Crosby tide mill in Arrowsic

There’s a lot more detail on the technology of a ca. 1900 tide mill on pps 6-7 of the following newsletter: http://arrowsic.org/arrow/arrow9-08.pdf

Tide mills old and new

A convergence of factors has had me thinking about tidal power and the history of Georgetown Island recently.  First, the additional clearing for orchard expansion is opening up a vista almost from the height of land on the eastern peninsula down to the cove (at this time of year at least, when the leaves are off the trees).  Though an unusual sight nowadays, open land was the rule rather than the exception in the 1800s into the early 1900s, as can be seen in the image below, sent to me by Will Ansel of Georgetown Center:

This is a photo of the Trafton Mill ca. 1900; it was located on a rock dam across the smaller west arm at the head of Robinhood Cove.  A couple of posts ago I reported that Will and the students of the Georgetown elementary school are planning to build a demonstration tidal mill at the site of the former Trafton Mill, and though I knew from paddling around the remnants of the dams that these mills existed, the photo brought home to me how significant these structures were, and how recently they were in use and in apparent good repair.

As best I can tell from the photo, (at least some part of the house on the hillside is still intact, belonging to a one Dick Green whose son I went to school with) the mill building was actually located over the cove, extending from the breach upstream = to the south (presumably on wood piers, as rock supports would still be intact), with its long axis oriented with that of the cove.  Of course the next question to a renewable energy engineer is, how much energy could this mill have potentially extracted?

I did a bit of modeling in order to help out Will and the kids, and now I’ve extended it to an estimate of the potential energy available in the impound above the dam.  Will gives the dimensions as 1600′ long, 133′ wide, and 8′ deep.  But I measure it on google maps as 1800 by an average of 320 feet.  So I’ll use these numbers.  Next I need a model of the cross section (since the volume of the cove is not a rectangular prism, but rather tapers significantly as it dries out on the ebb tide).  Based on nothing more than recollection, I generated the model below:

I think if anything this under-estimates the volume of the impound (ie. the slope is initially steeper, and the mudflats are relatively flatter) – keep in mind that the scale is off by about a factor of 10.

I converted to SI units and calculated the potential energy of the water in the impound, in sixteen vertical slices.  The number that results is approximately 1.4GJ, or about 390 kWh – about the energy content of 10 gallons of gas.  Of course, a primitive tide mill probably isn’t going to extract more than about 30% of the potential energy that’s available, on the other hand, 30% is probably a generous estimate for the thermodynamic equivalent of a 10hp gas engine as well.  The amount of energy in the impound could be considered impressive or pathetic, depending on how you think about it.  On the one hand, the Trafton Mill would surely be a million-plus dollar facility if built today (by any but the most crafty scavenging hackers), and accesses an energy stream worth at most $35 per day (assuming 30% conversion, 2 tides a day, 15 cent electricity) – that’s a measly ~1% simple gross annual return on capital.

But in historical context, by the standards of the day, the energy stream corresponds to 289 man-days of human labor per day (assuming 30% conversion, 2 tides a day, 100W useful human effort 8 hours a day).  In a time when the alternative was human or animal labor, a tide mill accessing the equivalent of 300 laborers would be a pretty sweet thing to have.  And I recall from working on old houses around town as a kid, there were quite a lot of boards in them with the coarse linear saw marks characteristic of the sort of gang saw that would likely have been used in such a mill.

Tinkering back America

An episode of On Point on NPR caught my ear the other evening, inspired by a piece in the WSJ about the resurgence of tinkering in the US.  The stories highlighted people using increasingly accessible fabrication technology to design and make tangible stuff, and featured Makerbot, a FDM-based tabletop rapid prototyping machine designed by and marketed to hacker types.  Ashbrook focused on the question of whether this perceived increase in tinkering is basically just a human interest story, or whether the growing ranks of garage tinkerers might hold the key to getting the US economy out of the ditch.

