I do not know which of the following is applicable to our case “You cannot have your cake and eat it” or “What you gain on the swings you loose on the roundabouts”. On the one hand we had bright sunshine and a six day old waxing moon that was situated very nicely but, on the other hand, we had a brisk and fairly chilly South-Easter that pushed clumps of fluffy clouds across our field of view all afternoon and, to top it all, there were only two minuscule sunspots visible.
Auke was already there and Eddy and Jannie arrived shortly after us with Dirk about 30 minutes after them. Alan and Rose weren’t there because Alan had to work and Wendy could also not make it as her husband was ill and had been hospitalized.
The brisk South-Easter was quite cold and, as we had suspected the wind drove a never ending series of fluffy clouds across the face of the Moon limiting viewing to the intervening gaps between them. I decided not to even try the Sun as the two diminutive sunspots were really not worth the effort and concentrated on the Moon.
There were fewer people around and this seems to be the pattern when there is a bit of wind. I also think that in the wind people tend to bunch up more at the Swing Bridge and are less inclined to look around. There seems to be a greater sense of urgency to get across. Also for the people coming from the other side they seem to move straight on and not fan out as they do on days when there is less wind.
There were fewer clouds as the afternoon wore on and by sunset we had almost uninterrupted views of the moon. I decided to give viewers a special treat and added a 3x Barlow to my 25 mm eyepiece. That never fails to draw Wows, OMG’s, Awesome’s. Nooo’s and even a You Lie or two from the viewers. It takes a bit more nudging and shoving, but the effect on viewers is more than worth the trouble. In addition Lorenzo has the advantage of being more stable and less prone to wind induced vibrations than the smaller telescopes.
Once the Sun was down it became really chilly and one once again had to marvel at the fact that one could actually show people celestial objects from such a heavily light polluted site as the Pierhead. Unfortunately Venus and Saturn were not well placed for viewing from our position and the best position would have been under the coloured fairy lights on the quayside.
We had bright sunshine and clear skies but on the way into Cape Town there was a suspicious looking cloud hanging around over the Eastern end of Table Mountain and the Devil’s Peak. I say suspicious because clouds like that, more often than not, are the forerunners of a South-Easter in Cape Town. This proved to be correct in this case although it did not develop into a full scale gale it was cold and a nuisance on the Pierhead.
By the time the Noon Day Gun (there is an informative piece on Wikipedia about this Cape Town icon) had sounded we were on site and setting up, followed shortly by Alan and Rose and then by Dirk. Auke and Wendy arrived a bit later. Wendy was just back from gallivanting around England and had brought het new telescope along for its inaugural session. The wind very quickly gave us to understand that today was not a day for banners, or A-frame poster displays. Later on it even toppled our trestles with the A2-framed posters and some of the gusts turned over tables and caused general mayhem. Dirk and Wendy’s smaller telescopes constantly had the jitters and even Alan’s eight inch Dobby and Lorenzo were not completely steady.
The moon was well up by 13:30 so Dirk could get his scope set on that as he does not have a solar filter for viewing the Sun. The Sun, by the way, was sporting a nice crop of sunspots unlike on our previous outing. I don’t know if it was the wind but the people were disinclined to look through the telescopes and needed quite a bit of coaxing. We eventually tallied up just under 600 visitors but felt that, with the sunshine, we should have had more.
The Chairperson of ASSA’s (Astronomical Society of Southern Africa) Cape Centre, Eddy Nijeboer also paid us a visit. Thanks Eddy it was nice to have somebody from the Cape Centre joining Wendy at the Pierhead. You can go here to find out more about ASSA and visit this page to find out more about the Cape Centre. If you are interested in astronomy please join ASSA or, if you live in Cape Town join the Cape Centre.
