room. (see Earnshaw's
     Astronomical Timepieces, M129)

IA5* Refractor by John Dollond. 42-inches focal length.
     This refractor was used by Dr. J. A. Hamilton to make a
     series of measures of the Sun's apparent diameter in
     1794-95, in order to test the relative accuracy of a
     wire-micrometer and an object-glass micrometer (both by
     Dollond). See Trans. Roy. Irish Acad., 10, 109-117.

IA6 Astronomical Clocks by Thomas Earnshaw. c.1792.

.1* The transit clock, Earnshaw's first ever long-case
    clock, is described by him in his "Appeal to the
    Public" in 1808, where he states his claim to a
    national reward for his contribution towards the
    solution of the determination of longitude problem.
    In manufacturing the clock, Earnshaw employed devices
    used in chronometer making, among which were the use of
    high numbers, small teeth, large amount of jewelling,
    and a small angle of escape, 0.5 degrees in the (Graham)
    escapement. On the advice of the then Astronomer
    Royal, Revd. N. Maskelyne, he made the case as nearly
    air-tight as possible. The clock originally had a 9-
    bar gridiron pendulum of alternate steel and brass
    rods which was replaced in 1830 by a mercurial pendulum
    made by Mr Sharp, Sen., of Dublin. Compensating
    barometers were added to the pendulum in 1832 to
    endeavour to correct for the effects of varying
    atmospheric pressure. These barometers were removed
    in 1835.
    
    Extracts from M129: "The clock has an 8-day movement,
    with finely jewelled pallets and pivot holes. The
    winding is effected through a valve in the glass front,
    which when its index points downwards is closed air-
    tight; when the key with a bit of buff leather on its
    shank is put into the winding hole, and a compressing
    spring from the case brought to bear on it by turning
    the index of the valve up; the key will run in on the
    axis of the barrel, when the clock is wound, the key is
    only to be withdrawn till a circular scribe on the
    shank becomes visible - then the index of the valve is
    to be brought back to its downward position, before the
    key is to be intirely removed. The case is made
    extremely strong and with great care and attention to
    make it as airtight as possible - which is effected by
    laying all the necessary opens with waxed cloth, and
    screwing all home by a great many screws with milled
    heads".
    
A6.2* Earnshaw's second clock has a 5-bar compensation
      pendulum of steel and zinc, an 8-day movement, rated
      at very nearly sidereal time. Its pallets and some of
      the pivot holes are jewelled.

IA7* Theodolite by Dollond. In case.
   			
IA8 Object-glass Micrometer by Dollond? c. 1790s.
    2-inch aperture.
	       
IA9* Equatorial Telescope by E. Troughton. c. 1795.
     2.75-inch aperture, 3-feet focal length.
     The Troughton equatorial arrived in December 1795 and
     was mounted, in the English style, under the south
     dome on two stone piers resting on a massive pillar,
     round which the staircase of the dwelling house winds.
     There is no polar axis, but the right ascension circle,
     4 feet in diameter, is attached to the polar pivots by
     four stays. The declination circle is of the same size
     and is similarly attached by stays to two pivots, which
     turn in Y's fastened to the right ascension circle. A
     description of the instrument appears in Dr. Rees's
     Cyclopaedia,
    
     The equatorial was used for general observations and to
     measure the declinations of standard stars (see J.
     Pond, Phil. Trans. Roy. Soc., 453-454, 1806). The
     correction of observations made with equatorial
     instruments was the subject of a study by T. R.
     Robinson the results of which were published in the
     Trans. Roy. Irish Acad., 15,3, 1825. The instrument
     was also employed by R. Finlay in the rocket
     experiments to determine the distance between Armagh
     and Dublin in 1838 (see T.R. Robinson, Trans. Roy.
     Irish Acad., 19, 121, 1839).
	 
