Heavens above! – panel discussion on the 1883 Grubb refractor telescope
Kirsten Wehner, Vince Ford and Hermann Wehner, National Museum of Australia, 30 May 2009
KIRSTEN WEHNER: Good evening, everybody. Welcome to the National Museum of Australia and to our lovely evening tonight. The evening is going to be in a couple of parts. We have about an hour inside to have a chat about amateur astronomy and particularly about this beautiful telescope behind us. Then we will head outside to actually do some star gazing. For the next hour we will all have to cross our fingers and hope that the clouds that are passing across decide to pass on.
VINCE FORD: Actually pass across -
KIRSTEN WEHNER: That’s right, exit the vicinity for at least for the next couple of hours. But I am pretty hopeful. I think it is looking reasonably good.
My name is Kirsten Wehner and I am a senior curator here at the Museum. I am very pleased to be able to welcome two members of our panel tonight. On the far left is Vince Ford in the marvellous waistcoat, which I believe we have to thank his wife for. [laughter] She’s taking orders, I am sure, as we speak.
VINCE FORD: She never takes orders; she gives them.
KIRSTEN WEHNER: Vince is an astronomer, and worked at Mt Stromlo as an astronomer for some 40 years. Is that correct?
VINCE FORD: Forty years, yes.
KIRSTEN WEHNER: And now is devoting more of his time to the Canberra Astronomical Society. We are very thankful to the society for being able to make the star gazing possible tonight. It is a wonderful thing. And then Hermannn Wehner, who is an astronomical engineer and who was at Mt Stromlo for -
VINCE FORD: Even longer than me.
KIRSTEN WEHNER: Even longer - [laughter] We won’t be specific. Over the last several years Hermann has been working with the Museum as a volunteer to help us conserve and refurbish this 1883 telescope. I should also ‘fess up and say Hermann is my father. So if I break into calling him ‘Dad’ in the middle of it, don’t worry too much. We are very keen on our volunteers; we call everybody ‘Dad’ in here. [laughter]
VINCE FORD: It gets confusing with the women. [laughs]
KIRSTEN WEHNER: It does, but strangely they don’t seem to object. Why do we have the telescope on display tonight? Many people here tonight will know that 2009 is the International Year of Astronomy. It was declared this year principally because it is the 600th anniversary since Galileo turned a telescope to the night sky and really began the field of observational astronomy, and of course in the process irritated a lot of people in the church hierarchy. His legacy is what we’re starting to connect with - even tonight, 600 years later.
VINCE FORD: Four hundred -
KIRSTEN WEHNER: Four hundred, OK. So it has been a long time. [laughs]
VINCE FORD: Galileo’s ancestor 200 years earlier -
KIRSTEN WEHNER: That’s right. I wrote ‘600’ on my note.
VINCE FORD: Who was also called Galileo.
KIRSTEN WEHNER: That’s right. His great-great-great-great-grandfather was also very interested in astronomy. The Museum decided to mark that event and to participate in the international year by launching this particular telescope. This is a telescope that we bought back in 2005 and have spent almost the last four years working on bringing it back to its working condition round about when it was manufactured.
The telescope was manufactured in Dublin, Ireland, in 1883, and it came out to Australia in 1885. I might get Hermann to talk a bit about the story about acquiring it. I can begin it to say that one of our curatorial staff at the Museum just got a phone call out of the blue. Someone came on the phone and said, ‘I’ve got this telescope. It hasn’t been used for a while. Would you be interested in acquiring it?’ Since I had some interest in astronomy I said, ‘I’ll investigate that one.’ We talked to the person who owned the telescope at that stage, and he said, ‘Why don’t you come and have a look at it?’ So David Thurrowgood, one of our then conservators, Hermann and I went up to Brisbane to have a look at it. Hermann, do you tell a little bit about going up to see it?
HERMANN WEHNER: We found the telescope in a shipping container - in pieces, of course, not as nicely looking as it is now - all tucked away. The tube was fairly well protected in a canvas bag, but other smaller pieces were stored haphazardly. We looked at it in detail, particularly the objective and other parts of the optics, like eye pieces and so on. It soon became apparent that a few small pieces were missing - not the objective or the eye pieces fortunately - but smaller items, which one does not by necessity need to use the telescope in a fairly semi-professional way. In the end, these shortcomings and the good sides of it were written up and handed to the Museum directorate, and they decided eventually to purchase the instrument.
KIRSTEN WEHNER: It only took a bit of fast talking, that’s all.
HERMANN WEHNER: Well, perhaps that; I wasn’t involved in that bit. But eventually it turned up here at the depository in Mitchell. Kirsten said, ‘Would I come and have a look at it?’ We then made a long list of what should be done to the telescope. It is important to note that the process decided upon was not restoration of the telescope but conservation. That is, go back to square one - go back to the time when the telescope was actually purchased and brought out to Australia and try to get the telescope back into the same ‘perfect’ condition.
Looking at it now, after what we have done to the initial purchase, I think we have succeeded in achieving that, right down to the coat of paint on the telescope tube, which was meticulously analysed by spectrographic methods to find out what paint had been used - what was the undercoat, the overcoat and so on. Apart from the intermediate paint layers - that is, after purchase to the present date - the initial paint coat was established and was replicated. That is what is on the telescope now.
So if the builder of the telescope, one Thomas Grubb of Dublin, would able to be around, I think he would be pleased and say, ‘Gee, this is the way it was when I shipped it to Australia.’ That would be a feather in our cap, I think.
KIRSTEN WEHNER: I think that was one of the most common questions we asked ourselves when we were working on it: What would Mr Grubb have done?
HERMANN WEHNER: That is not what he would have said, but what would he have done. Because of my age I got roped in, and please cast your mind back to 1883 and see how they would have done this knob or this something or whatever. It was a difficult job, I tell you, but with a bit of a wink and a nod I think we succeeded.
VINCE FORD: What amazes me about 1880s telescope builders is your choice. If you wanted an instrument about this similar size, you had your choice of three manufacturers: there was Grubb in Dublin; there was Slough in Scotland, and there was Cooke in London.
