August 2015 archive

Book Review: Stargazers–Copernicus, Galileo, the Telescope and the Church by Allan Chapman

stargazersIt’s been a while since my last book review here but I’ve just finished reading Stargazers: Copernicus, Galileo, the Telescope and the Church by Allan Chapman.

The book covers the period from the end of the 16th century, the time of Copernicus and Tycho Brahe, to the early 18th century and Bradley’s measurement of stellar aberration passing Galileo, Newton and others on the way. Conceptually this spans the full transition from a time when people believed in a Classical universe with earth at its centre, and stars and planets plastered onto crystal spheres, to the modern view of the solar system with the earth and other planets orbiting the sun.

This development parallels that in Arthur Koestler’s classic book "The Sleepwalkers”, however Chapman’s style is much more readable, his coverage is broader but not so deep. Chapman introduces a wealth of little personal anecdotes and experiments. For instance on visiting Tycho Brahe’s island observatory he recounts a meeting with a local farmer who had in his living room a marked stone from the Brahe’s observatory (which had been dismantled by the locals on Brahe’s death). Brahe was hated by his tenants for his treatment of them, a hate that was handed down through the generations. Illustrations are provided in the author’s own hand, which is surprisingly effective. He discusses his own work in reconstructing historical apparatus and observations.

Astronomy was an active field from well before the start of this period for a couple of reasons: firstly, astrology had been handed down from Classical times as a way of divining the future. To was believed that to improve the accuracy of astrological predictions better data on the locations of heavenly bodies over time was required. Similarly, the Christian Church required accurate astronomical measurement to determine when Easter fell, across increasingly large spans of the Earth.

The period covered by the book marks a time when new technology made increasingly accurate measurements of the heavens possible, and the telescope revealed features such as mountains on the moon, sunspots and the moons of Jupiter visible for the first time. Galileo was a principle protagonist in this revolution.

Amongst scientists there is something of the view that the Catholic Church suppressed scientific progress with Galileo the poster boy for the scientist’s case. Historians of science don’t share this view, and haven’t for quite some time. Looking back on Sleepwalkers, written in 1959 I noted the same thing – the historians view is generally that Galileo brought it on himself in the way he dismissed those that did not share his views in rather offensive terms. Galileo lived in a time when the well-entrenched Classical view of the universe was coming under increased pressure from new observations using new instruments. In some senses it was the collision with the long-held Classical view of the universe which led to his problems, the Church being more committed to this Classical view of the physical universe rather than to anything proposed in Scripture.

The role of the Church in promoting, and fostering science, is something Chapman returns to frequently – emphasising the scientific work that members of the Church did, and also the often good relationships that lay “scientists” of different faiths had with Church authorities.

Chapman introduces some of the lesser known English (and Welsh) contributors to the story. Harriet who made the earliest known sketches of the moon. The Lancashire astronomers, who made the first observations of the transit of Venus. John Wilkins whose meetings were to lead to the foundation of the Royal Society. He also notes the precedent of the Royal College of Physicians, formed in 1518. The novelty of the Royal Society when compared with earlier organisations of similar character was that the Fellows were responsible for new appointments, rather than them being imposed by a patron. This seems to have been an English innovation, repeated in the Oxbridge colleges, and Guilds.

Relating to these English astronomers was the development of precision instruments in England. This seems to have been spurred by the Dissolution of the monasteries. The glut of land, seized by Henry VIII, became available to purchase. The purchase of land meant a requirement for accurate surveying, and legal documents. Hence an industry was born of skilled men wielding high technology to produce maps.

I was distracted by the presence of Martin Durkin in the acknowledgements to this book, he was the architect of “polemical” Channel 4 documentary “The Great Global Warming Swindle”, so it cast doubt in my mind as to whether I should take this book seriously. On reflection Chapman’s position as presented in this book seems respectable, but it is interesting how a short statement in the acknowledgements made me consider this more deeply.

Overall, Stargazers is rather more readable than Sleepwalkers, not quite so single-tracked in it’s defence of the Catholic Church as God’s Philosophers and a different proposition to Fred Watson’s book of the same name, which is all about telescopes.

The London Underground – Can I walk it?

caniwalkitThere are tube strikes planned for 25th August 2015 and 28th August 2015 with disruption through the week. The nature of the London Underground means that it is not all obvious that walks between stations can be quite short. This blog post introduces a handy tool to help you work out “Can I walk it?

You can find the tool here:

http://www.caniwalkit.co.uk/

To use it start by selecting the station you want to walk from, either by using the “Where am I?” dropdown or by clicking one of the coloured station symbols (or close to it). The map will then refresh, the station you selected is marked by a red disk, the stations within 1.5 miles of the starting station are marked by an orange disk and those more than 1.5 miles away are marked by a blue disk. 1.5 miles is my “walkable” threshold, it takes me about 25 minutes to walk that far. You can enter your own “walkable” threshold in the “I will walk” box and press refresh or select a new starting station to refresh the map.

The station markers will show the station names on mouseover, and the distances to the starting station once it has been selected.

This tool comes with no guarantees, the walking distances are estimated and these estimates may be faulty, particularly for river crossings. Weather conditions may make walking an unpleasant or unwise decision. The tool relies on the user to supply their own reasonable walking threshold. Your mileage may vary.

To give a little background to this project: I originally made this tool using Tableau. It was OK but tied to the Tableau Public platform. I felt it was a little slow and unresponsive. It followed some work I’d done visualising data relating to the London Underground which you can read about here.

As an exercise I thought I’d try to make a “Can I walk it?” web application, re-writing the original visualisation in JavaScript and Python. I’ve been involved with projects like this at ScraperWiki but never done the whole thing for myself. I used the leaflet.js library to provide the mapping, the Flask library in Python to serve the data, Boostrap to make it look okay and Docker containers on Digital Ocean to deploy the application.

The underlying data for this tool comes from Open Street Map, where the locations of all the London Underground stations are encoded as latitude and longitude. With this information in hand it is possible to calculate the distances between stations. Really I want the “walking distance” between stations rather than the crow flies distance which is what this data gives me. Ideally to get the walking distance I’d use Google Directions API but unfortunately this has a rate limit of 2500 calls per day and I need to make about 36000 calls to get all the data I need!

The code is open source and available in this BitBucket repository:

https://bitbucket.org/ian_hopkinson/london-underground-app

Comments and feedback are welcome!