This website has covered the Brunton pocket transit and its clones in-depth, but there’s one design that shares some of the classic pocket transit DNA that we haven’t looked at yet – the Brunton Cadet pocket transit.

I’m not sure when the Cadet was introduced, but I’m guessing they hit the market in the late 1950’s or early 1960’s. The next question is, why? The cadet offers about 50% of the functionality of the classic pocket transit design (it lacks a needle dampening system, leveling bubbles, extended sighting vanes and an adjustable clinometer) and comes in at less than 1/4 the price of a base model Brunton pocket transit. My guess is that Ainsworth (the original manufacturer of both the Brunton pocket transit and the Cadet) was getting a lot of requests for a compass that had most of the features earth science students needed to get the job done, but at a much lower cost as compared to the classic pocket transit.

To answer the demand Ainsworth produced an all-plastic compass that is the same basic size and shape of the classic pocket transit but is greatly simplified. My example was produced sometime in the 1960’s, judging by the marking on the box. It offers a sighting mirror, clinometer and a compass ring set off in both degrees and quadrants (a neat idea that could have been migrated over to the standard pocket transit but, alas, never made it there). On my example the sighting mirror is a heavy piece of mirrored glass with a sighting line scored down the center and (I’m assuming) glued to the compass lid. The undampened needle has no obvious north markings on it save for a small hole punched in the needle to indicate the north end. The clinometer is a simple free swinging indicator affair set off in degrees of slope, but not percent.

Ainsworth claimed this is a ‘training’ compass, intended to teach students how to use the full featured pocket transit. Printing on the side of the box even states that the Cadet affords “… all the applications of the Brunton Pocket Transit, Basic Mapping Procedures, Plotting, Dip & Strike, Clinometer, Alidade, Prismatic Compass”. Boy that’s a load of bull! Without bubble levels it is impossible to do accurate strike and dip measurements on rock formations, so the Cadet’s usefulness for geology field work is limited. Without the sighting vanes it is impossible to use it as an alidade. With an undampened needle it’s extremely difficult to use it as a plotting tool or to accurately set a bearing. And it’s not a prismatic compass, it’s a mirror compass. Clearly the advertising guys at Ainsworth never took these things to the field before writing the copy. What the Cadet does remind me of is an old forester’s compass, but with a few added features. Perhaps it was designed to steal market share from the Silva Ranger compass, which was gaining in popularity in the US in the post-war period among foresters and others who needed to do rough field work with a map and compass.

Ainsworth Brunton pocket transit and the Ainsworth Cadet. Both were manufactured around the same time period

But the Cadet design (or price) must have resonated with many college and university earth science departments because I remember seeing them in the pile of pocket transits available in the geology department when I was attending school. I never used one – as a poor geology student I relied on my Silva Ranger for map and compass work and if I needed to do strike and dip measurements I just borrowed someone’s pocket transit.

Brunton Cadet owners manual (click to open)

Which leads, I guess, to the point of this post. The Brunton Cadet is interesting if you like to study the lineage of pocket transits, but it really doesn’t work all that well in today’s world. If you need a pocket transit just suck it up and buy a full featured model. The Cadet is still produced by Brunton and right now is sells for a little over $40 on Amazon. It’s a big step up in price to the cheapest full featured pocket transit, the Brunton ComPro (at just under $250 on Amazon), but the ComPro is a professional instrument and well worth the investment. If you just need a sighting compass there’s any number of mirrored sighting compasses available close to the Cadet’s price point that do a much better job. My personal recommendation is the Suunto MC-2.

We’ll just call the Cadet an evolutionary dead end on the pocket transit tree of genetic diversity. An interesting item for study, but one pushed out of the ecosystem by more evolved competitors.

Brian