By Pietro Baracchi, F.R.A.S.,

Government Astronomer of Victoria.

“The Commonwealth of Australia; Federal Handbook, prepared in connection with the eighty-fourth meeting of the
British Association for the Advancement of Science,
held in Australia, August, 1914.”
pg.326-390. (1914)

By British Association for the Advancement of Science.
Federal Council in Australia, Australia.
Commonwealth Bureau of Census and Statistics, George Handley Knibbs

(e) Determinations of Australian Longitudes.

Until the year 1883 the adopted fundamental meridians of Australia were those of the Observatories of Sydney and Melbourne, and the longitude assigned to these meridians depended on the observation of moon culminations and moon culminating stars.

Until these two Observatories came into existence, the fundamental meridian of Australia was that which passes through Port Macquarie, on one of the picturesque headlands of Sydney Harbour. [pg.367]

The longitude of this meridian was derived chiefly from the lunar observations of the early navigators, from Captain Cook in 1770 to Admiral King in 1817, and, later, to Sir Thomas Brisbane, Rümker, and others the results of these observers fluctuated over a wide range which, however, is quite compatible with the conditions of the time.

Port Macquarie was one of the points on the longitude circuit measured all round the globe by transportation of chronometers during Captain Fitzroys famous voyage in H.M.S. Beagle in 1831-36. The longitude found for Port Macquarie was 10h. 4m. 32.14s., and if the correction 0s. 115t = + 20.52s. as proposed by Dr. Auwers (22) be applied to it, it becomes, which is only 0.75s. in excess of what may be considered the most probable value of the longitude of this point at the present day.

The meridian of Port Macquarie remained for many years the basis from which explorers and surveyors established geographical positions inland and originally ascertained the meridional subdivisions of the Australian Colonies geodetically or by transportation of chronometers.

One of the earliest and most interesting undertakings of this kind was the definition of the 141st meridian of east longitude, which was proclaimed as the eastern boundary of the Colony of South Australia by an Act of King William IV. in 1834.

In 1839, owing to the discrepant positions assigned to this meridian on different maps of the time, Mr. Surveyor C.J. Tyers was commissioned by Sir George Gipps, Governor of New South Wales, to ascertain its true place.

Tyers, adopting as his base the longitude of Port Macquarie as 151° 15′ 14″ = 10h. 5m. 0.93s., determined the longitude of a point on Batmans Hill, near Melbourne, by transportation of chronometers, and thence by triangulation with a small theodolite fixed the position of the 141st meridian, which he verified by sextant observations of lunar distances.

Captain Owen Stanley recalculated Tyers work, and the result he arrived at differed by only 16.2″ from that of Tyers.

Tyers, having adopted a longitude base, which, according to more modern determinations, was more than 2 miles in error, and having carried out his own work with all the accuracy which was possible under the circumstances, the consequence was that the boundary was fixed, and afterwards (in 1847) actually marked on the ground more than 2 miles to the west of the 141st meridian east of Greenwich.

The longitude of the Parramatta Observatory was determined by Rümker by transit observations of the moon and moon culminating stars. Its value is given in the Philosophical Transactions for 1829 as 10h. 4m. 6.25s.

In M.N. of the R.A.S., Vol.VI., page 213, Rümker, rediscussing his Parramatta observations, gives as a corrected value of this longitude 10h. 4m. 7.217s.

The first value of the longitude of the Sydney Observatory was obtained by the Rev. W. Scott in 1858, and was derived from the observations of 21 transits of the moon. The result was 10h. 4m. 49.0s.

In 1859 Mr. Scott observed 38 moon culminations which gave as the resulting longitude of the Sydney Observatory 10h. 4m. 59.86s. (23) [pg.368]

Similar observations, 50 in 1860, and 56 in 1861, furnished the value 10h. 5m. 6.84s. (25)

Stone, from a rediscussion of Scotts moon culminations, observed at Sydney in the years 1859 and 1860, obtained longitude of Sydney Observatory 10h. 4m. 47.32S. (24)

In 1861 the first determination was made of the difference of longitude between the Observatories of Sydney and Williamstown by the telegraphic exchange of clock signals, and the value obtained was Sydney-Williamstown 0h. 24m. 55.38s. (26)

The longitude of the Williamstown Observatory was determined by the observations of moon culminations in the years 1860, 1861, and 1862, the adopted result being 9h. 39m. 38.8s. E. (11)

The difference of longitude between the Williamstown and the Melbourne Observatories was found by accurate triangulation to be 16.00s., giving for the longitude of the Melbourne Observatory 9h. 39m. 54.8s. (27)

This value was adopted and used until the year 1883.