     A comment by T.R. Robinson in 1844 on the condition of
     the instrument is worth noting: "The West equatorial while in the 
     hands of Mr. Troughton was injured by a frost which condensed on 
     it moisture charged with the sulphorous vapours of the London smoke,
     and spotted it all over. I fear this change has increased with time,
     and may at last corrode the brass to some depth. I would therefore 
     suggest that it should be painted and varnished, which has been 
     found sufficient to arrest such an injury in other instruments".

AI10* Meridian Marks.
      J.A. Hamilton was responsible for the original marks. From the
      Observatory Minute Book for 6 Oct 1848, p.2:
      South meridian mark repaired, substituted a massive iron ring for
      the former copper one. The north mark, a light arch, is singularly
      so chosen for a purpose where the utmost steadiness is required.

IA11* Sextant by Dollond with case.
      Containing two lenses, one lens cap and three filters.
	
IA12* Refractor by Dollond, London.
      No object glass, one internal eyepiece lens, internal diameter of
      mahogany tube: 2.75 inches.
	
IA13* Refractor by Dollond, London.
      2.75 inch object glass, tripod stand, no eyepiece.
	
IA14* Pocket telescope.
      1.5 inch diameter, with 4 eyepiece lenses on small turret wheel.
	
IA15 Metal rod. 18 inches long.

IA16 Two connected metal rings.

IA17* Part of Pyrometer by J. Whitehurst, Derby.

IA18* Barometer by P. Newman, 122 Regent St., London.

IA19* Celestial Globe on Stand by H.&L.H. Bardin. c.1800.
      18" diameter.

      The inscription reads: To the Rev. Nevil Maskelyne, DD,
      FRS Astronomer Royal this new British Celestial Globe
      containing the Positions of nearly 6000 stars,
      clusters, nebulae, planetary nebulae, &c. correctly
      laid down to the present period from the latest
      observations and discoveries by Dr Maskelyne,
      Dr Herschel, The Revd. Fr. Wollaston, &c. &c.
      respectfully dedicated by his most obedient humble
      Servants H.&L.H. Bardin.

      Sold by W. & S. Jones, Holborn, London.

IA20* Celestial Globe by J. & W. Cary.

IA21* Brass Orrery by Gilkerson and Co., Tower Hill, London
      c. 1810.

IA22* Two Terrestrial Orreries.

IA23* Equatorial Theodolite by G. Adams, London.

IA24* Gregorian Telescope by G. Adams.
      No.60.

IA25* Portable Altazimuth Telescope by Gilkerson & Co.
      2" aperture.

IA26* Transit Instrument by Thomas Jones. 1827.
      3-inch aperture, 63 inches focal length.
      This instrument was described by T.R. Robinson in the
      Armagh Observations for 1828 and 1829.
      Power of instrument: 120 diameters, changed in 1840 to
      195 diameters.

      "The transit was supported by piers of Armagh marble,
       6' high, 24" by 18" at their base, 12" by 18" at top,
       secured by cement and bronze dowels to a block of the
       same marble, 6' by 5' and 10" thick.
        
       A small circle made by Mr. Gardner and divided by Mr.
       Grubb has been attached to the axis of the Transit.
       The tube and the cones of the axis are connected by
       tension-screws, as described by Sir James South (Phil.
       Trans. Roy. Soc., 1826, Pt.III, p. 423); the braces
       shown in his figure are not applied. The axis is 30"
       long, and the central ball 9" in diameter. The pivots
       are 1" diameter, of bell-metal. The instrument has, at
       the eye-end, Troughton's altitude circles, but a circle
       8.5" diameter, was later attached by Grubb of Dublin,
       to the perforated end of the axis, in 1844. The Y's
       are carried by strong semicircular disks of brass 13"
       diameter and 1" thick, let into the piers flush with
       their surface. The adjustment for level is made at the
       western Y by check-nuts on a screw; that for azimuth at
       the other Y. The surfaces of the Y's are inclined at
       60 degrees instead of 90 degrees, to reduce the effects of friction,
       and are faced with Brazil pebble. The counterpoise
       levers were originally similar to those which Troughton
       had applied to the Greenwich transit, however, they
       were seen to be unsuitable. The rollers were removed
       from the annular levers and replaced by gibbets, from
       which were suspended Y's, faced with agate, to take the
       projecting parts of the pivots". In October 1832,
       Thomas Jones came to Armagh to re-divide the circle,
       and Robinson availed himself of the opportunity to have
       the pivots reground. The pivots were again examined on
       25 May 1839 on the occasion of a visit by Mr Dent.
        
