Author: Chris Aldrich

I'm a biomedical and electrical engineer with interests in information theory, complexity, evolution, genetics, signal processing, IndieWeb, theoretical mathematics, and big history. I'm also a talent manager-producer-publisher in the entertainment industry with expertise in representation, distribution, finance, production, content delivery, and new media.

Filing Index Cards with a C-Line Document Sorter

Not surprisingly, I don’t always file away my index cards as quickly as I probably ought to. Every now and then I go through my deck of unfiled cards and try to sort them into my card index/zettelkasten. The end of the year seems like a pretty good time to clear the decks.

Because I haven’t documented some of this portion of my process before, I thought I’d take a few photos of my C-Line document sorter which I use to do a fast sort of cards before filing into my card index. I bought it a while back from Brodart Library supplies and it comes in quite handy for sorting and filing documents. It’s got sections for sorting by alphabet, days of a month, months of the year, days of the week, and numbers up to 30,000 (which I primarily co-opt for Dewey Decimal sorting). The days of the month and month sections come in handy for use with my Memindex work, and the months of the year are useful for sorting receipts for expenses and at tax preparation time. In all, it’s fairly flexible analog office tool.

Side view of a C-Line index card sorter sitting on a wooden table. We can see about 100 cards slotted into the various flaps of the sorter

As I go through my stack of index cards, I use a Mitsubishi No. 772 pencil (the vermillion side) to underline topics for filing and cross-referencing purposes. This allows me to cross-index topics quickly as well.

A box of Mitsubishi No. 772 pencils with a sharpened one sitting in front of it. One end of the half red/half blue pencil is vermillion and the other end is Prussian blue.

I went through several hundred cards the other day and only had about 150-200 left for filing into the commonplace book section of my card index. Most of these cards were from 2025, but some dated into 2024 with a handful from as far back as 2023. 

Over the coming days, I’m hoping to finish cleaning up some of the notes from this year’s reading work.

A comparison of A5 sized notebooks with 4 x 6 inch index cards on a cost per square foot basis

Notebooks

Product Sheet width
(inches)		 Sheet height
(inches)		 pages price Area
sq. ft.		 $/sq. ft.
Hobonichi A5 Graph 5.8 8.3 288 $23.00 96.3 $0.24
Leuchtturm 1917 A5 5.8 8.3 251 $25.95 83.9 $0.31
Moleskine Hard Cover 5 8.25 192 $20.00 55.0 $0.36
Travelers Notebook 4.3 8.3 128 $11.90 31.7 $0.38

 

4 x 6 inch index cards

Product Sheet width
(inches)		 Sheet height
(inches)		 sheets price Area
sq. ft.		 $/sq. ft.
Amazon Basics 4×6 Index Cards 4 6 500 $7.30 166.7 $0.04
Oxford 4×6 6 4 1000 $16.49 333.3 $0.05
Stockroom Plus 4×6 (grid) 6 4 300 $13.67 100.0 $0.14
Exacompta 4×6 6 4 100 $15.77 33.3 $0.47
Notsu 4×6 6 4 50 $14.99 16.7 $0.90

Generally, Exacompta cards are the closest in price per square foot to the nicer notebooks while most 4 x 6 inch index cards are comparatively much cheaper (even if you’re only writing on one side).

Acquired 1964 Sears Cutlass portable Typewriter (Smith-Corona Marchant)
Serial Number: 6ASP-103936
Sears Futura typeface (aka SCM Numode No. 61 typeface), pica, 10 CPI, 6 lines/inch, American 88 No. 423 keyboard, bichrome, 44 keys, 88 characters, Change-A-Type, ¶ key
A red typewriter for Christmas! And it was hiding the uncommon Sears Futura typeface (aka Smith-Corona Numode No. 61) for its American 88 No. 423 keyboard which also features the Change-A-Type functionality. (Sadly it’ll be a slog to try to find matching Numode typeface slugs to match, though some of my math slugs may work well.) This means that it meets my current collector’s criteria for an interesting model I don’t already have as well as an uncommon typeface.