In 1867 the difference of longitude between the Observatories of Melbourne and Adelaide was measured by telegraphic exchange of clock signals, giving the result 0h. 25m. 33.76s., which, being applied to the longitude of Melbourne, gave longitude of Adelaide Observatory 9h. 14.21m., which value was adopted, and remained unaltered till 1883. (28)

Soon after the longitudes of the Sydney and Melbourne Observatories had been determined from lunar observations, it became evident that the longitude of the earlier fundamental meridian of Port Macquarie, adopted by Tyers, was considerably too great, and that, consequently, the boundary between the Colonies of Victoria and South Australia had, very probably, been marked too far west, and the error was further verified by the results of the trigonometrical survey of Victoria, which connected the Melbourne Observatory with a western station of the survey near the South Australian boundary.

It thus became an important matter to ascertain the position of the 141st meridian by a fresh determination, and the Governments concerned ordered the work to be done by the Government Astronomers of the respective States.

The plan adopted by Todd, Ellery, and Smalley was to determine the difference of longitude by the exchange of time signals by telegraph between a temporary Observatory, erected for the purpose, near the northern end of the marked boundary, and the Observatories of Sydney and Melbourne. Todd occupied the station at the boundary, using the transit instrument by Troughton and Simms, of 3½−in. aperture, which had been used at Adelaide. Smalley operated at the Sydney Observatory, and Chief Assistant White at Melbourne Observatory.

On 9th May and 10th May the transits of ten stars, over the meridian of the Observatories at Sydney and at the boundary, were recorded simultaneously at both stations, and on 13th and 14th May the transits of 21 stars were similarly recorded at the boundary and at Melbourne Observatory. Exchange of time signals was effected also between the two Observatories of Melbourne and Sydney. [pg.369]

The results were as follow :—

Difference of longitude— h.  m.   s.
Boundary-Sydney 0 40 59.72
Boundary-Melbourne 0 16 3.77
Melbourne-Sydney 0 24 55.81
The adopted longitude for Melbourne was…  9 39 54.80
The adopted longitude for Sydney was… 10 4 48.97

The adopted longitude for Sydney was the mean of the value 10h. 4m. 47.32s. calculated by Stone from Scotts lunar observations of 1859 and 1860 (24), and the value found by applying the difference Sydney-Melbourne 0h. 24m. 55.81s. to the longitude of Melbourne Observatory 9h. 39m. 54.8s.

From these data, and the measurement, by chaining, of the short distance between Todds transit instrument and the boundary, it was found that the north end of the marked boundary line was about 2¼ miles to the west of the 141st meridian.

In the light of the present experience the longitude operations of 1868 can hardly be regarded as fundamental, and, moreover, the adopted longitudes of the Observatories of Melbourne and Sydney being at the time entirely dependent on transit observations of the moon, were not entitled to great confidence. Yet the means and methods employed in this later determination were so far superior to those of 1839 that a considerable error in the position of this boundary line, amounting to probably more than 2 miles, could be accepted as a tolerably well ascertained fact.

Then commenced the dispute between the adjoining States of South Australia and Victoria, the former claiming the strip of land upon which the latter State was encroaching. And the dispute grew even more vigorously after 1883, when the chain of telegraphically determined longitudes between Greenwich and Australia was completed; and further confirmed within sufficiently narrow limits the results of 1868. Eventually, in February, 1911, the case was taken before the High Court of Australia, which decided that the marked boundary having been accepted as such by the two States concerned, the fact that it did not exactly coincide with the 141st meridian of east longitude did not warrant the Court in ordering the re-adjustment claimed by South Australia.

In 1882 an arrangement was made between the British and Australian authorities that Captain L. Darwin, K.E., should go to Singapore for the purpose of carrying out, in co-operation with an Australian observer, who was to be stationed at Port Darwin, a determination of the difference of longitude between the two places, by the exchange of clock signals through the cable lines of the Eastern Extension Company, thus completing the longitude chain Greenwich-Australia by the telegraphic method.

The writer was sent to Port Darwin equipped with a transit instrument, by Troughton and Simms, of 3-in. aperture, clock, chronometers, and all necessary requisites.

