What is the purpose of the hole in some pens?
815268
It allows the ink to flow.  If not, the flowing ink would create a vacuum inside.  It the same principal with can of oil (i know this is going back but oil used to be in cans)  You poke a second hole to allow air to replace the oil so it can flow easier.
787133
First off...it's stenography...It's a method once used by "secretaries" to record what their bosses wanted to say to someone else.  Sort of like  the "boss" would want his secretary to communicate his opinion.  No conspiracy in the markings at all. It was simply a way for the secretary to not have to write it all out longhand.  Simple as that.
375527
good question.. i think the best answer is..\n \n              TO SAVE SPACE!
113374
i found this explanation interesting:\n\n"circular manhole covers have the advantage that you don't have to get the corners lined up when dropping them into place."
1048608
Honestly?  I think it has to do with pens in space... and I swear, it explains a lot.\n\nThe first time astronauts went up into space, they discovered their pens didn't write.  No gravity, nothing to push the ink out of the pen and onto the paper.  The astronauts came back, they reported their pens didn't work, and NASA literally spent fifty million dollars or so to engineer a new type of pen which could operate independent of gravity so no matter how you write on it, if you're writing while the pen is pointing down, while it's pointing up, whatever, the pen still writes smoothly.\n\nThe first time Russia sent cosmonauts up into space, they discovered their pens didn't write.  No gravity, nothing to push the ink out of the pen onto the paper.  The cosmonauts came back, they reported their pens didn't work, and the people assigned to fix the problem walked up and said "here are some pencils, use those next time".\n\nI'm sure that's probably an apocryphal story (though, oddly, we do have a "space pen" which works from any angle and without the need for gravity... and we must have had some reason for designing it and then naming it the "space pen"), but it gives a glaring example of a point which we may not always keep in mind:\n\nA lot of the time, we just don't have a lot of common sense, so the easy, everyday solution often doesn't dawn on us, even as we're reaching for the stars... \n\nAnd are you really surprised?  You are talking about people who, in their genius, never thought "maybe it would be a good idea if the filters one part of the space ship can be swapped with the filters in another part in case they need to be changed".
27282
it's a way to write about whatever you want. some people use it as a sort of public diary (you can even use it just as an electronic private diary if you don't tell anyone about it), some use it to write thematically about something they are interested in (books, their field of study, whatever). And you can become part of groups and read and post to thematic "diaries" (called weblogs or blogs), everything from sex to math....
22056
There's a chamber filled with several pencil leads, along with a little funnel with a hole at the end. What ends up happening is that a lead gets into the hole and falls through (Graphite is a very good lubricant). Whenever you click the eraser, or a button on the side, it hits a spring that pushes the lead forward just a little bit. Another type of mechanical pencil allows you to spin the tip to get more lead out, but that one simply works like a screw.
723279
Hey, are you talking about two "eyes" in the sides of the end of the foley tube that sits inside the bladder? If so, they're there to let the urine drain out more efficiently. If there was just the one big hole in the end of the tube that sits in the bladder, then "low-lying" urine would be too low to make it out of that hole.  That's why there are those two "eye" holes in the sides of the end of the tube.
760755
it is a wind instrument without reeds.the holes control the length of the vibrating column and hence the frequency of the note.it corresponds to the western flute
93941
I have refilled lexmark 27 carts. There are no holes. You have to make them yourself. If you buy a refilled cartridge, you will see where they belong. I finally gave up doing it, too messy and did not last long.
719560
I'm a natural Lefty.\nUse the composition notebooks instead that have the three ring holes added.  They will have a serrated edge so that they may be removed and put into the three ring binder when he is done witting on it.\nThere are also legal type pads that fold OVER that have three ring holes in them and are the same size as loose leaf notebook paper.  They can be torn out and put into the three ring binder as needed.\nThe three ring notebooks are the main reason so many Lefties write SIDEWAYS....with the binder middle hanging over the TOP of the desk so they can write.\nBut that is not needed anymore with the notebooks and writing pads.\nAlso, Lefties learn to TYPE very early on.  Lefties tend to have "interesting" if not rotten penmanship.\n(But don't worry....we ARE smarter <wink>)
907280
Its caused by holding pencils or pens.... many people have them...