Futura typeface sample of a 1964 Sears Cutlass'

I’ve been on the hunt for one of these for over two years and always lost out in online auctions which generally went in the range of $150-200 in part because of the hot reddish/burgundy paint job with white racing stripes and the fact that Taylor Swift used this same typewriter in her All Too Well: The Short Film.

In the last two years I’ve only seen three of these on ShopGoodwill, so they definitely don’t pop up often. There are only 5 others on the Typewriter Database. Many of the online auctions where they went for a few hundred on ShopGoodwill.com had them being relisted by flippers on eBay in the $600-800 range within two weeks with no cleaning or restoration work. I’ve seen prices for them on eBay for $1,000 and over. For comparison, similar typewriter models in the 5 and 6 series of the period would otherwise be selling in the $25-50 range in this condition. (Ultimately, I’m glad I waited.)

1964 Sears Cutlass sitting at an angle on a sea green metal bar stool in front of a barrister bookcase flanked by card index filing cabinets.

Close up angled from the top of a burgundy 1964 Sears Cutlass which has a pair of racing strips on the right side of the hood.

1964 Sears Cutlass with the hood open to show the stickers underneath the hood and a portion of the basket. One of the stickers indicates the type as "Futura".

This one is in generally exceptional shape and works well out of the box. The shop it came from (or more likely the prior owner) was definitely on the liberal side with their lubrication. One of the two carriage release levers is broken off, which is extremely common on the 6-series models which used plastic which apparently brittled with age. I’ll give it a once over to touch up some of the dirtier parts and make some subtle adjustments. I will probably hold off on a major overhaul at the moment because it’s in such good condition. The platen is solid and plastic-y feeling. It definitely needs an upgrade on this front.

This model seems to bridge the gap between the 5 series Smith-Coronas into the 60s and the 6 series machines like the Galaxie. It’s a top-of-the-line model with the keyboard tabulator and the hood hinges up and back like the 5 series rather than sliding forward like the 6 series models. I don’t have one, but I would suspect it’s closest to the Sterling 5AX typewriter which started in 1963. It’s also got a great little paragraph indent button for use at the beginning of new paragraphs. I look forward to seeing how they implemented this feature mechanically.

A 1964 Sears Cutlass sits on a stool in front of a Christmas tree. To the side is a wooden bureau with a wide screen television on it featuring the face of Joe Pesci as Harry in Home Alone. It almost appears as if he's squinting at the typewriter.

A 1964 Sears Cutlass sits on a stool in front of a Christmas tree. To the side is a wooden bureau with a wide screen television on it featuring the face of Macauley Culkin as Kevin in Home Alone as he claps his hands to his face and screams.

A 1964 Sears Cutlass sits on a stool in front of a Christmas tree. To the side is a wooden bureau with a wide screen television on it featuring the face of Kieran Culkin as Fuller in Home Alone. His face is being squished up against a chair and it gives the appearance that he's trying to look at the typewriter in front of the television.

Acquired Brodart Colored Blank Punched Catalog Cards (shopbrodart.com)
Medium-weight colored blank punched catalog cards
blue, green, buff, ivory, white, salmon
Stocking stuffers anyone? Santa brought 6,000 index cards down the proverbial chimney today. Should have enough now to index all the books in the house? 

A library card catalog with a red Christmas stocking hanging on it with a box full of index cards next to it.

Four drawers of a library card catalog full of index cards in blue, green, buff, and ivory.

Five card catalog drawers lined up and full of ivory, buff, green, blue, and salmon index cards

A library card catalog covered in stacks of Brodart index cards.

Breaking News: Brodart No Longer Manufactures or Sells Library Card Catalogs

With no advance notice or apparent fanfare, Brodart, one of the major library supplies and furnishing companies in the United States, has quit manufacturing, distributing, and selling library card catalogs and library charging trays. This seems sad news for analog library enthusiasts coming just two days after Melvil Dewey’s 174th birthday on December 10th. 

