Shot Towers

By Anupum Pant

The way of making lead musket balls before 1782 involved a lengthy process. And if you had a huge army, then you were in for a massive task. To make each ball:

  • A chunk of lead was melted in a crucible
  • Poured into a mould
  • It was let to stand to solidify
  • The mould was broken
  • Final finishing of each ball was done
  • and each ball was checked for roundness by rolling it on an inclined plane

Then everything changed in the year 1782, when a plumber from Bristol William Watts, got this seemingly simple idea – Drop molten lead from a long tower and let the surface tension do the work.

He got this idea by observing raindrops, which formed perfect spheres while they were free-falling. Before telling anyone about it, he tried implementing his idea. He dropped molten lead into a bath of water from the tower of his local church. It worked perfectly.

He did a couple of other experiments at home and finally patented his idea by the end of the same year. It wasn’t long until shot towers started sprouting all over the world. William made a good fortune out of this.

A shot tower is a long hollow building, like a light house, which has the machinery to melt lead at the top point. The molten lead is dropped into the long hollow shaft through sieves, and the bottom part of the building has a bath of water to catch lead balls. The free falling lead turns into a sphere due to surface tension and solidifies in air due to flowing air. After shots are made, they are lifted from the water and checked for roundness by making them roll on an inclined plane. Defective ones are sent back to the top.

The tallest shot tower ever built was 263 meters long and was constructed in the year 1882. It still stands in the Melbourne suburb of Clifton Hill in Australia. There are several others around the world which are still standing. While many others have either been destroyed by men or nature.

via [PSSA]

Up or Down – Cats in Space

By Anupum Pant

Cat’s righting reflex

Cat_fall_150x300_6fpsThanks to the Vestibular righting reflex, animals like cats are able to land on their feet after a fall. This is great because it helps them avoid injury. In fact, it helps them avoid injuries in a very counter-intuitive manner.

In a study done in the year 1987, researchers found that cats falling from 6 storeys or less usually have greater injuries than cats falling from places higher than 6 storeys. There have been cats who have survived a fall from as high as 32 storeys. It’s so absurd, I had to mention that.

Also cats have been often found falling from high rise buildings due to a phenomenon known as the high-rise syndrome. This happens because cats mostly have a natural attraction towards high places, often get distracted by a prey and fall.

Cats In Space?

All said, there’s no doubt that cats can right themselves pretty well. But to do it, they need to have a sense of what is up and what is down. That sense, of course comes from gravity. What happens to them in micro gravity? A little kid asked me that and I had no answer. Who would have tested that, I thought.

So I checked. To my surprise, cats-in-zero-gravity-tests (simulated weightlessness) have actually been done previously by the USAF medical division and Russian cosmonaut training centre. Here’s an interesting old video of how cat’s natural reflex to right itself by spinning longitudinally fails in a simulated zero-G environment. The video also has confused pigeons flying upside down in zero-G. The whole film can be seen here.

Through experimentation it has been found that when it comes to animals in space, there are three different kinds of behaviours seen among various animals.

The first ones are the kind of animals who freeze in zero-G and wait for the weightlessness to go away. There are others, like cats and pigeons, who start moving about madly, trying to figure out which side is up. In fact, pigeons in zero-G have been seen flying upside down too. And the third ones are who stay calm and find the best way to move around.

Geckos have been seen to take on a free-falling stance in zero-G. Fish and fruit flies are some of the creatures who can deal with zero-G very well.

And if you wish to see some long slender legs before you go, here is a video of frogs in space. The video also talks about aliens entering the earth – tadpoles born outside the earth were brought back. Technically they were aliens and they entered earth!

The Leaping Shampoo Trick – Kaye Effect

By Anupum Pant

This is really interesting and I can’t explain why. You’ll have to see it for yourself.

Long time back, researchers at the University of Twente in The Netherlands thought of something very weird. They decided to drop a thin stream of shampoo from a height of about 20 cm, ended up discovering an absurd physical effect and winning great accolades for it – The Kaye effect.

The seemingly weird effect can fairly easily be achieved at home by dropping a thin stream of shampoo on a relatively hard surface. In individual steps, this is what happens when you do it:

  • As the stream gets collected, it forms a little shampoo heap.
  • Amazingly, and counter-intuitively, a secondary stream ejects off the heap.
  • The mythical secondary stream becomes bigger, shoots further.
  • And finally hits the incoming stream – this collapses the Kaye effect.

Of course, everything happens really fast. But, if you look at it on extremely slowed down film, you’d see the individual steps happening one after the other.

True, the secondary stream collapses too quickly, scientists weren’t happy about that either. So, they tried tilting the hard surface slightly to achieve a stabler version. Lo! And they had a stable Kaye effect.

This happens because due to certain physical forces the viscous liquid becomes slightly less viscous temporarily – they call it shear thinning. As a result, it causes a new stream to emerge. May be the same effect could be achieved with other thicker liquids like lava, ketchup, whipped cream, blood, paint, and nail polish. But, then lava is too dangerous, and others (barring blood and paint) seem to be too thick. I’m guessing, dropping thicker ones from a higher place could make this happen.

If you find this interesting,you’d definitely love the egg and milk effect, also the chain of beads defying gravity.

Here, watch it on video.