A significant feature of the tortoises is so often referred to as "An Imitation of Life". As well as their behaviour, the tortoises construction had to be such that autonomy could be exhibited. This is somewhat driven by the technology and parts available at the time. For Grey Walter's purposes, the models had to be self-contained and as light as possible for transportability.
also referred to as "Accumulators"
Pre 51 “Elsies” had 45 Volt 'Ever Ready' “B” batteries designed for 2-vacuum tube hearing aids. You can see the words “Hearing….” in some of the pics of the tortoises internals. The colour of these (Red ends, white sides and corners) suggests war-time Ministry of Health HT (High Tension) battery.
We also know, from the Festival of Britain – Exhibition of Science of 1951 catalogue, that the batteries used in the batch of 6 were 'Exide' accumulators, "Gel-cel" PRA 3S made by Chloride Batteries, 45-V batteries, "Batrymax" B109 made by The Ever Ready Company (Great Britain) Ltd.
[ Note: RH 2009 – Its interesting that Gel Cels were around then, being a motorcyclist myself, I thought they were a relatively recent invention.]
In the circuit schematics for M. Speculatrix, you will notice the on-off power switch is only on the 6 V side. The Vacuum tubes (also known as valves), don't function unless the heaters are on, and the heaters are on the 6 volt circuit. However, we know from notes on usage of the tortoise that the plug for the "B" battery is disconnected during transit. An article by F.H. George (John Bull 1956) informs us of how George heard noises coming from the hutch when transporting the tortoise from a demonstration. It had accidentally turned itself on and was looking for light inside its closed hutch.
Pierre de Lati mentions in his book Thinking by Machine, 1957, mentions of an "ingenious mechanism" and comments of "going back to the hutch to feed". He elaborates further in the section "The Secrets of the Tortoises" when he says "As soon as the tortoise is in its hutch, in contact with the mains, the voltage of this current cuts off the contact A which link the accumulators to the mechanism; they recharge instead. But when the accumulators are charged up to 7 volts, the relay R4 makes contact again at A and the tortoise moves away, since now that it is replete it has regained its movement and will avoid bright light". (See diagram below). This is achieved using a special relay wired in a particular way. These are labeled R3 and R4 in the schematic. They are in fact a single unit described below.
The relay used in the re-charging circuit is a different type of relay than more common types, it's a two-coil relay (sometimes referred to as a double-coil relay).
One coil in series with the supply switches the supply to the motors OFF when the battery starts to charge, so immobilising Elsie, as the charge current reduces and the voltage rises the other coil takes over and restores the supply to the motors. So Elsie then backs away from the intense light in the hutch. “Double-coil" relays – these relays are so constructed that if the current through both coils is the same, the clappers are such that the contacts remain open. If the current through one coil is greater by a sufficient amount than that through the other, the clappers will move in unison, making contact.” – Kubanoff's Timothy Turtle, 1953.Note: The re-charger for Timothy Turtle charges through the solenoid (i.e. one of the solenoid wires is connected to one of its own contacts.) The relay closes due to this current and remains closed until the condenser (i.e. battery substitute) is charged/re-charged. It would need the two coils to reduce the lock-in effect of just one in the supply line. By following the circuit diagram of deLatil's, you can also see the contact wiring connected to the coils. Normally relays are wired such that coils are isolated from the switching circuit.
Its quite possible that the early version of the tortoises antennae may have been the contacts for the automatic re-charging capability.
Elmer – none at all but with jacks mounted on the rear of its segmented shell; Early Elsie had wire antennae from top ‘metal’ shell.
Later antennae appear to be clear plastic curved strips (ref. Time Life pic above) They even appear to glow a little, not sure if this affects PEC or not. Later the transparent antennae are removed and we just see the remaining 'holes'.
Of the ‘batch of 6' from 1951, we see the copper tube extension for the on-off switch. For those models without a hutch, this tube is largely for convenient finger control. However, to simulate the earlier automatic re-charging system and to ensure motors, etc. don’t overheat if Elsie entered the hutch and thrashes about in ‘hunger’ mode at the end of the hutch, Walter appears to have installed a metal trip bracket on the RHS (facing inwards). (see colour pic) So with the copper extension trip lever appropriately positioned, and the clockwise steering, Elsie will bump along the RHS until the switch is tripped.
In viewing some earlier film footage, we actually see the deft hand of WGW switching the tortoise off as it enters the hutch before closing the hutch door. A later film clip c1972 shows '#6' entering the hutch on the LHS. The trip bracket can't be seen in this clip. This aspect is pure speculation by me, but maybe Owen Holland, current custodian of the Hutch, could have a look to confirm.
