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The Scientific Observations

By 1882 many experts doubted that observation of any transit of Venus by any means could be the royal road to discovery of the astronomical unit. Nonetheless, Rear Admiral Dr. William Harkness of the United States Naval Observatory spent years reducing photographic measurements of both nineteenth-century transits. The preference in England and its colonies was to revert to primarily visual observation for the 1882 transit, in contrast to American and continental practice.

In Canada, only the times of visual contact were sought, and considerable effort went into obtaining the best times possible. Strange to say, but the optical/physical phenomena of the transit, such as the aureole and black drop effects, receive little if any mention in the official reports of results. That they were in the mind of some Canadian observers is implied by articles in the Manitoba Free Press of Dec. 5, The Evening Telegram of Dec. 6(!), and The Globe & The Gazette of Dec. 7 (see below). There is no mention of Canadian interest in looking for evidence of the Venusian astmosphere during the transit within the context of the extraterrestrial life debate. To judge by the official transit publications, the Canadian program was an unimaginative and derivative affair, an extreme instance of bare Baconian data acquisition. One is tempted to speak of the Canadian transit results as as analogous to resource extraction, with the raw materials (the observations) being sent to Britain for processing (reduction). By 1882, there was already a network of meteorological observers under the supervision of Charles Carpmael in Toronto. He had had some astronomical training in England (he was a grammar-school student of the Rev'd Charles Pritchard, and graduated 6th wrangler from Cambridge), before emigrating to Canada in 1872, and was eager to combine solar and meteorological research. Perhaps he saw the transit as an opportunity to obtain a decent telescope to pursue that post-transit research agenda (the telescope was duly acquired at public expense). By 1881 he was Superintendent of the Meteorological Service and was the organizer of the 1882 Canadian transit of Venus campaign. One of the tasks he and his assistants undertook each year was the preparation of the astronomical part of The Canadian Almanac. For the 1882 edition, he provided formulae to calculate the Greenwich mean time for each of the four contacts of Venus with the Sun, listing in tabular form the values for Fredericton, Quebec and Toronto. These formulae, taken from The Nautical Almanac and Astronomical Ephemeris for the year 1882, required the distance to the centre of the Earth, the geocentric latitude, and longitude of each observing station to be known.

The times calculated using these formulae are about 2 minutes ahead of the times found using the online ephemeris generator. Presumably this discrepancy is a measure of the error in contemporary theory which world-wide observations of 1882 would help to improve.

A considerable portion of the work of Carpmael and his tiny staff lay in making weather forecasts from observations telegraphed to Toronto by a large network of observers, mainly unpaid volunteers. Some of these observers, such as H. J. Cundall at Charlottetown, and the Bishop of Rupert's Land at Winnipeg also played a part in preparing for the transit. Some other official transit observers – W.A. Ashe at Quebec, Professor Clement H. McLeod of McGill College in Montreal and Professor James Williamson at Queen's University in Kingston – were at established observatories which were partly supported by the Meteorological Service. Still others, such as Professors William Brydone Jack in Fredericton, A. R. Bain in Cobourg, J. J. Hare at Whitby and Newton Wolverton at Woodstock, Ontario, were at universities and colleges with no connection to the Meteorological Service. Whilst there were "national" societies which could theoretically connect scientists, such as the Royal Canadian Institute (est. 1849), and the Royal Society of Canada (est.1882), it probably says much for both bodies that Carpmael did not view either as an effective instrument through which to coordinate a transit campaign, or communicate with potential observers. He preferred to comunicate directly with potential observers such as Jack and Bain, requesting information on the available instrumentation available to them. It may also account for his seeming unawareness of the transit plans of observers such as Lt.-Col. Oliver of the Royal Military College, Kingston, and Lindsay Russell ("the Father of Astronomic Surveying in Canada"), Surveyor General and Deputy Minister of the Interior in Ottawa. There were others with telescopes who hoped to observe the transit, and who did correspond with Carpmael. They included William Saunders of London, Ontario, Canada's foremost expert on agriculture, Alan Miller and Mungo Turnbull (who was apparently rebuffed by Carpmael), the latter two among the early members of the Toronto Astronomical Society (of which Carpmael became President in 1890-1894), and a Mr. Williams of Leamington who intended to buy a 6 inch (15 cm) telescope to make observations of the transit.

The impetus to make accurate timings of the transit seems to have come from an outside source. Carpmael wrote to G. G. Stokes, the Secretary of the Royal Society, on 10 October, 1881:

A copy of the report of the Committee of the Royal Society appointed for the purpose of advising the Treasury and Admiralty with respect to the conduct of the transit of Venus observations in 1882, which was forwarded through the Colonial Secretary to the Government of Canada, was submitted to me ...

