Slide rules, calculators and the new iPhone. I'm thinking about these things right now.

It all started because I needed to buy a new scrubber sponge. I'd grabbed the first sponge at hand the other day when more than a few areas of the bathroom needed some attention.

And then I tossed that sponge back into the kitchen sink. Last night, I stood there merrily scrubbing plates when I realized, damn, this is the same sponge that last night had biblical knowledge of the toilet rim.

The fascinating website Hidden Dangers Revealed has this to say about kitchen sponges and dishrags:

Some sponges have enough bacteria to cause serious gastro-intestinal distress. A bacteria filled dishrag used to dry dishes could actually be transmitting a host of bacteria to the dry dishes, which could make you sick the next time you use them.

Holy moly, huh? I can't begin to imagine what they'd say about using a toilet sponge to scrub pizza off your plates.

So, I set out this afternoon to buy a new sponge. First stop: The Ace Hardware store near Milwaukee and Lawrence avenues about two blocks from Chez ChicagoScope. To my chagrin, the store is closed -- and, apparently, has been for several months. I guess I never managed to figure this out because displays remain in the front windows and the place is still filled with inventory.

A major clue should have been the signs in the windows offering "space for lease," but I assumed that, like the Foot Locker situation that I'll get to in just a moment, that there was unused square footage that an independent locksmith or such might use.

Well, duh.

This building used to house the Jefferson Park Woolworth's, and ever since it shut down about 10 years ago, the space has been cursed. First, the space became a Foot Locker store, probably because Foot Locker is the surviving Woolworth vestige. Trouble is, the store always looked pathetic because they only utilized about a third of the available space. As a result, it gave the impression of a desperate retailer on its last legs, which isn't the case with Foot Locker at all, as the the operation is quite successful in other locations.

Then, a couple of years ago, Foot Locker pulled out and Ace Hardware moved in. I had high hopes when this happened, since I hoped that it signaled a revitalization of the entire Jefferson Park commercial district. But that didn't happen.

So, I walked up the street a block and bought the sponge at the CVS drugstore. By the way, there are two CVS drugstores within two blocks of my place. I can't imagine how this makes any market sense, but CVS has always done things that I can't comprehend. Not the least of these is the sucky design of their checkout stations.

Instead of designing their stores with separate checkout lanes, CVS puts all of their clerks behind one central counter at the front of the store. This might be OK if customers were steered into queues like at airline checkins or banks, but CVS actively discourages this by placing impulse-purchase merchandise at the checkout area -- including most candy. This only encourages jerks to jump ahead in line.

I've complained about this to several CVS managers and they confirm that the stores' checkout procedure is customers' No. 1 beef and they can't do anything about it.

But back to the sponge saga. To get to the housewares aisle at CVS, I had to walk past office supplies, and I paused to look at a display of electronic calculators. Most were made by Casio, and even the most expensive scientific model cost less than $20. This was sure a change from when I was in high school. In those distant times, you still wielded a slide rule unless you were one of the few kids whose family was wealthy enough to pop for one of the new electronic calculators -- which cost several hundred dollars at the time.

I had a pretty good slide rule, though. Dad drove me over to the University of Colorado at Denver's bookstore, where he bought me a circular slide rule. I was disappointed because it didn't look much like a "real" slide rule. My definition of a real slide rule, of course, was one of those higher-end Pickett models resplendent in bright yellow lacquer.

But the circular slide rule did have a major advantage: It didn't get knocked out of alignment if dropped, a big consideration during tests in math-heavy PSSC Physics. (This was the only class in which I ever earned an "F" -- but that's another story.)

I used my little circular slide rule for 20 years almost daily in my job. I didn't calculate engineering projects or check calculus results or anything like that. I simply used it to specify enlargement or reduction percentages for photos and graphics at newspapers.

Today, I perform such calculations within Photoshop or InDesign, or on the iPhone's nifty calculator. But I still have that circular slide rule tucked away in a closet somewhere around here. I wonder if I still know to use it.

I also wonder whether I managed to smear feces onto the plates used for last night's dinner -- and whether I'm going come down with food poisoning. I'll keep you posted.

Learn more about slide rules:

Eric's Slide Rule Site

The Oughtred Society

Vintage Instruments: Slide Rules and More

ChicagoScope feedback line: 312-683-5272. Send e-mail to ChicagoScope@gmail.com.