Trestles

To do woodwork well, I need a decent bench and some trestles. To make these, therefore, I went to my parents’ in Baldock. The trestles were more complicated than I was expecting, as the legs need to meet the top out-of-square in two dimensions (making it less likely to tip in those dimensions). They are made from yellow pine, strengthened with some chipboard.

We have made the frames that will form the ends of the bench, but we will have to make the rest in situ.

Trestles

The completed trestles

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3D Printed Sphericons II

Here is a video of the k=6 sphericon Chris K. Palmer modeled.

You can download his models here.

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3D Printed Sphericons I

The standard sphericon has a square section, but you can make sphericons from any regular polygon (as is described here). We use the variable k to represent the number of sides of the polygon.

Chris K. Palmer emailed me today to show me some fascinating models he has made of sphericons from k=4 to k=10.

Sphericons

Sphericons, k=4 to k=10

He printed these in 3D from models he created on the computer. The holes are to contain magnets so that the sphericon halves can be turned and rejoined to make different shapes.

Sphericon Paths

Sphericon Paths

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Solar System II

The subject of yesterday’s post was a ray-traced video of the solar system I had been working on. The frames have now finished being rendered and have been combined into a video. The soundtrack is the finale of Act 1 of Tchaikovsky’s Swan Lake (the Philharmonia Orchestra dir. John Lanchberry).

We start 4 million kilometers above the sun (remember, distances are a factor of 500 shorter than reality), and fly to Venus. We then visit Mars, Phobos (the larger of Mars’s two moons), Earth and Jupiter, before returning to the point at which we started.

The smallest body we visit is Phobos, and the largest is Jupiter. The radius of Phobos is only 0.013% of that of Jupiter. In fact, even Ganymede, a moon of Jupiter, has a radius 260 times larger than Phobos.

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Solar System I

When we were at University, Ben Heley and I created a video in C++ as a piece of coursework. We worked on it quite obsessively, possibly at the expense of more important work.

Ray tracing is a technique to render a scene based upon the path light takes through it. Imagine tracing a beam of light backwards. Start at your eye, go through a pixel in the screen, and into a virtual world. When it hits an object, trace it on to all light sources. Using the texture of the object, the angle at which you hit it, and the colour and intensity of the light sources (and of any ambient light) you can calculate the colour of the pixel.

Ray tracing is typically used to render closed indoor scenes, where each ray travels only a short distance and always hits an object. We decided to turn it on its head and render the solar system, where each ray would have to travel very large distances, and most never hit an object.

Venus

The Planet Venus

We rendered the five planets closest to the sun, and ten moons (two orbiting Mars, seven orbiting Jupiter, and ours). The textures of these bodies were downloaded from NASA.

We reduced all distances by a factor of 500 for aesthetic reasons (if distances were accurate, the every planet would merely be a dot in the sky from every other), and therefore we also reduced the size of the sun. However, the size, orbit speed, spin, and axial tilt of the planets and moons are correct.

Because of deadlines, there were a few enhancements we didn’t manage to make at the time, so I recently found the code and made them. I will post the video tomorrow, when the processing should have finished.

Earth, the Moon and Jupiter

Earth, the Moon and Jupiter

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The Gentleman’s Magazine

I have been interested in antiques ever since I can remember, particularly in antiquarian books and maps. Of all antiquarian books, I think for me the most pleasurable to read are 18th and early 19th century magazines.

I find it fascinating to read the almost conversational articles and correspondence from people of that time. To see what they viewed as important, and what they did not, and whether they approached issues in the same way as we do today.

The first ever magazine was the Gentleman’s Magazine, which was founded in 1731 and edited by Edward Cave (under the pen name of Sylvanus Urban). There have been three series. The original ran 1731 – 1833, the “new series” ran 1834 – 1868, and the “entirely new series” ran 1868 – 1907.

Gentleman's Magazine Contents Page

Gentleman's Magazine Contents Page from July 1788 (click to enlarge)

The first regular writing job of Dr Samuel Johnson was writing parliamentary reports for The Gentleman’s Magazine. This was illegal at the time, so they were published as fictional “Debates of the Senate of Magna Lilliputia”. For this, he invented names for people and countries. His name for the American colonies was Columbia, which was later adopted by the United States as their Latinised name.

The Gentleman’s Magazine in October 1745 contained one of the earliest published versions of the British National Anthem, God Save the King. It was listed as being “a new song set for two voices” “as sung at both playhouses” (Theatres Royal at Dury Lane and Covent Garden).

The Gentleman’s Magazine had the motto, E Pluribus Unum (Out of many, one), which was taken by Pierre Eugene du Simitiere for the motto of the Great Seal of the United States, and so is now on every dollar bill. The Gentleman’s Magazine was widely-read in America at the time.

Most monthly magazines contain a number of articles, correspondence, book reviews, poetry, Parliamentary proceedings, foreign news, births and obituaries, stock prices and a meteorological table.

I currently own 35 volumes of the Gentleman’s Magazine, and find it very enjoyable to dip into them every now and then. So far, my favourite quote was from July 1823, from correspondence by the Rev. Samuel Hopkinson to Sir Joseph Banks1.

The Toad, though a loathsome, is not generally considered a venomous animal by the common people, many of whom so far from indicating any disgust at its sight, will frequently grasp it in their hands, and throw it wantonly at each other.

He goes on to give an example of the toad’s venom at work. This caused Sir Joseph Banks and a Mr. Bufon-Amicus to reply, both saying that they often rub toads around their faces to prove they are not venomous. Mr. Bufon-Amicus has even gone so far as to put one down his bosom!


1. Sir Joseph Banks was the naturalist and botanist who accompanied James Cook on HMS Endeavour on his first great voyage to Australia.

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A Beginning

A blogger should not begin, in my opinion, without introducing himself. After all, it is only polite. Don’t worry, I shall be brief.

My name is Paul Roberts, I am in my mid-twenties, and I live in Surrey, England. I have passions for photography, programming, antiquarian books, writing, and woodwork. I tend to be an excitable and obsessive fellow, which I am sure is a constant worry for those that know me.

I feel that will do for now. A proper update will follow shortly.

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