The 1882 Transit of Venus:
Observations from Wellington, South Africa.
|Download MNASSA paper (2.2 MByte PDF-file) on the American expedition to Wellington|
|Download MNASSA paper (900 kByte PDF-file)on the British expeditions to South Africa|
|Download MNASSA paper (2.4 MByte PDF-file) follow-up on above papers and 2004 observations|
|Hierdie blad in Afrikaans|
|Belorussian translation by Bohdan Zograf|
Miss Ferguson was always interested in astronomy with "a knowledge of a keen amateur, quite sufficient to infect others with her enthusiasm, and to give them the knowledge they needed to read books intelligently". From the start she offered an astronomy class at the Seminary and being a personal friend of Dr (later Sir) David Gill, Astronomer Royal at the Cape, he often visited Wellington and gave lectures to the class. In 1881 the Williston Observatory at Mount Holyoke was built and the observatory's original telescope, (a 6" Fitz, like this one (18k)), first installed there in 1853, was given to the Seminary in Wellington. Under Gill's supervision it was erected in an observatory in the grounds just in time for the transit of Venus which occurred on December 6, 1882.
Two of the three Seminary staff (photographs about 1880) who observed the transit through their own telescope which stood alongside those of the American expedition.
(Builders of Huguenot - 1927)
Abbie Park Ferguson
Mary Elizabeth Cummings
(Later Mrs Gamble)
The year 1882 was special in astronomical terms for two reasons. First the Great Comet of 1882 appeared, becoming bright enough to be seen in daytime. In photographing this, Gill realized the potential of photography in astronomy which started a whole new era of observational astronomy. Secondly, it was the last time until the years 2004 & 2012 that a transit of the planet Venus across the Sun's disk, would occur.
The tracks of Venus across
the Sun's face during the
six mentioned transits.
(Sky & Tel. Dec.1982)
Only the two inner planets, Mercury and Venus, can show this phenomenon when they move in between the Earth and the Sun. In contrast to Mercury, where transits happen at a rate of 13 to 14 per century, transits of Venus are very rare. They currently happen in pairs, 8 years apart which repeat only after more than a century. Previous transit pairs were in 1761 & 1769 and 1874 & 1882 - it was to observe the 1769 transit from Tahiti that Captain Cook had astronomers on board his ship. As early as 1609 Kepler could determine very accurately a model of the Solar system by using his laws, but only after (at least) one distance was accurately measured, could all the others be deduced with equal precision. One of these direct methods of determining the distance between the Earth and Sun is to observe the transit of Venus simultaneously from different places on the globe.
(Here is a very good explanation.)
A young Prof Newcomb
(Sky & Telescope Sept.1988)
Gill originally suggested that the American scientific party to South Africa, led by Prof Simon Newcomb of the US Naval Observatory, should observe the transit from Beaufort-West. However, when Newcomb heard about the American connection of the Huguenot Seminary he decided to use the Seminary grounds and by arrangement with the trustees set up his equipment in the garden there. He encouraged the teachers and students to actively take part in the observations and set them up well enough that they eventually observed the transit through their own telescope. Today the names of Miss ME Cummings, Miss AP Ferguson and Miss JN Brown can still be found listed amongst those of the professionals and they are each credited with a transit observation. The book Builders of Huguenot even claims that the amateurs made better observations than the professionals! Prof Newcomb's reply was that "it was partly the result of good fortune, and partly due to the quickening of the faculties which comes with intense interest", but the ladies took it "as a tribute to the greater powers of their own sex."
These events are probably best described by one of the observers herself. In a letter of Mary Elizabeth Cummings (Class of 1876 (Holyoke) and a teacher at Huguenot from 1877 to 1887) to her classmates written on December 22, 1882 she wrote:
"I must tell you of our telescope before I close. Some of you perhaps know that it is the one through which we had a few peeps when pupils of Mt. Holyoke. When it was no longer needed there, Mr Williston kindly presented it to the So. African daughter of Mt. Holyoke. An observatory was erected for it in our garden, and the telescope was mounted under the direction of Dr Gill, the Astronomer Royal, from Cape Town. It was scarcely in order when the "Transit of Venus Expedition" from the United States, arrived in Cape Town, and soon after decided upon Wellington as the best astronomical station for their purpose. Our garden was selected as the best site, all things considered, and four buildings were erected. Prof Newcomb, the Chief of the Expedition, instructed the pupils in Miss Ferguson's astronomy class and several of us teachers, in the art of reading time quickly on the chronometer, and several of us were invited to share the practice of the astronomers, in observing an artificial transit of Venus, by means of an apparatus invented by one of the party. The actual transit took place the day before our anniversary and in the midst of the examinations and hurry of anniversary week, and to several of us teachers was the most important event, as it had been arranged that we should observe it through our own telescope, which was in excellent condition and gave a splendid view of all that could be seen."