VINCE FORD: Lots of people bought a Cooke telescope.
HERMANN WEHNER: Yes, they did indeed.
KIRSTEN WEHNER: I should say before we go on, and I meant to say at the beginning, that we are thinking of this evening as an informal chat. So if you have questions, please interrupt. I don’t want to keep them all until the end. I will just get you to put your hand up and we will bring a microphone around. Leanne will kindly run around with it, just so that everyone can hear the question, let alone the answer. I will also just let you know that we are recording this evening, so your lovely dulcet tones will go down in posterity as part of this evening’s events.
I thought we might take a little step back to talk about how the telescope came to Australia. A lovely part of my job at the Museum as a curator is, when we are offered a new collection, to try to discover what the history or what we call the provenance of that collection is. I was very lucky when we got offered this particular telescope, because I discovered that a lovely chap called Dr Wayne Orchiston, who is up in Townsville at James Cook University, had very helpfully written a few papers about the history of amateur astronomy in Australia and had indeed traced the history of the telescopes that were like this one that came to Australia in the late nineteenth and early twentieth centuries.
He had done that by basically going and sitting in the Mitchell Library up in Sydney and reading through vast reams of correspondence between all the amateur astronomers in Australia who were writing to each other to tell them: ‘I have just bought this absolutely fantastic telescope and it is at least a bit bigger than yours. I am sure I will be able to do much more important work.’
VINCE FORD: They are still the same today.
KIRSTEN WEHNER: Yes.
HERMANN WEHNER: It is called ‘aperture fever.’
KIRSTEN WEHNER: That’s right. I’ve got a bigger aperture than yours.
VINCE FORD: ‘Aperture envy’.
KIRSTEN WEHNER: What we discovered was that this telescope was purchased around 1885 by a chap called William John Macdonnell and we think that Mr Macdonnell may have purchased it directly from Grubb in Dublin via a catalogue. He looked it up in the catalogue and decided what kind of instrument he would like, how big and with what features, and presumably sent off a deposit, I would imagine. Around 1885 the telescope arrived in Australia, and Mr Macdonnell took it to Port Macquarie where he was living at the time. WJ Macdonnell was a bank manager. He wasn’t a professional astronomer by any means; he was a bank manager; and he had been sent to Port Macquarie to head up the Bank of New South Wales which is now Westpac Bank.
I think he must have been quite a keen astronomer because not only did he add this to an expanding stable of instruments that he had accumulated over that period and in the years leading up to it, but he also built a special-purpose observatory in the back yard of the Bank of New South Wales to house this and his other instruments. [image shown] In this image up there, that is Mr Macdonnell standing outside his lovely new observatory behind the bank. I do wonder if he was a bit like one of the early governors of Australia, Governor Darling, who was also a very keen astronomer and came to Australia in the middle of the nineteenth century. A short while later he got told off by the colonial office because it seemed he was neglecting his administrative duties because he was staying up all night watching the stars. I do wonder if Mr Macdonnell got in a little bit of trouble as well that way. Macdonnell kept the telescope for around 10 years. He did a range of observing programs with it and with other instruments that he had with him. Vince, can you talk a bit about what amateur astronomers at that time would have been actually doing, what kind of work?
VINCE FORD: It was kind of an interesting and busy time because it was a time where astronomy was changing from just noting the positions of stars, which was vital for timekeeping, navigation and so on. In fact, the state observatories that were set up back in the nineteenth century, that was their main job - timekeeping and navigation. What the amateurs did was to turn it more into looking at the universe as a whole and trying to figure out how it all worked. Telescopes of this size were used a lot for actually investigating double stars. A third of all the stars in the sky are at least double. They are not one star; they are two or three stars and sometimes four up to half a dozen stars, locked together by gravity, waltzing around one another, but to your eyeball they look like one.
Hopefully if it clears up we can show you one of these things tonight. Why do you want to investigate double stars? It is a way of finding out how massive and how heavy stars are. If you can figure out how long it takes them to go around one another, you can figure out the relative masses of them. That was kind of important. The whole business of what is out there besides stars, mapping the rest of the sky and finding out what these big gas clouds were, the so-called nebulae. In these telescopes they just show up as fuzzy blobs, clouds, which is what nebula means in Latin - cloud. It turns out what nebulae are the places where stars are being born all the time.
Finding things - comets. Most comets up to the time that a few satellites were launched were discovered by amateurs. There are a couple people in this room who have actually discovered comets. I think I saw one of them come in a while ago.
KIRSTEN WEHNER: Put your hands up if you are comet discoverers.
VINCE FORD: They might be outside setting the telescope up. Anyway there are three or four people in Canberra that have a string of comets after their names. So it is not just guys like John Tebbutt who found the great comet of 1861 – Tebbutt actually used this telescope. This is one of Tebbutt’s telescopes at one stage. So it is a direct tie back to one of the great nineteenth-century amateur astronomers. I don’t like that word ‘amateur’, I have to say, because there’s really not much difference. The only thing is that amateur means someone who does it for the love of it. Professionals do it for the love of it too.
VINCE FORD: So discovering comets. The sunspot cycle - while we don’t know what effect it really has on the earth. There have been attempts to tie sunspot cycles to weather and it is still going on. It looks there is some effect but we are not really sure what yet. Nova and supernovae, stars that just all of a sudden brighten up enormously. Nova, because most of them before they brighten up, are beyond the limit you can see with your eyeball and all of a sudden ‘bing, there is one there - ah, it is a new star, it is a nova.’ In Latin nova is new.
These sorts of discoveries were what amateurs were doing through the nineteenth century and through the twentieth century and are still doing today. These days they do even more than that. We have a guy in the Canberra Astronomical Society that is producing images of the planets that rival the ones being taken by Hubble and he is doing it with a telescope about twice the diameter of this one.