Venus was a nice early evening target for a short while and Saturn was well positioned for viewing. The Moon is always a good attraction and never fails to elicit exclamations of surprise, delight or amazement from even the apparently disinterested viewers. Despite what looked like clear skies, it soon became apparent the wind was driving moisture through the atmosphere somewhere above us, because the view through the telescope was just not as crisp as we would have wanted it to be. This wasn’t as visible when looking at the Moon but the effects were quite pronounced when looking at Saturn.
After the show we all had coffee at Den Anker served by our favourite waitron, Patrick, before heading home. Go here to find out more about this Belgian restaurant in the Waterfront.
The October 2015 edition of MNASSA (Monthly Notes of the Astronomical Society of Southern Africa) is available on line. Below is the title page and list of contents. You may, sickness however, go here, to download the full edition.
MNASSA DOWNLOAD PAGE
Monthly Notes of the Astronomical Society of Southern Africa
In support of the efforts currently underway to document the history of the Royal Observatory a lot of historic material has been made available in digitized form by Auke Slotegraaf. While attempting to work my way through this formidable volume of information I came across the following in Royal Observatory, Cape of Good Hope, 1875 (iii).
“The “meridian mark” referred to in Table III, is on an undulation immediately to the east of the mountain called Blaauw Berg, and is situated some 13 miles north of the Observatory. It is a pillar built up to serve as a permanent meridian mark for the 10 feet Dolland’s Transit. The transit instrument is about 512 feet west of the meridian of the Transit-circle. The azimuth of the mark from the meridian of the Transit-circle, assumed in the determination of the azimuthal errors given in Table III, has been 2’ 40” west. It would appear that the assumed azimuth is too great by about 1”.3, and that the true azimuth of the mark is nearly 2’ 38”.7 west. The azimuthal errors derived from the position of the mark have not been used in the reductions, except for the approximate determinations of the clock error for time-ball purposes. The mark can only be well seen near noon on rather cloudy days; on bright, clear days it can only be observed soon after sunrise and near the time of sunset. The value of the mark as an indication of changes in the position of the Transit-circle, is not so great as it would be were observations possible at any hour of the day.”
So where was this meridian marker? After several e-mails between Auke Slotegraaf, Dr Ian Glass and I, it soon became clear that this specific object had not been seen by any members of the astronomical fraternity for many, many years. Ian produced correspondence dating back to 2012, in which a Mr. Seymour Currie, verified that that the object was in fact on his farm. The correspondence was conducted via the staff of Cape Nature at the Blaauwberg Nature Conservancy, and no mention was made of the farm’s name. Not knowing the farm’s name becomes a crucial point as the story develops.
I sent an e-mail to Mr. Currie who promptly phoned back. He had no objections to us coming to view, measure and photograph the meridian mark and he agreed to phone back again with instructions on how to get to his farm and an evaluation of how difficult it would be for us to get right up to the meridian mark. By Saturday morning, the 05th of December I had heard nothing from Mr. Currie and all telephone calls were answered by the dreaded voice message, “The subscriber you have dialled is not available ……”.
On the 05th a party consisting of Auke Slotegraaf, Chris Vermeulen, Dr. Ian Glass, Chris de Coning, Johan Brink, Kechil Kirkham, Dirk Rossouw and I, assembled at the Observatory. We were confident that, thanks to previous efforts by Ian and the help of Google Earth, we had the position pinned down and it looked as if there were useable access roads, but we were all anxious to hear from Mr. Currie.
The first task though, was to get up onto the roof of the Observatory building and try and see the meridian mark from there. Unfortunately the Eucalyptus trees that had been planted over the years successfully cut of, not only any possible view of the marker, but of the entire Blaauwberg. I had still not been unable to raise Mr. Curry on the phone so we decided to go with Google Earth and Google Maps and the coordinates of the marker. The route seemed pretty straight forward but Dirk several times expressed concern that we were venturing well of the beaten track and he had prior experience of the fact that Google did not take cognisance of fences and assorted farm gates in out of the way areas like this. In the absence of any communication from Mr. Currie we had little choice but to set off, guided by Google.
