Hobbies
The Basel Problem
One sometimes gets very interesting results when one turns divergent sums upside down. The Basel problem was asked by Pietro Mengoli in . He asked what is the exact summation of the reciprocals of the [more…]
Science
19th Century
Milestones in Nineteenth Century Firearms Development, Part One
Some weeks ago, and quite by chance, a friend offered to sell me a rare mid-19th century rifle, the design of which I had long found to be of interest. Although I was not at [more…]
Arts
Going Postal New Year’s Eve
© EJ 2018
Arts
Hobbies
The Möbius Function
The Möbius function is denoted by , where is the Greek letter mu. Depending on the factorisation of , the function takes the values . The last says that if is even, then and if [more…]
Engineering
Making A Ruby Laser – Part Five
Melting a hole through steel: The above image needs a little explanation! The Doc messed up his camera settings and under exposed the image. So I loaded it into Gimp and played with the curves [more…]
Engineering
Making A Ruby Laser – Part Four
The Doc’s ruby laser focused onto a lighter flint. The flint has been glued to the end of a match stick. The ‘explosion’ measures approximately 4 inches diameter. Interesting things to note are the ‘candy [more…]
Engineering
Making A Ruby Laser – Part Three
More information on laser speckle can be found here: Speckle pattern A Mirror Alignment Tool The most important part of constructing a ruby laser (or any laser with external mirrors) are getting the mirrors alligned [more…]
Hobbies
The Fields Medal
“Rise above oneself and grasp the world” These are awarded every four years for advancement in the field of mathematics. There is an age limit of 40 on the recipients. It is a recognition of [more…]