One of the virtues of living in a house continuously occupied for 62 years by the same family, headed by survivors of the Depression, is that there's a reasonably good chance that whatever you think you might need already resides somewhere on the property -- if you can just figure out where to look.

I figure that in six months I've saved over $200 on things that, if I lived alone, I would have had to go out and buy, but since I live here, I've managed to find some suitable substitute by rummaging in the garage or in the back of various closets and such.

And the proportion of things for which a suitable substitute is on hand increases exponentially when you not only have a house full of things that might come in handy some day, but the imagination and skills of an engineer with 80+ years experience of tinkering with objects mechanical and electrical who still enjoys his hobby of making things work.

So I mentioned at dinner a couple days ago that I was thinking about getting a detachable screen curtain for the back door. Because of our proximity to the ocean, it cools down nicely in the evenings around here. When I'm in the kitchen after dinner, tidying up or making applesauce or what have you, I like to leave the back door open -- especially if I've heated the kitchen at all, even just by using the stove for a few minutes. We don't have much of a bug problem, so I've been doing it sporadically even without a screen without any trouble. But I'm sufficiently socialized against leaving open doors or windows unguarded from creeping things that I thought a curtain that I could velcro up over the door as needed might be a nice addition.

In response, GrandDad has rigged up an air-motion system, inspired by the one he witnessed at the hospital emergency room entrance.

Some weeks ago, he dismantled his old microwave, which he had kept for years over his daughters' protests because it still worked -- it just had a busted timer, so you had to keep track of the time separately and remember to manually turn it off when your food was finished cooking. "Dad!" my aunts protested, "You have a PACEMAKER! We don't want you living around a faulty microwave!" They finally pestered him into replacing the machine, but convincing him to discard the old one was another matter.

So, as I was saying, he found a little blue plastic fan among the innards of the old microwave -- (of course, every microwave has a fan inside, but most of us probably have never seen what they actually look like). He mounted the fan on a block of wood and attached a standard electrical cord to the mounts for the fan's little motor so he could plug it in.

Last night, he mounted the little fan over the back door of the kitchen pointing down, so that when I open the door and plug it in, it creates a "curtain" of moving air sufficient to discourage any little flying thing from breaching our threshold.

This morning he got up and decided to add a microswitch that would be triggered by the opening of the door, so that whenever the door is opened the fan goes on, and when it is closed the fan goes back off again. He spent part of the morning scavenging the requisite parts from his collection and modifying the copper fitting so that it would be the right size for the doorframe, and is attaching the unit as I type these words.

UPDATE: It works!