One section of the party, Auke, Kechil and Johan would stay behind and find a spot near the bird hide, at the northern extremity of the Observatory property, from which they hoped to observe the other section’s arrival at the marker. Chris dC had to first make a delivery and would join us later guided by Google. Chris V and Ian took the lead followed by myself and behind me Dirk. Somewhere on the N1 I lost sight of Dirk behind me but it turned out he had made a detour into Century City to refuel. I also lost sight of Chris V and Ian ahead of me but I had the Google turnoff from the N7, Frankdale Road, memorized so I was confident I would not get lost. I found the turnoff and after 1.3 km the tarred surface gave way to a track which became progressively worse, slowing me down to walking pace for long stretches. About 4.2 km from the N7, Zonnekus Road links up with Frankdale Road at a T-junction. There is a large, imposing, locked gate and, much to my surprise, parked on the other side of the gate were Chris V and Ian. While I was explaining to them how to get to where I was, Dirk pitched up, on my side of the gate. Chris V and Ian headed back to the N7 and Dirk and I waited. While we were waiting Chris dC arrived, also on the wrong side of the gate! More explanations and he also retraced his steps. After Chris V, Ian and Chris dC joined us Dirk once more voiced his concern that, although we were headed in the right direction, we might run into the Blaauwberg Nature Conservancy fences before reaching our target. Our cell phone signal had faded on us shortly after leaving the N7, so we were unable to update Google maps or try Mr. Curry again.
Off we went once again with Chris V and Ian in the lead, followed by Chris dC, then myself with Dirk bringing up the rear. Just over three km after leaving the gate, we encountered the gate and game fence of the Blaauwberg Nature Conservancy, as predicted by Dirk. Ian and I walked along the fence for quite a way trying to find higher ground on order to get a better view of the area where we thought the marker was and eventually we thought we had it. Unfortunately it was a case of so near and yet so far. After some debate we decided to call it a day and head home. I had to refuel as I did not have enough to get me home to Brackenfell and Chris dC very kindly offered to follow me to the filling station in Killarney in case I ran out of fuel completely. So we said our goodbyes and off we went.
After filling up in Killarney I parked the car and had a sandwich while going over the day’s events and checking that Mr. Currie had not tried to contact me. The more I thought about the day’s events the more I felt that Dirk had been right after all and we should have tackled this expedition from a farm called Blaauwberg on the northern slopes of the mountain. By now everyone else was well on their way back home or back to the Observatory, so I set of on my own. On the farm Blaauwberg I found that the owner was none other than Mr. Curry! It turned out that he and Willem Steenkamp had been very busy out in the veldt that morning planning the Battle of Blaauwberg Commemoration scheduled for the 09th January 2016.
After coffee we set off to the marker. Mr Curry and his wife took a quad-bike and I followed in their 4×4 all the way up to the marker, accompanied by their two magnificent Ridgebacks, racing along with the vehicles. The first kilometre after one leaves the farmyard is fine and can be attempted in any vehicle but the next just over one kilometre is uphill, sandy and riddled with mole tunnels. I would not venture up there in anything but a 4×4 vehicle.
Anyway, there the marker was and, after my hosts departed, I set about measuring and photographing. Both tasks were complicated by the fact that three sides of the marker were overgrown with very thorny bushes reaching almost to chest height. A section, which I think was added at a much later date than the original construction, has come off the top of the marker. The reason I think it is a later addition is that the cement looks quite different from that used in the construction of the marker and also, the removal does not seem in any way to have damaged the top of the marker. The marker is not, as stated in the reference at the end of this post, 14 feet (that’s over four m) high.
Mr Curry reports that up to about 10 years ago the military actually come round once a year and cleared away the brush around the marker but that no longer happens, as I can testify. It was not only the surrounding bush that made photography difficult but also the fact that the sun was fairly low in the west, which caused all sorts of complications with shadows. After finishing up I drove back to the homestead, reluctantly handed back the 4×4, said my goodbyes and headed home.
