Rising butt hinge

The office bathroom has an unusual hinge on the cubicle door, which I’ve often wondered about while ensconced behind that door.


What’s clever about that design is that the spiral shape of the joint makes the door close itself automatically, as the weight of the door pulling downwards is transformed into a torsional motion.

I finally learned today that such hinges are called rising butt hinges, and that one popular use of them is for doors in rooms with heavy carpeting – the door lifts upwards slightly as it opens, and in the process is able to clear the carpet layer.

What a simple, elegant design!

3D vision with the Pulfrich Effect

The Pulfrich Effect is an optical phenomenon where objects (or images) moving in a single plane can appear to be in 3D when the light reaching one eye is dimmed, e.g. with a filter. It also has a curious history – Carl Pulfrich (biography – pdf), who discovered the phenomenon, was blind in one eye and never observed it for himself, but nonetheless made many contributions to stereoscopy (the study of 3D vision) in both theory and the construction of apparatus.

Unlike other forms of stereoscopy, this only works with moving objects or animations; it does not work with still images! But what’s really cool is that you don’t need any special equipment to view it, beyond a piece of darkened glass or plastic to act as a filter. Videos exhibiting the Pulfrich effect can be viewed on a normal monitor or TV screen.

I’ve made my own Javascript animations as demos for the Pulfrich effect (posted as GitHub Gists and rendered by bl.ocks.org):

Screen Shot 2017-01-10 at 00.57.42.png

Screenshot from my animated explanation of the Pulfrich Effect

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Language evolution in action

Here’s an example of how a word can completely reverse its meaning, from a BBC article about the Mid-Levels escalator in Hong Kong (also a cool subject in itself):

“We did the planning in 1984,” says architect Remo Riva, director of P&T Group, which consulted the government.

The verb “consult”, when used in a sentence like “A consulted B”, usually means that A asked B for their opinion. However in this case, it’s the P&T Group which were offering advice to the Hong Kong government, and not the other way around. So the sense of the word “consult” appears to have evolved like this:

“The government consulted the P&T Group” → “The P&T Group were consultants for the government” → “The P&T Group consulted for the government” → “The P&T Group consulted the government”

Funny to see this in action. And yet it’s still very strange to imagine that the word “nice”, for example, used to be pejorative, meaning a foolish or silly person.

Or in the case of the word “sanction”, made me completely misinterpret this headline: “Thai people urged to ‘socially sanction’ critics of monarchy”.

Lonely negatives

My sister and I are great fans of the British political comedy series Yes, Minister and its sequel Yes, Prime Minister. A joke from the episode “The Greasy Pole” that she recently reminded me about:

Joan Littler: What does “inert” mean?

Sir Humphrey: Well it means it’s not… ert.

Bernard: [to himself] Wouldn’t ert a fly.

(via Wikiquote)

I’ve been keeping a little list of words like “inert”, that appear to be a negative form, but whose positive partners aren’t in common use. I’m not sure if there’s already a term for them, but I’d like to call them “lonely negatives”. They’re a curious crowd; here I dip into an etymological dictionary (Concise Oxford Dictionary of English Etymology, ed. T. F. Hoad) and attempt to make a taxonomy of these rogues….

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Biography of Seah Eu Chin now online

Many moons ago, I researched and wrote up a biography of my ancestor Seah Eu Chin (1805-1883). He was a pioneer in the agricultural development of Singapore and Johor, and also one of the founders of the Teochew organisation the Ngee Ann Kongsi. The draft has been sitting around for a long time, and I have now finally converted it to a website, seaheuchin.info.

Working on his biography has stimulated my interest not only in Singapore history, but also in the broader fields of economic and social history. I hope that the way I present his story does not seem like hagiography, but instead puts his life into the context of the times that he lived in. Like a fish oblivious to the water it swims in, we tend not to think too much about the origins of the social order we live in and the institutions embedded in it. The 19th century seems irrelevant to most Singaporeans, and we only learn the barest outlines of the political history of this period in school. The history of immigration, for example, is often depicted as a dichotomy between faceless coolies on one hand, and the rags-to-riches stories of rich merchants like Seah Eu Chin on the other.

In fact, echoes of the 19th century are still with us. Some of these are indeed forgotten corners waiting to be rediscovered – the tomb of Seah Eu Chin was long thought to be lost and was only found again in a wooded area of Toa Payoh in 2012. But other traces are right in front of us just waiting to be seen:

Why do we have several place names in the north of the island that end in “Chu Kang”? This is a relict of gambier agriculture that used to be organized around river or inlet “harbours”, from which the goods and provisions could be loaded. These plantations were not just on Singapore island but also along the Johor coast, and boat traffic connected the Johor plantations with the merchants, like Seah Eu Chin, in the port of Singapore.

Why is one of the biggest malls in Orchard Road called Ngee Ann City? What business does a charity have in owning a shopping centre? It turns out that the site used to be a Teochew cemetery, run by the Ngee Ann Kongsi on land that it bought in 1845, and Seah Eu Chin was one of the original trustees.

Many issues that were once argued over in private homes, at clan organizations, and the legislative chamber are still with us today. I found it remarkable to read in the archives about disputes over the regulation of gambling, anxiety about immigration, and potential tax evasion. Of course the details may differ – people now bet illegally online and not in shady gambling dens, convict labourers are no longer a key source of manpower for public works, and opium is not subject to tax – but it is still surprising how many parallels remain.

In retrospect I should have done this sooner. With content on the web, I can easily update the pages with new information, and embed media including maps and videos. I hope that this work will be interesting to more than just myself and other Seah descendants, and that it will get at least some readers interested in connecting our present to the past.

Plotting data as ratios? Think again

We are often interested in ratios between two quantities. As an example, let’s use data from a study on the sugar content of soft drinks, where the the sugar content declared on the drink label was compared to the actual sugar content measured in the laboratory (Ventura et al. 2010, Obesitypdf). The paper includes a nice table summarizing their measurements, which I have adapted to produce the plots shown here.

How can we present this data to get the most insight? In my opinion, presenting such data as ratios can obscure useful information; showing scatterplots of the two quantites can make it easier to spot patterns.
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