Archive for the ‘Tech stuff’ Category

Bells

Sunday, January 8th, 2012

Whitechapel Bell Foundry
Something like thirty years ago, I was on a bus with my grandfather passing The Whitechapel Bell Foundry; he told me a little about the place and promised to take me for a visit when I was older. Three years ago, I bought a ticket for a tour the following year, then forgot to go. Yesterday I finally toured the foundry with around 25 others, I was probably the second youngest in the tour party – very few other the others were below retirement age.

The bell foundry is the oldest manufacturing company in the UK, having been formed in 1570 (and with good evidence that it may date back to 1420 from earlier foundry works in the area). The foundry site on Whitechapel Road dates from 1738, originally having been The Artichoke coaching inn, built c1670.

The tour was interesting and through, we learned the bell-metal casting temperature, 1170 degrees C; the composition of the casting molds, a brick core covered in goat-hair, clay, sand and horse manure shaping mixture (photo); the number of harmonics a modern bell is tuned for, 5 – the same note in 3 octaves and a minor 3rd and a 5th.

At the back of the works, in the yard, a new set of bells and mounts (photo) were being prepared for St Dunstan in the west.To make best use of limited space, the hand-bell workshop and the woodworking workshop are built above the foundry floor. These workshops have rather low ceilings and beams – no one taller than 5’8″ works there. In the wood workshop where bell wheels are made, is the foundry “graveyard” commemorating those that have died while working (no details give for those, possibly an interesting story) and in retirement.

I’d love to re-visit when they actually cast a bell, but understandably they prefer not to have members of the public around when sloshing tons of molten metal around.

DG visited in 2008, around the time I booked my first, forgotten, tour.

A darker than usual morning at this time of year

Sunday, January 2nd, 2011

Going back to work on the 4th of January might be enough to darken anyone’s spirits, the mornings are dark enough, but come the 4th dawn will be even darker for us here in London. A partial eclipse will have the moon covering up the rising limb of the sun, the uncovered portion will still be below the horizon at sun-up (08:06am).

Seeing as it will almost certainly be too overcast to take photographs and I’ll have no clear view to the low horizon anyway, I’ve prepared some simulations of what you would see (or I would photograph) were conditions perfect (with no atmosphere glare either).

The start of the eclipse as you'll not see it from East London

The Sun will clear the horizon by 8:15, but a good portion of it will be eclipsed by the moon.

9am

Just as you’re starting work, the sun will be high enough to clear low roofs and trees, you might get to see a chunk missing from it if you’re outside or near a window.

But it’ll probably be too overcast.

All over
9:30, and the sun is definitely high enough to see now, but you’ve missed all the action.

It’s a shame hardly anyone in London will see this eclipse, because it’s one of the best London will see for a long time. The centre-line passes right though London, skirting the west-side of central park in East Ham, passing right over Ilford station and just clipping the eastern edge of Valentines Park.

A fun toy for working out where the eclipse is visible is this map from NASA. The next total solar eclipse visible from London isn’t until June 14, 2151, so armchair eclipse hunters have a bit of a wait.

X-rays

Wednesday, November 25th, 2009

Now I have an xray machine to play with at work, I can take photographs of the insides of things. I shall make full use of this. Here’s an old transistor to start with.

Xray image of an old  Mullard OC44 transistor

Image details : Mullard OC44 PNP Germanium transistor, glass envelope. 90kV polychromatic xrays, filtered with 1.5mm Al and 0.2 mm Cu. CsI scintillator, 6 sec exposure.

Bad joke.

Sunday, October 11th, 2009

And so it was to be, that after the waters receded, Noah commanded all the animals to “Go forth and multiply.”

The ark quickly emptied, except for two small snakes, who stayed behind.
When Noah asked them why, they replied, “We can’t multiply. We’re adders.”
Noah, being the resourceful man he was, immediately got busy cutting down trees and building a large table with the unfinished lumber therefrom.

And he saw that it was good.
The snakes were overjoyed when Noah picked them up and placed them on it. Noah and the snakes both knew that even adders could multiply on a log table.

GPS

Monday, May 11th, 2009

I needed a GPS antenna for a frequency standard I bought. So I built one.