       The Transit Instrument and Jones Mural Circle were used
       by Robinson to compile the publication: "Places of 5345
       Stars observed from 1828 to 1854 at the Armagh
       Observatory". The main purpose of this catalogue was
       to re-determine the positions of the stars observed by
       James Bradley in the middle of the 18th century, to
       which a number of other stars, chiefly from Lalande,
       had been added. Several special investigations were
       also entered into, such as the determination of
       longitude of the Observatory by chronometers, rocket
       signals and other methods (see Mem. Roy. astr. Soc.,
       4, 293-304; Trans. Roy. Irish Acad., 19, 110-146).
       
IA27* Mural Circle by Thomas Jones. 1831.
      Diameter: 56"; 3-inch aperture telescope of 63" focal
      length.
      The telescope was a duplicate of that of the Jones
      transit instrument. This instrument was described by
      Robinson (see Mem. Roy. astr. Soc., 9, 1835) where he
      mentions the peculiar shape of the pier: "built of
      Armagh marble, joggled together, and cemented with
      mortar of marble lime and Loughneagh sand, which in a
      few years attains the hardness of compact limestone.
      The bracing circle is continuous and clasps each radius
      rather than being screwed to it. The axis is 36" long
      with steel pivots. The motion-wheel, a uniform plate
      of copper, is 55.5" extreme diameter. The reading
      microscopes are of unusual size, being 24.5" from the
      micrometers to the object glasses which are triple
      achromatics by Tulley of 0.75" aperture and 7" focus".
       
      Robinson composed a paper on the constant of refraction
      from observations with this instrument (see Trans. Roy.
      Irish Acad., 19, 177, 1843).
       
      In 1848, Robinson formulated the plan of converting the
      mural circle into a transit circle, by adding to it a
      second axis supported on a pier, and substituting a
      telescope of larger aperture (7") and about the same
      focal length as the original telescope. The new
      telescope was made by Thomas Grubb of Dublin and was
      attached to the circle, but without a second pier. Two
      small collimators were mounted in the same room on iron
      pillars, north and south of the circle. These
      improvements were completed in 1862 and a new series of
      observations of stars selected from those observed by
      Lalande at the close of the 18th century was then
      commenced.

IA28 Eyepiece with attached micrometer by Thomas Jones.
     For use with the transit instrument or mural circle?

IA29 Range-finder telescope by Thomas Jones.
     1-inch aperture with scale along length of tube.

IA30* Syphon Barometer Pendulum by Romney Robinson.
      Used to correct the clock rate for changes in the
      atmospheric pressure (see Mon. Not. Roy. astr. Soc.,
      2, 40, 1831).

IA31* Discharge Tubes.
      Set of six intricately-made discharge tubes.
        		