Captain Darwin, similarly provided with the necessary instruments, established his temporary Observatory at Singapore.

Captain Helb, of the Netherland India Staff of Batavia, was instructed by his Government to proceed to Banjoewangie, where the two brandies of [pg.370] the cable between Port Darwin and Singapore join, and to take part in the longitude operations, so as to determine the intervals Banjoewangie-Singapore and Banjoewangie-Port Darwin, as well as the direct interval Singapore-Port Darwin.

Clock signals were exchanged by Port Darwin with Banjoewangie on 4 nights, with Singapore on 8 nights, with Adelaide on 6 nights, and with Melbourne on 4 nights, between the dates 28th January and 2nd March, 1883, inclusive.

By these operations the meridian of Port Darwin became the origin of Australian longitudes, and the following results were obtained and adopted at the time (26):—

h.  m.   s.
Longitude of Port Darwin 08 43 22.49
Longitude of Adelaide Observatory 09 14 20.30
Longitude of Melbourne Observatory 09 39 54.14
Longitude of Sydney Observatory 10   4 49.54
Longitude of Hobart (Barrack Square) 09 49 19.80

A comparison of the telegraphic values of 1883 with those derived by absolute methods up to that time showed a more satisfactory agreement than could reasonably be expected.

Before dealing with the comparison, it will be necessary first to point out some results obtained by the method of occupations and culminations which have not yet been taken into account.

Russell observed a large number of transits of the moon and moon culminating stars in the years 1863, 1871, 1872, 1873, and 1874, from which he derived the value 10h. 4m. 50.81s. for the longitude of the Sydney Observatory, which he adopted from 1878. (29)

More transits of the moon and a number of occupations were observed at the Melbourne Observatory in the years 1874-75 for further verification of the adopted longitude, which confirmed the previously adopted value.

Also, Mr. John Tebbutt had very regularly observed many occultations of stars by the moon, and laid great stress upon the superior value of this method for improving the longitude of the Sydney Observatory and his own.

From 1863 to 1867 he had observed some 169 occultations, and by the end of the year 1878 had increased the number by 63 more, and having in the meantime determined the difference of longitude between his Observatory and that of Sydney, on several occasions, both by direct exchange of time signals telegraphically and by transportation of his chronometer, deduced the value of the longitude of Sydney Observatory based entirely on his own observations as follows :—

h.  m.   s.
Longitude of Windsor 10  3 21.81
Difference Windsor-Sydney   0  1 28.83
Longitude of Sydney Observatory … 10  4 50.64 (30)

In 1884 Dr. Auwers deduced a fundamental value of the longitude of the Sydney Observatory based on the Australian observations both of transits of the moon and occultations (31). He found longitude of—

h.  m.   s.
Sydney Observatory 10   4 49.60
Melbourne Observatory   9 39 54.17
Windsor Observatory 10   3 20.77

The comparison of results depending on the entire chain of telegraphic longitudes completed in 1883 with those derived by Dr. Auwers from lunar observations shows a discrepancy amounting to less than one-quarter of second of time, which was justly regarded as a nearly perfect agreement.

Subsequent longitude operations in Australia until the year 1903 were confined to those specified as follow :—

Are determination in 1887 of the arcs Windsor-Melbourne and Windsor-Sydney by telegraph exchange of time signals which gave—

 m.   s.
Windsor-Sydney  1 29.39
Windsor-Melbourne 23 25.87
Melbourne-Sydney computed … 24 55.26 (32)

A re-determination in 1887 of the interval Windsor-Sydney by transportation of chronometer on seven different dates and by triangulation, given two new values for this, are as follow :—

Windsor-Sydney m.   s.
  By transportation of chronometer  1 29.49 (18)
  By triangulation  1 29.77 (32)

Determinations of the longitude of the Brisbane Observatory, Queensland, by exchange of time signals telegraphically between Sydney and Brisbane in the years 1884, 1891, and 1892.

Determination of the longitude of Broome, Fremantle, and Albany, Western Australia, in 1890 and 1891, by telegraphic exchange of clock signals between Commander Moore and Lieut. Parry at the above stations and the Adelaide Observatory.

Determination of the longitude of the Perth Observatory in 1899 and 1901 by exchange of clock signals telegraphically with Adelaide and Melbourne.

