Bradfield's Memorial Plaque and Dawes' Observatory.

by Richard de Grijs (School of Mathematical and Physical Sciences, Macquarie University, Sydney)

    On 23 March 1926, John Job Crew Bradfield (1867–1943), Chief Engineer of the Sydney Harbour Bridge, sent a request to Karl Reginald Cramp (1878–1956), Secretary of the Royal Australian Historical Society. Prompted by the Minister for Public Works, The Hon. Mr. Martin Matthew Flannery, M.L.A., Bradfield suggested that “… a brass plate suitably inscribed …” might be affixed to “… one of the granite-faced piers for the Bridge …” to commemorate “… the old battery at Dawes Point which I understand was built in 1856.” The Chief Engineer requested the Historical Society to suggest suitable wording for the plaque.

Letter from Chief Engineer Bradfield to the Royal Australian Historical Society’s Secretary, 23 March 1926. (Courtesy: RAHS Library).

Letter regarding building stone ‘R. R. 1789’ found at Dawes Point from Kathleen M. Butler to the Principal Librarian, Public Library of New South Wales, dated 19 February 1926. (State Library of New South Wales).

    From the Royal Australian Historical Society’s Annual Report of 1926, we learn that the Society’s President, Captain James Henry Watson (1841–1934), and Cramp reached agreement on the proposed wording:

    At Dr. Bradfield's request, a suitable inscription for a brass tablet to be affixed to one of the granite-faced piers of the North Shore Bridge [the Sydney Harbour Bridge], was suggested by your President and Secretary. The proposed inscription is worded as follows:–

On this site

Lieutenant William Dawes (Artillery Officer)
erected a breastwork in 1788,
replaced by a stone battery in 1791,
known as Dawes Battery,
the whole being remodelled and enlarged by
Governor Denison, 1856.
— feet west of this tablet,
the first Observatory in Australia
was erected
under the direction of Lieutenant Dawes
1788

Daily Telegraph, 29 May 1926, P20.

Sydney Morning Herald, 17 June 1932, P8.

Dawes’ memorial plaque affixed to the Sydney Harbour Bridge, western pier closest to the harbour. Note that in August 2023 the plaque is within a work compound and not accessible. (Photo: Author supplied).

Blue dot: location of Dawes’ Observatory implied by the text on the plaque (Map reproduced under ‘fair use’ principles).

    The memorial plaque, which was formally unveiled on 16 June 1932, did not only make reference to the establishment of Dawes’ Battery, it additionally included a postscript referring to William Dawes’ (1762–1836) astronomical observatory, ostensibly located “90 feet west of this tablet”. This latter location is at odds with the majority of extant cartographic evidence, however. In our careful analysis of contemporary maps and charts, we concluded that the site of Dawes’ (first) Observatory was almost certainly located on the eastern slope of the headland now known as ‘The Rocks’, situated against a rocky bluff. However, any physical evidence has been erased by later fortification work (which likely remodelled the hillside) and, perhaps more importantly, Harbour Bridge construction.

Building stone ‘R. R. 1789’. (State Library of New South Wales. Call number: XR 9; record: 16AJ2aqn).

    The location implied by the wording on the plaque coincides almost exactly with that reported for the stone marked ‘R. R. 1789’ by Kathleen M. Butler (1891–1972) in her letter of 19 February 1926 to the Principal Librarian of the Public Library of New South Wales, that is, 1260 feet (384 m) east and 1652 feet (503.5 m) north of the time-ball staff at Sydney Observatory. Butler advised the librarian that this particular stone was:

… probably part of the first Observatory, being afterwards incorporated in the Military buildings, which consisted of four rooms with stone walls nearly three feet thick. It was discovered at about the centre of the building in the wall of the room marked on the plan as the Non-Com’s room, the inscription being covered with plaster.

The great thickness of the stone walls of this part of the building prove that they were of a much older type than the other portion – which was constructed of brick – many of the bricks being marked with a broad arrow and others with various old brickmaker’s marks.

    Butler was Bradfield’s Confidential Secretary, and so it is likely that her letter closely represents Bradfield’s own words. We therefore suspect that Bradfield himself may have been the source of the incorrect identification; after all, Bradfield’s letter to Cramp was sent shortly after Butler’s report on the building stone.