The Curries say that during military exercises with helicopters, it appears as if they fly to a point directly over the marker and then change course. Perhaps somebody could investigate this because it would be interesting to know if the marker is in fact used as a beacon, why and since when.
Dr Glass has also tracked down two more references to the meridian marker which seem to pinpoint its construction to August 1841. The references are to be found in Verification and Extension of La Caille’s Arc of Meridian at the Cape Of Good Hope by Sir Thomas Maclear. Vol 1, Published by order of the Lords Commissioners of the Admiralty, 1866.
Page 403: “Having obtained permission on the 10th of August, 1841, from the trustees of Dirk Gysbert Kotze, to erect a pillar on the Blaauwberg estate, on a hill south-west of his dwelling house, in the meridian of the transit room of the Royal Observatory, a party was told off for this service shortly after the return from the measurement of the Base. The pillar is a truncated pyramid 14 feet high, constructed of stone and lime masonry, cased with Roman cement.
By observation of the consecutive transits of circumpolar stars in the winter season made with the 10-feet transit instrument, the azimuth of the centre of the pillar is 179° 59’.57”, reckoning from the south round by the west; and by triangulation its distance is 68415 feet, or nearly 13 miles north of the transit instrument.”
Page 444: “The position of the pillar is on the undulation, immediately to the east of the mountain named Blaauw Berg, distant nearly 13 miles north from the Royal Observatory. The pillar was built to serve as a permanent meridian mark for the 10-feet transit instrument; also for obtaining the azimuths, by direct angular measurement of the trigonometric points, that are visible from the Observatory.”
Leeuwenboschfontein visit: 09 October to 14 October 2015.
The main objective of the weekend was to try out the enclosure the owner of Leeuwenbosch, Johan Roux, had built for the use of astronomers visiting the farm. Barry Dumas had been there during the Solar eclipse in September and found it to be very satisfactory. We had invited the members of the Cape Centre as well as Auke, Martin, Leslie, Iain, Willem and Wendy along but only Leslie, Willem, Iain, Jennifer and Wendy could eventually make it.
Our trip got off to a good start in the sense that we did not spend the entire night packing, as we often do. We were also finished and ready to go about 20 minutes before our planned departure time of 10:00 on Friday. Then disaster struck because Snorre was nowhere to be found. So we waited and notified Joan at Leeuwenboschfontein and all other parties that we were delayed. We looked everywhere, then we looked everywhere for a second, third and eventually umpteenth time, but Snorre was missing and the clock was ticking. Should we leave without Snorre and let Lynnette’s sister, Petro, feed him until we returned after the weekend? Should we cancel the trip unload everything and continue searching for him? Should we unload all the perishables, put them back in the fridge and freezer and just wait until Snorre pitched up? We decided on the last course of action. So 12:00 came and went, followed by 13:00, 14:00 and 15:00 and with each passing hour the tension mounted. Finally at about 15:30 His Nibs, Woolly Britches appeared from heaven knows where, stretching and yawning as if nothing was wrong!
Action stations! Snorre was shoved, rather unceremoniously, into his carry cage to prevent him doing another duck and Lynnette and I got everything we had unloaded back into the Vito, phoned everyone to notify them that Snorre had been found and hit the road at 16:30; a mere six and a half hours late. By the time we exited the Huguenot tunnel Leslie was already at the first stop-and-go of the road works in the Hex River-valley. The rest of our trip went very smoothly and we arrived at Leeuwenboschfontein around 18:50 to find Leslie already set up. Jennifer, who had taken the scenic route via Robertson, Ashton, Montagu, the Keisie and the Koo to Leeuwenboschfontein, had also arrived and settled in. Iain and Willem were expected the following day on their way back from Victoria West and Wendy was only due to arrive on the Sunday.
