Mar 182011

Several years ago, I was a juror on a trial in which Goeffrey Loftus was an expert witness for the defense. He testified regarding the fallible nature of eyewitness testimony. If his name sounds familiar, it’s because he’s the ex-husband of noted memory researcher Elizabeth Loftus. In an effort to discredit Loftus the prosecution asked whether Loftus had also investigated the moon illusion, which of course he had. It was an obvious appeal to the lowest common denominator intellectually, as there are always going to be those who have no idea what the moon illusion is, therefore the study of it must be “loony.”

I’ve read a number of essays regarding the moon illusion, some written prosaically and some highly technical. In all the work I’ve read on the subject, I’ve yet to come across what I believe is a rather simple possible explanation, and one whose fundamental principles were understood several hundred years ago!

At this point I need to make an admission. I have failed to do the serious bibliographic work required to get an essay like this taken seriously. I don’t have a degree in psychology or art history so some might dismiss my musings due to lack of credentials. I accept that, yet I’m convinced that my suggestion is at least plausible. Please take this essay for what it is, a suggestion, a preliminary sketch of an idea, not a rigorous argument.

For those not familiar with the moon illusion, it’s the psychological phenomenon whereby a full moon on the horizon seems unusually large; larger than when it’s high in the sky. Astronomers are quick to point out that it’s not an astronomical phenomenon, and defer to psychologists and those specialized in human optical and spatial perception.

For many people “perspective” in art means spatial perspective, i.e. how is three dimensional space depicted? But there is also “aerial perspective” which is (roughly) what effect the atmosphere has on perception of objects at a distance.

Let’s take a look at two paintings from the Renaissance, which will hopefully demonstrate what I’m talking about. The first is Giovanni Bellini’s Pieta’. Obviously the figure of Christ is the focus of the painting, but carefully examine the hillside behind Mary. It doesn’t seem quite “right,” does it? It almost feels composited, as if George Lucas had created it.

Now compare Bellini’s painting to Da Vinci’s Virgin of the Rocks. The rocks in the far distance are far more realistic, and part of the reason why is that Da Vinci’s work was more attentive to aerial perspective than Bellini’s.

When objects are seen at great distances in our atmosphere, they are seen through large masses of air. This tends to do several things. It reduces the contrast of the object as compared with objects at close range, and it reduces detail.

A weird counter-example is how astronauts walking on the moon have reported underestimating the length to big boulders seen at a distance. Da Vinci understood this hundreds of years ago, and astronauts of the 20th century discovered it for themselves: The mass of air between one and a distant object affects one’s spatial perception of the object’s distance.

So how does this factor into the moon illusion? When the moon is at the horizon, several factors are in effect. First off one is looking through a greater mass of air than when the moon is high in the sky. Just like the distant rocks in Da Vinci’s painting, the moon has less detail than when it’s high in the sky. Because the full moon rises not long after the sun sets, the moon also has less contrast against the still-illuminated sky in which it rises.

In my opinion, these two characteristics are sufficient to trigger the brain’s natural perception that the moon is at a great distance. From there our brains naturally adjudge the object to have great absolute size, thus the perception that the moon is larger at the horizon.

In my opinion, the moon illusion is nothing more than a rather unique example of the brain’s natural reaction to aerial perspective.

 Posted by on 03/18/2011 Art, Opinion, Science Comments Off on Thoughts on the Moon Illusion
Feb 072010

For a time, I built and sold lamps for a living. This is a large cubic die that I modified into a finial.

I would thread two 1/4″ fine thread nuts onto a bolt such that they abutted each other, or nearly so. Then I MIG welded the joint together in three spots. Inevitably, the heat of welding would make the threads misalign, so I would run a tap through the newly created coupling nut.

Why use two nuts and not one? Because only one nut would not have enough thread engagement to prevent wobble when the finial was on the harp stud. Two nuts also helped maintain vertical alignment in the die itself.

Then I would drill out a hole in the die big enough for the coupling nut to fit in. I would seal the end of the nut that went into the die with tape to prevent the adhesive from fouling the threads.

