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John Stephens Wood

From Wikipedia, the free encyclopedia

John Stephens Wood
Member of the U.S. House of Representatives
from Georgia's 9th district
In office
January 3, 1945 – January 3, 1953
Preceded byB. Frank Whelchel
Succeeded byPhillip M. Landrum
In office
March 4, 1931 – January 3, 1935
Preceded byThomas Montgomery Bell
Succeeded byB. Frank Whelchel
Member of the Georgia House of Representatives
In office
Personal details
Born(1885-02-08)February 8, 1885
Cherokee County, Georgia
DiedSeptember 12, 1968(1968-09-12) (aged 83)
Marietta, Georgia
Political partyDemocratic Party
Alma materMercer University

John Stephens Wood (February 8, 1885 – September 12, 1968) was an American attorney and politician from the state of Georgia, USA. He served as a Democrat in the United States House of Representatives, 1931–1935 and 1945–1953.

YouTube Encyclopedic

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  • ✪ The Most Amazing Thing About Trees
  • ✪ David Stephens, Auguries of Idolatry


Sometimes the simplest questions have the most amazing answers. Like how can trees be so tall? It's a question that doesn't even seem like it needs an answer. Trees just are tall. Some of them are over 100 meters. Why should there be a height limit? I'll tell you why. Tress need to transport water from their roots up into their topmost branches in order to survive. And that is no trivial task. There is a limit to the height that water can be sucked up a tube - it's 10 meters. If you suck on a long vertical straw, the water will go no higher than 10 meters. At this point there will be a perfect vacuum at the top of the straw and the water will start to boil spontaneously. For a tree to raise water 100 meters, it would have to create a pressure difference of 10 atmospheres. How would trees do that? When I posed this conundrum, a lot of people said the answer is transpiration. And that's when water evaporates from the leaf, pulling up the water molecules behind it. Now that's clearly a mechanism a tree can use to create suction, but it doesn't help us overcome this 10 meter limit. The lowest the pressure can go is a pure vacuum, which I imagine is not happening inside of tree leaves, right? Right, Hank. So you might suspect that a tree does not contain continuous straw-like tubes The tree effectively has valves in it. So you don't have a column of water This big tube that you're saying needs to be full of water is actually made up of cells. Although these are good speculations, they don't turn out to be correct. Scientists who study trees find that the xylem tubes that transport water do contain a continuous water column. So how else could the tree transport water from the roots to the leaves? They don't suck, they don't use a vacuum. OK, so how do they do it? Squeezing like a cow udder all the way up. They have little tree muscles in there. Yeah. Besides being a giant waste of energy, all of the cells that make up the xylem tubes are all dead. What about osmotic pressure? If there is more solute in the roots than in the surrounding soil, water would be pushed up the tree. But some trees live in mangroves, where the water is so salty that osmotic pressure actually acts in the other direction so the tree needs additional pressure to suck water into the tree. Then it must be capillary action. The thinner the tube, the higher the water can climb. But the tubes in a tree are too wide - at 20-200 micrometers in diameter, water should rise less than a meter. So how do trees do it? Well one of the assumptions we made is wrong: The lowest the pressure can go is a pure vacuum pure vacuum pure vacuum In a gas, this is true. When you eliminate all of the gas molecules, the pressure is zero and you have a perfect vacuum. But in a liquid, you can go lower than 0 pressure and actually get negative pressures. In a solid, we would think of this as tension. This means that the molecules are pulling on each other and their surroundings. As the water evaporates from the pores of the cell wall, they create immense negative pressures of -15 atmospheres in an average tree. Think about the air-water interface at the pore. There is one atmosphere of pressure pushing in and negative 15 atmospheres of suction on the other side. So why doesn't the meniscus break? Because the pores are tiny, only 2-5 nanometres in diameter. At this scale, water's high surface tension ensures the air-water boundary can withstand huge pressures without caving. As you move down the tree, the pressure increases, up to atmospheric at the roots. So you can have a large pressure difference between the top and bottom of the tree because the pressure at the top is so negative. But hang on, if the pressure near the top is negative 15 atmospheres, shouldn't the water be boiling? Yes. Yes it should. But changing phase from liquid to gas requires activation energy. And that can come in the form of a nucleation site like a tiny air bubble. That's why it's so important that the xylem tubes contain no air bubbles, and they can do this because unlike a straw, they have been water-filled from the start. This way, water remains in the metastable liquid state when it really should be boiling. It's just like supercooled water remains liquid when it really should be ice. So you could say that the water in a tree is supersucked because it remains liquid at such negative pressures. And why are trees moving all this water up the tree? I want you to make a guess, say it out loud. For photosynthesis? Actually, no. Less than 1% of the water is used in photosynthetic reactions. Any other ideas? Ok what about growth? Well 5% of the water is used to make new cells. Well, so then what happens to the other 95% of the water? It just evaporates. For each molecule of carbon dioxide a tree takes in, it loses hundreds of water molecules of water. Woah. Can you believe how amazing this is? Trees create huge negative pressures of 10's of atmospheres, by evaporating water through nanoscale pores, sucking water up 100m, in a state where it should be boiling but can't because of the perfect xylem tubes contain no air bubbles, just so that most of it can evaporate in the process of absorbing a couple molecules of carbon dioxide. I will never look at a tree the same way again. I'd like to say a huge thank you to Hank, Henry and Professor Poliakoff for making on camera hypotheses. This is an essential part of the scientific process even if your hypothesis turns out to be wrong. As Einstein said, "a person who has never made a mistake has never tried anything new." I've always wondered what it would be like to be on this side of a Veritasium video. Now I'd be surprised if you weren't already subscribed to these guys, but if you're not, go click on these annotations and check out their channels. You may just learn something. I'd also like to thank Professor John Sperry from the University of Utah. He walked me through all of this in an hour-long Skype conversation so I'm going to put a link to his website in the description. We're looking at pressures here below atmospheric, is that right? That's right. Below atmospheric. This is liquid pressure not gas pressure. So it's a common misconception that oh, you can't have you know negative pressures because there's no molecules left. You know, the definition of pure vacuum is zero molecules. That's for a gas, ok. So just to be clear... I think this was one of my big problems in understanding this. This video would have been impossible without CGP Grey. When I told him in London about this idea in London... And I felt like 'pssshhh mind just blown with this whole thing' He said it was going to be really hard to explain and when he says it's hard to explain you know things are going to be tough. So thank you for all your input to this script. And thank you for watching. Making this video has been a real odyssey for me so thank you for joining me on this journey. I really appreciate all of your comments and if you haven't subscribed to the channel already you can click the annotation or click the link above and join me on my next scientific adventure. I made a video promising to make a video about the answer to this. I proposed the problem like a couple months ago, and I was like "subscribe to the channel and I'll give you the answer next week." Hahaha Oh, the lies. Drive it at the right frequency. Oh Yes!! Success is frightening.