We unpacked, had supper and set up as fast as we could. It was dark but lights from the two ablution blocks were a problem especially for Leslie’s astrophotography. As fast as Leslie switched them off somebody would switch them on again! We did not see our way open to driving down to the enclosed astronomy area about a kilometre away in the dark and, as there was no power down there, the move would have been entirely counterproductive for Leslie. One camping family came along to see what we were up to so I did a basic what’s up tonight with them. They were, however, such nice people that I really did not mind spending the time doing that. It was dark, very, very much darker than at any site in or near Cape Town, but the seeing was not very good because of the windy conditions and corresponding turbulence in the atmosphere.
By midnight I was having problems with dew despite the fact that the wind had freshened quite considerably so Lynnette and I decided to call it a night and go to bed, leaving Leslie to brave the elements. Before going to bed I took a set of dark sky readings and also used the new Loss of the Night application on my cell phone as a comparison.
On Saturday we had a cold, blustery wind that had developed during the early hours of the morning, and a sky full of large fluffy clouds. Poor Leslie had spent a miserably cold night on his stretcher and his set-up and camp had been so vandalized by the wind that he decided to pack it in and head back to Cape Town. No amount of persuasion, offers of more and warmer bedding or the lure of better conditions later in the weekend, could change his mind. He did agree to let me show him the astronomy enclosure but he wasn’t all that impressed because there was no power, so his equipment would not be able to function. Iain and Willem arrived later in the day and by then the wind had abated considerably and the clouds had become a lot smaller with much, much larger gaps between them too. By Saturday evening the wind had all but died down, but the wandering clouds made constructive observing very difficult even though we had eventually convinced the remaining campers that the lights in the ablution blocks did not have to be on continuously.
On Sunday the weather was much better and by the time Wendy arrived it was looking very promising for the evening’s observing. We decided to try out the observing enclosure and found, to our satisfaction, that the Guest Farm’s lights were only visible if one stood right up against the eastern wall and looked west. The 1,8 m vibracrete walls also provided ample protection from the wind. The headlights of cars passing on the road, about one km away did catch the top slabs of the western wall. Although night traffic is infrequent this problem will be discussed with the Johan Roux’s (snr. & jnr.). Despite the very dark skies the seeing was at best fair to good but not excellent or exceptional, probably due to instability in the upper atmosphere caused by the approaching front. Wendy, Iain and Willem left at about 23:00 and Lynnette and I packed up just after midnight, when the dew got the better of us. We left our telescope, well wrapped, to keep Wendy’s company for the rest of the night. Being able to leave ones equipment in safety is another advantage of having the enclosure.
Wendy headed home on Monday and as the camp was now empty, other than for Lynnette, myself, Ian and Willem we decided to observe from the camp as it would be possible to switch off all lights. When Lynnette and I went to fetch our telescope we found that the staff was applying liberal amounts of very smelly chicken manure to the grass in the enclosure in order to speed up its growth. Observing there would have been a very smelly activity. That evening Johan Roux (snr.) joined us for some star gazing. I was astounded when he admitted that he had never spent time outside at night to specifically look at the stars. He, on the other hand, was very surprised to see what a negative effect the exposed outside lights around the homestead and guest house had on ones night vision. We will in future be allowed to switch them off when doing stargazing at Leeuwenboschfontein. Shortly after Johan left us to go to bed a sheet of thin, high cloud rolled in and put an end to our stargazing. I got up after 01:00 to answer a call of nature and found that the clouds had departed, but I was too bloody lazy to get dressed and set up the telescope again.
On Tuesday the weather was beautiful but in the afternoon the clouds came in again and stayed. Lynnette and I decided to stick it out until Wednesday, hoping the weather would clear but it actually got worse and by 21:00 on Wednesday night it was raining steadily with some distant thunder as appropriate background music. We both had our doubts about getting the Vito through the few sticky patches on the gravel road between Leeuwenboschfontein and the R318 but it did not rain enough to adversely affect the road and by Thursday morning it was clearing nicely.