By the end of the year in his annual report to the Minister of Marine and Fisheries, Carpmael stated:

Having been requested to report for the information of the Department on the advisability of Canada taking part ... I should deem it exceedingly unfortunate if the opportunity were allowed to pass without being utilized to the utmost

Parliament responded in May, 1882, by granting $5,000 to cover expenses in connection with the transit. This was in addition to the regular Meteorological Service annual budget of $37,500.

Carpmael lost no time in despatching his assistant, Lt. Andrew Gordon, R.N. (p. 1), to England to learn firsthand how observers were being trained, to purchase equipment, including a 15 cm equatorially-mounted refractor from Thomas Cooke and Sons, and to visit observatories such as Radcliffe and Kew to see what other useful information (or equipment) he could obtain. Gordon returned with a mechanical model of the transit of the same design as those used by the British expeditions, solar wedges, and a couple of borrowed chronometers. Using the model, Carpmael organized two training locations – one at McGill which followed directly after the AAAS meeting there, and a later one at Toronto. Arrangements were made to connect observers telegraphically, so that they could receive reliable time signals on the night before the transit (and the night after, if necessary), and chronometers were lent to observers who did not have them, so that accurate time could be kept during 24 hours between telegraphic signals. At some of the observing sites with uncertain latitude and longitude a series of accurate stellar measurements had to be made with meridian telescopes in order to improve the geographic co-ordinates. The details of the thirteen sites, names of the observers, equipment, and times can be found in Carpmael et al. (1882?/1883?). In recent years, they have also been listed by Thomson (1978) and discussed by Jarrell (1988). Only at Winnipeg, Kingston and Ottawa were the skies clear enough to time more than one of the contacts. At Belleville and Cobourg, third contact was timed through an unsteady atmosphere, but the Belleville results were further vitiated by uncertainties in the time signals. All the observations which Carpmael reported to the Royal Society are listed in Table 1. Local mean times are used, since standard time zones were not adopted until 1884. Carpmael also co-ordinated observers at other sites (Woodstock, Toronto, Whitby, Montreal, Quebec, Halifax, Charlottetown, Fredericton), but as there were at best only short breaks in the clouds allowing Venus to be seen briefly, no useful observations could be made from those locations.

 

Additional Information at the Sites of the Scientific Observations

Many interesting details are found in the official reports (Carpmael et al. 1882?/1883?, and Johnson et al. 1883), but they will not be reiterated here. The following newspaper accounts from centres where accurate timings were made add some colour to the formal reports. Similar reports are often found in several different papers, so these are only a sample:

Winnipeg: ... A small and unpretentious looking rough board shanty has been constructed a few rods east of Main Street, a little north of the St. John's Ladies College. The only circumstance likely to attract the attention of the passer-by is the divergence of the telegraph wire from its line along the street , and its attachment to the building. Here is the spot from which the important and anxiously expected observations are to be taken. ... [Aside from the times of contact] efforts will be made to discover whether or not Venus has any satellites; though from previous observations it would seem to be pretty well established that there are none. The appearance of the planet in its various positions will also be carefully noted, as, for example, the ring of light which has been seen to surround it when about half of its surface is upon that of the sun. ...Winnipeg is the most northerly station in America at which observations are to be taken; and it was selected on account of the greater probability here than elsewhere of favourable weather at this time of the year. ... (Manitoba Free Press, Winnipeg, Dec. 5)

 

Winnipeg: The only shelter which the observers enjoyed was that afforded by the walls of the building, as the roof had to be opened for the taking of the observations. It may readily be supposed that the exposure was trying in no small degree on such a day, when the cold was by far the most severe of the season. At one o'clock or about the time when the last observations were taken, the temperature as recorded at the St. John's College meteorological observatory, was about eighteen degrees below zero [Fahrenheit]. The velocity of the wind was about twenty-three miles per hour. Fortunately, the drifting snow did not greatly obstruct the vision at the time of the internal contact at egress. (Manitoba Free Press, Winnipeg, Dec. 7) [The observers and equipment came from McGill College, Montreal. See Carpmael et al. (1882?/1883?)]