KIRSTEN WEHNER: If only we could get the Hubble budget for the Canberra Astronomical Society -
VINCE FORD: Indeed. Just before the fire [2003 bushfires] that removed most of the telescopes from the top of Stromlo, those telescopes were being operated most nights by members of the Canberra Astronomical Society who were providing observers for Stromlo so that us professionals could get on with the business of data analysis rather than spending our time on the cold end of a telescope collecting the data. Amateurs have always been a very important backup for the professional.
KIRSTEN WEHNER: One of the other things that I found really interesting about Macdonnell and which I think is a very strong continuation with our evening tonight is that he like the other amateur astronomers were very active in promoting astronomy in public education, in writing articles to the newspaper to say that the government should be giving astronomy more money and letting people know about what happened when they saw a comet in the sky.
VINCE FORD: There is, of course, still a small public observatory, operating in Port Macquarie. It is probably the oldest operating public observatory in Australia. Other amateurs have actually funded observatories. James Oddie, the Mayor of Ballarat, made a fair packet out of the goldfields and was the superintendent of the school of mines and so on. He had quite a large observatory at Mt Pleasant in Ballarat. That’s still there. One of the things he did at the time of Federation when it was decided that there would be - for want of a better term - a Commonwealth observatory in the Australian Capital Territory, he presented the Commonwealth Government with one of these gadgets one and a half times the size with a nine-inch diameter lens in it. That Oddie telescope was on Stromlo from 1910 up to the time of the fire. It was the telescope that from 1970 onwards was the one that we used for school kids and visitors to show them the sky.
The last research work on the Oddie was done in 1974 when Don Mathewson and I used it, with a new-fangled electronic camera on the back end of it, looking for the remains of supernovae in our galaxy. We also used the twin of this thing, the six-inch Farnham telescope, at Stromlo with an electronic camera on it. Why? Because we could get it for 100 per cent of the time, and the other thing is the optics happened to match quite nicely the field size we wanted for that particular survey.
One of the girls we had helping on that one, one of our students, actually fell through the floor one night. The Farnham was in a little dome on the end of the old Commonwealth Observatory building up there, which has now been rebuilt, the dark room was down below the telescope and underneath that was the drawing office. Martha comes racing out of the telescope with a couple of undeveloped photographic plates ready to go down to the dark room to process them, and she hit the floorboards that had rotted through. So ‘thonk!’ down in to the drawing office, and the drawing office was locked and she couldn’t get out. She was stuck there until half past eight the next morning when some of the drawing guys appeared for work. Martha was a red-headed Irish lass and I am told that someone should have recorded the language. Astronomy is full of little ‘pitfalls’, shall we say. But telescopes like this really did help get Australian astronomy on its feet.
KIRSTEN WEHNER: Vince, it is interesting that you mentioned the Farnham telescope, because it is certainly a telescope that has played a more recent role in this telescope’s life. Hermann, can you talk a little bit about how we went about the process of rebuilding the telescope and the Farnham’s role in that?
HERMANN WEHNER: Yes. This telescope here was built by Grubb in Dublin in 1883. We have a very good write-up done by Ian Glass called Victorian Telescope Makers, which cites throughout the book letters to and from the two Grubbs - that is, Thomas the father and Howard the son - that states which telescopes they were building, their discussions with astronomers, and on new departures in telescope construction. It lists both Grubbs’ special ideas on how they could improve on the goods they were, of course, trying to sell. So 1883 was for this telescope - it was by no means the first telescope Grubb ever did. The first Grubb telescope was around about 1832, I believe, a somewhat larger one than this one. But because it was so good it set that firm on its path to build basically just telescopes. When I say ‘just telescopes’, I have to include also eventually certain attachments like spectrographs or perhaps even photographic plate holders at a much later stage. That was Howard Grubb by then - but also bigger and bigger telescopes. The aperture fever comes back in again. Somebody wrote, ‘I have an objective which is that diameter. Can you build me a telescope?’ And somebody else wrote, ‘Ah, but my objective is bigger than yours. Can I have a telescope for that?’ So it went on and on like that.
When we talk about telescopes of this vintage, we talk mainly about refractors; that is, telescopes which employ an objective which comprises usually two lenses. Two lenses are a special development, which was made prominent by Dollond in London around about the same time, to reduce the achromatic error, the colour error, in a single lens system. With two lenses with different glasses this can be avoided, and that was really a step in the right direction. People could then look through a telescope and then see every star blue or every star red, depending on the correction of the lens -
VINCE FORD: Or sometimes both.
HERMANN WEHNER: Or most often both.
HERMANN WEHNER: But they could see it essentially without those coloured rings around it. So these achromatic objectives had to be produced as well. Grubb had a process going to purchase the glass from somewhere, pressed it, and, as Ian Glass says in his book, often enough rejected some chunks of glass because they weren’t good enough. Nowadays, we may have rejected all the chunks of glass which Grubb got, because our testing methods have been vastly improved. But at the time he had tests of clarity of the material. That means no inclusions, little sand particles in it. He could test stresses within the glass. He could polish part of it and see if that is readily done. And other similar tests which in the end produced very good objectives indeed.
Where does the glass come from? Well, most of it had to be imported. There is a brief article which talks about the glass tax which the British government put on to locally produced glasses - something which stifled the glass-making industry in England and with it the production of telescope objectives from local makes and shifted all the focus to importation of particular glasses. You could get some from a chap in Switzerland; you could get some from several people in France. And eventually, by hook or by crook, they ended up in Mr Grubbs’s hands and he produced, by his newly developed grinding and polishing methods, very good objectives.
We have one of those objectives, an achromat, in this telescope here, and by general inspection it looks very good indeed. We had great hopes that we could try the telescope on the night sky after we had finished the conservation work on it. We scheduled a particular Wednesday for this. We all turned up and we rolled the telescope out and so did the clouds as well. So we had to push it back in again, because the next day it was put in place here. So I must admit that we haven’t in earnest looked through the telescope yet on a star. Certainly I’ve looked at other things and done certain adjustments to the optics, and it is good to go.
VINCE FORD: The optics in the Farnham and the Oddie were absolutely magnificent.
HERMANN WEHNER: Yes.