As a precautionary measure Mr Wanderlust was put into his harness and his leash tied to a pole where one of us could always keep an eye on him. While I went of to wash the breakfast dishes Snorre attempted to pull off one of his Houdini-style escapes from the harness but Lynnette was too quick for him, I then shoved him into his carry cage. Needless to say, Snorre was not a happy cat having his freedom of movement curtailed like that.
So, what are the prospects for Leeuwenboschfontein as a stargazing venue? I think it has definite potential and here is my list of positives, in no particular order.
The owners are very positive about hosting astronomers.
The average annual rainfall is much lower than that in and around Cape Town.
It is within easy driving distance of Cape Town.
There is fairly priced accommodation available for all tastes.
The availability of an astro-enclosure means that astronomy enthusiasts do not have to fight with campers about the lights in the camp or their smoky braai fires.
Astronomers will not be pestered by campers wanting to look through their telescopes or discuss astronomy down at the astro-enclosure. If anyone feels the need to do outreach they just have stay in the camp and they will be inundated.
We have the concession that the outside lights of the homestead and guest house can be switched off to further reduce any influence they might have on viewing from the enclosure.
Negative aspects are possibly the following:
The horizons are not ideally low in all directions but from the astro-enclosure they are more than acceptable.
For the astrophotographers the non-availability of power at the enclosure is a problem but, at least for the present, a large battery and an inverter will provide a solution.
Please go here to visit Leeuwenboschfontein’s website or you may view their Facebook page here.
In my opinion there is no other site that is safe, offers the same amenities and has the same astronomy potential within easy driving distance of Cape Town. Some amateur astronomers might have private access to comparable sites but, for the average amateur in Cape Town, I think Leeuwenboschfontein offers a viable solution to a long standing problem.
Musings on the Standard Length markers by of a would-be amateur astronomical digger.
There are five of these structures which I previously labelled North (N), medicine North+1 (N1), viagra North+2 (N2), purchase North+3 (N3) and North+4 (N4) going from the most northerly to the most southerly one. Auke and Evan very carefully measured the distances between these structures and found that, by using them in various combinations; it was possible to obtain very accurate lengths of between 10 to 100 English feet in any multiple of 10 feet.
We still, however, do not know what was mounted on these bases and it certainly appears as if, whatever that was, differed from mounting to mounting. This assumption is made purely on the basis of the current appearance of the remains of the Standard Length bases.
Below are images of the five objects in question.
N and N-2 are similar in design but not in size. N-1 and N-4 have similar designs but their sizes differ slightly and the block with the hole in is situated to the north in N-1 and to the south in N-4. The odd one out is N-3, although it seems to have been similar to the plinth still present in N, N-2 and N-4 and presumed to have been present in N-1 judging by the markings and fragments present there. This plinth, therefore, appears to be common to all of the Standard Length bases.
N-1 and N-4 distinguish themselves from the others by the presence of the smaller block with the square hole in it and the two metal lugs on the north and south sides of that hole. In both of these structures the metal lugs seem to have been later additions.
However, closer inspection of N-1 and N-4 reveals another difference. The basic construction between the larger and smaller sections differs in both cases. The smaller block seems, in both cases, to have a courser concrete foundation which also appears to be shallower in both cases.
I think that the smaller structure with the square hole and two metal lugs in N-1 and N-4 was added after the construction of the larger sections with the plinth. I also think that the two metal lugs were added after the construction of the base in a third operation. Something fitted into that hole which, based on the fragments found on site, was lined with wood but that something was not stable enough, so the metal lugs were added as anchor points.
If you want to read about the work leading up to this post go to
The search for the foundations of old buildings at the SAAO continues
Friday & Saturday 15/16 August 2015.
Auke has soldiered on without me, very competently assisted by Johan, Chris Vermeulen, Leslie and several other stalwarts.
