20 October 2015

Failing To See You're Freezing To Death

“Are you drunk?”
“You swore to me there was no more booze down there!”
“I’m not fucking drunk!” shouted Gerry miserably. “I had grease on my glasses and I started running them under hot water and one of the lenses cracked because it’s minus fucking thirty. I can’t see shit.”
“Oh. Sorry.” The Berg glinted in the sunshine. “I thought you ate all the grease. And hot water?”
“Not edible grease. Grease grease. For the engine.”
“Hmmm.” The Berg drifted away from the boat a little as if to get a better look at Gerry; wavelets sploshed energetically against the hull. “Your head doesn’t look oversized.”
“My head’s not oversized! What’s that got to do with it? You’re really being very irritating today.”
“Sorry. Something’s too big though, more likely your eye than your actual head. That’s why you can’t see. Your eye focuses light on a point in front of your retina. If your eye was smaller you wouldn’t have a problem.”
Gerry kicked a bulkhead. “Well I do have a problem! I’m starving to death and freezing to death. I spend my days talking to a fucking iceberg. And now I can’t see!”
The Berg trickled sulkily. “Well, if that’s the way you feel… we don’t have to talk. I suppose it means nothing that I could help you get a new prescription.”
“A new prescription?”
“That’s the spirit!” said the Berg, butting against the boat and sending a clatter of shards on to the deck. “Have you got a ruler?”
“Uhh… I’ll see if I can find one.”
Gerry returned twenty minutes later to find the sun had gone in and the Berg floating in a stew of sea ice that had seemingly appeared from nowhere. The temperature had dropped alarmingly.
“Got it? Great. Now measure the distance between your eyeball and the lens you have left in your glasses. Actually don’t! It’s pretty nippy out here. Don’t want the ruler stuck to your eyeball. It’s probably a centimetre. We’ll say a centimetre.”
“OK. Where did you learn all this anyway?”
“I’m made out of ice. I’m reflecting, refracting, all that stuff. Optometry’s easy. Now. Which lens is broken? Left? So hold the ruler up to your cheek and close your right eye. Look along the ruler and move your finger towards you till you can focus on it. How far away’s that?”
“About ten inches.”
“Metric, man! We’re not barbarians.”
“Sorry. Maybe 25cm.”
“Wow, you are blind. OK. 25cm is your farpoint. That’s the point your left eye focusses at when it’s resting. If you weren’t myopic that’d be infinity.”
“Technically, yes. The moon, the stars, they’d be in focus.”
“OK. So you need a diverging lens, one that’s concave on both sides. That’s more bad news actually.”
“If you ever need to start a fire in the wilderness you have the wrong type of lens. It won’t focus the sun’s rays to a point.”
“That’s OK. When I get too weak to move I’ve still got a few matches and a cup of diesel put aside. I’m going to set the boat on fire and be warm again before I die.”
The Berg groaned and cracked. A tern that had been perched out of sight on its far side flew off across the water with a mournful cry.
“That’s the spirit! Getting your sense of humour back – that’s good, just let me know before you torch the thing so I can drift off a bit.”
Gerry smiled. He didn’t want to admit it but the Berg’s high spirits were making him forget the sense of hopelessness that had descended on him ever since the lens had cracked in his numb fingers.
“So your diverging lens will make things appear to be at your farpoint. It’ll move things all the way from infinity to 25cm from your face. Neat, hey?  We just need to figure out the focal length for your lenses. That’s just your farpoint in metres, so 0.25, minus the distance of your lens from your eye, call it one, so let’s say 0.24. You bang a negative in front of that and there’s your focal length! Negative 0.24.”
“I thought prescriptions were in whatsits… dioptres.”
“No problem at all. Dioptres are just a bullshit measurement that optometrists like to use. They’re just one divided by the focal length. So… one divided by -0.24 equals... -4.16.”
“Nice mental arithmetic.”
“Thank you. Now optometrists like the steps to be in 0.25 increments, so your prescription, Gerry, for your broken lens, is… -4.25!”
“Wait I thought you were getting me new glasses?”

“Pay attention. I said prescription. Where am I going to get new glasses? I’m an iceberg. The North Pole is just there over the horizon.”