VINCE FORD: The Oddie in particular - the nine-inch clone of this - had some of the sharpest optics I’ve seen in anything. Getting back to double stars again, it could split double stars much closer than most other telescopes that size. One of the reasons is that these things were designed to match the unaided eyeball.
HERMANN WEHNER: Well they were at the time.
VINCE FORD: At the time. yes.
KIRSTEN WEHNER: As opposed to now using actual instruments to record data -
VINCE FORD: Exactly.
HERMANN WEHNER: The telescope is equipped especially for double star observations. As Vince pointed out, it is a longish process. One has to acquire a view of the star, do certain measurements, and then do it again and again and again and again, and over years come to some conclusion how do these two stars move around each other and so on, and also the brightness of stars and the distance, and something which is called the position angle. That is, if you have one star here and one star there, you can measure from some fiducial mark the angle of the line which connects those two stars - it is called the position angle. The telescope has a micrometer available to be used for that purpose and a position angle rotation at the eyepiece end of the telescope, which is the lower end on the tube.
We found when it was opened up that the beautiful glass scale which was produced by Grubb at the time had broken into three major pieces and a small collection of little ones. The conservation staff at Mitchell put it together again into one piece. I think that was absolutely wonderful, trying it out with different cements and different facilities and ‘careful, don’t lift it too hard. It might break again.’ There were doubts in there. We had been winning with that. It must be nice to mention here -
KIRSTEN WEHNER: Let’s take a question, Dad - is that OK? Sorry, Hermann. [laughter]
QUESTION: That was one of the unique things with this telescope that it was designed for double star observation. Were there any other particular things that were put in this telescope and perhaps not in some of the others at that time that reflected the interests of Macdonnell and his observations?
HERMANN WEHNER: Yes. Nowadays, when we want to buy something, we look at a catalogue and, lo and behold, Mr Macdonnell would have been able to do that as well. We have as it happens - again through Ian Glass – a copy of the Grubb catalogue of about that vintage. It lists refracting telescopes that can be produced in any size up to, I think, 12 inches of lens diameter or something like that. And there were two types of telescopes he could select from: type A and type B. Marvellous, isn’t it? He chose type A. The main difference between the two types was - and still is in fact - that type A, which this one is, has the facility to set the telescope onto an object by merely having to know the sidereal time at the point of observation and the right ascension coordinate of the object you want. Whilst the type B doesn’t have this facility, and there you have to know those two data but you have to do some arithmetic calculations to work out the hour angle and then turn the telescope to the hour angle.
KIRSTEN WEHNER: What does that mean?
HERMANN WEHNER: Yes, I am coming to that.
KIRSTEN WEHNER: Because I am confused.
HERMANN WEHNER: It gives you a chance to make some mistakes right away. You find the star should be there, but the telescope says it is there - well plus or minus got intermixed there or something like that. This one here made the observational procedure much simpler. I have mentioned certain technical terms here, which perhaps should be explained - if everybody has another half hour I would be happy to do so. [laughter]
We live at a place and we have two coordinates which we call longitude and latitude, and this coordinate system has been also applied to the position of stars in relation to some fiducial lines, which we might not have to go into right now, only that they are not called longitude and latitude - they are called declination and right ascension - or the other way around because longitude is right ascension and latitude is declination. Declination is easy. You just move the telescope up and down until you have the right number – you can read the number off the scale - provided, of course, your telescope has initially been set up to coincide with that stellar coordinate system, and that is difficult.
VINCE FORD: Perhaps you should point out – the vital bit that Hermann is getting at -
KIRSTEN WEHNER: The assistant will
VINCE FORD: Unfortunately, I don’t have the tights and the right sort of shape, but what the heck. The vital bit here is this axle. That axle has to point straight at the pole. It sets this axle parallel to the rotation axis of the earth. So at Canberra this angle has to be 35 degrees 19.3 minutes roughly - that is Canberra’s latitude.
If you are on the equator that axis would be flat. If you were at the pole, it would be pointing straight up. So that is the axle that compensates for the rotation of the earth. If you drive this axle backwards for the rotation of the earth, at the same rate the earth is spinning, the telescope will effectively stay pointed at that spot in the sky.
The other one that Hermann is calling declination is this axle, and that lets you move the telescope north and south. So east-west motion around this axle, north-south around that one - declination, right ascension. And sidereal time - I think the only way I ever understood it was it is time corrected for your latitude, and it gains three minutes and 57 seconds on ordinary time every day because the earth is moving as well in its orbit.
HERMANN WEHNER: That had to be said that sidereal time is time measured against these stars, whilst the normal time we live by is measured against the sun. It means once the earth has rotated once around and the sun is again in what is called the meridian or a particular point in the sky, this is what we call 24 hours. If you do the same for a star and you go around once, you find you do it already in 23 hours and 56 minutes, roughly. So there is roughly four minutes’ difference, and that is because the earth has rotated part of the way around the sun.
Since the astronomers work with stars, they have to use this device called sidereal time. One of the pieces of instrumentation Mr Macdonnell acquired fairly early in his observational career was a clock which he could keep to the sidereal time so that he could observe properly. This possibility of setting the telescope without a time consuming and perhaps erroneous calculation to get the telescope pointing in the right position was one of the class A-type instrument points in their favour. Macdonnell saw that straight away - and it has been commented upon later on by subsequent owners of this particular telescope that this was a great step forward in the right direction – and is one of the many things which both Thomas and Howard Grubbs devised and built into the telescope.
So now you get this catalogue and then compare with the instruments which we have knowledge of, like this one, the Farnham and perhaps others as well. There is one in the Science Museum in London and more around the place. It becomes apparent that yes, they are the specification. But Mr Grubbs said, ‘You know for the few pounds I can make this so and so and make this much better.’ All the astronomers said: ‘Excuse me, Mr Grubb, you couldn’t do it this way and then make this better still?’ That process still exists nowadays.
VINCE FORD: Too right it does.
HERMANN WEHNER: When the astronomer says: ‘Oh, this is the new telescope. Can you do so and so with it?’ We don’t say, ‘Yes, this can all be done.’ Sorry, ma’am, you were going to ask something.