The Ron Atkins Observatory (RAO) has been tidied up by Johan, the Moreas have flowered and Auke has started a programme to document everything on the site using photogrammetry techniques. It is really a fantastic technique but it means I will have to exhume the Standard Length Markers – for the third time.
More about these developments later but here are some of Auke’s photographs showing the progress in the meantime.
If you want to read about the work done before and after this post go to
The search for the foundations of old buildings at the SAAO continues
Sunday 19 July 2015.
On Sunday the 19th of July a drop or two of rain was forecast for around 11:00. Auke, Evan, Johan and I decided to ignore that and carry on digging and measuring. Episode four covers my efforts to clean and measure the remains of the five Standard Length Markers (SLM). To do this I had to first exhume them, after having buried them as a protective measure, the previous week.
For my own reference I have, rather unimaginatively, called the most northerly one “North” and, working my southward, called the others “North+1”, “North+2”, “North+3” and “North+4”. I will abbreviate this even further and refer to the SLM as N, N1, N2, N3 & N4 so please remember that I am not referring to South Africa’s highway marking system. An important feature is that no two of these Standard Length Markers (SLM) are identical. They do, however, share certain features.
The picture shows the entire North (N) SLM. Its longer dimension is orientated North-South
This is 10,0 cm thick and seems to be common feature of all five SLMs. This seems to have been a base for a second layer, about 7,0 cm thick, but no remnants of this were found for N, although they do feature in other markers. The pedestals all seem to have had three metal pegs (P1, P2, P3 in the photo), 3,0 cm in diameter, about 8,0 cm long with a notch or groove in one end, presumably the top. The rust spots in the photo are not the remains of the actual pegs but show where they rested on this lower section. The upper section of the pedestal seems to have served the specific purpose of holding pegs in position. One such peg was found loose in the soil covering this marker.
The pedestals seem to have been encased in a wooden framework. In four of the five cases (N, N-1, N-2 & N-4) this was attached by a metal fixture on each of the pedestal’s four sides. These points are marked by a star and an arrow in the photograph. No wood or any parts of the actual metal fixture were found at N. The faint cross marked as the “Centre Point” is the point from which the distance between the markers was measured by Auke, Evan and the rest of the team.
The second SLM (N-1) consisted of two sections. The smaller, northern section had two metal fixtures on its northern and southern edges that looked as if they had been put in after the initial construction, In the centre of the northern section, centrally positioned between the two metal fixtures, is a square hole. The sides and base of the hole appear to have been lined with wood; remains of this lining were found in the hole.
This was the smallest of the five structures. The wooden frame around the pedestal was also constructed differently.
One metal peg was still in place and one was found loose but both were very badly corroded. Two holes that once held pegs can also be seen on the top slab of the pedestal. On the right hand corner there is still one bracket in place and it appears that each corner had two brackets. There are no metal fasteners on the base section of the pedestal, as in the three SLMs to the north of this one.
The most southerly SLM had many characteristics in common with N-1.
There was nothing left of the wooden frame although the same metal fasteners as in SLMs N, N-1 & N-2 seem to have been used. No trace was found of the top slab or of the pegs from the pedestal. Neither was there any sign of a wooden lining for the square hole, as in N-1. The two metal anchor inserts (B1 & B2) were also similar to those in N-1 and also appear to have been added after the initial construction.
We can only hope that somewhere there is a description of how these SLM’s were used and what was mounted on them. I doubt if we will be able to deduce too much more from what we have uncovered.
If you want to read about the work done before and after this post go to
The search for the foundations of old buildings at the SAAO continues
Sunday 12 July 2015
On Saturday 11th of July Auke, Evan and Johan braved the rain to expand the diggings. I had been too chicken to get wet on the Saturday so I only joined them on the Sunday. Ketchil also visited us on the Sunday, fresh from her recent overseas gallivanting and Leslie arrived later in the day. He had been delayed for three hours while becoming intimately acquainted with his new cell phone. The main digging objective was to uncover as much of the Franklin Adams Observatory (FAO) as possible. At the same time we would take accurate measurements and photographs of everything we found.
