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I love to use the slide rule, personally, but I get why most people have moved on to electronic calculators. ...except in one place: the kitchen. So much of ki
by kqr 4y ago
I love to use the slide rule, personally, but I get why most people have moved on to electronic calculators.
...except in one place: the kitchen. So much of kitchen work is about scaling proportions up and down. With a slide rule, this is literal child's play -- I have taught children to do it for me. You just set it once based on the key ingredient ratio and then you can immediately read off all other amounts without touching it again.
It is much easier than with any other calculation device -- as evidenced by the number of recipes I find where people hand-scrawl equivalent proportions onto them. They do that because they don't have a convenient way to scale up and down on the fly, so it's easier to make the huge effort (with an electronic calculator) once and then cache the result. (Only to have to do it again when you want to scale by a different amount.)
I honestly don't understand why a simple C/D scale slide rule with conversions on the back is standard kitchen equipment.
- thunderbong 4y agoThat's very interesting. Can you elaborate?
- kqr 4y agoRecipe is based on e.g. 5 eggs, but I want a smaller output so I want to use only 3 eggs[1]. I set the slide rule so that 3 is lined up under 5. Then for any other ingredient in the recipe, say 7 tablespoons of milk, I look up 7 on the upper scale and read off 4.2 on the lower scale. It doesn't matter which scale is upper or lower, and you don't have to keep track of whether you're multiplying or dividing, you just pick one to mean "recipe amount" and one to mean "actual amount". You anchor them against each other based on the critical ingredient, and then read off all other amounts. That's part of what makes it so easy to use even for children. [1]: Or maybe I'm cooking to use up an ingredient about to expire, so I want to use all of my seven eggs, and so on.
- pjscott 4y agoOh, that actually sounds really convenient. Next time I'm scaling a recipe by a factor other than 2, I'll get out the slide rule and enjoy the incredulous looks from everybody nearby. I can hardly wait!
- xattt 4y agoI can imagine that the way most people tend to cook, that getting food into the grooves of the slide rule are a major issue.
- bregma 4y agoIt's no worse than getting food into the cracks on the phone screen, and easier to clean. We will not even discuss problems with USB-C in the kitchen.
- argiopetech 4y agoMost Pickett rules (once popular with secondary schools and still in abundance) are aluminum. Remove the slide, wash under warm water, lube with the nearest oil or fat, reassemble. Takes under a minute. Usually I'd use Vaseline or a silicone lubricant, but expedient lubricants are fine if you'll wash it frequently and aren't trying to make multiple slide moves per minute. The cursor requires a screwdriver if you really gunk it up (I'd be surprised), but it's still pretty easy. You don't need the cursor if you're just using the rule as a single-proportion lookup table, so you could take it off and put it away if it's a problem.
- xattt 4y agoMy only experience with a slide rule is a Hughes-Owens Versatrig, which is made from some bamboo-like material. Knowing that metal slide rules were widely used makes me think that IKEA might come up with this “revolutionary” kitchen gadget in the next decade or two.
- ilyt 4y agoI wish recipe sites just did that; enter a base for some product, get the rest based off percentages, rounded up to unit ingredients as best as possible
- mongol 4y agoPersonally, I have used HP48 matrix division / multiplication for this.
- ghaff 4y agoThere used to be all sorts of cardboard "slide rules" that basically used slide rule-like principles to do calculations specific to some particular industry or function. I saw a bunch of them when I was in the oil business. Kitchen can be a little harder with Imperial because you're often switching between units like fractions of cups to tablespoons etc. Must say I've never thought of using a slide rule of which I have a number--and I do usually use grams for weight.
- cscheid 4y ago> There used to be all sorts of cardboard "slide rules" that basically used slide rule-like principles to do calculations specific to some particular industry or function Those are nomograms, and agreed - they're really freaking cool: https://en.wikipedia.org/wiki/Nomogram https://en.wikipedia.org/wiki/Nomogram
- fsckboy 4y ago>Those are nomograms, and agreed - they're really freaking cool: https://en.wikipedia.org/wiki/Nomogram https://en.wikipedia.org/wiki/Nomogram I'm going to start making these to help Europeans convert back to Imperial measures: no mo grams(tm)!
- nyrath 4y agoTechnically, the ones with slides are called "perrygrafs" or "slide charts". https://sphere.bc.ca/test/perrygraf.html https://sphere.bc.ca/test/perrygraf.html Nomograms have no moving slides, they are static printed scales read with an angled straight edge.
- nikanj 4y agoI think the most convenient way is the metric system. You had 1.5 desiliters of milk and 4 desiliters of sugar, but want to a half batch instead? Must be 0.75dl and 2 dl then
- Gordonjcp 4y agoMetric or imperial doesn't really make a difference here. Say the recipe is for five things and you want to make twelve. You've got the same scaling problem no matter how you measure. You don't get "metric eggs", so solving "it needs two eggs for five so how many eggs for twelve" is the same.
- kps 4y agoAlso, unit price calculation when shopping — I did this for a while some years ago when I was actively collecting slide rules. And currency conversion — set to the current exchange rate it becomes a temporarily-fixed table. I was talking with someone recently about computer floating point and now wonder to what extent the common use of slide rules and log tables influenced its development. I've read a lot of the early computing papers and only recall seeing discussion around whether or not the exponent (or characteristic) should be handled directly (i.e. floating point) or separately/implicitly (fixed point). (And sliding back to rules, the A/B scales are analogous to one bit of float denormalization, although their primary purpose was extracting square roots.)