The discussion glossed over some important distinctions which I think ought to be understood, especially relating to the idea that rapid prototyping machines can “make just about anything”, and that with this technology you can design and manufacture whatever you want.  I spent a few years in the MIT lab that invented 3D printing, and I have worked my entire career for companies that manufactured stuff or were attempting to manufacture stuff, so I have some background in this area.  The basic fact is that in most fields of engineeering there is a chasm of difficulty and effort at least two orders of magnitude wide that separates designing and prototyping some device, and developing volume-manufactured goods that can be sold at a profit sufficient to pay back the capital investment and keep the operation afloat.  Three-dimensional printing (and other related SFF techniques) are brilliant for making look-and-feel prototypes and reasonable short-term approximations to molded plastic components, but they are universally too slow, too expensive, and too limited in the palate of workable materials to be competitive for manufacturing.  At the MIT lab, one of the smartest engineers I know struggled for 10 years to find some angle by which 3DP could get beyond Rapid Prototyping applications, and out of the half-dozen startup companies that came out of the lab, the only one that ever attained any kind of escape velocity was Zcorp, the one focused on RP.  The closest 3DP came to manufacturing was the use of a Zcorp machine to print a complex plaster mold, which could in turn be used to pour aluminum castings, theoretically cheaper than the cost of alternative approaches.  This product was on the market at least for a while, and I think it could actually be a viable, but as I understand the effort stalled due to lack of vision on the part of the team attempting to execute it and the sclerotic nature of the casting industry.

The basic theme here is not just that SFF is effectively limited to prototypes and hacking (for which it is admirably suited, and by appearance the Makerbot is a brilliant achievement), nor that displacing established manufacturing technologies is hard to do.  More generally the point is that real product development and manufacturing is genuinely difficult, and not nearly so well suited to dorm-room tinkering.   The reasons are fairly fundamental.  Modern manufacturing has developed in a very competitive environment and benefited greatly from economies of scale; the basic techniques (such as injection molding, metal stamping, etc) are dramatically more cost effective and flexible than SFF, CNC machining, laser cutting, or other prototyping techniques, but they require massive machines costing hundreds of thousands of dollars, and part-specific tooling costing tens of thousands of dollars.

Another basic issue is that many of the hacker types I know have a certain artistic bent, such that the stuff they make, while incredibly impressive and cool, often tends towards the expressive and offbeat, rather than having an end-user product focus.  Take for example the ubiquitous LED lighting projects, or the 10-foot long pair of wooden vice-grips, built for fun by my roommates when we lived in a warehouse in Central Square.  Some might even claim that pedal-powered cidering equipment falls in this category;-)

It could be fairly argued that I’m picking nits here; and I want to emphasize that the physical hacking trend is really awesome, it combines some of the most admirable human traits of creativity, resourcefulness, innovation, and the noble calling of salvaging and repurposing cast-off technology.  It gives people something to do that is active, engaging, and social, much more interesting than drinking beer and watching TV.  If industrial society ever collapses, this kind of ingenuity and hacking (which has been going on continuously under the radar in farm country all along) will become immensely more important.  And I do believe that the cost of doing real manufacturing is coming down and speeds increasing, probably mostly due to overseas competition – witness the rise of rapid low cost injection molding suppliers (where low cost is in the $3-10k range).  But the engineering that interests me most is the development of technology that enables the provisioning of basic human needs (food, shelter, heat, light, transportation, information) in a more energy efficient and environmentally friendly way.  And those areas seem to be the ones where competition, technology, and the economies of scale have been working hardest and longest.  To make a real impact requires scale, scale requires cost-competitiveness, and cost competitiveness requires all the tools that engineering brings to bear – which these days far exceed the capabilities of even the coolest CNC router, Arduino, and 3D printer.

GCS Tide Mill Demonstration Concept

A talented boatbuilder of my acquaintance who lives at the head of Robinhood Cove is working with the kids in the local school to build a demonstration floating tidal mill at the site of the historic Trafton Mill, just a few hundred yards from the school.  The plan involves hobie cat hulls procured for a different (but similarly unique) project by Keith Richtman; that project was postponed indefinitely and the hulls ended up in my parents’ yard, but now they are going to good use.  This is a neat idea and a great educational opportunity, and I’ve attached the concept sketches so that the renewable energy engineers in the audience might provide some input. Will Ansel tide mill docs I did some quick calcs to get them started – just 50W mechanical at full flood – plenty of opportunity for optimization.

