Sunday, January 14, 2007



Oh, be a fine girl: kiss me.
That sentence is a mnemonic device for remembering the spectral classes of stars: O, B, A, F, G, K, M. (Our sun is class G, a “yellow” star.)

Mnemosyne, in Greek mythology, was one of the titans, and the mother of the Muses. She represented the embodiment of memory. A mnemonic device, named for Mnemosyne (or, more accurately, her name and the word both came from the same Greek root), is something that helps us remember something else.

The acrostic is a common mnemonic device: we have a sentence wherein the initial letters of each word match the initial letters of the sequence we want to remember. Our minds generally find it easier to remember a silly, if arbitrary sentence, such as the one above, than an equally arbitrary sequence. There are lots of other mnemonic devices, of course. Acronyms are another, where we have the initial letters of the sequence put together to form a word or phrase directly. We often use these sorts of mnemonics to remember telephone numbers, making words out of the letters that go with the numbers. A friend of mine used to have a phone number ending in 3266. Damn, that was easy to remember!

Roy G. Biv
Why is it any easier for us to remember that bogus “name” than it is to remember the colours in the rainbow? And what is “indigo”, anyway, apart from a mood?[1]

Every good boy does fine.
That's probably the most well known acrostic mnemonic, along with its variants (the Moody Blues used an English version, “Every Good Boy Deserves Favour”, for their 1971 album; one of my childhood schoolmates came up with “Every green bug does fart”). It's the sequence of notes, using English notation, on the lines of the treble-clef musical staff: E, G, B, D, F. The notes in the spaces form the word “FACE”, another acronym mnemonic.

Eli the ice man.
In electrical engineering, this phrase helps us to remember the phase relationship between voltage (E) and current (I) in inductive circuits (L) and capacitive circuits (C): voltage leads current in an inductive circuit (E comes before I in “ELI”), and voltage lags current in a capacitive circuit (E comes after I in “ICE”). I can never remember that without the mnemonic. On the other hand, I never have to remember it, but thanks to Eli, I'll never forget it.

Bad boys rape our young girls, but violet gives willingly.
OK, this one's pretty icky, but it did help me remember the colour-coded bands on electrical resistors. Black, brown, red, orange, yellow, green, blue, violet, grey, white, for the numbers 0 thru 9. The sequence also has the rainbow imbedded in it (minus that pesky indigo), another mnemonic device. One interesting thing here is that the sentence is sufficient, even though there are three “b” words and colours. I never have trouble knowing which is which among black, brown, and blue.

Be careful driving elephants into small ford garages.

Let me now help out your punctuation with <commas>.

Villains usually take <3em-spaces> and run.

Here's a set that's truly obscure, and quite obsolete. The California Job Case was, in the days when printing used type slugs, a flat drawer that was used to hold the type. It had three main sections (see the rendition in the link above, or try this photo); the first two sections, which had three main rows in each, held the lower-case letters, while the third section held the upper-case letters. The upper-case letters were in alphabetical order except for J and U, which were at the end after Z. The three sentences above give the mappings for the three rows of lower-case letters (the missing letters, along with most punctuation marks and ligatures, bordered the three rows). It was very important to remember the sequence, to avoid putting slugs back in the wrong compartments — it's awfully hard to quickly tell the difference among b, d, p, and q when you look at the type slugs, so you really have to make sure they get back in the correct compartments.

Another sort of mnemonic device is the doggerel poem, and I'll leave you with a classic one, which reminds us all of the correct way to dilute concentrated sulfuric acid to avoid having it spotaneously splatter all over the hapless chemist:

If you're doin' what you ought'er
Add the acid to the water.
May your rest be long and placid
If you add water to the acid.


[1] It's a rhetorical question; I know that it's a sort of “blurple”.


henli17 said...

I believe mnemonic devices have missed out (i.e. failed) on being upgraded and extensively propogated in this age when so many of us can easily "compare notes" and share each others work on every sort of topic. I don't think these aids have become more "robust" even though there are people "out there" (and I don't mean myself) who have the practical talent and creativity, to do so. Let me toot my horn, this one time, with one of my best "robust" mnemonics: "Captain Aquarro picks artillery targets; General Canfield leads village liberation, Scott said." There are two A's two C's two L's and two t's, in this list of twelve names, and yet there is no amibuity or reason to mix up order of those words which start with the same first letter. Can you figure out what twelve names I'm referring to ? If so let me know:

henli17 said...