IA32* 15-inch Newtonian-Cassegrain Reflector by Grubb. 1835.
      This telescope was made by Thomas Grubb of Dublin and
      was equatorially mounted, with clock movement, under
      the East dome. The mirror was of speculum metal. The
      Earl of Rosse made and presented the Observatory with a
      duplicate of the mirror in 1843. In the Observatory
      Minute Book for 1843 it was noted that two micrometers
      were applied to the declination circle, its cast iron
      axis was replaced with a stronger one, and a machine to
      polish the specula was completed. The mirror cell
      was, it is believed, the first ever to employ a
      compound triangular system of balanced levers to
      support the main mirror (see Proc. Roy. Soc., 135,
      p.iv, 1932 and H.C. King in 'The History of the
      Telescope', Griffin & Co., 1955). T.R. Robinson spoke
      well of this telscope as the resolving power was good
      enough to separate some difficult double stars (see
      Phil. Trans. Roy. Soc., 159, 132, 1869). The mirror
      was re-figured in 1871 by Grubb. A good observation of
      the 1882 transit of Venus was obtained (see Copernicus,
      3, 18, 1882). The only parts of the instrument
      remaining at the Observatory are parts of the clockwork drive,
      the mirror cell, secondary mirror (3-inch diameter), and
      equatorial mounting.
           
IA33* Celestial Globe on stand by W. Newton, Son & Berry.
      1836. 16-inches diameter, with compass points at base.
      The inscription reads: Newton's new and improved
      Celestial Globe, on which all the Stars are taken from
      the elaborate and most improved Catalogue of Piazzi,
      the Nebulas from Bode and the Double Stars and those
      with proper motions from South. The Right Ascensions &
      Declinations of the whole having been recalculated and
      accurately laid down for the year 1840. By Mr W Newton.
      Manufactured by Newton, Son & Berry, Chancery Lane,
      London. Published 1st May, 1836.
 
IA34* Brass Draw-tube of telescope with graduated circle.
      No lenses, 1-inch thread for eyepiece, diameter of
      main brass tube: 3-3/16 inches, total length 22".
      Part of Tulley telescope?
 
IA35.1* Cup-anemometer by Munro. 1846.
 	The Robinson Cup-anemometer was first erected on the
 	roof of the Observatory in 1846. However, regular
 	meteorological observations had commenced in 1833. In
 	1867, when the Board of Trade decided to establish
 	seven first class meteorological stations throughout
 	the British Isles, where complete sets of self-
 	recording instruments, working by photography, should
 	be in action day and night without interuption, Armagh
 	Observatory was selected as one of the stations. From
 	a note in the Observatory Minute Book, the clock work
 	of the registry of the anemometer had been in action
 	since March 1847. A description of the anemometer
        appeared in Trans. Roy. Irish Acad., [1850], 22, Pt.1,
 	Science, 155, 1855. The results of Robinson's
 	researches into the constants of the cup-anemometer
        were given in Phil. Trans. Roy. Soc., 169, 777, 1878
        and 171, 1055, 1880.

2* Wind-speed Recorder by R.W. Munro, London. 1870.
   Serial number 11.

IA36* Orrery by Phillips. c. 1840s.

IA37 Two finder telescopes.

IA38* Micrometer.

IA39* Clock Drive Governor in square-pyramid box.

IA40 Part of pendulum.

IA41 Concave mirror in mount.

IA42 Two lenses in brass mounts.

IA43 2" diameter Lens in mount, surfaces ground.

IA44* 4" diameter Split-lens in brass mount.
      T. Blunt, London.

IA45 Eyepiece holder. 1-5/8" diameter and 3" diameter.		 

IA46 Eyepiece mount, push fit tube, 1" diameter.

IA47 Eyepiece holder. 3-5/8" diameter thread, 6.75" long.

IA48 Self-centring eclipse carriers for slides.
     R.R. Beard.

IA49 1/lO" Wollaston Doublet.

IA50* Box containing bronze cylinder and glass screen.

IA51 4" diameter condenser lens.

IA52 4" diameter lens in metal holder.

IA53 4" diameter lens.

IA54 Metal flange. 7" diameter.

IA55* Thermometer by Troughton and Simms.
      "Gift of General Sabine" written on reverse.

IA56 Eyepiece, 1" diameter lens in 2" diameter tube, 4" long
     with lamp inside, terminals at front end, lens off-set.
  
IA57 Condenser lens in brass mount. 3-7/8" diameter.

