Hobbies
Euler’s Totient Function
Euler’s totient function counts the number of positive integers up to that are relatively prime to , where is considered to be relatively prime to all . These numbers are called the totatives of . [more…]
Science
Engineering
Making A Ruby Laser – Part Two
(a ruby rod lit by two bright blue LEDs. Due to the IR filter in my camera the pink colour is actually red. What you are seeing is the absorption of the blue light and the [more…]
Engineering
Making A Ruby Laser – Part One
Introduction For many years the Doc has had the desire to attempt the construction of a ruby laser. After six months of hard work, disappointment, late nights, lots of booze and a drained bank account [more…]
Arts
Shunting Review
Some of you who have stumbled upon this wonderful site in recent weeks and months may be wondering what various references to shunting and occasional photos of a railway scene are all about. You may [more…]
20th Century
The Spitfire, of course
Ask anyone from the general public to name a great aeroplane or a great British fighter of WWII, and chances are they will say, without hesitation, “The Spitfire of course.” If you ask why you [more…]
Engineering
The Castle
I love castles and have always found their development and changing functions fascinating. They show social, military and political history. They are a physical representation of the past, and yet many of them are still in [more…]
Engineering
Shunting to the end
If you remember back at the start of this series, I came up with the idea of a ‘winter project’. Well it is no longer winter, even in the North, so time to bring it [more…]
Engineering
Shunting into colour
A shorter update this time, primarily due to other activites taking precedence – not weather related over the past weeks, but the Easter holidays threw routines out of the window. The eldest came home and [more…]
Engineering
Shunting Cobbles
With spring just around the corner, allegedly, this winter project should be coming to a close, but so far there is little sign of that. The return of the eldest son from Uni meant decamping [more…]