Rachel Lance

So that's when you start to see the chamber divers getting in their tubes and you start to see Horace Cameron Wright climbing into the lake along with dozens of volunteers to blast themselves.

Exactly.

When Horace Cameron Wright climbed out of the water, after each explosion, he would use a stethoscope to measure where in his own lungs there was blood.

The lungs can handle a surprising amount of injury.

Long term, I'm not sure how he survived himself, but...

The lungs can handle up to 15 percent injury or so without having severe symptoms.

Like if you try and sprint, you'll you'll probably have an issue.

But you can have low grade levels of damage to your lungs and still be OK.

So I think he just took some days off and then tried again, to be honest.

One of the big things that these scientists contributed was the improvement of their ability to use not only regular sized submarines, but miniature submarines.

These tiny subs had a smaller gas volume, which made the rules of breathing physiology even more time critical.

And the scientists who were conducting these experiments on themselves were really the ones responsible for determining how much people could tolerate carbon dioxide buildup in there, how much chemical scrubber material they needed to bring with them in order to remove carbon dioxide to fulfill their missions, and how much oxygen they also needed to carry as well.

So when we had the development of these mini subs called X-Craft, they were then used by the British to start scouting the beaches of Normandy.

Because the tiny submarines, which were only about 10 feet tall, could get so much closer.

And they could dive down to the bottom and wait offshore for night to come back around again.

So using the work by these scientists, they had the subs full of carbon dioxide scrubber.

They knew what their safe limits are.

They knew what to do with the oxygen levels.

And they would go over to Normandy in advance of D-Day and sink down to the bottom during the day, breathe inside their safe enclosed environment, and then come up at night, crawl ashore, measure the sand, measure the beach angles, provide detailed maps, everything, and then go home.

A lot of that credit can be due to this research lab at UCL, who again did this experiment by just putting themselves in a tank, closing the door, and waiting to see how long they could physically handle the amount of carbon dioxide in there before they ended up with migraines and projectile vomiting.