QUESTION: I was actually just thinking when you said ‘just for a few pounds’. At the time when this was produced and you said there’s a type A and a type B, what was the difference in the price for the two, and what did they actually sell for?
KIRSTEN WEHNER: Before we answer than question, let’s ask the audience what they think Macdonnell paid for this in 1885. Have a guess. How many pounds?
HERMANN WEHNER: Pounds sterling to the nearest bidder.
AUDIENCE MEMBER: Five hundred.
KIRSTEN WEHNER: Fifty guineas? How many pounds is 50 guineas – one hundred pounds?
HERMANN WEHNER: No.
KIRSTEN WEHNER: Fifty, right - sorry post 1966. [laughs]
HERMANN WEHNER: Somebody already bid 500 pounds. The price which we know he paid was 250 pounds, and don’t forget he was only a bank manager in a branch of a larger bank.
VINCE FORD: Did they check the books soon after?
QUESTION: What was his salary then?
HERMANN WEHNER: Ah, that’s the point, we don’t know that.
KIRSTEN WEHNER: We are still trying to do some investigation on that, but I think it was probably about 40 pounds. So that’s a lot of money.
VINCE FORD: That’s a year – not a week.
KIRSTEN WEHNER: What was the difference between A and B - do we know?
HERMANN WEHNER: Yes, we do.
KIRSTEN WEHNER: In pounds – forget the technical stuff.
HERMANN WEHNER: Yes, we know that too, but unfortunately the catalogue price list which Grubb offered does not list a telescope at 250 pounds. It only goes for type B to 170 pounds and for type A - I don’t think I have figures - so I can’t really compare this. So there is already ‘if you want that it will be a little bit more’ type thing. There may be, of course, cartage included. It might only have been free on board in Dublin and you have to buy the ship to cart it to - [laughter] - pay them the rate to get it to Australia.
KIRSTEN WEHNER: We know that he paid 250 pounds, because when it arrived in Port Macquarie he wrote a letter to John Tebbutt, who was in Sydney, to say, ‘I have just bought this wonderful telescope and I paid 250 pounds for it.’ I often wonder if he regretted that later on, because in around 1895 he was forced to sell the telescope because he got into some deep financial problems. Australia in the 1890s was going through part of the global financial crisis of the 1890s, and he was forced to sell it. He sold it for 150 pounds. So in ten years he had lost 100 pounds on it, which I suspect was not very good news to him.
HERMANN WEHNER: Not good news at all. I happen to know that - again, from odd correspondence by Grubb to others - that Grubb paid his best qualified tradesmen about 30 to 40 pounds a year to make telescopes. That is peanuts we would say today, wouldn’t we?
KIRSTEN WEHNER: When I look at the photographs of Macdonnell with his telescope [image shown] particularly the one which is an image of him inside his observatory with the telescope, you will notice that the telescope is not quite set up for use yet. You can see differences, for example, the strings that are attached to the slow motion and so on are not installed. I rather think - I don’t know for sure – that that photograph was probably taken when the telescope had first arrived in Port Macquarie and Macdonnell had set it up in his observatory and he thought ‘Man, look at me with my telescope’ and got the travelling photographer who used to travel around the region to come and take a series of photographs of it.
HERMANN WEHNER: I claim that he bought himself a new hat, when you look at this picture.
VINCE FORD: Kirsten, I think it is worth mentioning that the drive system in these telescopes is an absolutely fantastic little mechanism. It is a governor, a speed controller that has a couple of spring-loaded balls on arms. If the telescope tries to go too fast, it spins the balls up a bit and gravity drags them back; if it goes too slow, the balls drop and the springs push them back - it is a marvellous mechanism. The only other place I have seen it other than in Grubb telescopes is in old lighthouses. It is exactly the same sort of mechanism that used to spin the lights in lighthouses to keep a nice regular flash, because the ones in lighthouses revolved a hell of a lot faster than these do.
HERMANN WEHNER: We have introduced the term ‘drive’. Why do we drive the telescope? If you watch out and observe the sun, you will find that it will rise in the east in the morning and it will set in the west in the afternoon. It seems to go across the skies. So if we want to look at the sun or a star for that matter as well - the sun is a star, I know - for any length of time we have to follow that around across the sky. That is why the telescope is driven around the right ascension axis, which Vince pointed out a while ago. Why is this so? Because the earth rotates the other way. You can’t just have ‘stop the earth, I want to get off,’ because we would all fall off in any case and leave things as they are. So the drive has to be applied to the telescope.
How do we do it if we have no posh electric motors with electronic speed controls or anything like that, as we have nowadays? There is a weight in the central column, in the pedestal of the telescope suspended from the drive unit by a steel cable. If you wind this weight up and you stop, it will just plonk down again. But it doesn’t do that. It has the governor, which Vince mentioned, attached to it. You can see when you walk around later on that there is a little dial in front with a little needle, and you can move that to the different speeds for the telescope to operate at. Once this is happening, the weight falls down very, very slowly and after a while - perhaps two and a half hours or so - it has reached the bottom. Suddenly you look at the star, and the star goes ‘zip’ and it is gone. And you say, ‘Now what’s wrong?’ The weight fell down. Right-oh. Then you have to go and wind it up again and reset it all. That is where later developments to the drive system were so much better, because nowadays you don’t have to this winding up of weights and so on.
KIRSTEN WEHNER: And Hermann, I understand that the pillars of this kind of telescope, which are hollow, also make very good houses for possums.
HERMANN WEHNER: They do. They love that. We had that Farnham telescope at Stromlo which has a very similar arrangement of a central pedestal, and hidden from view around the back there are some holes. One at the bottom so that you can see that the weight is down below and you can adjust it and do things like that, but also another hole about three-quarters of the way up. One night the observer at the Farnham was winding up the weight and looked to see if it had arrived at the upper hole. Instead he didn’t see the weight but he saw a lovely little possum nose sticking out. The possum had made its house there. So it was being fed apples and it was left there for a while and then taken away.
