It's easy to find out that "a BTU (British Thermal Unit) is the amount of heat that will raise the temperature of one pound of water by 1 degree Fahrenheit." No power on earth, however, not even the experts at the Air-Conditioning & Refrigeration Institute in Arlington, who know just about everything you'd want to know about air conditioning and then some, can easily explain exactly what heating water has to do with making a room cool. Suffice it to say that he who has the most BTUs will be the one to host the party at the end of the softball season.

More than 500,000 pounds of ice, during 58 days, was used to comfort President James Garfield as he lay dying at the White House of an assassin's bullet in the summer of 1881. Unfortunately, even half a million pounds of ice was not enough: The president was finally moved to the Jersey shore.

Before Willis Haviland Carrier, "the father of air conditioning," discovered in 1902 that the key to cooling air mechanically lay in the relationship between temperature and moisture, people had to depend on common sense. The ancient Egyptians, Greeks and Romans used wet mats to cool indoor air: The mats were hung over doorways, and when the wind blew, the evaporation of the water cooled the air. Sort of.

Italian genius Leonardo da Vinci, around 1500, built the first mechanical fan. It was powered by water.

Air conditioning can slow down or speed up the curing of cheese.

What with summer full upon me yet again, I've entertained lately the passing noition that it's high time I got air conditioned, air conditioned in a permanent sort of way as it does not somehow seem anymore wholly respectable to me to own just a fan that, on occassion, oscillates. But for reasons I can't quite name, I'm deep in my soul a little reluctant to have my climate controlled, suspect I was maybe born to swelter, meant to take supper in my underwear, made and manufactured to sleep evermore atop the bedclothes come June or July. I've been so long just oscillated at that the wonders of Freon have come to seem remote and unenchanting.

Time was, however, this was hardly the case. As a child growing up in North Carolina, I was fairly desperate to get refrigerated. For a considerable while in our house we didn't have anything but windows, and whenever a breeze passed through one we consulted each other about it and inquired if wasn't it bracing and wasn't it delightful as we tried to convince each other it was. But I was never myself persuaded as I'd been ruined already for breezes, having had occasion to get soothed and ventilated at the pharmacy up the road. It had a Salem cigarette decal stuck to the doorpane with a polar bear on it and underneath him the words "air-cooled" hanging all over with icicles and suited with frost like truly suited the pharmacy as it felt, most especially coming in from the outside, fairly arctic in there. Cold air poured out from the ceiling vents and circulated up alongside the notions and back around by the bunion pads with inordinate force and velocity, and I'd wade full into the draft and stand there in my short pants on my naked feet and make to be perusing the Chiclets for as long as the cashier would let me just stand and just peruse. Naturally, then, I couldn't get exhilarated by a wispy dose of humid air through a window screen. I'd been air-cooled; I didn't have any use for a breeze.

Presently, I campaigned for a window unit, drew my sister in with me and together we shared with our parents the woeful news of how we sweated nights and tossed on the sheets and hardly ever closed our eyes tight shut like wasn't, we figured, probably healthful for children and left us ill and churlish, which a solitary Fedders could remedy entirely that we shared with our parents the news of as well. My father in particular, however, was not at the time convinced we had need of a window unit and so negotiated us down to another item altogether: an attic fan. We'd always had a hole in the hall ceiling for one but just never had bothered to stick the fan in it like seemed to the bunch of us purely foolish once my father had explained how, in the hypothetical, an attic fan worked. It pulled, he told us, the cool air from up under the eaves into the house and sucked the hot air in the house up into the attic where it discharged presently out the gable vents and got cool under the eaves again. The simplicity of the thing was fairly stunning, and we all came to be a little took with the notion of it and figured we'd get eased and get soothed until we found how an attic fan did not work near so well in the hole in the hall ceiling as it worked in the hypothetical instead.

We came to be improved, though, came to be moderately refrigerated just the summer beyond the attic fan summer when we all got pressed to endure a rainless, windless, thick and sticky spell of weeks that left us feeling like we'd swum everywhere we went. My father even got a little done in himself and so did not speak of fans to us when we told him again of the sweating and the tossing and the general discomfort but seemed instead fairly ripe to get refrigerated on his own, went anyhow one night to the Sears, Roebuck and brought home a sizable Kenmore just up and of a sudden. It had some inordinate heft to it and a plastic wood-grainy front grille and vents that turned and swiveled and a fan knob and thermostat knob and a vague unidentifiable sort of a knob along with, my father told us, appreciable BTUs, tens of thousands of them like struck me somehow as an altogether potent manner of revelation.

