A Survey Problem

Or maybe not.  Here's an interesting postcard I recently picked up -

It's unused, so there's no postmark on the back that I can use to nail down the date, but we can glean a few clues from the photo itself.  First, quite obviously it's a WWII-era photo.  Probably early WWII because the rifles at stack arms are the M1903 Springfield.  Since Camp Roberts opened in March, 1941 and the US Army had effectively replaced the venerable '03 Springfield with the new M1 Garand by early 1942 I'll date this photo to mid-to-late 1941.

Next, I don't think these Soldiers are 'surveying'.  Since Camp Roberts was primarily an Infantry and Artillery training center my guess is that these are soldiers taking a class in Field Artillery plotting using plane tables.  Plane tables were a common item in Field Artillery battery TOEs, intended to be used as a field expedient plotting table.  I have one in my collection with the case stenciled 'HQ FDC' - Headquarters Fire Direction Center.  I have no idea which headquarters or which fire direction center, but clearly it was a piece of Field Artillery equipment (and identical to the plane tables used by Engineer survey units).  Another clue that this is a Field Artillery class is the use of large artillery plotting protractors.  You can just make them out on the plane tables in the foreground - large semi-circular protractors with a rotating plotting ruler mounted at the center.  Plus, there are no alidades visible, a key piece of equipment for any survey plane table work.

Yup, these are Field Artillery soldiers learning how to plot artillery fire.  But I will forgive the publisher's gaffe because it's still a neat picture of Army training in early WWII. The stacked rifles, the ammunition belts with canteens hanging from the tree, the Soldiers working the problems at the plotting boards while their classmates sit behind them studying their manuals.  I love how the plane tables are arrayed in an arc to best utilize the shade from the tree.  Looking at aerial photos of Camp Roberts on Google I'm guessing these guys found one of the very few shade trees available in this part of California.

Neatness Counts

Earlier we discussed the use of field notebooks and the lost art of field note taking.  I fear that neat, disciplined and structured field note taking is a lost art in the today's world of texting, instant messaging, and email.  Even in the engineering, surveying and topographic field (where I work) the use of field notebooks appears to have been brushed aside by smartphones, laptop computers, data collectors and the assorted electronic bric-a-brac that has come to dominate the field.  And yet - and yet - all this powerful technology still leaves us with critical information gaps.  The problem is not so much that people aren't writing stuff down, it is that they are writing it down in formats that are so very disjointed, disconnected and perishable.  An email here, a quick scribble on a random notepad there.  It gets lost or never gets integrated into the project file.  Months or years down the line engineers and maintenance personnel are left to wonder just where something was placed or how it was constructed because the story of that project was not properly documented.

Now, I'm not implying that the use of field notebooks will solve all of these problems.  Field notebooks are not a panacea for lousy project management.  My point is really that disciplined and structured note taking should be viewed as a key skill - and a requirement - for surveyors, engineers, topographers and other key staff.  Of course the ideal place to write all this down is in a field notebook, a field notebook that gets turned over to the organization, copied, indexed and integrated into a document management system at the completion of the project.

Neat, disciplined, complete and structured note taking.  Just what does that mean?

The disciplined and complete parts are easy.  Notes need to be made on any issue, topic, observation or discussion that directly impacts a project.  It is really nothing more than getting in the habit.  Get in the habit of having your notebook with you and writing stuff down.  Complete means get it all down.  Think of each record you create in the notebook as a miniature story - it needs to have a beginning, a middle and and end.  What you observed, when and where you observed it, what was important about it, who was there, what was agreed to, what conclusions were reached and, if necessary, sketches or diagrams that are key to the issue at hand.  Make it a complete story!

Neat and structured are two somewhat subjective concepts.  Everyone has their own style of organization and handwriting.  The important thing is to make it neat, legible and logical in structure.  Always remember that the intent is to make it easy for you and others in your organization to reference in the future.  How far into the future?  I routinely reference survey records for the airport I work at that are 60+ years old.  The neatness and structure (and completeness) of those records allow me to rely on them for locating structures and utilities that were abandoned and forgotten about decades ago.

I can only offer suggestions for the concepts of neatness and structure.  As I mentioned in my earlier post, field note taking used to be a topic taught in all beginning surveying and civil engineering courses.  Colleges, universities, government agencies (like the USGS and the USC&GS) and even individual companies used to have their own field note format requirements.  Some agencies, like the US Army Corps of Engineers, would even have entire bound books printed with pre-formatted pages.

A few agencies still provide specific field note standards.  Surprisingly, most are state departments of transportation (DOT).  For example, the Oregon DOT, provides specific guidance for field note structure.  Their Survey Field Note Standards (October 2006) provides very specific field note examples.  The same for the Montana DOT.  Their Survey Manual provides a chapter on sample notes that contractors are expected to follow.