VINCE FORD: I have seen the opposite effect on the Oddie. I had a very scared student appear at the 74-inch one night, white as a sheet. They were working away and the drive had stopped and they thought: ‘Oh, well, perhaps we’ve hit the end of the travel.’ But they looked in the middle hole and they could see the pulley there with the rope around it, so they figured the weight hasn’t gone down to the bottom yet. So they put the hand in the bottom to see where the weight was, and something warm and furry grabbed and bit. They were down like a shot, trembling. So we went back with a torch and shone the light in, and here’s a possum with half a hundred weight of lead spreadeagled across the hole with the weight on its back. We said to him, ‘It is easy, it is just a possum caught. Just wind the weight up and he’ll come out.’ We left him because we knew what would happen. Do you know what happens when you are standing with a hole about here with an irate possum in it and you have to stand here to wind the weight up and let him out?
QUESTION: Good evening, I was just wondering whether you had any information on how the telescope would have been transported. Would he have had to do a fair bit of assembly or it just turns up in a box like that?
HERMANN WEHNER: No, not in one piece, I sincerely hope. When we shifted it from Mitchell to here, it was suggested that we need a very high truck because of the telescope standing up. And I said, ‘Well one thing is you turn the tube horizontal.’ Oh yes that is much better but even then it is still very bulky. What I sincerely hope had been done was that the pedestal which is a jolly heavy piece of equipment and very cumbersome was separate. Then the whole right ascension and drive unit was by itself and then the tube was by itself. Then of course a box with lots and lots of little pieces hopefully all marked A to A, B to B, C to C so that you could put it together again properly.
KIRSTEN WEHNER: Unfortunately the instructions were all in Swedish.
QUESTION: So the bank manager probably would have had some skills so he could assemble it?
HERMANN WEHNER: I should think so. What is more, if you have the knowledge of telescopes and Mr Macdonnell had this because he had already two or three smaller telescopes previous to the purchase of this one here, he’ll know the function of various components on the smaller telescopes. It is relatively easy to enlarge this knowledge by just comparing the smaller example with the newer instrument here. No doubt Mr Grubb would have had notes written with it to point out the sequence of assembly. Certainly he has written a paper which we have a copy of as well, on the adjustment of the telescope itself and its use at night. That is of importance that the purchaser of course knows what a telescope can do and not just look through and say, ‘This is lovely. But what do I do now? It is not quite in the middle, which little knob do I turn to adjust all that?’ I think that would have been explained.
VINCE FORD: The sort of thing that is never explained in the little telescopes that people tend to buy in toy shops for their kids for Christmas and thereby spoil any interest the kid will have in astronomy. If you do intend to buy a telescope at any time, please contact CAS and talk about it first. There are more traps for young players than there are possum traps in Grubb telescopes.
HERMANN WEHNER: End of commercial.
KIRSTEN WEHNER: I do think it is a very interesting question, how many people from the town must have been involved in assembling it because when we put it back together, we actually had to assemble it and then disassemble it again because we didn’t quite understand exactly some parts of it and reassemble it. For example, to put the tube on, we used a very large gantry crane to be able to pick it up and actually position it without damaging it while we put it on. There are quite a few dents in the tube which we chose not to repair when we were doing the work on it. We thought that’s part of its history, let’s leave the dents in. But I do wonder as it is being assembled and disassembled through its life, it has had a bit of a rough trot at times. There is still quite a bit of that history of it in the telescope itself that we have chosen not to repair. I do imagine everybody in the town having to come down on the night it arrived to help put it up.
HERMANN WEHNER: Macdonnell was very keen in propagating knowledge of astronomy in a very general sense. He was as bank manager fairly - is important the right word - notable person within Port Macquarie, small as it was at the time.
KIRSTEN WEHNER: He was president of the pony club, I believe.
HERMANN WEHNER: He was instrumental in getting a choral society going. He did all sorts of township groups to get them to get together in the first place and then to further their knowledge of whatever they were doing and enjoy this knowledge.
VINCE FORD: So plenty of hands to lift the tube.
HERMANN WEHNER: yes, if they are tall enough of course.
KIRSTEN WEHNER: Macdonnell standing there giving directions, I would imagine.
HERMANN WEHNER: he would have had enough people to come and knock at the door and say, ‘Excuse me, Sir, can we perhaps look at this new star up there’ or whatever or the moon and so on. I think he would have obliged because it was in his way of operating, I believe.
QUESTION: You talk about him having used it for binary stars and things, because that is what it was designed for doing specifically. Do we have records of what he was actually observing and so on? I notice with the information panel you have that Mr Beattie then used it and published many scientific papers on it.
HERMANN WEHNER: that is right.
QUESTION: Do you actually have information on the other sorts of things and comets that Macdonnell might have observed using this telescope at the time as well?
HERMANN WEHNER: Wayne Orchiston whose name Kirsten mentioned before wrote a nice paper on William John Macdonnell and the development of astronomy in New South Wales and in it he quotes the type of observational work which Mr Macdonnell did. He splits this up into transitory events and into long-term monitoring processes and search programs sort of thing, you will find. I won’t read it all out, but the years that Macdonnell did this is mainly for transitory events - not solely but mainly. That means he did not in my estimation start a long-term binary star or double star observational program. He was active in looking at comets and no doubt noting their position and brightness and things like that, of course. But not only just look how pretty and then leave it. But really do some work with it. That is a transitory event - the comet comes, the comet goes.
VINCE FORD: He also observed a couple of transits of Mercury, passing across the face of the sun.
HERMANN WEHNER: That is another one, the transit of Mercury in front of the disk of the sun, also the transit of Venus.
VINCE FORD: Port Macquarie was one of the seven New South Wales stations for observing the 1847 transit of Venus. It was totally clouded out.