Two guys on a tandem

I hope that readers accustomed to the usual apple, ag, and energy-themed material will excuse a bit of indignant ranting social criticism.  The 2009 cider madness was made possible by the generosity of a guy I scarcely knew at the time, a friend of a friend who lent us a tandem bike to power the grinder.  It worked beautifully, grinding apples at an unprecedented rate and adding significantly to the social aspect of the cidering.  What with busy schedules we’re only now arranging to get the tandem back to him.  I hadn’t ever actually ridden a tandem on the road before, and it seemed only proper to make sure it was in good working order before returning it, so Holly and I hatched a plan to take it out to work one day, about a 12 mile ride.

Today was the day, and I am pleased to report that riding a tandem bike is very efficient and a lot of fun.  The dynamics are a bit wobbly getting started, but once under way it smooths out and the inherent efficiency of double the power for the same amount of wind resistance becomes readily apparent, especially to the rider in front – it’s possible to go much faster with the same or less effort as compared to solo biking.  And the social aspect of having a conversation going all the while makes the miles fly by.  All in all a very cool piece of technology, and despite the inherent logistical issues definitely worth considering for serious bike commuting.

Now on to the rant part – what didn’t occur to either of us, but seems to occur to everyone else we talked to, is the assumption that two guys on a tandem bike must necessarily be homosexuals.   It’s not as if anyone was actually rude to us or hecked or anything; this is Massachusetts after all, America’s own Gomorrah, but the guys at the gas station where we met up were clearly having a good time with the concept, and we passed by a young mother with two young children who smiled as if to say “aren’t we so progressive here in Cambridge” and pointed us out to the kids.  Even at the place we work, which is an MIT solar cell startup company no less, not exactly a bastion of redneckedness, folks had the same impression – “I expect to see a guy and a girl on a tandem, or maybe two women who are really close friends.  But two guys on a tandem – that’s gay.”

This brought back distant memories; as it turns out both Holly and I were the sort of kids who got called gay with some regularity back in high school, not because of anything specifically gay that we did, more probably because that’s just what kids at least in rural high schools say to taunt the nerdy kids who are even moderately intelligent, thoughtful, or quirky.  And it’s genuinely easy to laugh about it now, having long since absolved ourselves in the nerd-heaven that is MIT, and having been married to our wives well over a decade between us.  But I find myself shaking my head at the whole concept – isn’t this the 21st century?  What is so gay about two guys on a tandem bicycle?  I mean, football players dress up in skin-tight pants, line up, and bend over for the purpose of passing a hunk of leather between one anothers’ legs, and nobody is calling them gay.  You aren’t even touching the other rider on a tandem bike.  Are most guys so laden with leftover teenage trauma that they wouldn’t ride a tandem with another guy, so as not to risk getting verbally assaulted (or worse)?  It can’t be that full-grown guys are actually that insecure in their sexuality – it must be more of a reflexive thing.  And so what if there were two gay guys on a tandem bike?  This is 2009 in New England, where last I knew all six states allow gay marriage (fingers crossed for my home state of Maine this election night).  How are we ever going to arrive at an enlightened understanding of gender if two guys can’t ride the same tandem bicycle without folks sniggering? It puts me in mind of accounts from the time of Abe Lincoln, when it was apparently common for two (or more) men to share a bed without any implication of sodomy.    So, gentlemen, if guys in 1850 could manage that, surely we can manage tandem bicyclery.

Bike PTO design – work in progress

The hardware design phase of Cider Year Five is only 48 hours or so from complete (or at least, that’s when parts start arriving) and the major remaining design task is to figure out the coupling of a bicycle to the dual-stage hydraulic pump that has been ordered.

The bike PTO that we use for the apple grinder is dirt simple – we remove the chain from the front chainring and ziptie it out of the way, then install a new, longer chain that runs forward and up to a jackshaft with a standard freewheel attached to it.  The front wheel is removed and the front fork attached to a wooden stanchion on the grinder frame, fixing the bike more or less in place but allowing the rear wheel to swing right and left.  This swinging is used to tension the chain, as there is no derailleur in play, and by this means it’s possible to adjust through 2 or 3 gearings before the chain starts scraping too badly on the front fork.

This setup is nice in that it is very quick to engage and disengage the bike, and because the operator gets a nice view of the apple-grinding action.  But it’s already in use for grinding apples, and if we need to build another bike PTO anyway, it might as well be a more universally adaptable design, and one that takes better advantage of the existing bike drive system.  I toyed with ideas that used an actual bike rear wheel, perhaps inflated with cement instead of air to provide a substantial flywheel.  But if we are destined for a higher speed shaft anyway, that’s where the flywheel belongs, and it’s hard to see fitting the freewheel, PTO sprocket(s), AND a standard wheel in between the rear dropouts of an unmodified bike in any case.

