A Slight Price Change

I recently acquired a mid-1900’s copy of Ainsworth’s Brunton Pocket Transit owners manual. This is the small manual that was included with every pocket transit sold.

Brunton Pocket Transit 1957 - Front Cover

Click on the image to open the manual as a PDF

Included with this manual was a 1957 price list and the prices it shows makes for some fun comparisons to prices today

Brunton Pocket Transit 1957 - Price List

In 1957 an Ainsworth manufactured pocket transit would set you back $49.50. Wow! Compared to current pricing for the same item made today by the Brunton Company – $400 – that was quite a bargain.

Or was it? There’s no direct comparison between 1957 prices and 2016 prices. If we calculate for inflation using consumer price index numbers, $49.50 in 1957 dollars = $417.52 in 2015 dollars. So the pocket transit buyer in 1957 was actually paying about $17 more in inflation adjusted dollars for his compass.

Any way you calculate it a new pocket transit is a pricey piece of equipment. It wasn’t (and still isn’t) a purchase decision a young college student or newly graduated geologist made lightly, but it was a necessary and critical piece of his professional kit. That probably explains why there are so many well used but well cared for examples available today on auction sites like eBay.



The Brunton Cadet

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.

Brunton Cadet

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.

Brunton Comparison 2Ainsworth 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 Manual Front

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.


An Unusual Ainsworth Compass

A few months back I picked up an unusual William Ainsworth & Sons surveying compass that closely resembles an Ainsworth-produced Brunton Pocket Transit.  The resemblance is so close, in fact, that the lid of the compass is even marked ‘D. W. Brunton’s’.  There’s no doubt that this is an original Ainsworth instrument (as opposed to a copy or knock-off), but it certainly isn’t a pocket transit.


 From the outside it looks like a common pre-WWII pocket transit

So what do we have here? Well, it appears to be a survey compass built using a pocket transit case.  I’ve never seen or read about an instrument of this type, so I assume it’s fairly rare.


However, inside we see something quite unusual. It’s not a pocket transit but a surveyors compass!

Two key questions are, when was it made, and for whom?  Based on the case design and markings this is instrument was made after 1914, and we can be sure of that based on the ‘figure 8’ peep sight design which was patented by D. W. Brunton in 1914. But going a bit further, I’ll also wager that this instrument was built post-1927 when Ainsworth acquired the manufacturing rights to the Brunton pocket transit from D. W. Brunton’s estate.  This would account for the use of the pocket transit case and a lid that carries all the Brunton patent data on a device that is clearly not a pocket transit.  I doubt Mr.Brunton would have allowed his name and patent information to be used on something that was not of his design.

William Ainsworth & Sons was a well known instrument maker and produced high end instruments for the mining, geological exploration and surveying industries. The idea that they would consider using a pocket transit case to produce a small survey compass is not at all far-fetched. In fact, it makes perfect sense. The cases were already in production, the pocket transit was a well known and highly regarded design and it would have been easy to simplify the housing design to contain just a compass needle. In theory it would also have been cheaper to build since the bubble levels, clinometer arm, scales and external clinometer lever are all left out of the design.


This compass leaves out the standard pocket transit bubble levels, clinometer arm and scales. It also uses a type of bar compass needle commonly found on surveyors compasses but never seen before on an Ainsworth pocket transit from this era

But was this an attempt to bring a simpler and cheaper pocket instrument to market or was this made to answer a product requirement submitted by a customer? We may never know, and there aren’t enough clues we can glean from the instrument itself to make a good guess. This particular instrument is painted in a dark green, very similar to Army olive drab. The paint job is well executed and was probably done at the factory. It’s also stamped with the serial number ‘1042’, but the serial number placement, text size and style are not what we’re used to seeing on other Ainsworth instruments. This indicated it may be part of a special production run for a large customer – perhaps the US military or another federal agency such as the USGS or the US Forest Service.

Another interesting design feature relates to how the compass is mounted to a tripod. Pocket transits are secured to tripods using a ‘U’ shaped bracket the slides into grooves machined into the side of the transit case. This compass design takes a more common approach, and one used by most surveyor compass manufacturers. That is, the mounting thimble or bracket screws into the base of the instrument. Pocket transits can’t use this arrangement because of the clinometer lever that extends through the bottom of the case. But since this compass doesn’t have a clinometer Ainsworth was free to use the more conventional mounting method.


 The compass mounting thimble screws directly into the base of the compass. A common arrangement with surveyors compasses, but not seen with pocket transits


This view shows the mounting socket at the base of the compass

So there we have it. An interesting instrument that represents the adaptation of the popular pocket transit design for another purpose.

If any of my readers have any additional information on this instrument I’d love to hear from you. Please just leave your comments on the blog for all to see. Thanks!

– Brian

More Money Than Sense?

Last night on eBay someone plunked down $1,200.00 (plus $25 shipping) to purchase a used Brunton pocket transit. Silly impulse purchase? A case of SUI (Surfing Under the Influence)? Or does the buyer know something I don’t?


This auction opened and closed on the same day. The opening bid price (set by the seller) was $700, with a buy-it-now price set at $1,200. I thought $700 was somewhat high, but clearly someone else thought $1,200 was just right

You see, this particular Brunton appears to sport the serial number 232 (although it’s hard to make out in the lousy photos the seller provided). If the serial number is valid this puts it somewhere in the first or second year of production – around 1895. This is by far the earliest production Brunton I’ve ever seen for sale.


Given what information could be gleaned from the poor photos the seller provided, this transit looks right for an early model – hand engraving on the lid (with no sine tables), small view hole in the lid, no lid mounted peep sight, no tripod bracket slots and a single tube level on the clinometer

I sincerely hope the buyer is happy with his/her purchase. Who knows, perhaps it’s destined for a museum collection (which might explain why it sold so fast at the buy-it-now price). If the buyer happens to read this blog I’d love to hear more about your decision to purchase this pocket transit and perhaps provide a few detailed photos of this remarkable example to share with the readership.

I’ve added this Brunton to the Pocket Transit Serial Number Project spreadsheet so we have a record of its existence and sale. To date it is the second oldest Brunton on the list. I’d love to know more about its history – who owned it, where it was purchased, where it was used. These fine old instruments usually have a great story to tell.

– Brian