I’ve got word in for specific details about end dates for manufacturing and the last sales on some of these products. Apparently the last purchase of charging trays was someone wiping out their stock of 50 remaining units in the last two weeks.

This news comes a decade on the heels of the Online Computer Library Center (OCLC) announcing that it printed its last batch of library card catalog cards on October 1, 2015.

 

 

Brodart has recently discontinued their salmon card index cards with pre-drilled holes -188-218. This has been a shift since the summer of 2025, though they’re still carrying the standard salmon index cards (without predrilled holds for card catalog rods).

A conversation with their customer service team seems to indicate there aren’t plans for discontinuing their other cards (blue, green, ivory, white, and buff), but: caveat emptor as they no longer list their card catalog furniture or their charging trays on their website, their Dewey Decimal tabbed cards are now gone, and Demco recently quit carrying their buff/red-lined Library of Congress cards this past year.

Incidentally, they’re doing a 20% discount on their index cards (and related circulation supplies) for the holidays right now, so stock up if you need them. 

In honor of Melvil Dewey’s 174th birthday yesterday, I’ve just purchased 6,000 cards in an attempt to get them to continue stocking them all and to have a happier 2026.

Acquired Lochby Field Folio A6 (Lochby)
Keep your A6 notebooks, pens, and essentials organized on the go with the Field Folio A6. Durable, vegan waxed canvas, slim design, and flexible pockets—perfect for travel, journaling, or everyday carry.
Lochby Field Folio A6 sits closed on a brown wooden table with it's Lochby kraft identification tag sitting on top of it. The exterior of the folio features brown waxed canvas.

I recently asked the kind folks at Lochby “if the Folio A6 will comfortably fit 25-50 standard 4 x 6″ index cards which are slightly larger than an A6 notebook? If not, is it something you might consider for some of us ‘Hipster PDA’ tribe members in the future?”  

Erring on the side of caution their customer service replied, “Unfortunately, since the Field Folio A6 zips up, there’s no way to fit this many index cards in it without the potential for damaging them when zipping it up. But I’ll take note of your suggestion and pass it on to our product development team so we can consider it as well as gauge interest.”

Because I often use A6 sized notebooks, I couldn’t resist adding to my Lochby collection, so I went ahead and ordered it anyway.

Lochby Field Folio A6 surrounded by several pens and pencils. Inside the right pocket of the folio is a yellow covered Hobonichi A6 notebook

It arrived in the post yesterday. Today I’m happy to report that it actually will accommodate 4 x 6″ index cards reasonably well.  I can comfortably fit about 30 cards into the right side pocket and still have room to tuck a Hobonichi A6 notebook into the folio and still zip it shut handily. 

Lochby Field Folio A6 with a bunch of 4 x 6" index cards tucked into the right side interior pocket .The interior of the folio features yellow highlight material as well as two yellow ribbon bookmarks. The left side has pocket space for several pens and pencils. Sitting crosswise across the top of the folio is a burgundy Mitsubishi 9850 HB pencil

Because I usually have a few pre-glued decks of index card “notebooks” sitting around, I tried one of these and can happily report that the back cover/board fits into the right pocket easily (just as you’d tuck the back cover of a notebook into it) and works well with the Lochby A6 folio! (The center elastic bands are slightly smaller and fairly tight, and could work with these glued decks too, but will tend to cut the glue at the ends, so one should take care here or carefully only glue the center 5 inches of the deck for this use case.) I suspect that if one had a plastic wallet-photo type holder, it might work well in this, particularly if you’re carrying around some of your daily use cards in addition to blank cards for future use. 

Lochby Field Folio A6 with a deck of gridded 4 x 6" index cards on the right hand side.

Fundamentals Of Hypercomplex Numbers | UCLA Extension

Dr. Michael Miller, a retired researcher at RAND, has been teaching upper level undergraduate/graduate level math courses for fun at UCLA Extension for over 50 years. This winter, he’ll be introducing hypercomplex numbers to those interested in abstract math: Fundamentals Of Hypercomplex Numbers.

