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in electronics: see electron tubeelectron tube,
device consisting of a sealed enclosure in which electrons flow between electrodes separated either by a vacuum (in a vacuum tube) or by an ionized gas at low pressure (in a gas tube).
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A long, hollow cylinder, or other hollow shape; typically a flexible or thin-walled metal cylinder, as opposed to a pipe.


A narrow channel within the body of an animal or plant.
A long cylindrical body with a hollow center used especially to convey fluid.
A passage in a cave having smooth sides and an elliptical to nearly circular cross section.
The main part of a gun, the cylindrical piece of metal surrounding the bore; tube is frequently used in referring to artillery weapons, and barrel is more frequently used in referring to small arms.


1. A thin-walled pipe.
2.See lamp.


1. Anatomy
b. any hollow cylindrical structure
2. Botany
a. the lower part of a gamopetalous corolla or gamosepalous calyx, below the lobes
b. any other hollow structure in a plant
3. Brit the tube
a. an underground railway system
b. the tunnels through which the railway runs
c. the train itself
d. ™ the London underground railway system
4. Electronics
a. another name for valve
5. Surfing the cylindrical passage formed when a wave breaks and the crest tips forward


A CRT terminal. Never used in the mainstream sense of TV; real hackers don't watch TV, except for Loony Toons, Rocky & Bullwinkle, Trek Classic, the Simpsons, and the occasional cheesy old swashbuckler movie.




(IBM) To send a copy of something to someone else's terminal. "Tube me that note."


(1) (CRunTime) See runtime library.

(2) (Cathode Ray Tube) A vacuum tube used as a display screen in a computer monitor or TV. The viewing end of the tube is coated with phosphors, which emit light when struck by electrons.

In the past, CRT was a popular term for a computer display terminal. Today, "monitor" is the correct term as computer displays have long since migrated from CRTs to LCD panels (see flat panel display). Likewise, TV sets no longer use CRTs (see flat panel TV).

Electrons and Phosphors
The CRT works by heating a cathode which causes electrons to flow. Accelerating and focusing anodes turn the electrons into a fine beam that is directed to the phosphors by magnetic fields that are generated by steering coils. The viewing end of a color CRT tube is coated with red, green and blue phosphor dots, and separate "electron guns" bombard their respective colors a line at a time in a prescribed sequence (see raster scan).

The resulting color displayed on screen is derived by the intensity of the electron beams as they strike the red, green and blue phosphors and cause them to glow at each pixel location. See cathode and vacuum tube.

Back to the 1800s
The first oscilloscope tube was developed in 1897 by German scientist Ferdinand Braun. Using a fluorescent screen and still known as a "Braun tube" in Germany, his "cathode-ray oscilloscope" was used to display the patterns of electronic signals. Although better known for inventing the CRT, Braun shared the Nobel Prize in 1909 with Guglielmo Marconi for wireless telegraphy.

The Braun Tube - 1897
Using a bellows, it took a strong man to evacuate the air from this tube. The successor to Sir William Crookes' vacuum tubes some 20 years earlier, these tubes used unheated "cold" cathodes that required a huge voltage. (Image courtesy of O'Neill's Electronic Museum)

Bulky But Magic in the 1950s
Although clunky by comparison to today's color screens, millions of people were thrilled when they first watched CRT-based monochrome TV. (Image courtesy of Vintage Vibe,

CRT vs. Flat Panel
The CRT gave way to LCD panels in the late 1990s, taking less space, less power and emitting less radiation. This high-quality EIZO LCD monitor was state-of-the-art in 1999. (Image courtesy of EIZO Nanao Technologies Inc.)

CRT Front Projection
The first data and TV projectors used CRTs, and although mostly abandoned, they continue to provide the highest quality. In 2006, this home theater was built by a serious video enthusiast. See front-projection TV. (Images courtesy of Kal of

CRT Rear Projection
Although big and bulky, the Pioneer Elite Pro-107 was perhaps the best CRT-based rear-projection TV ever made. Still working fine after 17 years, this unit was sold for a pittance in 2010. See rear-projection TV.

vacuum tube

An electronic device that controls the flow of electrons in a vacuum. It is used as a switch, amplifier or display screen (CRT). Used as on/off switches, vacuum tubes allowed the first computers to perform digital computations. Although tubes made a comeback in high-end stereo components, they have long since been abandoned for TVs and computer monitors. See vacuum tube types, audiophile, tube amplifier and Vintage Radio Museum.

Early Vacuum Tube
Early vacuum tubes were used to amplify signals for radio and other audio devices. This one was made in 1915. Tubes were not used as switches in calculating machines until 1939. (Image courtesy of AT&T.)

Tubes in the 21st Century
Many audiophiles claim vacuum tubes amplify music better than transistors. These high-end Model One amplifiers (collectively weighing 212 pounds) were designed by legendary audio engineer Mark Levinson.

All Kinds
Vacuum tubes have come in myriad shapes and sizes over the years, and the Vintage Radio and Communications Museum has one of the finest collections. (Images courtesy of Vintage Radio and Communications Museum of Connecticut,
References in classic literature ?
All night through their destructive tubes advanced.
"How to get rid of our excessive carbon dioxide without unduly wasting our oxygen is a delicate and vital question," said Challenger, looking round him after the five iron tubes had been laid side by side against the wall.
Rouby, "Incidence of chest tube malposition in the critically ill: A prospective computed tomography study," Anesthesiology, vol.
If the tube is not labeled or is mislabeled, the specimen is rejected immediately and the nurse is then contacted to re-collect the specimen.
One of the latest tube projects from Evansville, IN-based Berry Plastics is a laminate tube that met the high environmental standards of Burt's Bees.
23 February 2017 - US-based steel tubular manufacturer Zekelman Industries has acquired Alabama, US-based structural steel tube manufacturer American Tube Manufacturing, Inc., the company said.
Correct tube storage and handling practices will reduce scratches and indentations that could lead to potential leaks.
Material and Methods: All patients of tube thoracostomies during Jan 2010 to Dec 2013 were included.
Thanks to an investment in a new UV coating production line, Steel Tube Inc.
Ideally, a gas tube should exit the back of the front sight housing and not touch anything all the way back to where it goes through the delta assembly near the rear of the barrel.
In this study, we aimed to assess the etiologies of proximal nasolacrimal system obstruction and compare the results of conjunctivodacryocystorhinostomy (CDCR) and/or conjunctivorhinostomy (CR) performed by two different tear drainage tubes, thereby assessing the relative advantages and disadvantages of each tear drainage tube, postoperative problems, and solutions thereof.
At the point of extrusion, die temperature, material pressure and, in many cases, air-assist pressure play critical roles in forming the tube profile.