A working hand-cranked Difference Engine made using LEGO® pieces
What is a "Difference Engine"?
Before the day of computers and pocket calculators all mathematics was done by hand.
Many machines of various designs were built, but the most advanced and famous of these was not. The
Babbage Difference Engine.
Because of engineering issues as well as political and personal conflict the Babbage Difference engines' construction had to wait until 1991 when the Science Museum in London decided to build the Babbage Difference Engine No.2 for an exhibit on the history of computers.
by Andrew Carol
This is the 3rd generation of Babbage Difference Engine made with LEGO. It is modeled after Babbages Difference Engine #1. The 3rd generation operates five times faster than the 2nd generation.
This machine can evaluate polynomials of the form Ax^2 + Bx + C for x=0, 1, 2, …n with 3 digit results.
A new answer is produced every 20 turns of the crank: 10 turns of the crank adds the bottom two digit register into the middle two digit register. The next 10 turns of the crank adds the middle two digit register into the top three digit accumulator, yielding the next result.
For more details, history, & what a difference engine is, as well as more photos and videos of it working, go to this link:
LEGO Difference Engine .
This machine, modeled after the ancient Greek original, can calulate the date and time of solar and lunar eclipses over a hundred year period. It is an analog computer with over 100 gears and 7 differential gearboxes. It is accurate to a day or two over it's range.
Link for more ideas, and the pdf instructions is here:lego.com (festivefun) 
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Ben Caulkins (aka Benny Brickster) created this helmet. Naturally, it’s wearable, and it includes some well-placed padding for comfort. For more info click this link here: 