IA58 Micrometer eyepiece with saw-tooth slide.
     7/8" diameter, 7" long.

IA59 Eyepiece holder. 1" diameter, 5" long.

IA60 Eyepiece, brass tube with one lens.
     1-9/16" diameter lens, 2" long.

IA61 Draughtsman's rule by Ertel & Sohn in case.
     13" long.

IA62* Object Glass, 7" diameter.

IA63* Electric Chronograph by Knoblich of Altona. 1865.
      In 1865, T.R. Robinson purchased and presented to the
      Observatory this electric chronograph for registering
      transits proving of great value in increasing the
      accuracy of the work. The clock movement was altered
      by Grubb in 1868. As a specimen of the work, Robinson
      published in 1879 the "Places of One Thousand Stars
      observed at the Armagh Observatory" (see Trans. Roy.
      Dublin Soc., Ser.2, 1, 101, 1879).
		    
IA64* Heliostat. c.1871
      6.75 inches in diameter, mirror: 1-7/8 inches diameter.
	
IA65* Two thermometers. (Inv.No.275)

IA66 18 inch Reflector by G. Calver. 1883
     This reflector was made for Colonel Tupman of Harrow at a cost
     of 800 pounds. John Pierce of the Wexford Engineering Works
     bought it for 200 pounds to replace his 8 inch Wray refractor.
     It was later given to Revd. W.F.A. Ellison, a former Director of
     the Observatory, as a gift. Ellison handed over the telescope
     to the Observatory by a deed of gift made on the 3rd January 1919. 
     Ellison lightly re-figured the mirror and made some studies of
     stellar spectra with it.
	
IA67.1*	10 inch Equatorial Refractor by Grubb. 1885.
	Dr. Dreyer started a fund to set up a telescope in T.R. Robinson's
	memory. The fund reached the sum of 100 pounds. With this and a grant
	of 2000 pounds from the Government, the 10 inch refractor and a dome
	for it were purchased. The telescope was mounted on 28th July, 1885
	and regular work with it began in September 1885, the first programme
	involving a re-examination of some nebulae which had been suspected 
	of change (see Dreyer, Mon. Not. Roy. astr. Soc., 47, 412, 1886).
	After 1893, micrometrical measurements of double stars, together with
	occasional work on phenomena such as the 1895 transit of Mercury were
	carried out (see Mon. Not. Roy. astr. Soc., 55, 213, 1895).
	W.F.A. Ellison was assisted by his son Mervyn, later Director of
	Dunsink Observatory, in double star observations. The pairs in Holmes'
	and Sheiner's catalogues were re-examined. Results were 
	published in Mon. Not. Roy. astr. Soc., 85, 1021,
        suppl., 1925; 87, 465, 1927; 89, 138, 1928. During the
        course of this work, Ellison discovered a number of new
        double stars. One of the most energetic stellar
        flares ever observed was seen by Dr A D Andrews with
        this telescope in 1969 - it may still be a record to
        this day (see "Out of the Zenith: Jodrell Bank 1957-
        1970" by B. Lovell, Oxford University Press, 1973; and
        Nature, 222, 1126 & 1129, 1969).
              
IA67
.2* Filar Micrometer by Grubb. 1885.
    This micrometer was presented to the Observatory by
    Grubb as a contribution towards the Robinson Memorial
    Fund set up by Dreyer. It was for use with the 10"
    Grubb refractor.
 
.3* Small Micrometer for use with 10" Grubb refractor.
 
IA68* Micrometer by Troughton & Simms, London, in case.
      With three lenses and two filters.
 
IA69 Electric photo-lantern.
     Butcher.

IA70 Box with filter on projecting tube.
     Filter diameter: 7/8".

IA71* Thermometer on ivory mount by J. Newman, London.