The resulting longitude of the Perth Observatory being based on the value 9h. 14m. 20.30s. for Adelaide and 9h. 39m. 54.14s. for Melbourne, giving—

Longitude of Perth Observatory— h.  m.   s.
Via Adelaide (1899)  7 43 21.74E. (33)
Via Melbourne (1899)  7 43 21.78E. (33)
Via Adelaide (1901)  7 43 21.97E. (34)

Determination of the longitude of a number of stations of the trigonometrical surveys of the States of New South Wales, Queensland, and Western Australia by telegraph exchange of time signals with the respective State Observatories.

The results of all these operations still depended on the value assigned to the longitude of the initial Meridian of Port Darwin in 1883. [pg.373]

The laying of the cable across the Pacific Ocean from Vancouver to Australia and New Zealand, some 8,273 nautical miles in length, was completed towards the end of the year 1902. It connects three intermediate stations on its course, namely. Fanning Island, Suva (Fiji), and Norfolk Island, and branches from Norfolk Island to Southport, in Queensland (Australia), and to Doubtless Bay (New Zealand). (35)

The importance of taking advantage of the first opportunity of determining the difference of longitude between Canada and Australia, along this route, was quickly recognised by the Canadian astronomers who, having previously established a chain of longitudes across the Atlantic between Greenwich and Canada, could now continue the chain to Australia to meet the end of the chain carried eastward from Greenwich to Port Darwin, thus closing a complete longitude circuit round the earth.

The work having been authorised by the Canadian Government, Dr. Klotz, of the Ottawa Observatory, was commissioned to take charge of it, and in March, 1903, in conjunction with his assistant, Mr. F.W.0. Werry, B.A., Dr. Klotz commenced his great series of Trans-Pacific longitudes, which he concluded in January, 1904.

The results of Dr. Klotz are as follow:—

h.  m.     s.
Adopted longitude of Vancouver   8 12 28.368 W.
Interval Vancouver-Fanning Island   2 25   5.406
Interval Fanning Island-Suva (Fiji)   1 28 43.837
Interval Suva-Norfolk Island   0 42   1.243
Interval Norfolk Island-Southport (Queensland)   0 58   1.364
13 46 20.218 W.
Longitude of Southport (Queensland) 10 13 39.782 E.

A second fundamental meridian was thus established in 1903 on the eastern coast of Australia, the longitude of which was based entirely on the telegraphic method, and was quite independent of any other Australian longitude previously determined.

The arc Southport-Sydney having been measured by exchange of clock signals between Klotz and the officials of the Sydney Observatory, the entire circuit round the earth was thus closed, and a comparison of the two independent values for Sydney, based on the eastward and westward chains from Greenwich, gave the closing error.

At the time when the comparison was made (1903) a re-discussion of the Port Darwin longitude, based on all available records up to 1894, had been made (36), according to which the adopted value 8h. 43m. 22.49s. required to be reduced to 8h. 43m. 22.34s by Colonel Burrard and Colonel Lennox Conyngham, which involved a further reduction of 0.04s., and finally in 1903 a re-determination of the arc Greenwich-Potsdam and the re-adjustment of European longitudes by Dr. Albrecht and Prof. Wanach (37) (38) showed that the reduction had been carried too far by 0.01s. [pg.373]

The values adopted by Klotz in his comparison were—

Longitude of Sydney— h.  m.     s.
Vid Eastern chain from Greenwich 10 4 49.355
Vid Canada and Trans-Pacific longitudes 10 4 49.287
Closing error = 1.02″ = 84 feet =   0  0    .068 (39)

On the basis of all data available at the present time, the most probable longitude values of those Australian stations which form part of the Canadian circuit may be assumed to be—

h.  m.     s.
Longitude of Port Darwin   8 43 22.28 E.
Longitude of Melbourne Observatory   9 39 53.93 E.
Longitude of Sydney Observatory 10   4 49.33 E.
Southport (Queensland) 10 13 39.82 E.