506644
1. Its impossible for a circluar shape to fall in. If it was a square, it could have easliy fallen in.\n\n2. Its easier to roll a circular cover to the hole, rather than carry a sqauare cover on a wheelbarrow.\n\n3. Its so easy to fit a circular cover to the hole, whereas a square one will have to be turned to the correct alignment to fit. (Sorry for the 3rd. LOL).
301612
The air flow that is being prevented is not the air flow over the hole you blow across. By holding down the keys or covering the hole passed where you blow to make sound, you are preventing the air from flowing out that way. When you do that you make a tone different holes, different tones. By making tones you play music. Thus you play by preventing the airflow thought selected holes.
157896
There are a few possible answers;\n-Some shells have holes in them because part of the creature's body protruded there; Keyhole limpets, for example.\n-Some shells may have been drilled by a parasite or a predator, for example, whelks have a rasped tongue-like organ called a radula - they use this to bore holes in the shells of other animals in order to devour them.\n-And some shells may simply have eroded naturally so as to have a hole in them.
914989
Well, lets see if we can think of six reasons ...\n\n1) Tap drill size is too small.\n2) No tapping fluid.\n3) Worn tap.\n4) Tap entering hole at an angle.\n5) Inclusions and/or hard spot in metal.\n6) Tap holder not centered over hole.
1083358
Your wife's right. And not right too. \n\n==========\nbackgournd \n\nInkjets work by squirting ink through very very small holes in a print head. Canon and HP and several others do that by heating the ink in a chamber just behind the hole, which 'boils' a small bit of it creating a bubble, increasing the pressure and forcing out a microdrop of ink. Epson has done it a different way, with piezoelectric pulsing of the chamber behind the tiny hole. \n\n==========\npossible failure modes\n\nThe holes are relatively easily clogged, so the fineness and uniformity of the particles in it (dyes and such) are important. So is reasonable behavior when partially dried out (not being used for two weeks during a vacation, say) and when heated or subjected to considerable pressure. Hence the cleaning cycles built into many printers (see your owner's manual for some vague and normally not very intelligible instructions).\n\nInks made by a knock off artist in some backroom counterfeit lab somewhere aren't likely to have uniformly ground particles, nor probably the required witches' brew of chemicals to behave well under stress. On the other hand, some third party ink producer might indeed take sufficient care to get it right for a particular type of printer / cartridge / etc. The problem in practice to how to distinguish amongst them. \n\n========\nexperimental test\n\nSome printers have the 'print head' built into the cartridge. You get a new set of teeny tiny holes with every cartridge. With other printers, the print head is in the printer and the cartridge carries only ink. Obviously, in the latter case, a poorly made ink can be rather more expensive. \n\nI had a long policy of buying only print head type cartridge printers for exactly this reason. And I was willing to experiment with cartridges and ink from apparently trustworthy vendors because important parts of the printer wouldn't be at risk. I cannot suggest the at home refill policy unless you can do it wearing latex gloves over a slop sink. A couple of cubic centimeters of ink can go a very very long way; you don't want to find out, but the refill kit I used did work, and the cartridges could be refilled three times at least. The very cheapest way to feed the ink monster that I discovered. Not counting the ink spilled on just about everytihint that one time... But, with printers costing less than US$100 nowadays, the cost of an experiemnt gone bad is limited, except for the time and trouble of replacing the printer damaged by the bad ink. \n\n=========\nDRM measures\n\nSome printer vendors have attempted to force their users to do the right thing (ie, buy their expensive ink -- fo rtheir own quality printing good, of course) by including in their printer measures which try to detect improper cartridges and punish the user by locking the printer to some lower performance level or some other punishment. I heard of a printer which self-destructed under when it detected fake ink cartridges., but never managed to figure out which one it was. You many find that your printer won't print any better than some draft quality if you use a third party cartridge. \n\n============\nalternatives\n\nWith the street price of laser printers below US$150 for low end black and white, and under US$350 for low end color (shop around, at least in the US and you'll find them), there are lots of reasons to avoid inkjets, and their expensive thirst for those .cartridges. Unless, of course you need photographic quality with special archival inks, in which case you might have to use an inkjet.