The adhesive was a compound of graphite and epoxy. Once the nut was set in place with the adhesive, I would tape the entire face and set the “5” side of the die down. If things worked out right, the adhesive would flow downward and completely fill the gap between the nut and the die, at least at the face, visible in this photo. Sometimes little bubbles would appear, but this was not a big deal, as this face would not be visible when the finial was on the lamp.

 Posted by on 02/07/2010 Art Comments Off on Lamp Finial
Jan 022010

Unconfirmed rumors are circulating that Soundgarden’s reunion tour is going to be sponsored by Leatherman.

 Posted by on 01/02/2010 Art Comments Off on Soundgarden Reunion
Oct 192009

The following is a modification of a post I submitted to my favorite website, Metafilter. I put a bunch of effort into photographing things I had made some time ago, and obviously I had put in a great deal of effort to create the items in the first place. Frankly I haven’t investigated whether or not other people have experimented with firehose for arts and crafts, or functional artifacts. I feel that more can be done with this unique material, but my interests have shifted as of late. But it’s worthwhile to document things, so I thought I would create this page.

When I was in high school, I used a conventional sewing awl to repair a leather belt I owned:

Sewing Awl by you.

This was a scan of an old ad from Popular Mechanics magazine. This tool has been around for a long time.

I stitched the entire perimeter of the belt, as it was composed of two pieces of leather that had been sewn together in the first place. As I recall, the initial stitching had failed, and so this was a repair.

The amount of labor that went into this project was enormous, and made an impression on me. You still see numerous leather items that are composed of two slats of leather that are stitched together, like this folding knife scabbard for a belt:

Traditional Leather Knife Belt Pouch by you.

Notice how the ends of the two belt loop slits terminate in round holes. This helps reduce the chances that the tear will propagate.

Stitching is not the most robust means of attachment, and so myself and others have sought ways around this design weakness. The venerable Leatherman tool scabbard is one superb example:

Leatherman "Supertool" Belt Pouch by you.

It has no stitching at all, and uses only four rivets:

Riveted Leather Leatherman Belt Pouch by you.

Despite the obvious advantage of rivets, only two kinds of rivets are commonly available to the average consumer; “pop” rivets, and “cutler” rivets. Pop rivets leave a large bump on one side, and are unsightly for an aesthetic craft project. Cutler rivets are nicely flat on both sides, yet are available only in thicknesses appropriate for knife handles, as far as I know. The rivets you see on the Leatherman pouch are obviously a proprietary design. Thus one needs to make peace with the venerable sewing awl, as it’s very hard not to need stitching at least somewhere…

Fast forward many years. In about 2003 I decided to modify the standard sewing awl to become a more functional tool. I  flattened and colored one side of the sewing awl to provide visual and tactile cues. When withdrawing the needle from the work, I place my thumb on the wound thimble which enables good control of thread tension. Since the tool is now asymmetrical or “two sided”, I placed the spindle in an “overshot” configuration.

I replaced the flimsy thimble axle with a #10 fine hex-head machine screw. Existing holes were re-tapped for #10 fine threads. A much more robust design, with much less “play” on the thimble:

Modified Sewing Awl by you.

A short section of 3/8″ fuel line formed an effective scabbard for the sharp needle. It fit over the needle chuck nicely:

3/8" Fuel Line Needle Protector by you.

I use 130 pound test Spectra fishing line for “thread”. It must be admitted that the enormous tensile strength of such a product is probably overkill, as the stitching is more likely to fail due to abrasion rather than stress and strain. Yet the relatively large diameter of the line has the counterintuitive advantage of being less likely to cut into the base material. Since Spectra is polyethylene, it can be literally welded, which is a much better way to terminate the line of stitching than with just a knot. But to ensure a proper sewn termination, tie the ends off with a knot, then weld the knot. If you do it right, you can flatten the heated polymer to a more aesthetic “button” shape before it cools and hardens. The spool of line seen here is for me most likely a lifetime supply:

130 Pound Test Spectra Fishing Line by you.

Having worn various tools in belt pouches for a number of years, It occurred to me sometime in the early 2000’s that if one started with a material that was tubular to begin with, that no side stitching would be required. Luckily for me, I was able to obtain sections of used firehose at an industrial supplier here in Seattle. Here is a flashlight belt scabbard that I made out of small diameter firehose. Note the inclusion of enlarged holes at the ends of the belt loop incision:

Firehose Flashlight Belt Pouch Side View by you.

