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Do horses legs leave the ground at a gallop?

There’s a famous photo series by Eadweard Muybridge that shows, unequivocally, that while galloping all four of a horse’s legs leave the ground. I’d always heard that’s what they trying to find out at the time, but from what I’ve read it was more a question of at what points do a horse’s legs leave the ground. The photos show the somewhat surprising state of leaving the ground while the horse’s legs are tucked, not when they are outstretched. It’s a lovely example of what Edward Tufte calls small multiples.…There’s a famous photo series by Eadweard Muybridge that shows, unequivocally, that while galloping all four of a horse’s legs leave the ground. I’d always heard that’s what they trying to find out at the time, but from what I’ve read it was more a question of at what points do a horse’s legs leave the ground. The photos show the somewhat surprising state of leaving the ground while the horse’s legs are tucked, not when they are outstretched. It’s a lovely example of what Edward Tufte calls small multiples.

23 Sep 2016

What is a 2.5D object showing a 2D, 2.5D and true 3D object

2.5D

A 2.5D shape is three-dimensional, but the use of the third dimension, usually height, is limited to simple top-down operations. I learned about 2.5D, or two and a half dimensions, from my engineering days. It turns out it’s really quite common to make 2.5D things because, for example, it’s easy to drill or mill down into something, and it's a pain to turn something on its side and drill from the other side. Or, as with vacuum forming, it’s easy to suck plastic onto a mold but a pain to get it off if you’ve got any overhangs as you can’t lift it straight up again. Hence, the plastic sandpit in our garden is a 2.5D object rather than true 3D. As we become more sophisticated at making things, more objects will be true 3D rather than 2.5D. But the simple two-and-a-half-dimensional option is still generally cheaper and easier and will not disappear soon. Civilization, in general, looks rather 2.5D from the air as we tend to build upwards, but we don’t find overhangs that easy or practical, thanks also to gravity, e.g., the Pyramids. I recorded a video of the drawing of this sketch. Watch making a sketchplanation—2.5D Also see: Orthographic projection Isometric projection One-point perspective Two-point perspective Three-point perspective…A 2.5D shape is three-dimensional, but the use of the third dimension, usually height, is limited to simple top-down operations. I learned about 2.5D, or two and a half dimensions, from my engineering days. It turns out it’s really quite common to make 2.5D things because, for example, it’s easy to drill or mill down into something, and it's a pain to turn something on its side and drill from the other side. Or, as with vacuum forming, it’s easy to suck plastic onto a mold but a pain to get it off if you’ve got any overhangs as you can’t lift it straight up again. Hence, the plastic sandpit in our garden is a 2.5D object rather than true 3D. As we become more sophisticated at making things, more objects will be true 3D rather than 2.5D. But the simple two-and-a-half-dimensional option is still generally cheaper and easier and will not disappear soon. Civilization, in general, looks rather 2.5D from the air as we tend to build upwards, but we don’t find overhangs that easy or practical, thanks also to gravity, e.g., the Pyramids. I recorded a video of the drawing of this sketch. Watch making a sketchplanation—2.5D Also see: Orthographic projection Isometric projection One-point perspective Two-point perspective Three-point perspective