HERMANN WEHNER: That was the difficulty. If you were part of a group to observe a major event, a transit of Mercury or Venus are major events at least at the time to determine the distance to the sun from the earth, and if it is all cloud, well tough luck. But you still have taken part in it. You still have learned how to use the instrumentation. You still have learned how to time these events and to reduce the values afterwards. It is written elsewhere but not in the English paper that some of Macdonnell’s timing values of such events were indeed used for the determination of the distance between earth and sun. There are various eclipses of the moon, eclipses of the sun, lunar occultation of planets, lunar occultations of stars - all transitory events you will agree. But they can all be noted, they can all be timed. They can be then made public so that others can use that data subsequently.
VINCE FORD: They are still things that amateurs are very much in the forefront of doing today.
HERMANN WEHNER: Absolutely.
KIRSTEN WEHNER: It is also a point to draw out that a collection like this within the Museum is an ongoing project. Even though we have done a lot of work on the telescope already, our understanding about its role in amateur astronomy and the people connected with it is ongoing. For example, one of the projects that is still on the list to do is to go and look at Macdonnell’s observing diaries which are held up at the Mitchell Library in Sydney together with a number of his books that he donated at some point. The next step is to go and get to know those much better to understand a bit more again about how he used it. Very much part of the Museum’s work is to draw together these paper documents with objects like the telescope to understand from the telescope itself what he might have used it for, how he used it and the way in which the technology itself shaped what he could do.
VINCE FORD: Just getting back to your question about did anything long term on double stars come out of it? Macdonnell might not have done much, but one of the guys that bought the telescope later on was very much into double stars and binaries – Innes. He wrote several of the papers that set up the physical investigation of double stars. He bought the telescope. He would definitely have used it for a long-term double star program but he got offered a job at the observatory at Capetown and shot through to there, so he never actually got around to using the telescope. But it came close.
HERMANN WEHNER: You mentioned that others have used the telescope - this is quite correct. Kirstie said that Macdonnell had to sell the instrument and others in his stable of astronomical instrumentation because of financial difficulties brought upon by the general times in the 1890s. I have written down here that all told Macdonnell had six refractors and one transit instrument to determine the position of Port Macquarie precisely and the timing as well and so on. Of those, he kept only two instruments and took them with him to Sydney, and this was not one of them.
This telescope in particular was then sold to Mr Innes who obviously immediately sold it on to Mr Gale who then sold it on to Mr Beattie. And there we start a period of long use of the telescope. We have one picture where Beattie stands next to the telescope with an attachment on it, which we can’t entirely encipher what it is but I think it is a very early type of photographic plate holder for the instrument.
VINCE FORD: I guess Gale would have used this telescope to do some observations of at least one of the four comets that he discovered.
HERMANN WEHNER: Yes. Beattie sold it on to one Hoskins, who sold it on to one Brims, who sold it on to one Otto who put it into the shed, and then Mr Benson discovered it and now we have got it. And are we pleased!
KIRSTEN WEHNER: An eventful life.
HERMANN WEHNER: The trouble is that all these personal difficulties made it necessary to sell on the instrument, which after all is a very useful and fairly expensive device. The telescope was not used as much as it could have been used had it been with one owner – not all the 150 years - for extensive periods of time, unfortunately. And of course every time you sell it, it is taken to pieces, it is packed onto a horse dray and it is carted around the corner.
VINCE FORD: Another two dents, another bit lost.
HERMANN WEHNER: And those dents we have left. We didn’t want to polish them all out and really make it look a Grubb ‘untouched by human hands’ type affair.
KIRSTEN WEHNER: I am conscious that it is coming up to 7 o’clock but if you have another question we certainly have time.
VINCE FORD: Has anyone actually checked the sky?
HERMANN WEHNER: We are just warming up, you know. [laughs]
QUESTIN: This question is very peripheral, but I wonder whether for a lay person maybe Vince could briefly explain how the sailors, the seafarers, used to use the stars to navigate around the world.
VINCE FORD: The first thing that you needed was a very good set of star positions. They didn’t need the whole sky, although eventually everything that was at least visible to the eyeball had its position noted in those two coordinates that Hermann mentioned, right ascension and declination. So you had a grid over your head that told the position of certain stars. You then needed to measure from the deck of your sailing ship at a known time what we call the azimuth - from the north point round through the east, that angle to the star - and its altitude, how far it was above the horizon. So you would get your sextant and your compass out and you would measure those two angles. Then you would go to a set of tables and try to figure out: ‘I know the position of the star. I know the time. I know the angle it is from where I am. Where am I?’ It was a batch of mathematics, simple trig.
The simplest way of doing it was the way that the Polynesians and the Arabs and a lot of ancient mariners did. Simplest way is that you know for example this star has got a declination of minus 35 degrees 19 minutes. That means it goes right over head at Canberra. So I am in my sailing ship and I am trying to find Canberra. You would find the last couple of hundred kilometres a bit rough but what the heck. What you would do is you start off from England and you sail due south, due south until that star at 35:19.3 is directly over the top of your mast as it goes across the sky and as it is at the highest point in the sky. You know then that your latitude is minus 35 degrees 19 minutes. So then knowing that England is a hell of a long way west of Australia you turn your sailing ship east and you sail due east, due east - and eventually if you can get your ship through Western Australia, South Australia and most of New South Wales you will end up at Canberra. That was the simplest method of doing it.
The Polynesians, for example, knew that Altair went straight overhead in Hawaii. So when they left Tahiti they would go north until Altair went straight over the top at its highest. Then they would turn east and sail down.
It gets a lot more complicated after that. The next step is to find out where your longitude actually is. Latitude is simple. You know how far the star is north or south of the equator. You measure the angle, and the difference in angle will tell you where you in latitude north or south of the equator. For longitude you need to know the time and you need to know the time very accurately. That’s what held up accurate navigation for centuries. It wasn’t until really accurate clocks came along that you could get your longitude safely enough to know which side of Australia you were on, for example.
HERMANN WEHNER: They are called chronometers.
VINCE FORD: Yes, chronometers. It is just a question of star position, angles measured from your boat and the time - and a good set of tables.
HERMANN WEHNER: And nowadays you use the satellites, don’t you?
KIRSTEN WEHNER: That is right, GPS, bring it on.