Anyway, here are my design requirements:

• Can use most bikes as a power source
• Utilizes existing front and rear derailleurs; allows shifting through the usual range of gearing
• Has a freewheel to decouple pedaling from load
• Enables driving a variety of rotary  loads including hydraulic pump via standard bike chain
• Compact, stable platform, can be set up on any flat surface
• Sets up and breaks down easily
• Incorporates flywheel?

Enough with “consumers” already

I can’t be the only one who is driven nuts by the constant media use of the term “consumers” in place of “people”, “Americans”, or  “citizens”.  As an engineer I tend to pay more attention to matter and energy flows, technologies of transformation, and evolutionary biological tendencies than to the language that frames discussions.  But it is not hard for me to imagine that a people constantly hearing themselves described with language better suited to feeder hogs might eventually suffer creeping slothfulness and lack of imagination.

Sure I consume things; chiefly a couple pounds a day of bread and beans and cheese; a couple dozen MJ of electricity, a few gallons of water, and a couple liters of gasoline, and the last thing I want to do is to downplay the significance of that consumption in terms of ecological impact, but it is hardly how I want to define my relationship to society, not what I want as my epitaph – “Here lies Ben: he was a good consumer”.  I don’t want my primary role in society to be one of dutifully buying whatever schwag my fellow man puts up on offer, the better to prop up the economy and fend off recession.

And so I shout (electronically speaking): CONSUMPTION BE DAMNED! – I am not a cow, not a hog, not an overfed mis-shapen broiler hen, KFC-bound.  I yearn to be a producer, a transformer, a creator, and I want to see my fellow citizens likewise engaged.  I seek to produce the basic substance of life – when it is complete in full production the orchard should produce around 20,000 pounds of apples per year, enough to feed 3-4 people.  If carefully managed the surrounding woodlands will sustainably produce several thousand board feet per year of high quality saw timber, suitable for building and repairing houses, boats, furniture, and barrels (for the cider).  The world is in desperate need of clean, renewable energy, generated in quantity proportional to the need, and for many years it has been the goal of my professional efforts to develop technologies capable of producing this energy, as economically as possible and at a meaningful scale.  On an individual level, the same compulsion leads to projects like the pedal-electric bike, which saves 130 MJ of gasoline a day and uses a mere 2-3MJ of electricity while delivering much-needed exercise.

This visceral desire to produce likewise explains why I find myself compelled to spend a hundred dollars worth of time making fifteen dollars worth of bread, and why I have an irrational urge to grow the grain for that bread myself. And it transcends the practical.  Nowadays the internets are happy to deliver for free a nonstop stream of high quality professionally-made music, any flavor I choose and without the din of commercials.  I will never produce music of that quality, but nonetheless there I go almost every night, sawing away on the fiddle, trying to create some of my own.  And I want you to do it too; I want to sit with my friends in the shade of an apple tree and play music, eat the bread we baked, and drink the cider we brewed.  I want these things even if they don’t increase the GDP or reduce unemployment, even if it means I’m a lousy consumer.

Mulch under the fence, berry patch

Alexis was on call this weekend so I headed down east.  After spending a good part of Saturday visiting with an old friend, Sunday was given over to orchard work.  I had wanted to mow the orchard and mulch around the trees with chips, but the wet summer and recent 3 inches of rain rendered regions of it downright soggy.  The rain had also had a stimulative effect on the grass growing under the electric fence, so I went around the inside and outside of the electric fence with a string trimmer, and concluded that the plastic netting that serves as backup to the electric  wasn’t going to survive very long with grass and weeds growing in and getting beaten back repeatedly.  So I got a big 2-wheeled wheelbarrow (ground way too soft for machinery after all the rain) and schlepped the wood chips we produced earlier in the summer, spreading them in a thick layer under the fence line.  Summer’s rank growth has demonstrated that the small amount of chips we put under the fence this spring were about 10% of the necessary quantity.  My folks showed up to lend a hand, and we got about half of the perimeter fence done.  By then it was lunch time, and I had had about enough of grunting the wheelbarrow over rough ground.  After lunch I spent a couple hours clearing in the new berry patch out behind the cabin, where the hazlenut bushes seem to be taking quite well to their new home.