12 Sep 2016

The Union Jack

The Origins of the Union Jack The Union Jack, one of the most recognizable flags in the world, is a combination of three historic flags. It represents the union of nations within the United Kingdom at the time the Union Jack flag design was created and is made up of: The Saltire of St Andrew for Scotland: a white diagonal cross on a blue background. The term “saltire” refers to this specific diagonal cross shape in heraldry. The Cross of St Patrick for Ireland: a red diagonal cross on a white background. Though Ireland is no longer part of the United Kingdom, it is still represented in the design. The Cross of St George for England: a red cross on a white background. You may notice that Wales, which is part of the United Kingdom, is not represented on the Union Jack flag. This absence is because Wales was considered a principality under the Kingdom of England, not a separate kingdom, when the flag was created. The Evolution of the Union Flag The Union Jack we know today didn’t always look this way. The first version, known as the Union Flag of 1606, only combined the crosses of St George and St Andrew, representing England and Scotland. It wasn't until 1801, with the Act of Union between Great Britain and Ireland, that the Cross of St Patrick was added, resulting in the modern Union Flag, often referred to as the Union Jack. Why is it Called the “Union Jack”? The term “Union Jack” comes from naval usage. A “jack” is a flag flown from the bow of a ship. Originally referred to as the Union Flag, it became more commonly known as the Union Jack when flown at sea. Over time, this name has become standard, even on land. According to the Flag Institute, the terms are often used interchangeably. However, some argue we should only call it a “Union Jack” when flown on a ship. The Union Jack on other Flags By representing the United Kingdom, the Union Jack appears on other flags. For example, the Union Jack flag is part of Australia's flag, which also includes the Southern Cross, and New Zealand's flag. It's also part of the flags of several Commonwealth countries and British Overseas Territories. It is often used symbolically to represent the UK in popular culture and events worldwide. Sometimes, people refer to it as the Great Britain flag, though this is not technically accurate, as Great Britain refers only to the island, not the full union. Vexillology: The Study of Flags If you're interested in flags, you might already know someone studying flags is called a vexillologist. Vexillology is the study of the history, symbolism, and usage of flags. Like the history of the Union Jack here, flags are both a symbol and a product of the history and culture of a country or institution. The history and construction of the Olympic Flag is a good example. Also see: Curious about the difference between Great Britain and the United Kingdom? The Olympic Flag and rings…The Origins of the Union Jack The Union Jack, one of the most recognizable flags in the world, is a combination of three historic flags. It represents the union of nations within the United Kingdom at the time the Union Jack flag design was created and is made up of: The Saltire of St Andrew for Scotland: a white diagonal cross on a blue background. The term “saltire” refers to this specific diagonal cross shape in heraldry. The Cross of St Patrick for Ireland: a red diagonal cross on a white background. Though Ireland is no longer part of the United Kingdom, it is still represented in the design. The Cross of St George for England: a red cross on a white background. You may notice that Wales, which is part of the United Kingdom, is not represented on the Union Jack flag. This absence is because Wales was considered a principality under the Kingdom of England, not a separate kingdom, when the flag was created. The Evolution of the Union Flag The Union Jack we know today didn’t always look this way. The first version, known as the Union Flag of 1606, only combined the crosses of St George and St Andrew, representing England and Scotland. It wasn't until 1801, with the Act of Union between Great Britain and Ireland, that the Cross of St Patrick was added, resulting in the modern Union Flag, often referred to as the Union Jack. Why is it Called the “Union Jack”? The term “Union Jack” comes from naval usage. A “jack” is a flag flown from the bow of a ship. Originally referred to as the Union Flag, it became more commonly known as the Union Jack when flown at sea. Over time, this name has become standard, even on land. According to the Flag Institute, the terms are often used interchangeably. However, some argue we should only call it a “Union Jack” when flown on a ship. The Union Jack on other Flags By representing the United Kingdom, the Union Jack appears on other flags. For example, the Union Jack flag is part of Australia's flag, which also includes the Southern Cross, and New Zealand's flag. It's also part of the flags of several Commonwealth countries and British Overseas Territories. It is often used symbolically to represent the UK in popular culture and events worldwide. Sometimes, people refer to it as the Great Britain flag, though this is not technically accurate, as Great Britain refers only to the island, not the full union. Vexillology: The Study of Flags If you're interested in flags, you might already know someone studying flags is called a vexillologist. Vexillology is the study of the history, symbolism, and usage of flags. Like the history of the Union Jack here, flags are both a symbol and a product of the history and culture of a country or institution. The history and construction of the Olympic Flag is a good example. Also see: Curious about the difference between Great Britain and the United Kingdom? The Olympic Flag and rings

1 Sep 2016

What's the difference between Great Britain and the United Kingdom - explained in a sketch with maps

Great Britain and the United Kingdom: What’s the difference?

This is generally the source of much confusion, even amongst those who live over here. If you look carefully at the description of the United Kingdom (on a passport say), you’ll see it’s the "United Kingdom of Great Britain and Northern Ireland". So the UK is both of those. Great Britain is the largest island in the British Isles and includes the three countries: England, Scotland and Wales. The British Isles is the group of islands as a whole, including all of Ireland. The British Isles also include several significant islands that are part of Scotland, such as the Hebrides (Inner and Outer), and the Northern Isles of both Orkney and Shetland. It also encloses the Isle of Man, which sits in the Irish Sea between England and Northern Island and is actually a self-governing British Crown Dependency with its own parliament and government. For a little more subtlety, there's the term the British Islands (as opposed to Isles), which includes the UK, the Isle of Man and the Channel Islands, which sit closer to France. For much further confusion, think for a moment why there’s a UK passport, Great Britain in the Olympic games, and in football, we compete as England, Wales, Scotland and N. Ireland separately. 🤔 Also see: the Union Jack: The making of a flag The Coastline paradox…This is generally the source of much confusion, even amongst those who live over here. If you look carefully at the description of the United Kingdom (on a passport say), you’ll see it’s the "United Kingdom of Great Britain and Northern Ireland". So the UK is both of those. Great Britain is the largest island in the British Isles and includes the three countries: England, Scotland and Wales. The British Isles is the group of islands as a whole, including all of Ireland. The British Isles also include several significant islands that are part of Scotland, such as the Hebrides (Inner and Outer), and the Northern Isles of both Orkney and Shetland. It also encloses the Isle of Man, which sits in the Irish Sea between England and Northern Island and is actually a self-governing British Crown Dependency with its own parliament and government. For a little more subtlety, there's the term the British Islands (as opposed to Isles), which includes the UK, the Isle of Man and the Channel Islands, which sit closer to France. For much further confusion, think for a moment why there’s a UK passport, Great Britain in the Olympic games, and in football, we compete as England, Wales, Scotland and N. Ireland separately. 🤔 Also see: the Union Jack: The making of a flag The Coastline paradox