Let me also add the the most import question about mnemonics that is too seldom asked, i.e. what information should people be making good mnemonics about, whether its little poems ("Thirty days ...In 1492 ...",) musical approaches, (A,B,C,D..., )of gimmicks of sorts (e.g. the "knuckle method" for the long and short months?)
Here's the most urgent mnemonic needed, I believe. The fifty US states and their capitals, whether learned singlely or in groups. It basic reference info available everywhere - but it's still basic to learn them all into your head, and no one says ... NOT. Same with foreign countries and their capitals, and the countries on several of the continents, or regions central America, S.E. Asia - in some geographically useful order. e.g. north to south. Of course, where necessary the multiplcation tables top everything. I leaned in 1957, "9 times 8 is 56, my do Fido can do tricks". The Chinese little kids learn "5 5 25" before they know what it means. Is there some downside to that ? hn

henli17 said...

Here's what could turn into a big very interesting mnemonics program:
The Beijing Olympics come up in 2008. It also happens that Chinese New Year in 2008 starts at the beginning of the cycle again with Rat/mounse. (Chinese culture does not make any kind of to do about beginning the cycle anew even the new century on their calendar. Nor do they use mnemonic devices.) That practice is somehow much more western. But let's say, "outsiders" got this underway on the web. Here's my "method" for those 12 animal words in order. Take each, animal and find an association for the month of the year in the same number position order. E.g. Rabbit and 4 (April), Pig and 12 (December). We all would have a differntassociation on at least some of these although perhaps similar ones on some others. The lists of 12 associations are likely to reflect the culture, age and even gender of the person making them. Comparing those intra- and inter- would be quite interesting for ever side of the matter. Perhaps even the Chinese would like to see how foreigners deal with this matter. Of course the very best answers, might become the standard for those who want other people to do their work for them which in some cases is not a bad idea.

Barry Leiba said...

Thanks for the comments...

«Can you figure out what twelve names I'm referring to ?»

Yes, sure. But the series should start with the second "A" (though I see why you have it start with the "C", of course).

Interestingly, that's a series I never used a mnemonic to learn (nor really cared much about whether I learnt it).

States & countries & capitals: I loved geography as a kid, and I learnt all of them (and was trotted out to recite them in front of my parents' friends). Alas, I've been tripped up, as an adult, with having to add all the former soviet republics (I did learn the European ones back then, but not the Asian ones), the countries of the former Yugoslavia (at least there are only six), and all the changes, especially in Africa. Whew!

But mnemonics for them would be tough. I can't think of any mnemonic devices that remind us of as many as 100 things (fifty states and their capitals). The most I know is the California Job case, which breaks it into three manageable sentences. It'd be a clever person who could come up with something for the states that really worked.

I don't agree about the multiplication, though. It's far better to learn shortcuts to actually doing the arithmetic than to learn discrete entries through mnemonics. Rather than learning, say, a poem that reminds us that 7 times 8 is 56 (uh, not 9, sorry; see, the mnemonic failed you), I'd rather see the kids taught techniques to speed it up in general. You start by learning how to multiply by 2 and by 3, and to take half. Those are then easily extended to do 4, 5, 6, 8, and 9 (leaving 7 as the odd one out, with no easy shortcut that I know of). Learn those, and the whole process is quicker, and you don't have to try to recite doggerel (and remember which pair of numbers it goes with).

henli17 said...

I understand about the western Zodiac series starting elsewhere in the order, but its usefulness to me had to include being able to tell "the 1st of which month" a sign covered as I expect you realized. It also could be useful as a data source for Astronomy 101. The Zodiac for astrology pur-poses is mostly starts as a "teen girl thing" as looking at any teen magazine will demonstrate.
I think the states/capitals and a few other facts (general location, NE, SE, nMW, etc. neighboring states, (perhaps all "coded" in) something(s) states famous for (lakes, dairy, horses, Yellowstone, smallest) I think would be best handle through short verses (not quarters), though not necessarily all strung together to epic length - (a task/contest for the state tourism depts. if you ask me.) In retrospect, tricks in multiplication are at least as useful as rote, but I suppose it depends on what age the the tables are learned. Personally learning arithmatic using an abacus might be more useful still but perhaps not more practical- is my opinion. I do like that Chinese kids before they understand its meaning lean some arithmetic skills.
Still unresponded to, what other educational data lists should be mnemonicized, and does the Chinese Zodiac "personal associations" grid sound of interest ? hn