As I prepared to head back to Boston, I noticed the front page of one section of the Portland Sunday paper, where the two stories were about the rise of electric bicycles in China and a new effort to produce locally-made wood pellets for Maine.  At least for a brief moment I had the sense that the world might actually be changing.

Electric hybrid bicycle prototype operational

For the last couple of weeks I’ve been working on an electric hybrid bike.  The motivation is that my place of employment is about 12 miles from home, and while I should be man enough to bike it both ways every day, the reality is that I usually drive.  It’s about 30 mins to drive, and 50 mins to bike, and I figured if I could reclaim some of the 40 min/day difference, I would be more likely to bike it more often.  I researched electric bike conversions, but they seem to be really heavy – one kit with a Crystalyte wheel motor tipped the scales at 50 pounds, not including the bike, for 360 Wh of lead acid storage.  I figured since I was willing to pedal, I didn’t need 700W of power, and I’d really like to end up with something I could still carry, so I designed and built my own.  Here’s an image from partway through assembly:

core drivetrain components of 300W power bicycle assist system

I found a 300W 24V brushless motor with an integrated controller online, along with a freewheel and a couple of sprockets.  I got two gel lead acid 10Ah 12V bricks from digikey, and hacked up a spring-loaded potentiometer to drive the input.  The bike is a nice simple Miyata road bike that I bought from Adam for $100.  The drive is entirely in parallel; the right side human power drivetrain is unchanged, and the trickiest part of the whole thing was to arrange the left side electric drive.  I bought a flip-flop hub at Wheelworks in Somerville, which has short 1.375″ right hand threads on both sides.  Though the thread is short it accepted a standard 7 speed freewheel no problem, but on the left hand side there was nothing to keep the freewheel (which also has a standard right hand thread) from spinning off under load.  There’s a smaller left hand thread on the right side of the flipflop hub, but it was too close in diameter to the larger freewheel thread to get a jam nut on there, since the freewheel was thicker than the two threads put together.  So I ended up threading another ring into the deep internal thread on the freewheel, and jamming it against the body of the hub.  With high strength loctite I am hopeful that it will continue to hold up.  The large sprocket on the wheel is driven by a 25 pitch chain from the motor, which I mounted to a plate fixed within the main triangle of the frame by brackets to the water bottle braze-ons.  With a few hours of hacking in the machine shop over the last few days I fitted all the pieces together and arrived at a working prototype.

This afternoon I put it to test, and I am happy to report that it performs quite satisfactorily.  I hooked up the batteries, kicked off, and engaged the electric drive, and was pleased to find that despite the high gear (only about 8:1 reduction) it accelerates reasonably smartly on pure electric, and fantastically with combined electric and pedal effort.  The top speed I achieved with moderate pedal assist was was about 30mph, but I was hampered somewhat by stoplights, traffic, and a sense of self-preservation.  If I had the throttle in a position that permitted more comfortable cycling stance I could have put more muscle into it and found the real top end, but 30mph is more than sufficient for everyday use.  I took a test ride over to Holly and Becky’s house in Somerville, and was pleased to find that I could rip up the Summer Street hill in top gear, again with only moderate effort on the pedals.  The entire rig weighs in at 47 pounds.

While the prototype works well enough to convince me of the validity of the concept, there are still some things that need attending to before making it a regular commuting setup.   The two main issues are the battery attachment system (consisting of aluminum angle, hot glue, and zip ties) which needs a complete rework, and the electric drive chain tends to slap against the chainstay and could use a spring-loaded tensioner.  I need to put the throttle in a better place, and I have a feeling I’m going to wish I had those fancy built-into-the-brake-levers type shifters for maximum efficiency in accelerating.  Also, it would be good to put a fuse in the battery circuit.

“A bad day up here is better than a good day in the city…”

The title quote comes from a fellow I got to know at MIT, name of Toby.  He used to teach a hands-on blacksmithing course in the basement for the Materials Science department.  A few days ago I had occasion to drive up into north central Vermont to pick up a piece of optical equipment for work, and my route took me right past South Randolph, where Toby and his wife Elizabeth have set up a homestead.  I had heard third-hand that they had a pretty remarkable off-grid place up there, and had intended to visit all the time we lived in Lebanon but never got around to it.