**Update 13 Jan 2011 from Owen Holland – "…the positioning of the stops on the right hand floor which would switch off the tortoise as it entered (see attached picture above). This worked most times when we tested it some 15 years ago with the tortoise that's now in the Science Museum."
We know from Owen Holland, probably in discussion with "Bunny" Warren during the restoration of Grey Walter's own tortoise, that there were two hutches built, the first having caught fire. They are easy to pick in the photos, as the first version does not have a door whereas the later model does.
It wouldn't surprise me if the fire was as a result of the automatic re-charging facility. I mentioned above the wire-looking antennae on an early version of ELSIE. There may have been an overhead wire set-up (similar to electric trams) where the antennae contacted different overhead wires that were those of the battery charger.
In any case, I have not seen any photographic evidence of the battery charging circuit mounted on ELSIE. I believe it was, but for only a short period of time. Thereafter, it is just "assumed" that it does exist.
**Update: 14 Jan 2011** Owen Holland sent me an email saying that when he met "Bunny" Warren, he mentioned that the lamp caused the fire, and not the charging unit.
In "Discussions on Child Development", Grey Walter gets asked of the tortoise,
"Why does it keep going round?"
GREY WALTER responds:
"It is looking for more lights. If you imagine a world which this thing is adapted to, and in which there are charging devices for its batteries, it would be important for it not to get stuck on one; it has a much better chance of being fed when it has several sources of food. It would wander around the room and always be near feeding sources. It is always looking for better and better light; it is never satisfied. If you made one of these things adapted to live in a tropical climate, you could make the shell of photo-electric cells and it would charge itself in the sun. It would be important for it to find a place where the sun's light was bright and steady, not between trees or houses, but a wide expanse of light; it would always seek this out and then sit and charge. At night it would have to collect dew-distilled water, so it would find two places, one where it could collect light and another where it could collect dew for its batteries; that is all it needs."
See the collection of Grey Walter and his Tortoise articles here.
See other early Cybernetic Creatures and Models here.
I have only come across two time-lapse photographs with both ELMER and ELSIE.
One has to be careful in interpreting time-lapse photographs as there are possibly different events happening at different times, off picture interference, and possibly different start times of each tortoise.
An important observation highlighted by Owen Holland is the direction of rotation of the scan, which is clockwise for ELMER, and counter-clockwise for ELSIE.
This is evident in both of the time-lapse photo’s and the diagrams by Bernarda Bryson (partner and later married to the artist Ben Shahn), as illustrated in Scientific American (Walter, W. Grey, "An Imitation of Life," Scientific American, May 1950, p42-45.).
Let's look at the first photo.
Firstly, we will look at the behaviour of each tortoise individually.
In doing so, it’s important to understand and observe the environment under which the photographic session was filmed under.
Observations to consider:
• Elmer’s trace is a lot heavier than Elsie’s – assuming same sized and intensity lamp/light, this indicates that Elmer is running slower the Elsie.
• Elmer slower than Elsie.
• Candle/Lamp on top/rear of shell.
• Both Tortoises end up at Hutch as if to ‘feed’ – therefore probably the whole time-lapse session is done with both Tortoises in ‘hunger’ mode.
• Hutch light possibly switched off for roughly half the time-lapse sequence.
Appears to travel the first .5 metre or so heading towards Elmer. If Elmer was a lot slower as described in the literature, quite possibly Elmer has had a head start, with somebody behind Elsie holding a torch to bring Elmer to Elsie.
Elsie then is attracted to the light used to highlight Elmer in the opening sequence. Elsie then, after a few sideways moves, heads towards the hutch light. (Maybe this is when the hutch light is switched on?). Although Elmer is slower, he spends less time stuck in patterns than Elsie does. To that extent, his path is a lot shorter, making up for his apparent slowness,
This next time-lapse photo shows ELMER and ELSIE in Grey Walter's lounge room as it appear in Life magazine (May 15, 1950). Recently  Life released the original image of this, which I have reproduced as well. (searchable under google images source:life)
Elsie’s steering mechanism appears to rotate in a clockwise direction. Elmer’s in a counter clockwise direction. Depending where the lamp/light is, one needs to check to see if this isn’t an illusion i.e. the trail of the tortoise re the rear wheels, rather than the scanning direction.
(Note: Although Grey is holding a cigarette in his right hand, there are several pictures of him holding a cigarette in either hand. He normally wears his watch on his left wrist, and you can just see it with his hand in his pocket. His shirt also buttons up the correct male way. All these indicate that the picture has not been printed in reverse, which could have explained the trajectory taken. As an aside, notice that Grey's feet have been 'lost' as a result of the double exposure.)
