Archive for April, 2010

Babbage’s Difference Engine Number 2

April 22, 2010

I love history. I do not read as much about history as I should, but I love to visit places, learn their history and, of course, visit their museums. In addition, I am a geek. I love computers and what they can do. In fact, I like these two subjects so much I started a computer museum here at the University called Grace’s Place. So when I had the opportunity recently, I jumped at the idea of visiting Babbage’s Difference Engine. To many, this engine is the beginning of computing as we know it. Certainly Babbage’s later machine, the Analytical Engine, is a computer in the modern day sense of the word. I would love to see how a 19th century inventor thought of computing, but Babbage never built his Difference Engine. However …..

Charles Babbage was a mathematician, inventor and philosopher. He was troubled by imprecision. He hated imprecision so much that he once wrote Lord Tennyson to note the imprecision of his poem, “The Vision of Sin.” In that poem Tennyson said, “Every minute dies a man, Every minute one is born.” But, Babbage wrote that the poem could not be factual or the population of the earth would be flat. He suggested instead that Lord Tennyson change the poem to read “Every minute dies a man, And one and a sixteenth is born.” Further he said “I may add that the exact figures are 1.167, but something must, of course, be conceded to the laws of metre.”

But, I digress. Back in the 1930s, all mathematical tables were computed by hand. (I realize that my students will probably have never seen a mathematical table since they now get all of those values directly from some computing device. They will just need to trust me that there was a time when people did arithmetic by hand and people used tables.) These tables were critical to computations needed for building, astronomy and navigation. Even minor errors in the tables could cause buildings to fall and sailors to be lost forever. And there were many errors. So Charles took off to create an “engine” that would do the computations exactly. How he came up with the idea of the Difference Engine, I cannot imagine. But, Difference Engine 1 was designed to include approximately 25,000 parts, weigh fifteen tons, and stand 8 ft high. He took his idea to the British Government for funding and they too thought this was a good idea, so they granted him funds to build the engine.

Unfortunately, Babbage was not a good project manager. He was, after all, a perfectionist, and so his project suffered from scope creep as he continually improved on his design. In addition, he was not an easy man for whom to work (remember his writing to Tennyson to change his poem?), and he suffered some significant losses close together. Needless to say, he did not get the project finished.

Learning this is important for two reasons. First, it was a surprise to me because I had learned that the problem was with the precision of tooling in the 19th century. Apparently that was not true. Second, think about how many inventions and developments never happened because of bad planning. It has been said that this first experience with calculating devices so soured the British Government that it would not fund projects of this type for some time which, in turn, stunted the development of calculating devices. I wonder how much more advanced our capabilities would be had Babbage been a good project manager!

Babbage was not discouraged and he went and designed Difference Engine 2. This one was smaller and had less moving parts, but the British Government had no interest in funding the project and he could not get funding from any other source. After his death, Babbage’s son gave the plans for this engine to the London Science Museum. In 1989 (about 150 years after its design), the London Science Museum decided to try to build Difference Engine 2. They used Babbage’s plans and 19th Century manufacturing precision. Where Babbage’s plans were incomplete, the builders used other functionality that Babbage had designed. In the end, it was all Babbage’s design. It was tested at the London Science Museum and returned the answer for a polynomial to 31 digits correctly!

It turns out that there are two Difference Engine 2 in existence. The London Science Museum ran out of money before it could finish the original piece; they had built the engine but did not have the funding to build the printing component (on the left in my photos) of the engine. They approached Nathan Myhrvold for funding. He provided the funding with the stipulation that they build him a replica of their engine.

Myhrvold agreed to display the difference engine in the Computer History Museum in Mountain View California for a year after taking delivery. It actually has been there longer than that because Mr. Myhrvold needs to fortify his living room floor before he can move the engine there.

So, during spring break my husband and I visited the Computer History Museum and Babbage’s Difference Engine No. 2. This is like visiting history that even the people involved never saw. It was a great experience.

I must tell you that it is a beautiful machine! The bronze set off from the black frame is just lovely. But all of that paled next to the idea that this piece of equipment was designed almost 200 years ago. It was like going back into history and seeing what inventors were doing. One can almost imagine James West and Artemus Gordon using this engine on the Wild Wild West (this was a television show that had detectives using fanciful inventions of modern conveniences as they might have looked in the Victorian Era).

We were lucky enough to be at the museum when they were demonstrating this engine. Someone literally cranked the numbers! Remember, Babbage didn’t have electricity. So, he had to control for sloppy cranking too. One put weights on the structure to control the polynomial that you wanted and cranked away. In the front you saw the gears moving around. But in the back you saw levers and switches that controlled all of the carrying that was necessary for the computations. It was captivating. At the end, the printer gave us the value of the polynomial and was ready to start again. If we wanted, it would also prepare a mold for a copper plate so the values could go right from the computer to the printing press. Just imagine!

To me, the experience was a lot like finding a long lost Renoir or Monet painting that no one knew about and having the privilege of being one of the few people who could enjoy the experience. It was like being a little kid again and being amazed. Yes, I know that makes me a geek.

But, go ahead and look at the machine. I have posted some photos in an earlier blog, “wordless Wednesday” and watch this thing work. Direct your browser to the Computer History Museum and watch the engine work. You too may be captivated. For more information about the history, there is a YouTube video. See the process of unpacking the machine when it arrived in Mountain View. Also watch the program from the opening of the Babbage Engine exhibit at the Computer History Museum.

Yes, it is history. Why is history important? For two reasons. First, it is important to see how far we have come in computing in order to project where we might go. Second, it is important to “get into the head” of great inventors to help ourselves learn to invent better so that we can solve the many problems of the 21st Century. In this case, the history is also beautiful and mesmorizing. Check it out!

My Clock

April 12, 2010

As anyone who has been to my office can tell you, I have a “thing” about clocks. It all started with one I bought at an art fair that was nothing more than a kit you get at Michael’s used to make an old hard drive controller card into a clock. But, then I saw a binary clock and bought it. Then I found a clock that is driven from computer boards and shows on old nixie tubes. And, I have a digital clock, but instead of numbers, it lights up squares in the four positions — oh yea, and the squares that are lighted change every second. I added one to our lab that runs backwards and has the line “think creatively” next to it. My clocks are fun. They don’t get me places any earlier, but they are fun none the less.

I had a birthday recently (and no, I won’t tell you how many). I want to brag about the gift my wonderful friend Margaret gave me — it was a clock. But, given my collection, not just any clock, would impress me! Margaret knitted me a clock as shown in the photo below.

She used all the colors I love and demonstrated her amazing knitting skills. I could not replicate this clock in a knitted form for all the tea in China.

But, look at the clock straight on as shown by the photo below. Do you notice anything about the numbers?

Yep, the numbers on this knitted clock are in binary! Isn’t that amazing? Can you make them out? Well, for those of you who cannot do binary quickly, I have given you a quick key below.

1: 0001
2: 0010
3: 0011
4: 0100
5: 0101
6: 0110
7: 0111
8: 1000
9: 1001
10: 1010
11: 1011
12: 1100

So Margaret gave me a perfect gift! It is a unique work of art. And, it has a technology theme. What could be better for me? The only thing better is a perfect friend — which, of course, Margaret is!

“Wordless Wednesday!” — Babbages Difference Engine No. 2

April 7, 2010

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