The boundaries of our ignorance were so much closer so recently.

I have recently loaded up my iPad with old books. The motivation is in part to reduce the volume of books I carry with me when travelling, though that is more a function of self-discipline than technology and if past is prologue, then the iPad won't really address that issue. The other part of the motivation is to have quickly available books that are on my reading list but unlikely to be read. In general the full range of classics, some of which I have read but not in a long time, some of which I have dipped into but never completed and many which I have never even seriously perused. My thought was that when I am travelling, there are lots of ten or twenty minute windows when it would be easy to dip into something on the iPad.

On this first venture, I covered a lot of old poetry. I also read a collection of Arthur Conan Doyle horror stories, some for the first time and some rereading from long ago.

One of the latter was The Horror of the Heights originally published in the venerable Strand Magazine in 1913.

You can read a summary of the story at Wikipedia. It is a fine little tale but what grabs my attention is how recently things were still relatively unknown to us. In this instance, it is the unknown, in those early days of flight, regarding what might be encountered at the stupendous heights of 30,000 feet or 40,000 feet.

A sampling of the story.

"It was a close, warm day for an English September, and there was the hush and heaviness of impending rain. Now and then there came sudden puffs of wind from the south-west—one of them so gusty and unexpected that it caught me napping and turned me half-round for an instant. I remember the time when gusts and whirls and air-pockets used to be things of danger—before we learned to put an overmastering power into our engines. Just as I reached the cloud-banks, with the altimeter marking three thousand, down came the rain. My word, how it poured! It drummed upon my wings and lashed against my face, blurring my glasses so that I could hardly see. I got down on to a low speed, for it was painful to travel against it. As I got higher it became hail, and I had to turn tail to it. One of my cylinders was out of action—a dirty plug, I should imagine, but still I was rising steadily with plenty of power. After a bit the trouble passed, whatever it was, and I heard the full, deep-throated purr—the ten singing as one. That's where the beauty of our modern silencers comes in. We can at last control our engines by ear. How they squeal and squeak and sob when they are in trouble! All those cries for help were wasted in the old days, when every sound was swallowed up by the monstrous racket of the machine. If only the early aviators could come back to see the beauty and perfection of the mechanism which have been bought at the cost of their lives!

And then a sense of the speculative wonder of what flying at heights might mean.

"It was about that time that I had a most extraordinary experience. Something whizzed past me in a trail of smoke and exploded with a loud, hissing sound, sending forth a cloud of steam. For the instant I could not imagine what had happened. Then I remembered that the earth is for ever being bombarded by meteor stones, and would be hardly inhabitable were they not in nearly every case turned to vapour in the outer layers of the atmosphere. Here is a new danger for the high-altitude man, for two others passed me when I was nearing the forty-thousand-foot mark. I cannot doubt that at the edge of the earth's envelope the risk would be a very real one.

"My barograph needle marked forty-one thousand three hundred when I became aware that I could go no farther. Physically, the strain was not as yet greater than I could bear but my machine had reached its limit. The attenuated air gave no firm support to the wings, and the least tilt developed into side-slip, while she seemed sluggish on her controls. Possibly, had the engine been at its best, another thousand feet might have been within our capacity, but it was still misfiring, and two out of the ten cylinders appeared to be out of action. If I had not already reached the zone for which I was searching then I should never see it upon this journey. But was it not possible that I had attained it? Soaring in circles like a monstrous hawk upon the forty-thousand-foot level I let the monoplane guide herself, and with my Mannheim glass I made a careful observation of my surroundings. The heavens were perfectly clear; there was no indication of those dangers which I had imagined.

"I have said that I was soaring in circles. It struck me suddenly that I would do well to take a wider sweep and open up a new airtract. If the hunter entered an earth-jungle he would drive through it if he wished to find his game. My reasoning had led me to believe that the air-jungle which I had imagined lay somewhere over Wiltshire. This should be to the south and west of me. I took my bearings from the sun, for the compass was hopeless and no trace of earth was to be seen—nothing but the distant, silver cloud-plain. However, I got my direction as best I might and kept her head straight to the mark. I reckoned that my petrol supply would not last for more than another hour or so, but I could afford to use it to the last drop, since a single magnificent vol-plane could at any time take me to the earth.

"Suddenly I was aware of something new. The air in front of me had lost its crystal clearness. It was full of long, ragged wisps of something which I can only compare to very fine cigarette smoke. It hung about in wreaths and coils, turning and twisting slowly in the sunlight. As the monoplane shot through it, I was aware of a faint taste of oil upon my lips, and there was a greasy scum upon the woodwork of the machine. Some infinitely fine organic matter appeared to be suspended in the atmosphere. There was no life there. It was inchoate and diffuse, extending for many square acres and then fringing off into the void. No, it was not life. But might it not be the remains of life? Above all, might it not be the food of life, of monstrous life, even as the humble grease of the ocean is the food for the mighty whale? The thought was in my mind when my eyes looked upwards and I saw the most wonderful vision that ever man has seen. Can I hope to convey it to you even as I saw it myself last Thursday?

Reading this brought to mind a later book but one which similarly brings to our contemporary senses the wonder of unexplored regions in the very recent past.

John Wyndham was a British science fiction writer of the 1950s and 60s. He is most famous for Day of the Triffids and The Midwich Cuckoos. Both classics now. The book that Horror of the Heights brought to mind, though, was The Kraken Wakes. Published in 1953, it is the story of an alien invasion. The aliens are not terrestrial though. Their initial landings are in the ocean. The deep ocean. Once there, they slowly prepare to conquer mankind. What is distinctive to the modern reader, or at least to me, is that in the mid 1950s, the deep ocean was still terra icognita to us. Deep ocean submersibles were still basically reaching down a few hundred feet and not the thousands of feet posited by Wyndham as the habitable region of the aliens.

That's what is striking to me. Our knowledge frontier has expanded so greatly and we have made the physical frontiers quotidian. Middle aged technology executives parachute from 135,000 feet. Our unmanned submersibles take us to the deepest trenches. Yes, there is much we don't know but the frontiers are far away. Only a few decades ago we couldn't reach the depths and we didn't know what might lurk in the heights. Now they are routine.