Contact Artefacts
please if you have any comments or more information regarding this record.
Menu
HomeUpfront
Now Up
Books
Towns
Structures
People
Firms
Lexicon
University of the Witwatersrand, Yale Telescope Building
Johannesburg, Gauteng
 |  |  |
Contact Artefacts | MenuHomeUpfront Now Up Books Towns Structures People Firms Lexicon | University of the Witwatersrand, Yale Telescope Building | | ||||
| |||||||
Click to view large map Coordinates: | This building is located on the west side of the east campus of the university. The astronomer Harold Alden used measurements - made with the Yale Telescope - of the position of Proxima Centauri, to prove that Proxima was the closest star to the Earth (after the Sun). Info provided by Dr. Claire Flanagan, the Director of the Johannesburg Planetarium. Submitted by William MARTINSON. __________________________________________________ Transcription of the complete article from a scanned copy of the original document. PUBLICATIONS The Yale photographic refractor of twenty-six inches aperture and thirty-six feet focal length (11.0 meters) is situated at Milner Park within the city of Johannesburg. Its approximate position is, longitude east of Greenwich 1h52m9’ latitude 26°11’ south, height above sea level 5700 feet or 1730 meters. The Union Observatory is also within the city limits of Johannesburg, about four kilometers directly east of the Yale Station. A large part of Milner Park has been set aside by the Municipality of Johannesburg for the use of the new University of the Witwatersrand. The Yale Telescope, by the courtesy of the authorities of this university, is situated upon these grounds. At the present writing four beautiful and impressive buildings have been erected by the university and others are to follow. These occupy the summit of the hill, the telescope being upon the north slope of the same hill and being thus protected from the south winds that prevail in the winter season (June to August). The university has set aside a plot of ground for the exclusive use of the observatory and in addition has agreed to put no other buildings containing artificial heat within a much larger area surrounding the observatory. About five hundred feet to the north-east of the telescope is one of the hostels or dormitories of the university. No residences of the ordinary kind can be built within several hundred yards of the observatory as this area is all within the park or within the adjacent and very large fair grounds, also owned by the Municipality of Johannesburg, and used for the purpose that its name indicates during only two weeks in each year. The university has also very generously erected a handsome building, shown to the right in Plate 2, which contains residence quarters for the astronomer in charge, an additional room to be used as sleeping quarters for an assistant, two large office rooms, and a laboratory and dark room. The nearest point of this building is approximately twenty yards east of the observatory. As the telescope is to be used only in or near the meridian its line of sight will not pass over the office and residence building. In this connection it should be mentioned that artificial heat is seldom used at Johannesburg and that the universal method of producing this heat is by means of cannel coal burned in open grates. I do not remember seeing any means of heating any of the many office buildings that I had occasion to visit while in Johannesburg and in residences it is customary to have one or at most two such open fires for an hour or two in the morning and perhaps two or three hours in the evening. This custom is chiefly explained by the mildness of the climate, but those of my readers who have been in England during the winter months will recognize here a custom that has been lovingly transferred from the mother country. The observatory building is of an unusual and very simple design, made possible by the fact that the telescope is to be used exclusively for astrometric work and that for such purposes the observations had better be confined to the neighborhood of the meridian. The building is 48 feet (15 meters) long in the north and south direction by 18 feet (5.5 meters) in the east and west direction. Its total height is 46 feet (14 meters) of which about 10 feet (3 meters) is below the level of the soil. Access to the sky is obtained by sliding the roof away in two halves, one of which moves to the north and the other to the south on iron trestles the nature of which can been seen in the photograph (Plate 2). The opening thus formed enables pointings to be made from 55° north to 55° south. To reach still greater zenith distances the north and south walls are provided with wide doors that open outward and permit observations to be made down to zenith distances 76° both to the north and to the south. The walls of the observatory are made of an outer shell of artificial stone separated by a two-inch air space from an inner brick wall. This air space has numerous ventilating holes or slits permitting the escape of warm air from the two inch space to the outside. The photograph shows three windows on the east side of the building. There are no corresponding windows on the west side so that the sun cannot shine into the building in the afternoon. Entrance to the observatory is obtained by means of a door on the north side. As further protection against the heating of the telescope or of the building in the hours preceding observation the observatory was placed next to a double row of tall gum or eucalyptus trees only a few feet to the west. Although these trees were planted less than five years before this photograph was taken the reader will notice that some of them are already higher than the observatory. The advantages of this type of building are: (1) Economy in cost. (2) Very rapid and effective ventilation of the interior; as the roof opening is practically the same size as the ground plan of the building any warm air that may have accumulated in the building during the afternoon flows out very quickly. (3) The protection against the wind is better than under an ordinary dome with a wide slit even if this is provided with a wind screen. The protection against an east or a west wind is always very complete. If there is considerable wind from the north or the south the observer need not open that half of the roof and may confine his work to the other half of the sky. (4) Economy of time is securing plates, since one operation, namely the frequent swinging of a dome from north to south azimuths, is thus obviated. Of course the great disadvantage of this construction is the impossibility of reaching large hour-angles, but in the work that we have in mind for this telescope for a long term of years we do not contemplate making any observations far from the meridian. It is