But since this is my blog and I love old stuff, particularly old stuff that still has relevance, we're going to take a trip back to the 1950s.  A time when cars had carburetors, space travel was the stuff of science fiction and real men did surveys with optical theodolites and steel measuring tapes, and wrote everything down in hard bound notebooks.  A couple of professors at the University of Missouri put together a course in introductory surveying and field measuring.  A large part of the class involved proper field note recording.  This course was to serve as the foundation for all surveying and civil engineering instruction to come, so the instructors needed to make sure the students got started on the right foot with disciplined, accurate, structured and comprehensive field data recording.  The two professors, Clarence Bardsley and Ernest Carlton put together a gem of a book titled 'Surveyors Field Note Forms'.

Bardsley & Carlton, Surveyor's Field
Note Forms (3rd Ed.)

The book opens with a treatise on the importance of field notes and the necessity of being an accurate, error free, neat and complete note taker.

"Allow no items for the memory; all facts should be on the record."


"A good surveyor takes pride in the appearance of his notes.  A neat-appearing, well arranged set of field notes commands confidence and builds prestige in the surveyor."


"Field notes should be clear and convey only one possibly correct interpretation.  Descriptions and narrative matter should be in acceptable English.  Sketches should be drawn to approximate, or convenient, scales.  All numerals indicating distances, angles, or elevation should be carefully formed.  Particular care should be exercised in obtaining a logical order and sequence of all notes, for they should be absolutely clear and understandable to the student, other surveyors, computers*, or draftsmen."


The book then goes on to provide specific examples of problems and how the field notes should be formatted (click on any image to open it full-size):

Length of Pace Measurement

It was once common practice for surveyors to regularly measure and record their pace count over various types of terrain (flat, hilly, uphill, downhill, etc.).  Before accurate handheld measurement devices like GPS surveyors used pace count to do help them with tasks like finding property corner stakes or do rough fence line measurements.

Correcting for Horizontal Slope

Don't you just love the name 'Trachoma Hospital?

Using Rough Triangulation to Determine Distance

Although the equipment has improved, surveyors and engineers still use the principal of triangulation to determine inaccessible distances.

Sewer Stake-out

Construction stake-out, whether for sewers, buildings or roads, is still bread-and-butter work for surveyors.

Use of the Grade Rod

Field notes are for more than writing down numbers.  Often the engineer or surveyor needs to write down a description of how a particular piece of equipment was used, or a methodology that might need clarification.

Height of Object

Again, the equipment may have changed, but the procedure is still the same.

Determining Azimuth From True North

Using solar or star shots is still an accepted practice for determining the relationship to true north.

The point of the above is not really what is on the page as much as it is the legibility, accuracy and completeness of the data.  One hundred years from now, when Microsoft .pst files are lost to eternity, digital CAD files can't be opened and survey data collector files are corrupted beyond recall someone will still be able to pull a notebook like this one off the shelf, open it and clearly understand what the author wrote and was trying to convey.

Neatness does count.

As I was wrapping up this blog posting I asked Roberta (5th Grade Teacher of the Millennium) if kids in grade school still get penmanship lessons.  I was disappointed but not surprised to hear that, in her school system at least, penmanship has been sacrificed on the altar of computer skills.  Apparently the school system feels that there is not enough time to teach and practice penmanship, and since kid are all wired up to computers these days the time 'wasted' on penmanship is better put to teaching computer and 'keyboarding' skills.  How sad...

Brian


(*Note - In the 1950s the term 'computer' meant something completely different.  Back then a 'computer' was an individual who was responsible for doing final computations against the surveyor's field notes and applying statistical methods to determine the accuracy of the survey results.)

Measuring Things

US Coast & Geodetic Survey leveling party working in Atlanta, 1927

In the olden days, like before GPS, before you could make an accurate map real men had to go out and measure things.  This 'measuring' was called surveying, and it involved the extremely precise and accurate determination of the horizontal and/or vertical location of points on the ground known as survey control.  This survey control establishes the accurate framework upon which a map is built.  Horizontal measuring was called triangulation. Vertical measuring was called leveling.

The picture above comes from the US Coast & Geodetic Survey 1927 Seasons Report prepared by Captain E. O. Heaton (USC&GS).  It shows a topographic leveling party at work in Atlanta.  If anyone can figure out where in Atlanta these guys are working I'd love to know!  

A few things to note.  The fellow holding the umbrella is most likely a black local laborer hired to help the party haul equipment and provide general assistance.  The umbrella he's holding isn't to keep the surveyor from getting sunburned - it is to protect the instrument from direct sun and prevent glare when sighting through it.  To ensure accuracy survey parties often used umbrellas to shade their instruments and stabilize temperatures.  