Now at the time I was not much acquainted with air conditioning after any technical fashion, had not yet become a student of the mechanism but grew of a sudden moved and inspired with the arrival of our Kenmore and studied the manual and pondered the World Book Encyclopedia and thereby accumulated what seemed to me a formidable body of knowledge. I learned how the Indians evaporated water off grass mats, which struck me as an attic fan sort of thing, and became acquainted with Mr. Willis H. Carrier, the father of modern air conditioning. I got a manner of grip on his "dew-point control" and pieced together how it was the regular air got took in and hauled across refrigerated coils that chilled it and metal fins that dehumidified it and so caused just the newly cooled air to blow back into the room while the water from it dripped into the shrubbery. I could not, however, make terribly much sense of a BTU and did not become truly enlightened until me and my father and our neighbor Buz from next door and his brother-in-law up from Sparta endeavored together to lift our new Kenmore up onto the window sill.

The World Book Encyclopedia suggested that a BTU was a variety of thermal unit. This turned out to be, of course, unmitigated nonsense. For all practical purposes, a BTU is pretty much like a pound only heavier, and consequently a Kenmore with near about 20,000 BTUs to it could not hardly be elevated by just a boy and just his father alone but required a neighbor from next door as well and a brother-in-law up from Sparta even. Tinier air conditioners, the ones the salesmen that never have to lift them anyway call "portable," can probably get toted around by the family with a hand truck and a son home on furlough, but we had a sizable model with four entire people's worth of BTUs to it, and we got it at last settled onto the sill where my father screwed it tight to the sash and went about closing in the gap either side of the thing with plywood somewhat and foam stripping somewhat and most especially duct tape, which, with your window units, is near about as pertinent as electricity.

The lights didn't dim but a little when we turned the thing on, and me and my father and my sister and my mother and Buz from next door along with his brother-in-law up from Sparta all got eased and soothed and refrigerated near about straightaway as we'd packed up tight against the vents so as to have cause right off to inquire and exclaim. Of course, we couldn't cool the whole interior with even four people's worth of BTUs but wrought a change there in the dining room where we'd put the thing and in the living room beyond it and off to the den on the one side and the kitchen on the other. But elsewhere the house was not much affected, though by a deft manipulation of various doors that we swung some of open and swung some of shut we could send a scant channel of cooled air partly down the back hallway and near about into a bedroom, not however into a bedroom altogether. So we were cool when we cooked and cool when we ate and cool when we watched the TV but slept still with sashes lifted like we hadn't maybe gone to the trouble to get any BTUs at all.

Naturally, the solution was plain to me. We needed a whole-house manner of unit. We needed central air so as to be ventilated everywhere inside we went. But the Kenmore didn't seem to want to give out even after the summers had fairly accumulated, so we ran it mostly in the daytime and switched on the attic fan every now and again at night like we probably would have kept at a while longer but for the change of life that August that overcame us, or the change of life that overcame my mother and got inflicted through her on most everybody otherwise. She grew flashy, like was cold flashy somewhat but hot flashy chiefly, and grew a bit peevish with it, and she carried a little battery-powered fan around with her to blow on her heated parts but found shortly how it didn't much cool her most especially at night atop the bed sheet with even the attic fan to compound and augment it. Consequently, the peevishness rose up and took over for a spell, and central air conditioning did not of a sudden seem too exceedingly far out of reach to my father, who found he was himself a little weary of the Kenmore as well.

So even if the inspiration was primarily hormonal, we all got thoroughly air- cooled on account of it. My father had a slab poured out back of the house and bought a Century brand central air unit to set and bolt atop it. It was broad and deep and ponderous to look upon and had to it so inordinately many BTUs as to be altogether and utterly unliftable. We got a new thermostat with it in the hallway and straight off rolled the thing pretty indecently backward until the chill air came billowing out from the ductwork and rendered even the bedrooms bracing and delightful both like we all four of us together agreed they were. And I thought right off how there could not possibly be a thing on this earth better than having out back of your house in August an unliftable Century with extravagant BTUs. I even continued for a while to believe it and slept under a sheet and under a spread and under a quilt too like I'd begun to think I'd never, except at the Ramada Inn, have occasion for.

But presently my enthusiasm waned. Summer just did not seem the same to me without the heat and the still air and the jarflies and the crickets and our neighbor's dog Winnie barking late into the night. I was pleased to be cool but troubled to be sealed up so and guessed after a while I'd just as soon live at the Hudson-Belk store. There seemed shortly to me even a virtue in sweat and discomfort, a manner of fortitude inherent in sleeping with the sash up and longing for the slightest breath of wind. Pretty soon, I felt near about BTUed to death and got of a sudden transformed myself in a change-of-life sort of way but maybe for the hormones and maybe for the peevishness too. I resolved not ever to come to be air-cooled on my own, resolved to evermore be just oscillated at, and except for college, when I got every now and again moderately refrigerated, I've stayed wholly BTU-less and inquire about breezes and have been known even to gush and exclaim on account of a rain shower. Still, though, every year come summer when the air gets heavy and the bugs get thick, I entertain the passing notion that maybe I should choke up a lone window with at least a portable unit, but once the fanhead swings around and blows across me that notion usually goes on and passes. ::

T.R. Pearson is the author of A Short History of a Small Place and Off for the Sweet Hereafter. His third novel, The Last of How It Was, will be published next month by Simon and Schuster.