His courses are thorough and rigorous, but geared toward lifelong learners and beginners in abstract mathematics to allow people better entry points into higher level mathematics. His classes are interesting and relatively informal, and most students who take one usually stay on for future courses. The vast majority of students in the class (from 16-90+ years old) take his classes for fun and regular exposure to mathematical thought, though there is an option to take it for a grade if you like. There are generally no prerequisites for his classes, and he makes an effort to meet the students at their current level of sophistication. Some background in calculus and linear algebra will be useful going into this particular topic.

If you’re in the Los Angeles area (there are regular commuters joining from as far out as Irvine, Ventura County and even Riverside) and interested in joining a group of dedicated hobbyist and professional mathematicians, engineers, physicists, and others from all walks of life (I’ve seen actors, directors, doctors, artists, poets, retirees, and even house-husbands in his classes), his class starts on January 6th at UCLA on Tuesday nights from 7-10PM.

If you’re unsure of what you’re getting into, I recommend visiting on the first class to consider joining us for the Winter quarter. Sadly, this is an in-person course. There isn’t an option to take this remotely or via streaming, and he doesn’t typically record his lectures. I hope to see all the Southern California math fans next month!

Course Description

A survey of those systems of numbers that can be constructed by adding “imaginary units” to the real numbers. The simplest and most familiar example is the two-dimensional system of complex numbers. Much less familiar, but equally fascinating, are the systems of quaternions and Cayley numbers, of dimensions four and eight, respectively. These “algebras” still enable meaningful notions of addition, multiplication, and division, but only at a price: the loss of commutativity and (in the case of Cayley numbers) associativity. Things get even more bizarre when sedenions (dimension 16) and trigintaduonions (dimension 32) are brought into play. The latter part of the course is devoted to the theorems of Hurwitz and Frobenius on the existence of suitably behaved division algebras over the real numbers.

The course should appeal to those seeking a better understanding of the arithmetical underpinnings of our number system.

Prerequisites: advanced calculus and linear algebra

January 6 – March 17
Tuesday 7:00PM – 10:00PM PT
REG# 407060
Fee: $450.00

Recommended textbook: TBD

Register here: https://www.uclaextension.edu/sciences-math/math-statistics/course/fundamentals-hypercomplex-numbers-math-900

If you’ve never joined the class before (Dr. Miller has been teaching these for 53 years and some of us have been with him for nearly that long; I’m starting into my 20th year personally), I’ve written up some tips and hints.

I now have definitive written proof of a numeric indexing system (delineated in a popular textbook for secretaries, and published by a company which did significant business in Germany) from the mid-1920s with increasingly more detail into the 1940s and a fifth edition published in 1950. It’s exactly like, but notably predates, Niklas Luhmann’s alphanumeric system which he started in 1952. I’ll write up some of the details shortly with specific references, but thought I’d tease it here a bit first.

Angle down on a small, light brown wooden card index. The box has several manilla 1/5 cut 3x5" card dividers inside along with some white index cards. Outside of the box on the table in front of it are a typewritten index card and a black metal Rotring 800 0.5mm mechanical pencil. Off to one side is a white ceramic bowl full of lemons.

While digging about in indexing and filing systems, I ran across this chart created by the Oxford Filing Supply Company for a special Filing Supplies section of the May 1934 issue of Office Appliances magazine (Volume 59, Issue 5). It delineates the broad characteristics of most of the major commercially available filing systems of the era.

Twenty Four Correspondence Filing Systems

Of course, by itself, it may not make much sense, so for those interested in older indexing and filing systems, take a peek at Remington Rand’s textbook Progressive Indexing and Filing (1950) which provides lots of images, examples, and full descriptions by many of the bigger manufacturers.

Perhaps these, which are all fairly similar, may help someone in designing their indexing system for a zettelkasten or commonplace book practices.

The rest of the articles in the magazine also have some fascinating history.