Notwithstanding the remarkable agreement of independent results obtained by absolute and telegraphic methods in the determination of Australian longitudes, and the powerful check afforded by the closing error of the Trans-Pacific chain, it has been pointed out (35) that such evidence cannot as yet be accepted as the measure of the accuracy of the last longitude values just given above ; and that a re-measurement of the intervals Southport-Sydney, Sydney-Melbourne, Melbourne-Port Darwin, Port Darwin-Singapore, Singapore-Madras is required before these values can be adopted with full confidence. The Commonwealth Government is desirous of establishing a primary meridian to which all the Australian longitudes should be referred for the purpose of connecting the various surveys of the States to a common meridian datum. The present Federal Observatory of Mt. Stromlo is indicated the appropriate point for the primary meridian of Australia. Indeed, this was one of the reasons for which Mt. Stromlo was selected as the site for the Observatory. This point could be very readily connected with one of the existing Observatories — Melbourne or Sydney — telegraphically or geodetically, but it has been suggested to the authorities (35) that adequate precision in the determination of the longitude of this meridian could only be obtained by completing a system of longitude measurements connecting Mt. Stromlo directly with the end of the Trans-Pacific chain at Southport on one side, and with. the end of the Indian chain at Port Darwin on the other, and by re-measuring the intervals Port Darwin-Singapore and Singapore-Madras.

Great stress has been laid on the importance of carrying out this work soon and with due efficiency, in order to strengthen Australian longitudes.

The Mt. Stromlo Observatory.

In the beginning of the year 1910 the Government of the Commonwealth decided to erect a temporary Observatory at Mt. Stromlo, within the Federal Territory, at a distance of 7 miles to the westward of the centre of the Federal Capital Canberra.

The immediate object was to test by astronomical and meteorological observations extending over one year, whether the atmospheric conditions of the site were sufficiently favourable to justify the authorities to establish on that site a permanent Astronomical Observatory of the highest order.

In due course an appropriate structure was constructed for the installation of a 9-in. refracting telescope equatorially mounted, and periodical observations were made for a few days in each month for nearly two years, [pg.374] at the end of which (July, 1913) the observers reported that the site was favourable for the intended purpose.

The selected site is the summit of a group of hills rising, by gentle and graceful slopes, to an elevation of some 600 feet above the general surface of the surrounding country, and 2,660 above sea level. It commands an uninterrupted view practically down to the horizon on all sides, it affords ample room for a great institution, and its orientation, in respect of the city and of the prevailing winds, is favourable.

The temporary building consists of a central dome, 18 feet in diameter, resting on a circular wall of concrete, 8 feet above the floor, and four small square rooms symmetrically placed north, south, east, and west for the accommodation of the observers and caretaker.

The Oddie telescope, which has already been noted in connexion with the private Observatory of Mt. Pleasant, Ballarat, is the principal instrument. It has an object glass of 9-in. aperture giving excellent definition. The telescope is mounted on a massive cast-iron stand, resting on a pier of concrete built on a granite foundation. A metallic camera is attached in which is fitted one of Dallmeyers portrait lens of 6-in. diameter and 38 inches focal length. The instrument is provided with a fine driving clock, excellent filar micrometer, electric illumination for dark or bright field, an Evershed prominence spectroscope made by Hilger, and every requisite for all classes of observations. The eyepieces range in power from 60 to 700.

This instrument was presented to the Commonwealth Government by the late Mr. James Oddie, of Ballarat, in July, 1910. I was commissioned to take delivery of it at Ballarat, and to erect it at Mt. Stromlo for the object stated above. As the instrument had never been taken out of its packing cases since the maker sent it out to Australia a quarter of a century before, it required a great deal of overhauling, and also several alterations and additions, which were done at the Melbourne Observatory.

The installation of the instrument at Mt. Stromlo was completed in September, 1911, after which observations were commenced and continued by myself and my chief assistant. Dr. J. Baldwin, during fifteen visits to the locality between 8th September, 1911, and 2nd June, 1913, each visit occupying about a week.

The observations were visual, photographic, and spectroscopic.

The visual observations were by naked eye and telescope.

The naked-eye observations were made for estimating the amount of scintillation at different altitudes, comparison of star regions, parts of the Milky Way, the Magellanic clouds, clusters, and nebulae. The telescopic observations included close double stars and detail of planetary surfaces. With the 6-in. doublet lens a series of photographs of rich star regions and nebulae was obtained.

The observation and delineation of solar prominences were also regularly carried out.

At the conclusion of our programme, I reported the result that in my opinion, taking into account all the circumstances, the site was decidedly suitable for an Astronomical Observatory of the highest order.

The question of proceeding with the establishment of a permanent Federal Observatory at this site is at present under consideration. [pg.375]


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