IA72* Chronometer by W.B. Crisp, London. c.1891.
      Serial number 8038

IA73* Micrometer-microscope by Troughton & Simms. 1899.
      The Royal Society provided 70 pounds towards purchasing this
      measuring machine. A survey of the positions of all
      stars and other objects within 25 arc minutes of the
      centre of the spiral galaxy in Triangulum, Messier 33,
      was conducted using photographic plates exposed by
      Isaac Roberts (see Proc. Roy. Irish Acad., 25A, 1904).
       
IA74* Pocket Barometer and Altimeter.
      Thomas Armstrong & Bros., Manchester and Liverpool.

IA75* Meridian Calendar. Late 19th century.

IA76* Pocket Watch. Early 20th century.

IA77 Henry Draper Eyepiece.
     1" aperture, 2" long.
     Believed to be an eyepiece used in the compilation of
     the Henry Draper spectral classification catalogue.

IA78* Binocular Microscope.
        		 
IA79 6" Refractor by W.F.A. Ellison. 1920.
     In 1921, Ellison mounted this refractor in the east
     dome, the equatorial and clock drive being those of the
     15" Grubb reflector which had been there since T.R.
     Robinson's day.

IA80* Astro Compass in case.
       MK2 GA/1174 2-4

IA81* Ship's navigation equipment.
      Model: BETEC 9.
       
IA82* Mechanical Calculator.
      Brunsviga, Model No. 20, Serial No. 260075.

IA83 Lena, mount and filaments.
     Short Lens Type G.45. Ref. No. 14A/1399*.

IA84 Mercury contact.

IA85 Stopwatch 1/10 sec.
     VC/2534, Serial No. 12509.

IA86* Armagh-Dunsink-Harvard Telescope.
      32"/35.6", f/3.75 Cassegrain Schmidt.
      The ADH telescope was of the Baker-Schmidt C4 type,
      being designed by Professor James Baker of Harvard
      University (see Proc. Amer. Phil. Soc., 82, 339-349,
      1940). It came into operation in 1950, and in
      1951 the then world's largest objective prism, 33" in
      diameter, was provided from funds contributed by
      Harvard and the Department of Astronomy at Queen's,
      Belfast (see Sci. Amer., p.46, July 1952). The
      telescope was placed on the Fecker mounting of the 24"
      Bruce refractor at the Boyden Station of the Harvard
      Observatory in Bloemfontein, South Africa. The two-
      mirror and corrector system give a flat field and
      reduced tube length (168") compared with the classical
      Schmidt telescope (see H.C. King, "The History of the
      Telescope"). Among the objects studied with photo-
      graphs from the ADH have been globular star clusters,
      cluster Cepheids, and the Magellanic Clouds.The ADH 
      optics are currently at Dunsink Observatory, though 
      still jointly owned by the two Irish Observatories.
           
IA87* 12"/18" Armagh Schmidt Telescope.
      The Calver reflector was converted into a Schmidt
      telescope in 1950. The Royal Society provided a grant
      for the conversion of the optical parts by the firm of
      Cox, Hargreaves and Thomson, who also provided a
      synchronized drive. The mounting of the Calver was
      retained. Through a gift from Mr. T. Scott of Armagh,
      a dome was built (see P. Moore, "Armagh Observatory
      1790-1967", p.49).

IA88* Rocking-mirror Meteor Cameras.
      Two rocking-mirror cameras were designed and
      constructed at the Observatory for the researches
      carried out by Dr. E.J. Opik (see P. Moore, "Armagh
      Observatory 1790-1967", p.49/50).

IA89 Spectroscope by E.B. Armstrong.


IA90 Iris-diaphragm Photometer. c.1955.
     This instrument, by Sartorius, was used to
     determine the magnitudes of star images on photographic
     plates.