A sketch from Prof Newcomb's Popular Astronomy (1878)
shows what the apparatus for simulating an artificial transit
looked like. The black sheet-metal disk (Venus), one foot in
diameter appeared and disappeared behind the white triangular
opening (the Sun) pulled by clockwork via the trolley. The whole
apparatus was then placed on a building 1 km away and
observed through a telescope
Prof Newcomb's reputation would continue to grow until he became the most honoured American astronomer of the 19th century - a crater on the Moon and probably one on Mars were even named after him! In comparison with the relatively ill-observed 1874 transit, very little of the 1882 observations was ever published. Prof Newcomb was put in charge of reducing the observations but had a most frustrating time accomplishing this with the US Treasury Department who kept re-allocating his funds, forcing him to repeatedly fire and re-appoint staff to do the work. When he wrote his autobiography The Reminiscences of an Astronomer in 1903, nostalgically recalling the transit 20 years earlier, he wrote:
"On our departure we left two iron pillars, on which our apparatus for photographing the Sun was mounted, firmly imbedded in the ground, as we had used them. Whether they will remain there until the transit of 2004, I do not know, but cannot help entertaining a sentimental wish that, when the time of that transit arrives, the phenomenon will be observed from the same station, and the pillars be found in such a condition that they can again be used."
This sketch from Prof Newcomb's Popular Astronomy
(1878) shows the working of the photo-heliographs
used by the American transit expeditions.
The original Huguenot Seminary later became the Huguenot Girls School which in turn tranformed into the Huguenot High School which still exists in the town today. The Huguenot University College has since matured into two seperate institutions, namely the Cape Technikon, Wellington Campus and the Huguenot College (24k.jpg) where social workers and missionaries are trained. The names of several buildings still recall the school's origins - Murray House (34k.jpg) and Bliss Hall (17k.jpg) are still residences of the Education College while Cummings Hall (28k.jpg) houses students of Huguenot College. Mary Lyon's (33k.jpg) name has been honoured in a hall called after her. Visitors are accomodated in the Holyoke Guest House (24k.jpg) while the headquarters of Bible Media today occupies Ferguson Hall (17k.jpg).
A view of the two pillars left by the British expedition to Touws River
taken in February 1936 before it was declared a National Monument
(South African Journal of Science - March 1937)
Recent picture here (22k.jpg)
Never in Prof Newcomb's wildest imagination could he ever have imagined that one day distances in the solar system would be refined to within centimetres by bouncing radar beams off Venus or laser light from a mirror put on the Moon by astronauts! This means that in 2004, his observing site reduces even more in academic importance since the 2004 transit will be of relatively little scientific value. Apart from this, Newcomb's wish unfortunately cannot be fully fulfilled because the two iron pillars have since disappeared.
The same observations were also made from Cape Town, Durban and Aberdeen-Road under Gill's direction, while a British expedition used Montagu-Road (Touws River today) as their observing base. H.E.Wood from the former Union Observatory in Johannesburg wrote an article in the March 1937 issue of the South African Journal of Science pleading for the retention of these important historic landmarks. In Touws River the two concrete pillars used by the British party still existed in the courtyard of the former Douglas Hotel, complete with a hand-written inscription of the names of the astronomers. Instigated by Wood, and with the permission of the then owner of the hotel, the legendary Mr. James D. Logan of Matjiesfontein, these relics were declared a national monument in 1938. In his article Wood also quoted Newcomb's sentimental wish and writes further:
"Unfortunately the iron pillars left behind by Newcomb have not remained undisturbed. Their existance has been forgotten and the piers have disappeared. Upon enquiries being made in April 1936, it was found that one of the garden boys remembered the position where one of the pillars had been and, on excavating, a foundation was found. At this spot an iron post has been erected to mark the site at which Newcomb's observations were made."
