The Mysterious Island

The Mysterious Island

One of the books I’ve read in the past few years that was most fascinating was “The Mysterious Island” by Jules Verne.

The book is about four men who made a daring escape in a balloon which was whisked by a powerful storm to an uninhabited island where they must use their resourcefulness to survive.

Verne stacked the deck in their favor. He has provided an island rich in natural resources, fresh water, useful plants, and game. One of the protagonists is an engineer who is inventive and knowledgeable about a range of modern crafts and techniques. Under his guidance the four men are able to start a fire without flint or matches and build many other fantastic things from what they find in nature.

The story is fantastic, if a bit hard to believe sometimes. Part of what makes it worthwhile is the marvel of discovering how many things are made from the most raw of materials. For a follow-up act, I recommend “Caveman Chemistry”.

One of the ways “The Mysterious Island” strains credibility is in what the engineer is able to accomplish purely out of his memory. Unlike the Professor in Gilligan’s Island, he does not have a trunk full of science books with him. He doesn’t even have a journal.

One of their amazing feats is the reckoning of their approximate location in latitude and longitude. This is accomplished through astronomical observations made with sticks stuck in the ground on a smooth sandy beach over several days, and by reference to one man’s watch, which kept the time of a known city. The problem is not that the measuring tools are insufficient. As we know Eratosthenes measured the Earth to within 2% in the 2nd century bc, using nothing but shadows, a reflection in a well and the known distance between two towns. A single “tin clock” was all that Joshua Slocum required to measure longitude on his famous trip, the first solo circumnavigation of the world. The bigger problem is remembering all of the facts relevant to make the measurements yield a meaningful location.

The characters, all native to North America, met in the city of Richmond, Virginia, yet when they found themselves on an island in the southern hemisphere they were able to recognize the Southern Cross, and use it to find the South Celestial Pole. One among them was a sailor, and I could readily believe that he could do this, but Verne gave the idea, the knowledge of astronomy and skill to use it, to the Engineer.

Later they determine local time using the sun. As I learned from reading about sundials, the length of the solar day is variable, and interestingly, local apparent solar time does not coincide with local mean time even on the equinoxes. It is a little off-set on those days. Knowing when noon, according to a clock set to your meridian will coincide with the point when the sun is highest in the sky, requires a bit of calculation. The days when this happens changes slightly from year to year like the actual dates of the equinoxes and solstices. I expect most people would need an almanac to tell them these things. However, I learned a verse from a book that will get you pretty close:

April the Fourth, and June the Sixth remember;
August the Twentieth, and Twenty-fourth December;
On these Four Days and none else in the year,
The Sun and Watch both the same Time declare.

This mnemonic seems no more difficult than “Thirty days hath September”. I could have believed that the characters had the knowledge to measure their latitude if one of them had spoken this rhyme. Without it, as I said, my credulity is strained. It plays havoc with my willing suspension of disbelief.

So measuring the height of the celestial pole gives you your latitude, and measuring the time difference between a known meridian and your current meridian gives your longitude. So you’ve calculated a couple of numbers; what does that get you? To make use of this measurement you need to know what else is near by. The problem here, is that at this point in the story the characters did not have a map. So, from memory, the Engineer discusses how many miles their island is from the coast of South America, Australia, and Fiji. I imagine that Jules Verne probably had a map close at hand for reference at all times. But I find it hard to believe that he would have more than a vague idea about the coordinates of the world’s significant coasts and islands. It is easy to know things when you have the map to look at. Maybe you don’t feel like you are looking up a fact so much as getting a tiny nudge for your memory, but you need that nudge.

Far fetched as it may be, what would you know how to do if you were stranded on a desert island? Could you remember how to find your location? Would you know the constellations? Would you know the meridian of your hometown? Would you know when you could set your clock by the sun? Would you be able to remember the formulas and procedures for making soap? Ceramics? Metal? Rope? Fabric? Fire? Its easy to know a lot in your study at home, but if you were forced to rely on your wits to survive, could you? And should you be capable of it?