Section B

IB1 Transit Instrument by James Waugh. c.1793. This 2" aperture transit instrument was employed for making observations of the Sun, Moon and standard stars commencing in July 1793 and continuing until 1827 when the instrument was dismounted. Some results were published in Trans. Roy. Irish Acad., 11, 25-44. Some observations of Moon culminating stars were made between 1795 and 1804, and a number of differences of right ascension of pairs of stars observed in 1802 and 1803 at Greenwich and Armagh on the same night, were intended to improve the accuracy of the Armagh results (see Dreyer, p.6). Dr Hamilton also made a series of measurements of the Sun's apparent diameter between 1794 and 1795 in order to test the accuracy of two micrometers by Dollond (see Trans. Roy. Irish Acad., 10, 109-117). The transit was sold to Mr Sharpe of Dublin (Observatory Minutes for 18 Oct 1827, p.l6). IB2 Variation Compass. c.1796. Note on inventory: Taken by Mr Holmes. IB3 Circumferentor and stand. c.1796. Taken by Mr Holmes. IB4 Clock by Waugh. c.1796. Taken by Mr Holmes. IB5 10' Newtonian Reflector by Sir William Herschel. Acquired before 1819. 10" aperture.(See Stuart, 1819, p.523). This telescope was mounted in the East tower on a stone pier. No trace of the telescope can be found. A Herschel eyepiece is still at the Observatory and may be part of this instrument. IB6 Clock by Sharp. This clock was used in 1838 in the determination of the distance between Armagh and Dublin. It disappeared in the 1970s. IB7 Platinum-wire Micrometer by T. R. Robinson. Sir William R. Hamilton accidentally broke this micrometer (see Irish Astron. Journal, 5, 161, 1959). IB8 Four telescopes. In April, 1918, Revd. C. Faris was authorized to place four telescopes at the disposal of the Lady Roberts' Field Glass Fund for the duration of the war, and in a letter dated 29 April Lady Roberts wrote stating that the instruments would be returned after the end of the war "should circumstances permit" (see M92.11). Registered numbers of telescopes: Z.191, Z.192, Z.193, and Z.194.

Section C

IC1 Barometer by Smith, Bath. c. 1796. IC2 Thermometer by Troughton. c.1796. IC3 Thermometer by Dollond. c.1796. IC4 Air Pumps and Receivers. c.1796. IC5 Electrical Machine, brass conductor, battery and jars. c.1796. IC6 Night Telescope. c.1796. IC7 Sundry parts of the old Philosophical Apparatus of Dublin College. c.1796. IC8 Horizontal Collimator by Dollond. Made entirely of glass (see Introduction to the Armagh Catalogue of Stars, p.viii). IC9 Hadley Sextant by Troughton. 10" radius. c.1818. The latitude of Armagh Observatory was found to the nearest second of a degree with this instrument. (See Stuart 1819, p. 525). IC10 Quadrant by Robert Hogg. 35" radius. c.1818. Revd. R. Hogg, deputy at Armagh Observatory, built an astronomical quadrant, with the assistance of James Waugh (see Stuart 1819). An article, possibly by Hogg, on "Solar Spots" appeared in the Newry Magazine, Vol.III, No.17, p.427, 1817. IC11 Transit Instrument by Higgins. c.1818. Referred to in Stuart's Memoirs of Armagh, p.525. IC12 Thermometer by Healy. c.1823. IC13 Self-registering Thermometer. c.1823. IC14 Kater's Hygrometer. c.1823. IC15 Robinson's Chronometer. c.1838. Used in connection with the rocket signal method (see Trans. Roy. Irish Acad., 19, p.l21). A reference appears in Armagh Catalogue of Stars, p.x. IC16 Wind-gauge. c.1839. Noted in the Observatory Minute Book, 12 Nov 1846, p.46: 'Wind gauge ordered in 1839 has been erected, though not with its graphic apparatus - vanes move with 1/3 of the wind's velocity - about to add a clock work apparatus, which will trace on paper, the movement and direction, so that every variation can be referred to - Dr Robinson requested by Government to construct two similar ones for the Observatories of St Helena and Toronto and one for the British Association at Kew.'

Last Revised: 2011 June 27th