Unfortunately there were not enough tangible relics left at the Wellington position to also be declared a national monument and this iron post has also since disappeared, probably due to the fact that it was never properly marked and the reason for it's erection indicated.
The southern pier carried the objective lens (left) and the
unsilvered heliostat mirror, driven by a clockwork (right).
(Sky & Telescope Dec. 1974)
Using two United States Naval Observatory publications, Instructions for Observing the Transit of Venus, December 6, 1882 and List of Articles Furnished to the United States Transit of Venus Parties in December 1882, I managed to make an exact scale drawing of the makeup and layout of Newcomb's observing post in Wellington (see sketch below). The telescope was effectively a static, horizontally mounted photo-heliograph (photographic sun-telescope) of 40 feet (12.1m) focal length, fed by a clock-driven unsilvered heliostat mirror. The two pillars mentioned were both hollow cast-iron pipes, 8 feet (2.4m) long with the lower 4 feet (1.2m) set into the ground, preferably in concrete. The pillars were placed on an exact north-south line, 40 feet (12.1m) apart. The diameter of the northern pillar was 12" (305mm) and 13¾" (350mm) for the southern pillar. Exactly 14 feet (4.27m) south of the southern pillar and on the same line as these two pillars, was another pier on a concrete foundation of roughly 3 feet (1m) square, 3 to 4 feet (1-1¼m) deep, upon which stood a Transit Instrument (8k.jpg). This instrument was used to accurately determine the north-south line for the main telescope by observing the stars and was therefore placed exactly on it's optical axis. The "Transit House" was built over this pier with a roof that could open in a north-south slit to give access to the night sky to this telescope (12k.jpg) which only had N-S movement. Around the photographic (northern) pillar (11k.jpg) the "Photographic House" was built where the glass photographic plates were both exposed and developed, thus acting like a camera and a darkroom. The thicker southern pillar carried the heliograph objective lens as well as the driven heliostat mirror but was not housed in a hut. The correct focus setting was determined through a complicated routine of measuring the temperature of the measuring rod and the distances from its ends to the objective and photographic plate by means of a special micrometer.
Apart from the photographic observations, all the American stations were equipped with an ordinary telescope (a 5" Alvan Clark equatorial refractor (29k.jpg)) for doing "contact observations". These were the main type of observations done by the British expeditions and presumably also by the Misses Cummings, Ferguson and Brown. The purpose was to determine the exact moments when the inside and outside edges of Venus and the Sun "touched". So-called first and second contact takes place as the disk of Venus moves onto the Sun and later third and forth contact as Venus clears the Sun's disk. (Only the first and second contacts were visible from South Africa in 1882 - the transit was still in progress at sunset.) This fits in well with Mary Cummings's description of Newcomb teaching them to quickly read the chronometer and practicing on the artificial transit apparatus. This telescope was housed in a building which had an octahedral base and a square pyramid-shaped roof which could turn through 360° and contained a vertical slit which could be opened. The fourth building served as store room for the party's supplies.
Miss Ferguson's telescope was housed in a rondawel
type building - the local name for a small round building - on the
northern (back) side of Murray House. With the 60th anniversary of the
Seminary in 1933, Mrs Gamble (formerly Miss M.E.Cummings, who should
not be confused with her sister Anna
(Photo: Wellington Museum)
"How did we enjoy the broad outlook in Literature, the nights with the telescope under the stars, the excursions into the realms of Science and the deep problems of Philosophy."
Mrs Gamble's writings implies that the observatory still existed in 1933. If one compares this information with an aerial photograph of Wellington here below, taken about 1937/38, a little round building fits the description well. This position was confirmed with the discovery of this 1935 postcard.
Taking into account that this aerial photograph was taken only a year or two after Wood's visit, a solitary post just visible, could well have been the one erected by him.
In answering a query from a member of the public asking about the Touws River monument, a former director of the National Monuments Council, Mr. B.D.Malan replied in July 1963 as follows:
"An American expedition under Prof Simon Newcomb erected instruments for the same purpose on the site of the Huguenot Seminary, Wellington, at a spot which is nowadays indicated by an iron standard placed there in 1936."