Early life, education and career

Wood was born on a farm near Ball Ground, Cherokee County, Georgia, February 8, 1885. He attended the public schools and graduated from North Georgia Agricultural College in Dahlonega. He earned his law degree from Mercer University in Macon in 1910. He was admitted to the bar the same year and commenced the practice of law in Jasper County, Georgia.


In 1915, Wood turned up at the scene of the lynching of Leo Frank, Jewish factory owner in Atlanta, with Judge Newt Morris on the morning after the murder. He drove the vehicle in which Frank's body was conveyed to the undertaker. Whether he had any prior knowledge of or involvement with the lynching is open to dispute, as he and Morris may have been simply trying to ensure Frank's body had a decent burial.[1][2][3]

Entering politics, Wood was a member of the Georgia House of Representatives in 1917; served as Solicitor General of the Blue Ridge Judicial Circuit, 1921–1925. He was elected as a Superior Court Judge, Blue Ridge Judicial Circuit, 1925–1931.

In 1931, Wood was elected as a Democrat from Georgia's 9th congressional district to the 72nd United States Congress and was reelected to the 73rd Congress (March 4, 1931 – January 3, 1935). He was unsuccessful in seeking renomination in 1934 and resumed the practice of law.

Ten years later, in 1944, Wood was elected to the 79th United States Congress serving until the 82nd Congress (January 3, 1945 – January 3, 1953). As chairman of the House Un-American Activities Committee, he had a prominent role in investigating the American Communist Party and the entertainment industry; the committee charged 10 persons with contempt of Congress for refusing to testify, and their careers and reputations were severely damaged in what was called the Hollywood Blacklist.

Wood was criticized for failing to investigate the Ku Klux Klan in the same period, as it was expanding in chapters in opposition to civil rights activism by African-Americans.

Later years

Wood did not seek reelection in 1952 and he resumed the practice of law in Canton, Georgia. Finally, failing health forced his retirement. Wood died in Marietta, Georgia, September 12, 1968, and was interred in Arlington Cemetery, Sandy Springs, Georgia.

U.S. House of Representatives
Preceded by
Thomas Montgomery Bell
Member of the U.S. House of Representatives
from Georgia's 9th congressional district

March 4, 1931 – January 3, 1935
Succeeded by
B. Frank Whelchel
Preceded by
B. Frank Whelchel
Member of the U.S. House of Representatives
from Georgia's 9th congressional district

January 3, 1945 – January 3, 1953
Succeeded by
Phillip M. Landrum

See also


  1. ^ New York Times, 18 August 1915
  2. ^ Steve Oney, And the Dead Shall Rise, pp. 564, 621
  3. ^ Harry Golden, A Little Girl is Dead pp. 294-295
This page was last edited on 13 April 2019, at 21:21
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