20 Aug 2016

What is the potato radius example explained: showing a bumpy potato-like asteroid at the centre of an expanding circle and how it becomes rounder and more planet like as it gets larger

The Potato Radius: When Asteroids Turn Spherical

Asteroids are often considered irregular, lumpy, potato-shaped rocks, while planets seem smooth and spherical. The “potato radius” is the fascinating threshold where this transformation begins—a concept that illustrates how gravity shapes celestial bodies. What is the Potato Radius? When a space rock’s radius (the distance from its centre to its edge) grows to around 200–300 kilometres, its own gravity becomes powerful enough to reshape it. At this size, gravity pulls the rock’s mass inward toward its centre, overcoming its irregular structure and creating a more spherical shape. Think of it like compressing a crumpled ball of paper into something rounder and smoother. Rocks smaller than this threshold retain their irregular, asteroid-like shapes, while larger bodies transition into planet-like spheres due to self-gravity. This natural process highlights the profound role gravity plays in shaping the universe. Potatoes as Asteroids in The Empire Strikes Back Our image of asteroids is so closely linked to potatoes that they have even served as asteroid doubles in movies. In a brilliant example of creative special effects, The Empire Strikes Back used potatoes as some of the asteroids in the famous scene where the Millennium Falcon flies through an asteroid field. Related Ideas The potato radius and other remarkable natural phenomena feature in Professor Brian Cox in the BBC series Forces of Nature. Also see: Not sure about Asteroids, meteors and meteorites? Solar System Sizes The Goldilocks Zone What causes the seasons? What is a blue moon? Phases of the moon The potato radius features, along with many other fun, spacey-sketches in my book Big Ideas Little Pictures…Asteroids are often considered irregular, lumpy, potato-shaped rocks, while planets seem smooth and spherical. The “potato radius” is the fascinating threshold where this transformation begins—a concept that illustrates how gravity shapes celestial bodies. What is the Potato Radius? When a space rock’s radius (the distance from its centre to its edge) grows to around 200–300 kilometres, its own gravity becomes powerful enough to reshape it. At this size, gravity pulls the rock’s mass inward toward its centre, overcoming its irregular structure and creating a more spherical shape. Think of it like compressing a crumpled ball of paper into something rounder and smoother. Rocks smaller than this threshold retain their irregular, asteroid-like shapes, while larger bodies transition into planet-like spheres due to self-gravity. This natural process highlights the profound role gravity plays in shaping the universe. Potatoes as Asteroids in The Empire Strikes Back Our image of asteroids is so closely linked to potatoes that they have even served as asteroid doubles in movies. In a brilliant example of creative special effects, The Empire Strikes Back used potatoes as some of the asteroids in the famous scene where the Millennium Falcon flies through an asteroid field. Related Ideas The potato radius and other remarkable natural phenomena feature in Professor Brian Cox in the BBC series Forces of Nature. Also see: Not sure about Asteroids, meteors and meteorites? Solar System Sizes The Goldilocks Zone What causes the seasons? What is a blue moon? Phases of the moon The potato radius features, along with many other fun, spacey-sketches in my book Big Ideas Little Pictures

14 Aug 2016

Information radiator

Shares information passively, with the neat effect that having a good one in an office can go a long way to getting people on the same page without explicitly calling meetings or sending out updates to do so. Handy to also have a good space in front of it for talking, discussing and generally collaborating. A common term in agile development, originally I believe from Alistair Cockburn of Thoughtworks. To quote from his article, of many possible: “A good information radiator: - Is large and easily visible to the casual, interested observer - Is understood at a glance - Changes periodically, so that it is worth visiting - Is easily kept up to date” HTs: Ewan Silver, Kevin Alves…Shares information passively, with the neat effect that having a good one in an office can go a long way to getting people on the same page without explicitly calling meetings or sending out updates to do so. Handy to also have a good space in front of it for talking, discussing and generally collaborating. A common term in agile development, originally I believe from Alistair Cockburn of Thoughtworks. To quote from his article, of many possible: “A good information radiator: - Is large and easily visible to the casual, interested observer - Is understood at a glance - Changes periodically, so that it is worth visiting - Is easily kept up to date” HTs: Ewan Silver, Kevin Alves

4 Aug 2016

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