We were also anxious to pinpoint some of the places from which photographs had been taken in the past. This was particularly tricky, because there are now trees where none had been before and there are trees on older photographs that are not there now. Buildings are also a problem because some have been demolished, or had bits added on, and other structures have sprung up where there were none on the older photographs. Evan and I were tasked with this activity and, after some deliberation we thought we had found the spot from which a specific photograph, showing the two piers and sections of the FAO, had been taken.
A Tecomaria hedge, which had not been on the photograph in question, now made it impossible to see the FAO from that point. To verify the correctness of our deductions we had to be able to see over the hedge. I climbed onto one of the Moonwatch Pillars (MWP) (number five from the northern end) on the western side of the hedge, while Evan climbed up a tree on the eastern side. Evan could see me but he could not see the position of the southern pier in the FAO. Evan stayed up the tree and I balanced a length of metal irrigation pipe against MWP number five and held a second section of pipe upright in the middle of the FAO’s southern pier. From Evan’s arboreal vantage point the two pipes lined up perfectly so we now knew exactly where the photographer had stood to take the photo. To provide hard evidence we found a rather rickety stepladder and, while I did my best to keep it steady and stop it toppling over while Evan balanced himself precariously on top of the ladder and took the photograph, clearly showing the two irrigation pipes in line. The farthest one (held in position by Auke and Johan) served as a substitute for the non-existent southern pier of the FAO.
The rest of the morning was spent opening up as much of the FAO observatory as we could find and cleaning away soil from the bits we had already found, so that we could see the construction details and also take measurements. Of note was the fact that the two piers had been constructed differently. The southern pier seems to have been a better construction, judging by the appearance of the concrete and the brickwork. In the photographs the southern pier is also the larger (taller) of the two piers so maybe it required a bigger and sturdier base.
We could find no trace of any foundations. Where the foundations should have been, we did find definite signs of filling in with stones, bits of brick and pieces of masonry. It appears as if trenches had been dug, filled in with pieces of stone and building rubble and probably stamped down firmly before the concrete sections were cast in boxes on top of the filling material. This observation ties in with the appearance of the beam on the site. It has three relatively smooth sides and one very uneven side with impressions that could well be from the stones in the foundation trenches. The FAO was a wooden construction so it would probably not have required conventional foundations.
While looking for foundations we found numerous pieces of glass, most of them in the north and north-eastern section. Most of them appear to be ordinary window glass but there was one piece of bottle, without any distinctive markings as well. In the south-eastern corner of the dig I found the base of a ceramic container which dates to the late 1800’s or very early 1900’s. This fits in neatly with the FAO’s time frame.
After lunch there was more cleaning and measuring and then we set about trying to find the row of Standard Length Markers (SLM) between the FAO and the Ron Atkins Observatory (ROA). Evan did his thing with the tape measure after careful examining the 1911 Gill-survey. With the first prod with his garden fork he struck cement! Some quick spade work followed to uncover the second marker from the southern end so that the cleanup and measuring team could swing into action. In short order we found the next three north of that one, and then zeroed in on the most southerly marker. Two of these markers still had the wooden frames, in which the concrete had been cast, in place.
There is still some uncertainty about exactly how these bases for the SLM were constructed or what had been mounted on them. They differ considerably in size and appearance and method of construction. After the measuring had been done, we covered them in lightly to prevent them from being disturbed and marked their positions with sticks stuck into the ground. We wrapped candy tape around these sticks to make them clearly visible. While placing these sticks I discovered that there was another slab about 20 cm north of the most northerly marker, which we hadn’t detected, and this raised the question as to whether we had not perhaps missed similar sections at the other SLMs. The sun was already setting, so we decided that investigation would have to wait until the next dig.
If you want to read about the work done before and after this post go to