Today I learned +

[overgeeked]

Today I learned that Lester Dent was paid between $600-750 per novel. Dent is the man who almost single-handedly wrote all 181 Doc Savage novels (40,000+ words apiece) at a rate of one per month for years. In today's money, that's about $18,000 a month or $216,000 a year. For context, the median household income of a single-income household in DC as of 2023 was $75,800. More context, Doc Savage was the #2 best-selling hero pulp magazine in the country while it was being published.

 

[Aeson]

Today I learned that Adrian Paul, who played the lead in the "Highlander" TV series, teaches film/stage sword combat via a school called "The Sword Experience."

I had heard he was a dancer before getting into acting. Fight chorography and dance chorography isn't dissimilar. This isn't surprising. Summer Glau was a dancer also. You can really see it in the fight scene in Serenity. That kind of background really lends itself to stage fighting.

 

[Ryujin]

I had heard he was a dancer before getting into acting. Fight chorography and dance chorography isn't dissimilar. This isn't surprising. Summer Glau was a dancer also. You can really see it in the fight scene in Serenity. That kind of background really lends itself to stage fighting.

She did some great interviews in which she referenced it and she also talked about it in "Browncoats Unite", the 10th anniversary film.

 

[trappedslider]

TIL that there is a max height to mountains here on earth


Short answer: In general, the maximum size of a mountain on a planet will be limited by surface gravity. The greater the surface gravity, the smaller the biggest mountain can be. On earth, it works out that Everest is probably pretty close to this limit.

Long answer: As a mountain gets taller, it gets more massive. As it gets more massive, the pressure on the rock at its base increases. Eventually, this pressure would exceed the breaking strength of the rock.

 

[Autumnal]

Yup. That (and plate tectonics) is why Mons Olympus is on Mars, not Earth.

 

[trappedslider]

Yup. That (and plate tectonics) is why Mons Olympus is on Mars, not Earth.

someone on reddit shared some math

That pressure could be written

P = rho g h
where P is the pressure on the base, rho is the density of the rock, g is the surface gravity of the planet, and h is the height of the mountain. If P is the breaking strength of the rock, you'll find a cool relation:

h g = P/rho
Since P/rho is just a constant, this relation tells us that as the surface gravity of the planet in question increases, the maximum size of a mountain it can support decreases.

This also tells us h g must also be a equal to a constant, which lets us relate the maximum height of mountains on planets of similar compositions but with different masses:

h_1 g_1 = h_2 g_2
You can do something really cool with this. If you take Mt Everest to be the tallest mountain that can be supported on earth, and if you know that Mars surface gravity is 2/5th of earth surface gravity, you can actually calculate the height of Olympus Mons, which is the tallest mountain on Mars, if you write

h_everest g_earth / g_mars = h_olympusmons

5/2 h_everest = h_olympusmons

 

[Reynard]

TIL that balloons were common sights over American Civil War battlefields -- used in reconnaissance, targeting artillery and occasionally even dropping bombs -- and the Union even had an Air Corps.

 

[Dannyalcatraz]

TIL that balloons were common sights over American Civil War battlefields -- used in reconnaissance, targeting artillery and occasionally even dropping bombs -- and the Union even had an Air Corps.

Yep.

In fact, a group of Union POWs hijack a balloon in the opening of Jules Verne's 1874 classic, The Mysterious Island.

 

[Aeson]

The post about the balloons made me think of the CSS Hunley, the first submarine to sink an enemy ship in combat.

My TIL from this. That mission was The Hunley's third time out to sea. In its previous two outings it sank killing all on board, including H.L. Hunley himself, the designer. It sank all three times killing the men on board each time. 21 men in total.

H. L. Hunley - Wikipedia H. L. Hunley - Wikipedia

 

[dbolack]

I can't pass the buck to him; I was already in my 40's by then.

I tend to find it a route/route situation. Sometimes it gets the emphasis on the NUKE, and sometimes it is correct.