what is escher's reproducible pencil?
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http://en.wikipedia.org/wiki/Pencil\n\nfind the answer in there ...
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Artist: Escher\nPhysician-Mathematician: Roger Penrose. He studied quasi-regular tessellation which were lately found to describe the structure of quasi-crystals, that is the chemical structure of some artificial metallic leagues.\n\nOh, I was forgetting another contemporary one: Raoul Raba. Made famous by the French mathematical organization of Kangourou, for which he created the logo.
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http://lsnhs.leesummit.k12.mo.us/projects/webpages/pencils.html\nwww.enchantedlearning.com/inventors/page/p/pencil.shtml
426121
In Rome, scribes wrote on papyrus (an early form of paper) with a thin metal rod called a stylus, which left a light but readable mark. Other early styluses were made of lead. Today we still call the core of a pencil the "lead" even though it is made from nontoxic graphite.  (Lead is toxic and leaches right through your skin, so it's not a great choice for a writing implement!)\n\nGraphite came into widespread use following the discovery of a large graphite deposit in Borrowdale, England in 1564. Graphite left a darker mark than lead, but was so soft and brittle that it required a holder. At first, sticks of graphite were wrapped in string. Later, the graphite was inserted into wooden sticks that had been hollowed-out by hand! The wood-cased pencil was born.
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Well, there are two kinds.\nOne is for orienteering.  It has a needle that points north.\nThe other is for drawing circles.  It is like an inverted "V".  One end has a point that is the center of the circle and the other end has a pencil attached to draw the circle.
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I have a number one pencil.  I never settle for anything less than number one.  Sorry, for all of you people who have to use some number two pencils.
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Bernard Lassimone, a French mathematician, applied for the first patent (french patent #2444) on pencil sharpeners, in 1828. In 1847, Therry des Estwaux invented the manual pencil sharpener.
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This is off the topic of your questions but may be the answer to your other issue of having a good image editor and other cool, free tools. \n\nhttp://www.usatoday.com/tech/columnist/andrewkantor/2004-03-26-kantor_x.htm\n\nTo answer your question:  \nVector graphics are composed of curves connected by points, mathematically defined. A circle is four curves connected by four points. A rectangle is four curves, connected by four points. (No, that wasn't a typo...they are considered curves even though they're straight lines. No, I don't know why...math and I never really got along all that well.) When you want to make the circle larger or smaller, the mathematical formula is redefined, and the circle keeps it's perfect crisp lines. Creature House Expression, Macromedia Freehand, and CorelDRAW are three examples of vector programs. These programs are considered object oriented because everything you make, even text, is an object that can be manipulated independent of other objects and the background (which can also be an object if you put something there, such as a rectangle covering the page.) You can arrange them so they are in front of each other, in back of each other, stack them, or group them. Vector programs are also sometimes called drawing programs, while programs like Adobe Photoshop and Procreate's Painter are paint, or raster programs. \n\nA raster program constructs what you see on screen by using pixels. When you enlarge the picture, the only way it gets bigger is for the pixels to get bigger too, and you lose the nice edges. So when you work in a raster program your best bet is to make your picture the size at which you'll ultimately be using it, because you will be limited in how much sizing you can actually do. And that is the beauty of working with vectors! You can work on a 4" object and enlarge it to 4' if you want. And it'll look just as good at 4' as it did at 4".
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Most are mass produced with a cost over quality approach. You end up with shoddy materials, poor quality checking at the manufacturing side and a "don't care" mentality.  American consumers purchase pencils based on cost more than quality though so you can't really fault their business model.
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pencil screiber marker
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The ones that are original and not simply a canned design.  I used to collect them, and still have a lot.  Some of the ones I have are drawn by hand.
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Simple:  Graphite is mixed with various amounts of clay in order to create different values of pigment.  \nThe lead "hardness" ranges from HB (super soft and DARK pigment -the higher the # followed by HB, the softer the clay with a higher content of graphite) to high #'s (not followed by an HB).  The higher the # on the opposite side of the scale, the harder the clay with diminishing amounts of graphite.  \n\nA #2 pencil has just the right amount of pigment to be read by scan-tron machines and is easier to erase than darker leads when mistakes are made.
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I http://www.ua.edu/sacs2/cv/esellis.pdf\ngoogled and only this and now I am really curious because there was nothing else! Sounds like something I would want to know about..I'll keep looking
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Generally, Incense-cedar (take a whiff when you sharpen it) For more info, go to www.pencils.com
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Modern pencils are made industrially by mixing finely ground graphite and clay powders, adding water, forming long spaghetti-like strings, and firing them in a kiln. The resulting strings are dipped in oil or molten wax which seeps into the tiny holes of the material, resulting in smoother writing. A juniper or incense-cedar plank with several long parallel grooves is cut to make something called a slat, and the graphite/clay strings are inserted into the grooves. Another grooved plank is glued on top, and the whole thing is then cut into individual pencils, which are then varnished or painted.
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Get this, I have the same thing, one on each hand. And I was unfortunate enough to sit on one in grade school, so I have graphite on my bum.  I have asked the doctor if it is anything to worry about, and he said "no".  As long as the pencil was graphite and not lead there is no problem.  Graphite is not toxic to the human body, so we are in the clear!!
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pencil 'leads' are made of graphite a form of carbon.\n\nIf the pencil is painted it could contain lead in the paint, also traces of lead are possible in the wood.\n\npencil 'lead' itself is primarily Carbon and not lead