When I was a kid growing up in the woods with no telephone, there was no way to set visits up on short notice, so it was common practice for friends to just appear unexpectedly in the dooryard.  So that’s what I did – I dropped in on them unannounced at lunch time with a bottle of cider.   From the intersection (not really even a village) of South Randolph I stopped where a quirky fellow was doing some repairs on an old farmhouse (using hand tools and an antique hand-cranked drill press) and asked for directions.  Up a winding dirt track between rolling pastures I found their remarkable homestead.  I had heard that they had spent two winters living in a tent, and had finally built a cabin.  What I found was a tiny timberframe building, perhaps 12×16 feet plus an extra bent on one end to form an open porch.    On the right just inside the door was a bed, then a small heating woodstove.  In the far corner there was a kitchen consisting of a small bench with a sink and an old cast iron wood cookstove.  In the middle there was a table for eating on, and the left side seemed to be given over to storage of various items.  The walls were a single layer of pine planks, and the floor was gravel or rough planks, I can’t remember which.  Lighting was by oil lamps and beeswax candles, which they had apparently just finished dipping.    Water was provided by a hand pump from a deep well that protruded up from the ground at the side of the kitchen, and there was a privy in the woods.

The entire place was furnished in a most agreeable rustic style, dominated by well worn wood, iron, and natural fibers.  A hand-cranked coffee grinder dominated the far wall.  They invited me to join them for lunch, which was excellent and consisted of good bread, various artisan cheeses, a salad of mixed greens including some from their garden, and sparkling cider.  This meal did not seem out of the ordinary for them and they had no notice that I was coming; in conversation it became apparent that despite the outward appearance of privation they were accustomed to eating very well.

The larger setting was 50 hillside acres, with pasture below and woodlot above, vegetable gardens, two workhorses, several head of cattle, and a small herd of sheep.  Despite the distinct rustic feel the homestead was not allergic to technology; they had a bulldozer which had been used to make the roads and the building sites, a battered pickup, and a small WoodMizer band mill for sawing out timber for a more substantial residence planned for the future.  There was apparently even a telephone, though it was half a mile down the hill in an old pre-existing barn on the edge of the property.  This was not a hairshirt existence; they didn’t seem to be preparing for an apocalypse and growing the majority of their food, nor did they seem in a hurry to do so.  Clearly a lot of work had been done on the place, but surely in three years more could have been done, had they been hell-bent on working, but this didn’t seem to be the goal.  They seemed truly to be living what they felt to be the good life.

Something about Toby and Elizabeth’s homestead struck a strong resonance with my memory.  Here was a homestead very much like the way I grew up, not implemented haphazardly by 25 year old hippies freshly moved east from teaching mountaineering, but rather by two professionals who had been living in the city for years and working in the heart of a modern university until they suddenly pulled the ripcord.  Here was a carefully-crafted simplicity executed more out of intentionality and style than governed by economic austerity as in the case of my own childhood.   If Toby and Elizabeth can transition from Cambridge to a hill farm, intentionally and consciously paring away so much of  modern life, subjecting themselves to all manner of physical hardships in exchange for the pleasures of a carefully crafted rustic rural life, then surely all kinds of other arrangements are workable as well.  I’m reminded of a guy named Snowberg who worked as an engineer at Southwest Windpower, all the while living in a cabin tent secreted away against all regulation  in the national forest that surrounds Flagstaff.  He did this through every season for years, showering at a gym, cooking at work, and saving his money, then embarking on a years-long kayak tour of the world.  How much cooler is that than the much more common story of professionals who make piles of money and manage always to spend a little more than they earn, living in constant fear of disruptions and feeling like they don’t have any options?

Visiting the homestead filled me with joy, not because I want to emulate what they are doing (I’m pretty happy to have electricity and the internet, and my ideal setup would involve a machine shop rather than a sawmill), but rather for the reminder that many different kinds of life are possible, and that positive changes can be made quickly and boldly, with creativity and intentionality.  Some aspects of modernity that on the face of it appear no-brainers are not so obvious on consideration.  It seems pretty sensible to hook up a small electric motor to the apple crusher, but then you have no need to throw a party and  invite all your friends to lend a hand.    Life is the most important engineering project most of us will ever execute; it seems a shame never to tinker with the factory settings.