    Butler’s letter includes a reference to two plans that included an indication of the location where the stone had been found; a marginal note implies that those plans had been transferred to the State Archives of New South Wales. Our inquiries at the State Archives and Records of New South Wales have only managed to uncover one of those plans: see below for an enlargement of the area of interest, excerpted from the original 73.5 cm × 96.5 cm document covering the entire Dawes Point promontory. A grainy photocopy of a sizeable section of this plan was included in the Annual Report of the Archives Authority of New South Wales of 1981, when the State Archives acquired it.

“Plan of Dawes Point showing the location of stone marked ‘R. R. 1789’ found during the excavation of Sydney Harbour Bridge in 1925. Signed by J. J. C. Bradfield.” (sections showing the location of the former Water Police Station and the Hickson Road area near Dawes’ original observatory) (State Archives and Records of New South Wales; Map AO 6317, F11/49).

    A recent topographical reconstruction of the Sydney Cove landscape during the first few years of British settlement also includes the location of Dawes’ Observatory at a site closely coincident with our best estimate. The primary sources used in that independent reconstruction included Dawes and John Hunter’s map of July 1788, as well as maps published by Mitchell et al. (1853) and Sydney Water. The placement of Dawes’ Observatory was predominantly determined by cartographic evidence from Dawes and Hunter’s map of July 1788 and Hunter’s 1788 plan of the Sydney Cove settlement.

    An independent clue as to the location of Dawes’ Observatory can be inferred from photographs taken during the demolition of buildings on Dawes Point in preparation for the construction of the Sydney Harbour Bridge. The top left and bottom left panels of the figure below show contemporary photographs of the construction site.

(top left) Sydney Harbour Bridge construction activity in 1926. (State Library of New South Wales, reference 130044, call number PXD 747). (bottom left) Demolition of the Sydney Water Police building on 22 January 1925. (State Archives and Records of New South Wales, NRS-12685-1-[4/8725]-4/8725-52). Both photographs, but in particular the bottom left image, show what appears like a natural cliff face towards the bottom (north) of Hickson Road, behind the original retaining wall on the east. (right) Present-day landscaping of the area, from ground level (top right) and from the rooftop of the Park Hyatt Hotel (bottom right). (Photos: Author supplied, May 2023).

    The top left photograph is a view from 1926 showing Harbour Bridge construction activity, whereas the bottom left photograph depicts the demolition of the Sydney Water Police building on 22 January 1925. Both photographs, but in particular the bottom left image, show what appears like a natural cliff face towards the bottom (north) of Hickson Road, behind the original retaining wall on the east. Dawes’ Observatory was most likely located at the point where the rock face exhibited a sharp edge, a location just outside of the field of view of the bottom left photograph. The two images on the right show the present-day landscaping of the area, from ground level (top right) and from the rooftop of the Park Hyatt Hotel (bottom right). The bottom panel of the figure above showing Butler’s ‘plan of Dawes Point’ includes an indication of the sharp ‘embankment’ alongside Hickson Road, which appears to have leveled off near the top of the flight of stairs allowing access from street level to Dawes’ Battery (in reference to the embankment, note the label ‘Top’ north of the stairs).

    In summary, our best estimate of the location of Dawes’ first Observatory is that it was sited approximately at the location of the (black) artefact on the Butler map. That location, straddling the edge of the bedrock, is almost identical to the planned observatory site indicated on Hunter’s 1788 survey map.

(a), (b) and (c) Examples of matching the contemporary record with a modern map (© Google 2020; permissible use; each panel is 1,900 m ×1,400 m). (d) Various locations of Dawes’ Observatory implied by contemporary records (the green star is likely an incorrect identification); orange ✜: Location indicated on the Harbour Bridge’s memorial plaque; pink ✪: Approximate location of archaeological excavations undertaken around the turn of the last century. The black dash-dotted line corresponds to the best match to a meridian line shown on a ‘Chart of the Coasts and Harbours of Botany-Bay, Port Jackson and Broken Bay on the coast of New South Wales as Survey’d by Captⁿ. John Hunter of H.M.S. Sirius (1789?). Panel (d) covers an area of approximately 850 m × 650 m. Figure source: de Grijs and Jacob (2021): Figure 17.