Question after watching Cosmos program regarding Edmond Halley's diving bell and DCS

[shoredivr]

I was watching the Cosmos: A Space-Time Odyssey 2014 series on TV and tonight it was about Edmond Halley, (of comet fame) and his diving bell which he designed and used in 1714. The TV show made reference to him staying at 10 fathoms (60 ft) for 90 minutes, and later for up to 4 hours, though the depth was not specified for the 4 hour dive. Of course, I got into a discussion with my family who was watching when I said "hey, how come he didn't get bent at 60 ft for 90 minutes?"


Here in this article are Edmond Halley’s own words about his diving bell and being inside it, including a method he designed to pressurize air long before compressors were invented! Also how much light came in through the window he had installed once he was at depth! However, nothing is said about an hour and a half duration at 60 ft. He notes barotrauma to his ears. He is also aware of compression increasing at increasing depths.
Sir Edmond Halley takes a dive! (1714) | Skulls in the Stars

Here in the link below the time is recorded as being 1 hour 15 minutes and depth is 60 ft without decompression sickness being recorded. See page 48 in this pdf. 75 minutes is just over the NDL (no decompression limit) for modern sport divers at a depth of 60 ft.
90 minutes is definitely over today’s limit to avoid getting decompression sickness for that depth.
http://archive.rubicon-foundation.o.../123456789/5991/SPUMS_V29N1_11.pdf?sequence=1


A commonly used dive planner has 55 minutes before you hit maximum NDLs.
http://www.dypscuba.com/uploads/5/3/2/8/5328783/s976877432205086904_p5_i1_w1052.jpeg


Even the more liberal US Navy no decompression tables say 60 minutes at 60 ft.
Scuba Diving - New Jersey & Long Island New York - dive Wreck Valley - Gear & Training - Basic Dive Planning


Going into the US navy decompression tables, scrolling down three pages and you’ll see 60 ft, then reading 100 minutes (no 90 minutes so going to next deeper) it is 14 minutes at 10 feet to avoid getting DCS.
http://www.matzenauer.org/diving/Navy_air_tables.pdf


So why didn't Edmond Halley get bent? Maybe they brought them up so slowly that they had in effect a rolling decompression stop?

I can’t find a depth described for the 4 hour dive anywhere.

Thanks Dr Decompression!


(Sorry these links don't work, you'll need to cut and paste)

 

[Dr Deco]

Hello shoredivr :

Halley might have been somewhat resistant to DCS or possibly had minor pains and did not notice them. In addition, if he were brought up slowly, as you suggested, he might have performed mild decompression. Sitting quietly in the bell [rather than finning] would have reduced his nitrogen uptake and micronuclei concentration.

He was definitely an adventuresome fellow!

Dr Deco :doctor:

 

[Wookie]

I was watching the Cosmos: A Space-Time Odyssey 2014 series on TV and tonight it was about Edmond Halley, (of comet fame) and his diving bell which he designed and used in 1714. The TV show made reference to him staying at 10 fathoms (60 ft) for 90 minutes, and later for up to 4 hours, though the depth was not specified for the 4 hour dive. Of course, I got into a discussion with my family who was watching when I said "hey, how come he didn't get bent at 60 ft for 90 minutes?"


Here in this article are Edmond Halley’s own words about his diving bell and being inside it, including a method he designed to pressurize air long before compressors were invented! Also how much light came in through the window he had installed once he was at depth! However, nothing is said about an hour and a half duration at 60 ft. He notes barotrauma to his ears. He is also aware of compression increasing at increasing depths.

http://skullsinthestars.com/2011/12/15/sir-edmond-halley-takes-a-dive-1714/

Here in the link below the time is recorded as being 1 hour 15 minutes and depth is 60 ft without decompression sickness being recorded. See page 48 in this pdf. 75 minutes is just over the NDL (no decompression limit) for modern sport divers at a depth of 60 ft.
90 minutes is definitely over today’s limit to avoid getting decompression sickness for that depth.

http://archive.rubicon-foundation.o.../123456789/5991/SPUMS_V29N1_11.pdf?sequence=1

A commonly used dive planner has 55 minutes before you hit maximum NDLs.

http://www.dypscuba.com/uploads/5/3/2/8/5328783/s976877432205086904_p5_i1_w1052.jpeg


Even the more liberal US Navy no decompression tables say 60 minutes at 60 ft.

http://njscuba.net/gear/trng_04_planning.html

Going into the US navy decompression tables, scrolling down three pages and you’ll see 60 ft, then reading 100 minutes (no 90 minutes so going to next deeper) it is 14 minutes at 10 feet to avoid getting DCS.

http://www.matzenauer.org/diving/Navy_air_tables.pdf

So why didn't Edmond Halley get bent? Maybe they brought them up so slowly that they had in effect a rolling decompression stop?

I can’t find a depth described for the 4 hour dive anywhere.

Thanks Dr Decompression!


(Sorry these links don't work, you'll need to cut and paste)

Try the links now...

 

[shoredivr]

double post

 

[bvanant]

"Just because the sheep didn't die doesn't mean it was a safe dive"

My guess is that he felt something akin to Rheumatism and that was pretty common then.
Bill