The most probable explanation is as follows:
As per most of the known traces, Elmer and/or Elsie are always photographed at the beginning of a trace. Obviously where they appear twice, only then are we seeing the tortoises at both ends of the sequence.
Therefore, to contradict the caption, Elmer and Else are pictured at the start of the sequence, and are moving away from the fire. There were probably torches outside of the camera's view guiding their path.
I know you’re not convinced yet, but the clincher is that if Elsie was to cycle in the apparent direction with its clockwise motion, then, as proven with the replica I have seen, Elsie would then creep to the left, and not to the right as shown.
So now knowing that information, it all falls into place.
Well, one of the 1951 batch of 6 tortoises was sent off to a museum. Actually, is was on loan to Charles Eames (yes, the same Eames who was a designer, amongst other things) who was contracted to design and mount an exhibition for the computer company IBM.
The exhibition was called "A Computer Perspective" and ran from 17th February 1971 and remained on view until the middle of 1975. It started life in the IBM Exhibit Center, New York , N.Y..
A catalogue, more a book was produced of the exhibition. One aspect of the exhibition was a display wall divided up into decades. Here is a picture of the wall. If you open and zoom in on the picture, you will see the tortoise in the upper right hand side.
Here is a picture of it as it appeared in the catalogue.
There is also a similar picture held in the BNI archives, but when I saw it it was not known when and where the picture was from. The Science Musuem archives now have the updated information.
The photographs are not sharp enough to see the chassis stampings, so we don't know which number it is (1 to 4). Another visual difference is the size and location of the rear wheels. The wheels are smaller than normal, and so a lower axle hole has been drilled to compensate.
I found a video clip of this exhibition, but it was before I knew much about saving video clips. I took a rather small still picture of it, but after many hours of trying to find it again I have to admit to not being able to relocate it. Being a static model it is not such an issue.
The exhibition ended 1975 . Grey Walter retired 1975 and died 1977.
CHALLENGE: Maybe someone living in New York or who works for IBM can track down the history of the exhibition. The tortoise may be in an IBM or Ray and Charles Eames archive, in someones possession as they could not find the loaner, or it was thrown out.
The Festival of Britain was a national exhibition which opened in London and around Britain on 3 May 1951 and finished the end of September the same year.
At that time, shortly after the end of World War II, much of London was still in ruins and redevelopment was badly needed. The Festival was an attempt to give Britons a feeling of recovery and progress and to promote better-quality design in the rebuilding of British towns and cities following the war.
The principal exhibition site was on the South Bank Site, London of the River Thames. As part of the Festival in London, a new wing was built for the South Kensington Science Museum to hold the Exhibition of Science. Some 214,000 paying visitors went through the Exhibition of Science.
We know from Owen Holland's discussions with the late Mr W. J. `Bunny’ Warren, one of the talented BNI engineers recruited by Walter after the war, that six more tortoises of an improved electrical and mechanical design were built for Grey Walter in early 1951. [from Legacy…] .
[OBSERVATION: When looking at photographs of the various tortoises with their shells on, it is easy to determine which tortoises are from the later batch of 6 and which are the earlier Elmer or Elsie (or CORA even!) by the shell locating mounts. The later models run front and back and are more widely spaced, while the earlier models run from side to side and spaced more narrowly (see right-hand-side photo).]
The Festival of Britain catalogue shows an illustration of two tortoises, showing the earlier shells (and also the transparent antennae). This is probably because the material provided for the catalogue was prior to or during the Batch-of-6 construction.
There were three tortoises on display at the Fob-EoS: Two of them were interacting in the pen, the third had a transparent shell and was used to advertise some of its internal components, namely [see page 50 of the catalogue]
ES500 Radio valves, type DL93, for electronic "tortoises"; Mullard Electronic Products Ltd., Century House, Shaftsbury Avenue, London W.C.2.
ES501 Exide accumulators, "Gel-cel" PRA 3S; Chloride Batteries Ltd., Exide Works, Clifton Junction, nr. Manchester.
ES502 45-V batteries, "Batrymax" B109; The Ever Ready Company (Great Britain) Ltd., Hercules Place, Holloway, London N.7.
The tortoises themselves were an item in the catalogue-
ES106 "Machina Speculatrix"; (Mechanical tortoises), Dr. Grey Walter, Burden Neurological Institute, Stapleton, Bristol.
Below is a photo from the Kew archives of the display pen (without the tortoises).
I've zoomed in and de-skewed the image (below). One can see the low-placed lamps inside the pen. The overhead photo is yet another image, slightly different to those already published, of the Buridan's ass dilemma being resolved by the tortoise's behaviour.