VINCE FORD: The satellites - to know where they are - need good star positions and accurate timing - so we are back where we started from.
QUESTION: Perhaps coming back to the Museum and stepping away from this, can I just ask what other artefacts you might have at all related to amateur astronomy or to the studies of the stars here? Is this the only thing in the collection or do you have a pool of other things as well?
KIRSTEN WEHNER: I am sorry to report that this is our sole object relating to amateur astronomy. It was a big basis upon which I argued that we should purchase the collection, which was a fairly significant investment for the Museum both in the initial purchase and then obviously in a long-term conservation project. I am hopeful that it may be the beginning of a collection, but so far the Museum hasn’t acquired a lot of material relating to amateur astronomy or indeed that much material relating to what we might call professional astronomy. Institutions like the Powerhouse Museum in Sydney, and certainly the Sydney Observatory have a very good collection around the Sydney Observatory. And the Melbourne Museum has a very good collection, including material from Mt Stromlo which has found its way back to there.
The only other astronomical material that we do have that is quite good, which is a bit to the side of our discussion this evening, is collections of bark paintings that really talk about Aboriginal astronomy. We have a very large bark painting collection and there’s a lot of information in there that in some ways still has to be investigated and researched about the significance of understanding of the night sky for Aboriginal people.
VINCE FORD: That comes back to navigation again. You needed to know where you were on the face of the earth as well because if you were an Aboriginal who wandered into the wrong tribal area, you were dead.
HERMANN WEHNER: Absolutely. You might know that Grubb also built the great Melbourne reflector - now we talk reflector rather than refractor. That was the 48-inch at the time and later on the 50-inch or, as I would have it, the 1.2-metre reflecting telescope which was at Mt Stromlo which got burned out. Now the remnants, which date back to 1868 when the great Melbourne telescope was being built by Grubb, have found their way back to Melbourne. The people there promise to make a concerted effort to rebuild that telescope. That will take them a while and it will take them more than 250 pounds.
VINCE FORD: Too right.
KIRSTEN WEHNER: They’re just trying to keep up with us.
HERMANN WEHNER: Not really.
QUESTION: Mine is a really quick question. How much does it weigh? I was just thinking about the assembly before. And how much did the Museum purchase it for today?
KIRSTEN WEHNER: Could you talk about the weight?
HERMANN WEHNER: You mentioned the weight. It is easily measured by using a forklift which has a little gadget on it and it says ‘You are now lifting 923 kilograms’. A third of that, if not more, is in the pedestal because it is good, solid old cast-iron, battleship-type stuff. Grubb, before he started into telescopes, made cast-iron stands for billiard tables in his factory in Dublin. He began to become interested in telescopes in about 1832 or something like that. In the end he chucked the billiard tables out and he only built telescopes.
So he was used to heavy castings and not only heavy but also precise castings, because you will find that some gearing in this telescope as well are actually cast pieces - not like we would do them today with high-precision grinding machines to produce those gears. There are other points in it which interest me, including how well in those days, 1883, can you an produce a gear which has precise spacing between the teeth – and I mean precise - down to a thousandth of an inch, or perhaps hundredths of a millimetre as we would say nowadays, and he managed that.
There is correspondence between him and astronomers using his telescopes where it is recorded how well the drive, and all these gears are a part of the driving system for the telescope, is actually behaving. If you look through the telescope just with your unaided eye and you see the star, if it moves a tiny fraction to one side or the other side you won’t even notice that. But if you now use photography that is entirely different - you have the photographic plate, the star image falls onto it, and it creates an image on this photographic plate. Now if the telescope moves, this image will move sideways or up or down or higgledy-piggledy all around the place. And then when you develop it, you say, ‘That doesn’t look a bit like I can see with my eye directly.’ And that is due to drive difficulties. They had to be overcome, and Grubb had later on – way after this telescope was built - produced an electrical control method to steady the drive and to improve on the gear behaviour to reduce backlash and have the spacing accurate to a very high degree, which would bring the price up admittedly but it certainly would have improved the dependability and the accuracy of the operating telescope very much indeed.
VINCE FORD: One thing you’ll notice when you go out to look at the sky is most of the telescopes you’re using will not look like this. These refractors that use lenses are not the way most telescopes are built these days. The main part of a telescope is the mirror. Why mirrors? Well, part one, you can’t make a lens bigger than about that and have it keep its shape. Lenses have to be supported around their edges, around their weakest point. So as the angle you’re looking through them changes, as you point your telescope around the sky, the lens sags, distorts and your image goes ‘boink’ - worse than what Hermann was just describing.
Mirrors, you can support them across the back and around the side – they are a nice solid thing. You can make mirrors up to about eight and a half metres in diameter if you’re so concerned. If you want to go bigger than that, you just make lots of hexagonal eight-and-a-half metre mirrors and mosaic them together. There are telescopes in action now with mirrors ten metres in diameter and one’s planned with mirrors up to 30 metres in diameter.
Lenses, you pass light through a lens, you can lose as the light goes from the air into the glass and from the glass out into the air anywhere between seven and ten per cent of the light or in the case of that particular lens anything up to 50 percent of the light. That’s not good for astronomy where you are trying to get every little bit of light you can. But a nice clean mirror reflects 98 percent of the light that hits it. So pretty well all telescopes these days use mirrors instead of lenses.
What’s the sky like? It is clear. So I suggest that there’s a batch of these telescopes waiting for you, that you get in before the cloud comes back.
HERMANN WEHNER: I’d like to say something else.
KIRSTEN WEHNER: Just before we go - is it more information?
HERMANN WEHNER: No. Please note that unfortunately we have no member of the conservation team here tonight, but I would like to put on record my appreciation of their expertise and their willingness to work together with me, and I with them, to get this telescope in this particular shape it is now, which I believe is about the best renovated telescope in the world.
VINCE FORD: Absolutely - yes indeed. [applause]
KIRSTEN WEHNER: Before we go out, let me just say thank you to Vince and Hermann for coming along this evening and enlightening us.
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Date published: 3 August 2009