impossible to secure a good photograph of the telescope in place, but Plate 3 shows the general construction. This is reproduced from a photograph taken at the Mason Mechanical Laboratory of Yale University, in New Haven, where the telescope was completely assembled before it was packed for shipment. The long polar axis is supported on two piers, a high one on the south and a shorter one on the north. The telescope tube is placed as close to this polar axis as the demands of rigid mechanical construction would permit. The driving clock is attached to the wall of the observatory, its last arbor being placed in a prolongation of the axis of the driving worm; the two are connected by means of a steel rod and two universal joints so arranged that the worm will function freely and correctly even if the clock changes its relative position in any one of the three coordinate directions. The advantage of the use of a long polar axis supported on two piers for a photographic refractor will at once appeal to those who have worked with the more usual type of mounting; with the latter, photographic observations are sometimes considerably hampered by the plate end of the telescope being brought into contact with the central pier as the telescope follows the diurnal motion. Thus with the Yerkes telescope this interruption may occur when the telescope has passed the meridian by only seven minutes. In the Allegheny telescope, with this disadvantage in mind, I specified a longer declination axis so that such interruptions can only occur when the telescope has passed the meridian by a minimum of half an hour. With our Johannesburg telescope no such interruption can occur unless the telescope is pointed far to the north. I have received many inquiries by letter and otherwise which show that there is some misapprehension concerning the completeness of the optical work on this fine objective at the time of Mr. McDowell’s lamented death in the fall of 1923. It may therefore be well to state here that this objective is altogether his own work and was not retouched or changed in any way after his death. The misunderstanding probably arises in the confusion of this objective with one of about the same size (27-inch) that Mr. McDowell had under way for the University of Michigan, also intended for the southern hemisphere. This objective was left uncompleted at the time of his death and has now been finished with success by Mr. Hageman, Mr. McDowell’s chief assistant. Most of the parts of the mounting were made in our own shop at New Haven from drawings prepared under my direction by Mr. R.W. Sellew. The clock, however, was made by George Klages and Sons, and the driving worm and the worm wheel by the Philadelphia Gear Works. By December, 1924, all was in readiness. On the 27th I sailed from New York to South Africa via Southampton, England, taking the lens with me as baggage, and hardly letting it get out of my sight. I reached Cape Town on February 1, and Johannesburg on February 8. Ground was broken for the observatory building on February 18; the construction was finished early in June. In the meantime, the telescope mounting had been shipped early in February on a steamer going direct from New York to Cape Town. Mr. O’Connell came on the same steamer to make sure that it was properly cared for. After two or three days out of New York this steamer had to put back to make some repairs to her machinery. A week was thus lost before she was ready to try again. This time she got half way to Cape Town before blowing out a cylinder head and then she completed the journey at half speed. Thus the mounting came to Johannesburg a month later than we had hoped. It was put completely together on the floor of the observatory building while the workmen were still constructing the walls, and then was lifted into place upon its piers as a unit. It was a great satisfaction to rest it in its final position and to find that its fit and operation were right. This we did in the last week in May. I remained in Johannesburg a month longer before turning the telescope over to Dr. Harold Alden, who had arrived May 29, and who remains permanently in charge. During that month we tested the mechanical and optical performance of the instrument in every essential respect. Definitive photographs began to be secured in September. June 22 was the day of the visit of the Prince of Wales to Johannesburg. At the suggestion of the authorities of the University of the Witwatersrand he was asked to open our observatory publicly. On the afternoon of that day the Prince unlocked our door and pulled the cord that starts the driving mechanism of the telescope "as a mark of respect for the United States and one of her great institutions." I must say a few words concerning Johannesburg before closing. The city is larger in area than Manhattan, Bronx, and Brooklyn Boroughs together, but contains only as many whites as New Haven, about 170,000, with about an equal number of blacks. The city covers a hilly country, with good roads, water, sewers, and so forth, throughout. As soon as one leaves the city he finds himself in open country with few roads and poor, with no water and no trees. This explains why we built within the city. The city itself is well wooded and is in fact one vast garden, with wide spaces between the very attractive one-storey houses, each one of which has its inevitable tennis court. Though one hears the usual complaints concerning hot and cold weather, it never gets really unpleasant in either respect. The one distinguishing feature of the climate that makes it superior to any other I have experienced, is the uninterrupted sunshine in the winter season, while the already moderate heat of the summer is still further softened by occasional clouds and rain. Our experience at Johannesburg up to the present time confirms the reports of good seeing that formed our chief inducement to locate there. In a few months we hope to have fuller data on this important point, covering the year’s round; and I shall defer discussing it in detail until these data are forthcoming. A recital of the names of those in South Africa who assisted our enterprise in substantial ways would make too long a list for this brief account. I must, however, mention here the great kindness of Sir William Dalrymple, Chairman of the trustees of the University of the Witwatersrand, of Sir William Thomson, Principal of that University, of Dr. Innes, Director of the Union Observatory at Johannesburg, of Mr. H. Spencer Jones, His Majesty’s Astronomer at the Cape, and of Mr. Robert Niven of Johannesburg. Yale University Observatory, April 29, 1926 (Submitted by William MARTINSON, Dec 2011.) All truncated references not fully cited below are those of Joanna Walker's original text and cited in full in the 'Bibliography' entry of the Lexicon. |