Here's an extract from Punch, June 6, 1951 p683 –
"Stop Press" deals with the realm of speculation, with the problem of life and death, the nature of the universe, the origin of cosmic rays, and so on; but, for anyone who feels unable to cope with such rarified theory, here are the two best toys in the exhibition. The first is the pen of electrical tortoises. Elmer and Elsie [note: not the originals], the creations of Dr. Grey Walter of Bristol, look rather like a couple of electric kettles crawling about the floor, the spout being replaced by a revolving periscope. Three lights are placed at floor level round the pen, which can be switched on (with a button, of course) by visitors; when a light is illuminated, the tortoise will creep towards it in a series of slow waltzing movements. Sometimes it will get temperamental and crawl off somewhere else; the public is warned that the tortoises' "behavoiur is complicated and sometimes unpredictable." Perhaps there was mutation in the family: this waltzing business can't be confined to mice.
[note: the second toy is the Ferranti "Nim" computer not discussed here.]
The inclusion of Grey Walter's Tortoises almost didn't happen…(Source: The Barrier Miner, [NSW, Australia}, 28 April 1951.)
Challenge: The British National Archives in Kew, London, also have a document about how the exhibition is to care for the tortoises. Due to bad advice only 2 days before I went out of my way to visit the Archives to view this document [June 2009] I was told that they were open. When I arrived, they were closed due to a public holiday on the following Monday. If someone who lives nearby was prepared to find this document and scan it / photograph it, and forward a copy onto me, it would be much appreciated. My contact email address is on the 'About' page. Here are the archive details: Dr.W.Grey Walter. Advice and supervision of Model of Electrical Tortoises. File No. G1/C 2/647 . Note that the Archive require advanced notice to pull the archive before you visit.
The 3 tortoises that were at the FoB were auctioned off at the end of the exhibition. Dr. Frederick Wesley "Wes" Clutterbuck and his wife Meryln were the successful bidders. The Clutterbuck's soon left England (1953), and spent some time in the West Indies before arriving in Australia. Originally stationed at Grafton in New South Wales, Dr. Clutterbuck contracted polio. He then moved to warmer conditions to Wynnum, near Brisbane in Queensland in 1966.
It is claimed that the two mobile tortoises (in dark shells) were destroyed in a fire in his surgery. The third tortoise, in the transparent shell, was later donated to the Smithsonian institute. Its chassis is stamped with the number 5 [Grey Walter’s is stamped number 6].
CHALLENGE: Wes and his wife passed away a few years ago (Wes -2004). I have been trying to track down the Clutterbuck's only daughter, Ms. Myvanwy Emery, persumably living in Grafton, NSW, if not then maybe living around Wynnum. I'm guessing she would be in her 60's by now. She had two sons, John and Christopher Emery. Between them we may be able to glean a bit more history about these tortoises.
Before the fire, the then Queensland Institute of Technology was loaned one of the tortoises. Here is the write-up and picture. Note that the Photo-electric cell is missing its shroud. Without this, performance and behaviour would have been erratic and disappointing to watch. The article says the unit was not operational at the time anyway.
I was successful in contacting Mr Paul Wilson , but after the initial contact, his email address became invalid, and I have been unsuccessful in locating him since.
I managed to contact Myvanwy [nee] Clutterbuck in Aug 2012. She is the late Dr. Wes Clutterbuck's daughter and was 12 y/o when the tortoises were won at auction at FoB closure.
The Clutterbuck family is from Bristol. Myvanwy confirmed that two tortoises were destroyed in Wes' surgery fire.
The tortoises were nicknamed "Slo", "Mo" and "Shun" by Wes.
Myvanwy also confirmed The Smithsonian has the third remaining tortoise that he donated to them.
Dr. Wes Clutterbuck with his tortoises nicknamed "Slo", "Mo" and "Shun".
The charred remains of one of the tortoises after the surgery fire.
Here are some photos of the Smithsonian tortoise.
Note in the photo the Photo-Electric Cell (PEC) is missing from this photo. Also the steering is pointing backwards. The shroud is also missing.
Here's a crisper black and white photo
A photo found on flickr
Where are the others from the Batch of 6 now?
**update March 2015
Only two tortoises are known to exist:
One in Science Museum London. #6 as used by WGW. Rediscovered by Owen Holland.
One Tortoise in Smithsonian (ex Clutterbuck ex Festival of Britain) – Clear shelled version.
Two tortoises destroyed in Clutterbuck's surgery fire. Ex FoB.
Picture of the late 'Bunny' Warren (left) assisting in the construction of the replicas. Chris Hart next to him assisted Ian Horsfield (not pictured), both of Bristol Robotics Lab, in their construction.