Note that only one end of the scabbard required stitching:

Lock Stitch Sewn Edge of Belt Pouch by you.

Being that firehose is a composite, with rubber on the inside bonded to a synthetic overbraid, the material’s edges can be heat sealed. Ultimately my flashlight scabbard was a mixed success; despite the heat sealing, the main flap began to pucker and fray:

Firehose Flashlight Belt Holster by you.

And one of the belt loop cut-outs began to tear.

Belt Loop Tear Extension by you.

Perhaps the material I chose was too intrinsically flimsy.  I had better luck with a key pouch made out of firehose:

Firehose Key Pouch by you.

I’ve used it for several years now, and am happy with the results. Again, note that only one edge of the pouch needs stitching, due to its tubular morphology. Unlike the flashlight pouch, I forgot to truncate the corners! Nevertheless, I’ve never been poked by the stiff corners, and I haven’t had any pockets wear out because of it. Were I to do it again, I hope I’d remember to include that simple feature:

Firehose Key Pouch Lock Stich by you.

It’s possible to get tubular synthetic firehose overbraid that has no rubber bonded to it:

Circular Braided Firehose Overwrap by you.

Being tubular, the ends of a segment can be everted, then sewn shut. This can provide a particularly aesthetic way to terminate an end.

I obtained a long section of some synthetic tubing in 4cm width. I don’t think it’s firehose overbraid though; I suspect it’s used for overhead crane straps:

Large Roll of 4cm Width Tubular Strap by you.

4cm Synthetic Tubular Strapping Width by you.

This width I found very useful, as I’ve made knife scabbards and belts out of it:

Knife and Scabbard by you.

Tubular Synthetic Strap Knife Scabbard by you.

As an aside, the yellow material on the knife handle is heat shrink tubing, a unique and valuable material in its own right.

Creating the knife scabbard was simple as pie, and being that the closed end experienced no mechanical stress, I didn’t even stitch it closed, I just heat sealed it:

Quick and Easy Heat Seal by you.

The belt buckle I welded myself:

Hand Made Belt Buckle  by you.

The bifurcation you see on the revolute joint is due to it being two steel washers welded to a segment of steel rod. Part of the main body I bent, and part I welded, thus accounting for the differences in the corners. Were I to do it again, I’d probably weld all joints.

Being tubular, the only stitching required on the strapping is what you see just below the buckle. A “tongue” was cut out of the tube, wrapped around the steel buckle, tucked back into the tube, then sewn shut.

The belt buckle holes were formed with a red hot poker (a sharpened machine screw). One could use a needle nosed soldering iron, but that would leave plastic residue on your iron. Over time mechanical stresses will distort the base material, so this is not an ideal, long term solution. But I’ve had this belt buckle for several years now, with no major malfunctions:

Belt Holes Formed With Red Hot Poker by you.

The most recent hole is to the far left, as I’ve lost weight recently. As you can see the middle holes have become distorted over time.

I have a strong intuition that firehose and tubular strapping are useful and robust materials for crafts projects, and I simply haven’t been able to think of further applications for it. Perhaps this webpage will act as a useful starting point for others who can see what I can’t. Good luck!

 Posted by on 10/19/2009 Art Comments Off on Adventures With Firehose
Oct 192009

I invented the duct tape wallet. Or at least I think I may have. Frankly, I haven’t gone to a lot of trouble to try and figure out the historical truth, and I suspect it would be a very hard thing to prove. Here’s the story:

I was one of the founding members of the Jim Rose Sideshow in the early 1990’s. We toured all around the world, and one of the highlight tours for me was Lollapalooza in 1992. It was a huge ego rush, being able to “hang out” with real live rock stars. Even more fundamentally, other performers appreciated what we did, and we got lots of positive feedback from them. But being a performer puts strange kinks into your lifestyle. One is that you have a great deal of “down time” while you are simply waiting around to perform. You can either do meaningful things with this time or you can waste it. Unfortunately on Lollapalooza, we usually performed in “sheds” or large outdoor performance spaces away from the big cities. You couldn’t just walk to a museum for an afternoon’s edification.

