Martin Vlietstra

The Bridge Strike Problem

The signposting of the clearance of bridges and other overhead obstructions in the United Kingdom is a mess. Clearances on service station canopies, access to buildings and car parks, motorway construction sites and airside at airports are given in metric units while until 2002 imperial units were used exclusively on road signs. In 2002, the use of metric units alongside imperial units was permitted on height, width and length restriction signs and in 2016 it became mandatory to use both metric and imperial units. It appears that the 2016 requirement to use both units is not properly enforced, possibly to placate voters who are opposed to metrication.

Digital Measuring Devices (Part 2)

In Part 1 of this article, we saw that one of the basic methods by which a digital measuring device operated was the conversion of an analogue signal (often a voltage or an electric current) into a set of digital bits. The number of bits determined the precision with which the device could take a measurement. The article went on to describe the workings of a digital thermometer and how domestic-quality thermometers are often designed around the use of degrees Celsius with displays in degrees Fahrenheit being an add-on where the Fahrenheit display is calculated from the equivalent Celsius measurement.

In this article we will look at how digital weighing devices work.

Digital Measuring Devices (Part 1)

In this two-part series, Martin Vlietstra will be looking at how digitisation is applied to measuring devices: In Part 1, he will examine what “digitisation” is and explain how it is applied to thermometers. In Part 2, he will look at how it is applied to weighing devices.

Richmond Project

Last year (Saturday 1 March 2025), The Times devoted a page to the Richmond Project, a charity that is being set up by the former prime minister Rishi Sunak and his wife Akshata Murty. The project’s purpose is the improvement of numeracy. Such a project poses quite a challenge. On 12 January 2026, the Sunaks were interviewed on the BBC Breakfast program about the progress of the project.

Why can I not record my cat’s weight as five pounds?

Recently, when surfing the internet, I came across some correspondence between a cat lover and a supplier of cat food. When the cat lover wished to order cat food the supplier’s web site required that he enter the cat’s weight in kilograms. However, he wished to enter the cat’s weight in pounds. He went on to say that he had measured his cat’s weight by first weighing himself (13 st 4 lbs, or 186 lbs) and then weighing himself while holding his cat. The rest of the article was devoted to correspondence between himself and the cat food company in which he voiced his preference for using pounds.

Do British road signs display symbols or abbreviations?

According to the Concise Oxford Dictionary, an abbreviation is defined as a “shortened form of a word in which part of the word is written” [rather than the whole word] while a symbol is defined as a “Mark or character taken as the conventional sign of some object or idea or process”. As a result, abbreviations are language-sensitive whereas symbols can be consistent across linguistic boundaries.

Report on Measure for Measure Conference

Martin Vlietstra attended the St Cross Centre for the History and Philosophy of Physics (HAPP) one-day conference in Oxford on Saturday 7 June 2025 and has written a report about the conference for Metric Views.

NHS to Fight Obesity

On 18 March, the Times reported that NICE (National Institute for Health and Care Excellence) had opened a consultation on an updated version of their general guidance document in which it proposed that millions should have an annual weigh-in to fight obesity. These weigh-ins would take place at doctor’s surgeries and will be aimed at those who have certain conditions including diabetes, arthritis and heart failure. The consultation runs until 15 April 2025. [Ref 1, 2, 3]

Speedometers and Metrication

How are speedometers designed to accommodate the change from mph to km/h? In this article I will examine a variety of techniques and at the end of the article I will propose a 21^st Century solution.

Is that really one kilogram?

When a retailer weighs out his product in front of the customer, can the customer trust the scales? It is usually up to local government to certify the accuracy of such scales, though in recent years, certification of measuring devices within much of the world has been privatised with various countries’ national laboratories overseeing the certification process.

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