This page contains a photograph which is one of several belonging to the photo gallery pages which are part of several pages relating to the invention of the world's first automatic totalizator in 1913 and Automatic Totalisators, the company founded to develop, manufacture and export these systems.
Brough Park Newcastle 3-3 shaft GT Adder top view - Electro-Mechanical Computing on an industrial scale
This photograph is of a Grand Total Adder for Brough Park racetrack Newcastle Upon Tyne. The installation of this system was in 1936. The photograph was taken in the ATL factory which is probably the one in Chalmers Street Sydney. The writing on the back of the photograph reads: 3-3 shaft Grand Totals on one frame. (W.P. and F'cast) Note "chasers" for transferring the odd units to drum indicators at close of betting. Also, cam operated tens transfer contactor. Picture taken in factory. Labels &c not put on machines at the time. W.P.and F'cast in this text stands for Win Place and Forecast pools. If you are not familiar with &c it is a contraction of etc which is a contraction of etcetera.
The Storage Screws a mechanical form of memory and the chasers and tens transfer
On the back of the previous photograph in the Photo Gallery which is a front view of this same adder, there is a very interesting comment about the storage screws which raises a very interesting point for technologists interested in computer history. Storage is a very important concept associated with digital computers. The storage screw is a form of mechanical memory in the form of a delay line. Rotation of the adding shafts which represent bets is stored and read at a slower rate by heavier equipment which cannot respond as quickly due to inertia. Additional information is available following this photograph.
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The storage screws, a mechanical form of memory can be easily seen. There are nine rods that are part of the framework of the adder running from the near end of each adding mechanism's side mounting assemblies at the rear of the adder seen at the top of the photo, to the mounting assemblies of the cogs at the front of the adder seen at the bottom of the photo. Below these rods are circular rotating shafts. These are the storage screws. They connect the adding shafts with their escapement wheels and epicyclic gears at the rear of the adder to nine large cogs in a row amongst the cogs at the front of the adder. They have the circular cam wheels on them that look like a Tea Biscuit. These cam wheels are the cams referred to in the text on the back of this photo quoted above, cam operated tens transfer contactor. The cam followers and the contactor mentioned can be seen on the left hand side of these cams. These contactors transfer the transactions recorded as units of rotation on their shafts to the display equipment via pulses. When contemplating the computer era analogies to this equipment this is a form of signalling. One of the simplest forms of electronic recording is the Return To Zero (RTZ) method and although there is some similarity there are considerable differences. The electrical transmission of investments is not a variable bit string and has no concept of bits or binary and hence does not define bit cells. Additionally the positive voltage transition is significant rather than the negative transition. The pulses transferring investment data is different but still recognisable as a method of data transmission long before the electronic recording and signalling methods that made this commonplace.
The purpose of the storage screws is to buffer the rotation of the rapidly accelerating adding shafts from machinery that is slower to respond due to inertia. For more detail on the storage screw have a look at the first photograph in the Brough Park section of the Photo Gallery which can be reached by clicking on this photograph. The nine adding shafts are clearly visible at the back of this adder. Also in the note on the back of this photograph quoted above, Chasers are mentioned, "chasers" for transferring the odd units to drum indicators at close of betting. I have not heard this term before however the note refers to the odd units. In addition the note on the previous photo in the Photo Gallery which is a front view of this adder states that this adder has two units shafts. We have just read that the cam wheels are on the tens shaft. From this we can deduce that the adder is arranged in three groups of tens shaft units shaft units shaft. Looking at the photograph there is an assembly with what appears to be two solenoids installed between each pair of unit shafts in the mid section of the adder. There are three of these assemblies and they are sensing something on the three shafts which have numbered drums on them. These three shafts, I presume sum the two units shafts either side of them. I deduce that these three assemblies with the two solenoids in them which seem to be sensing the units total shafts are the "chasers". It is interesting to note that the chasers and the tens transfer contactors are transferring investment information to indicator equipment for public display.
Regarding the equipment for public display, there is an image of one of these Counter Wheel displays in the last image in the Brough Park section of the Photo Gallery. One Chaser mentioned above and one Tens Transfer Contactor will be attached to their respective solenoid on this sort of Counter Wheel display. As this adder handles the Win Place and Forecast pools there will be a counter wheel display for each one.
For more information on the storage screws and the adding shafts have a look at the first photograph in the Brough Park section of the Photo Gallery by clicking on the photograph to return to the photo Gallery and scrolling up to the first photo in this section. For the technically minded there are Engineering Drawings of the storage screws and the adding shafts in the Figures from George Julius' paper presented to the Institution of Engineers Australia in 1920 section of the Photo Gallery which can be seen by clicking on the photograph to return to the photo Gallery and scrolling down to this section. George Julius presented a paper to the Institution of Engineers Australia on Thursday May 13th 1920 describing these systems, when a machine that had been built and tested capable of supporting 1,000 terminals and a sell rate of 250,000 bets per minute was demonstrated.The part of George's paper that is pertinent to this website is presented in the Mechanical Aids to Calculation Chapter of this website.
There is no photographer's stamp on this photograph.