Babbage's Difference Engine hits Silicon Valley
Wafers? Nah. How about bronze and wood?
Silicon Valley got its first look at the true roots of the digital age this week, with the arrival of a five-ton calculator made from the designs of the Victorian-age mathematician and Londoner, Charles Babbage.
The Computer History Museum in Mountain View, California is hosting the second replica of Babbage's Difference Engine No. 2.
Babbage's Difference Engine No. 2
The difference engine is astoundingly complex, housing more than 8,000 parts made of steel, bronze, iron and wood. So ambitious and ahead of his time was his design that Babbage was never able to complete the device, due in part to the unsophisticated engineering processes of the 19th century and a withdrawal of lavish funding from the British government.
Babbage's machine, using no electronic parts, adds with numbers up to 31 digits long to calculate polynomials up to the seventh order. It's capable of cranking out — literally cranking out — polynomials at the rate of one per six seconds.
Get yer' hand-cranked polynomials here
A view from the side
Looking close at the decimal columns
Although it was never built in his time, Babbage's engine is now considered the first known example of a automatic computational machine. The device also included plans for a printing device that would have been the first automated typesetter, capable of text wrap, two font sizes, and could be directed to print different column widths and line spacing.
But when Babbage died in 1871, he left behind only 20 pages of drawings and instructions on the device, and his hope for vindication from future generations.
Babbage, the original steampunk
Ye Olde PC Load Letter? What the...?
"Another age must be the judge," he wrote.
The first working model of Babbage's difference engine began construction in 1991 — some 142 years later than intended — by the Science Museum in London. Using his original design notes and materials that would have been available to Babbage at the time, the builders proved his astounding machine would have worked exactly as planned.
There on display, the completed device caught the eye of former Microsoft chief technical officer and millionaire, Nathan Myhrvold, who in 2002 commissioned a second difference engine of his own.
Only finished last month, the second difference engine replica will be on display at the Computer History Museum until May 2009. After that, it will be moved to Myhrvold's home in the Seattle area. And if this monster isn't a convenient conversation starter, we don't know what is. ®
One per desktop (et al)
The reason it is the size it is: the range in sizes of the various parts meant that for the smallest to be strong enough (great enough cross-section), the largest are, well, the size they are. It is possible that a 1/4-scale model could be built today, using today's materials, today's fabrication processes, and designed with today's clustered supercomputers running FEA software. However, the _point_ of the original exercise was to determine if _Babbage_ could have built it, with the materials and processes available at the time.
As to "It's a computer, just look at it", well, then EMERAC is a computer :-)
(NOT! Nor is this)
As to the "Swede" who built a difference engine, that one lacked many of the error-checking facilities of Babbage's and was as a result a bit "fiddly", IIRC.
As to crank effort: the current machine has a 4:1 reduction gear. It takes a bit of patience, "feel", or whatever to turn, but I have done so and I am no giant. It would be tiring to turn it at 1:1, and more prone to jams (error-detecting, again), because of the variance in load during the machine cycle, but IMHO, not out of the question. You perhaps underestimate the strength, stamina, and flexibility of the typical Victorian Navvy. :-)
To Quote Jakob Nielsen
"Building the machine according to the original specifications resulted in a working computer - with one exception: the Difference Engine runs on human power: a person turns a crank. Unfortunately, it's beyond the strength of any person to actually turn that crank, given the many wheels and other parts that it drives. The modern builders had to install a gearing unit to make it possible for a human to supply power to the Difference Engine. (And even so, it was a pretty big guy who ran the machine in the exhibit.)
I conclude that Babbage's machine, which is often called the world's first computer, had a human factors problem in its original design. Luckily it was easy to fix with some real-world testing - more than 150 years after it was designed."
Difference engine + 800 HP V10?
Nah, difference engine parts everywhere.
I remember reading about artillery tests conducted at Madras in the early/mid 19th. Accuracy was crap. British ingenuity had solved the problem by the time of the Indian mutiny though:
"...convicted mutineers were lashed to the muzzles of cannon and had a roundshot fired through their body..."
Sorry, this one wasn't from a web site, but an old history book. The 32 pounder was a very effective weapon and was the main stay of the ship of the line from the late 1700's. I imagine the tests done were from a ship at anchor with spring lines to stabilise it although I can't say for certain.
However, you are also correct in saying that a lot of fighting was done at much closer range; hence Nelson's comment that "no captain can do very wrong if he lay his ship along side that of the enemy". In many cases they were just blasting away until someone had had enough - and the descriptions of the fighting and the devastation afterwards are truly horrific - it makes some of the modern slash movies look like the teletubbies.
Note also that the limit of a country's jurisdiction around the coast was established by how far away a ship could sail without being pounded to bits by a shore based battery.