One thing to do to pass the time was arts and crafts. I began to notice that the technicians (don’t call them roadies) used a great deal of duct tape, and would often simply discard the roll before they got to the end and leave a significant amount of tape. I also noticed it wasn’t really duct tape, as the fabric was tightly woven into a crosshatched pattern. In fact I learned it was called “gaffer’s tape”, and indeed was a significantly superior product than ordinary duct tape. It was also available in black, and I think yellow. There was a lot of this stuff just lying around, waiting for something useful to be done with it.

I don’t remember what my inspiration was for my wallet. I recall being on the tour bus, and simply began to cut and fold the tape into a wallet. To do it for the first time is sort of a puzzle, as you have no instructions to go by. I was pleased with my new wallet as it came out rather well. I decided to make another one which I think was yellow. I may have shown my first wallet to Matt Cameron, then the drummer of Soundgarden, as I decided to give him my second one. I replaced my old Nylon wallet with my new duct tape version, and have never looked back. From time to time I would have to make a new one as the old one wore out. If I recall correctly, all this happened before all the duct tape books came out, but the one thing I’m sure of is that I figured it out for myself.

Fast forward to 1996. I had become a big Soundgarden fan, and remained friends with Kim Thayil after the tour was over. A Rolling Stone magazine article written by Charles Cross about Soundgarden’s new record Down on the Upside appeared in the Feb 8, 1996 issue. The article opens with an intimate description of how Chris Cornell makes a new duct tape wallet each time he records a new Soundgarden album!

“Chris Cornell cuts black duct tape with surgeonlike precision and pieces it together in the shape of a wallet. Soundgarden’s lead singer makes a new one every time his band records an album. “The last one I made was during this point in the recording of Superunknown”, he says, not bothering to look up from his handiwork. “I always want a new one to last until another album is in the works.” At that, drummer Matt Cameron pulls out his wallet, another duct-tape model crafted by Cornell during the last album. From the back of the recording studio guitarist Kim Thayil complains, “I guess I don’t rate. I had to go out and buy one for 10 bucks”

Looks like Matt Cameron taught Cornell the wallet thing! This got to me enough that I even asked Kim about it, and indeed Kim told Cornell that the idea originally came from me. I suspect, but do not know, that this Rolling Stone article was the real “break” as far as publicity goes for the duct tape wallet. During the late 1990’s I would see duct tape wallets around, and even saw them for sale on the Internet.

The article concludes: “After two hours of work, Cornell finally finishes up his wallet and gets ready to head back to the control room. He’s used a cut-up drum head for the wallet’s plastic sleeve compartment. Cameron razzes him: “You could mass-produce them and sell them at Lollapalooza: ‘the Chris Cornell signature wallet.’ ”
“Yeah, I could make a mint,” says Cornell, shuffling his credit cards from the old model to the new one. “The best part is that if your wallet rips, you can just put another piece of duct tape on it.”

In October of 2002, I believe, I “invented” the polypropylene tape wallet. Polypropylene is even superior to the gaffer tape, as the adhesive is stronger, and there is no “grain” or weave to split along. The tape I’m talking about is the kind used in conjunction with Tyvek vapor barrier house wrap. The Polypropylene film is incredibly strong, especially considering how thin it is. It’s much thinner than duct or gaffer tape. The adhesive is an acrylic, and is very “tacky”. This quality is needed to allow it to stick to Tyvek, which is itself quite slick. Tyvek vapor barrier and the associated tape are made by Du Pont, but Lowe’s Home Center makes a house brand that is comparable. Owens Corning makes a pink polypropylene tape. Thankfully, Owens Corning doesn’t insist on plastering their logo on their tape like Du Pont and Lowe’s do. Plain pink is good. Remember the Pink Panther? Look for the Pink Panther logo when buying your polypropylene vapor barrier tape! Here is a wallet I created using the Lowe’s house brand polypropylene house wrap tape.

This tape can be also be used in conjunction with ordinary Tyvek to make form fitting credit card envelope protectors. Surprisingly enough, the new gel ball point pens are able to create a durable mark on slippery Tyvek.

Now, go forth and make your own wallets and credit card protectors!

 Posted by on 10/19/2009 Art Comments Off on The Duct Tape Wallet