An image of one of the 1700 plates taken worlwide
during the 1882 transit, showing Venus crossing the
disk of the Sun. Also visible is the image of the ruled
glass reticle mounted in front of the plate and the
vertical line in the centre is that of a thin silver
plumb line that hung between the plate and grid.
The small dots on the picture were caused
by defects in the glass photographic plates.
(JHA XXIX, 1998)
From this it can deduced that the post still existed in 1963, but it could also have been that Mr. Malan simply consulted the Council's Touws River file which includes a copy of the Wood article. His reference to the post as an "iron standard" is very interesting, suggesting a larger free-standing post, a common name given to ornamental (gas) lamp posts in former days, compared to Wood's description of an "iron post" which rather brings to mind a smaller fencing type corner-post. This again compares well with the aerial photograph. Their relative positions also agree well with the following from The Builders of Huguenot :
"Miss Ferguson and Miss Cummings arranged to observe, in an amateur way, from their own observatory which stood alongside the more perfect instruments of the professional observers."
One aspect of Wood's report which seems strange is the fact that he only refers to one post. Given the above description of the apparatus, it is clear that as soon as the position of any one post is known, the other's location is automatically determined - it must either be located 40 feet due north or 40 feet due south. If Wood could still measure the thickness of the post from the foundation, it could have been identified as either the northern or southern pillar, fixing the direction to the other one. It could thus have been that either Wood did not have enough detailed knowledge of Newcomb's instrument or that the foundation of the other pillar had disappeared by then. It is also strange that Wood never referred to Miss Ferguson's observatory at all, which might mean that he was probably not aware of its use in observing the transit.
By taking careful measurements of this post on the aerial photograph and applying it to the terrain behind Murray House, it was determined that this position falls just ouside the present garden, right in the middle and at the extreme eastern end of a tarred footpath that runs alongside a ±1.5m high retaining wall holding the garden soil back from excavations made for building tennis courts. (For the record, this position is 40.03±0.3m east and 47.35±2m north of the north-eastern-most corner of Murray House.) Measurements using a metal detector have not shown up anything definite either. My best hope at present to pinpoint the exact lacation is to find the directions which, according to the document Instructions for Observing the Transit of Venus, December 6, 1882 required the observers to draw up a map accompanied by hand-written instructions indication the position of the observing site. This document had to be included in the observing report and is apparently kept in the National Archives in Washington DC today and I am currently trying to get hold of a copy.
Almost the entire 2004 transit will once again be visible from Wellington (map and data here). When the Sun rises over the town on 8 June 2004 the transit will have just started at 07h13 and it will take Venus until 13h26 that afternoon to cross the disk of the Sun. With sufficient optical filtering from the harmful sunlight, the black dot of Venus silhouetted against the bright Sun will even be visible without optical aid. A near identical "dress rehearsal" will took place exactly one year, one month and one day before the time with a transit of Mercury (map and data here). Also starting at 07h13 it took the planet until 12h32 on the afternoon of 7 May 2003 to cross the Sun. Because of Mercury's smaller size and greater distance, it was not visible without a telescope or binoculars fitted with adequate eye protection.
If I eventually manage to pinpoint the position
of Prof Newcomb's observing site, I would very much like to fulfil his
wish and observe the 2004 transit from this location. It would also be
appropriate to then mark the spot more permanently with a plaque for
the generations to follow. This re-enactment would be perfect if it
could be done with Miss Ferguson's original telescope which I am
currently trying to find.
This 6" Fitz refractor from the private collection
of John Briggs (23k.jpg) is probably a twin of the
missing telescope that once stood on the garden of
the Huguenot Seminary in Wellington, South Africa.
(Click here for a close-up of the telescope.)
If anyone reading this has any knowledge, or
knows of anyone who might have any more information on any of these
events, how ever insignificant it may seem, would you please
(Willie Koorts was born in Touws River and stayed there until the end of his Matric year. He later met Rieks Wessels while she studied Social Work at the Huguenot College and was resident in Cummings Hall. They presently live in Wellington where Rieks is a former Social Worker at the Murray Children's Home. Willie works as an Electronic Technician at the South African Astronomical Observatory in Cape Town and is also an amateur astronomer.)