 

Winnipeg: Yesterday, during the time in which the transit took place, smoked glass, opera glasses, telescopes and theodolites were universally in requisition. ...The amateur astronomers retired early [the night before], buoyed up by the hope that their observations would result in incalculable benefit to the human race. ... In their great joy at beholding the sight, our friends quite forgot to take the time, or make any calculations. The golden opportunity having slipped away and ... vowing to be more cautious in future, the embryo astronomers dismounted the apparatus, and went their way sadder, and it is to be hoped, wiser mortals (Manitoba Daily Free Press, Winnipeg, 7 Dec.) [a fine, and unedifying instance of incompetence – "amateurs night out", in a bad sense]

 

Cobourg: ... Internal contact at egress was observed and time taken, but the external contact was hidden by clouds. The illumination of the atmosphere of Venus after internal contact at egress was very distinct, and observed independently at the station by the three parties entrusted with the observations. The planet, when on the sun's disc, appeared of a greenish-grey colour, probably due to earthshine[!]. No black drop was seen (The Globe, Toronto, 7 Dec.).

 

Kingston: ... The ring of light around Venus long before internal [2nd] contact was very manifest. ... The following facts have been made public by Col. Oliver, of the Royal Military College. Venus appeared on the edge of the sun about 9 o'clock. The internal contact occurred at 9h, 18m, 10s. The conclusion of the transit was clearly viewed, the heavens being without a cloud. The internal contact, when the planet was even with the edge of the sun, occurred at 2h, 42m, 30s. Venus passed the outer edge at 3h, 2m, 30s. (The Gazette, Montreal, 7 Dec.) [assuming the times are LMT, the errors (observed - calculated) for the 2nd, 3rd and 4th contacts respectively are -88, +7, -34 seconds.]

 

Ottawa: ... Many persons interested in the transit visited the observatory on Nepean Point this morning, and viewed the progress of Venus across the sun's disc. Astronomers and curiosity seekers wended their way across the fields... The "observatory" ... is a small tent, about twenty feet square, arranged in such a manner that the top can be thrown back, thus allowing free scope for the observations ...Shortly after half-past two o'clock the clouds cleared away, the snow stopped, and the sun came out bright and shining. The great opportunity for taking observations [at egress] had come, and the discouragement previously felt was entirely dispelled. Quite a number of persons were present at the "closing ceremonies" of the observations. Among those in the observatory were the Hon. A. W. McLelan, Minister of Marine and Fisheries [the government department responsible]; and Mr. William Smith, the Deputy Minister; besides Mr. [B. C.] Webber, the "Young Probs" of the Meteorological Service, and Mr. Frank L. Blake, who was in charge of the observations. (The Free Press, Ottawa...) [if only that level of support and involvement at the political level existed today...]

 

Ottawa: Through the politeness of Mr. Frank Blake, D.L.S. who conducted the observations in Ottawa, a representative of THE CITIZEN had the pleasure of witnessing the transit. ...Many citizens took advantage of the information supplied in this journal and made observations on their own accord through telescopes and opera glasses, and many through plate smoked glass (The Daily Citizen, Ottawa, 7 Dec.).

 

Ottawa: Lindsay Russell, Surveyor-General, took observations at his residence on Cooper Street with a more powerful glass. He could not get the time of contact owing to the operations of a cloud at the critical moment, but reports having observed the "black drop." (The Evening Telegram, Toronto, 6 Dec.)

 

Concluding Remarks Concerning the 1882 Transit

Generally speaking, the papers were supportive of the scientific efforts but The Evening Telegram of Toronto had some reservations. They noted, "the observatory is not situated in a good place. It is too far to the north of the city. The chimneys and housetops are in the way." They did concede, "The transit will be a good thing for science, but it will not do much for humanity."

Carpmael forwarded the results from the four centres which had been able to time one or more contacts to Dr. Edward James Stone, the Radclife Observer at Oxford, who coordinated the 1882 Imperial transit campaign, and who had the responsibility for reducing the observations of timed contacts from throughout the British Empire. Eventually Stone (1892) completed his task, and it is clear from his earlier report (1888) that he made use of six Canadian internal contacts among 56 in all, and deduced a solar parallax of 8".850 ± 0".022. The American astronomer, Rear Admiral William Harkness, at the U.S. Naval Observatory, measured photographs and came up with a solar parallax of 8".842 ± 0".011. The Germans relied on visual heliometer measurements, and photoheliographs, the French used photoheliostats and visual means, and the some of the Italians used spectroscopic equipment. But in spite of the years of labour that went into the preparation for the transit and the reduction of the results, no one was too surprised that a disappointing amount of uncertainty still plagued the determination of the solar parallax. The situation was neatly summarized in Scientific American (1884):

Prof. Young, after showing in the fullest manner the many methods of measuring the distance from the earth to the Sun, and detailing all that had been hoped for, ... concluded that this last [transit] was a disappointment. ... The measurements made with the planet Mars by the astronomer Gill were upon the whole more satisfactory. ... The fact was becoming known that the system pursued by the French scientist Leverrier, that of calculating the earth's distance by the perturbations of the Moon, seemed to contain the best elements of approximation to the absolute truth.