The fellow squatting is a surveyor who is acting as the recorder.  He is writing down the readings being called out by the surveyor looking through the instrument.  The recorder's job was extremely important because he didn't just write down what the surveyor called out, he would do on-the-fly quality control checks on the values the surveyor gave him to ensure they were staying within the accuracy standards established for that particular survey.  If the recorder makes a single mistake, such as not catching an error in the surveyor's observations or by writing something down wrong (like inadvertently transposing a number or putting a decimal point in the wrong place) he could lose an entire day's work.  In my experience you wanted your  most meticulous guy and your best mathematician doing this job - perfectionists made good recorders.  The recorder is writing his notes down in a bound hardback book known as a survey field notebook.  That notebook would be turned in to the USC&GS at the end of the project and go on to become a part of the legal record of the survey.  I have no doubt that very notebook still exists in the archives of the USC&GS now held by the National Oceanic and Atmospheric Administration.  I'd love to take a peek at it!

(The job of recorder is one of those skills that has been replaced by computers.  Today's surveying instruments now automatically store the readings and calculate values internally.  The computer integrated into the survey level lets the surveyor know via a digital display if the readings are within the specifications set for the job.  It's called digital leveling.)

But what is the surveyor looking at?  Well, there are two people missing from this photo that make up the leveling party.  The surveyor is looking through the survey level at a stadia rod being held by another party member known as a rod man.  A stadia rod is a long pole marked off in feet and inches.  Behind the surveyor is another rod man with another stadia pole (the location of the stadia poles is determined by the survey party chief and is based mainly on topography and the ability to see both poles from where the survey level is set up).  The surveyor looks though the level and calls out the elevation mark he sees on the first stadia rod.  He then reverses direction and calls out the elevation he views on the second stadia rod.  The difference in numeric values he views on the two stadia poles is the difference in elevation between them:

Click on the image to open full size

Additionally, if this is a simple differential leveling job (and I think it is based on the type of level being used), there is another crew of chain men measuring the distance between the two stadia rods.  In 1927 this would have been done using steel survey tapes or chains.

Leveling is slow, tedious and physically demanding work.  There were no old farts out working on leveling parties except perhaps as party chiefs.  The rod men and the chain men were constantly moving, carrying the survey forward.  The instrument man and the recorder were responsible for moving and setting up the level in a new location, and the party chief was moving between all members of the survey party and scouting ahead for new setup locations.

Their work was absolutely critical, though.  The meticulous work of the surveyors of the US Coast & Geodetic Survey and the US Geological Survey created the accurate spatial framework that this countries maps and charts continue to be built upon.

But that's not the end of this story!  I got interested in this picture for a particular reason.  The vertical survey control for the airport I work at was established by this particular USC&GS survey project.  I would like to think that it was these three unnamed gentlemen who, sometime in 1927 or 28, ran their traverse down into College Park, GA and set the single elevation benchmark that became the origin point for all vertical survey work done at the airport until the advent of GPS-based survey in the late 1990s. 

Brian  

Inter-American Geodetic Survey

NOTE: This is an older version of my posting on the IAGS. All the material for this blog, to include an updated version of this post, is now available on my new WordPress blog site at www.oldtopographer.net.

You can access the new version of this post at http://oldtopographer.net/2011/01/23/inter-american-geodetic-survey/

Thanks!

- Brian

_____________________________________________________________________________

The Inter-American Geodetic Survey (IAGS) was one of those extremely successful, yet little known, US Army (and later, Dept. of Defense) programs established after WWII.

The IAGS was created specifically to assist Latin American countries in surveying and mapping their vast internal regions that were either poorly mapped or entirely unmapped. The IAGS was established in 1946 as part of the Army Map Service and was headquartered at Fort Clayton in the Panama Canal Zone. The Army Map Service set up a complete survey, cartographic and map reproduction school at Fort Clayton and over the next 30 years trained thousands of military and civilian personnel from most Latin American and Caribbean countries. Attendance at the IAGS school at Fort Clayton was seen as right of passage for many up and coming officers in Latin American militaries, and it was common to run across senior officers - colonels and generals - from South American countries who talked fondly of their time spent at Fort Clayton, taking surveying or cartographic classes (one infamous graduate of the IAGS schools just happens to be Panamanian dictator Manuel Noriega, who attended the cartographic school in the 1960s).

The IAGS didn't just provide training.  It also provided the equipment and personnel to assist the participating countries in establishing their own self-sufficient mapping and surveying programs.  The goal was to provide the training, equipment and technical support but have the individual countries take over their own mapping efforts.

Now, I'm not going to pretend that the IAGS was all altruistic good-will on America's part.  We learned the hard way during WWII that many Latin American countries were at best reluctant allies, at worst active sympathizers with the Nazi regime.  At the end of WWII the political systems in these countries ranged from shaky democracies to hard line dictatorships.  The US Government became concerned about the effects of political unrest and Communist influence in the region, and instituted a number of programs designed to bring Latin America firmly under American influence and to foster democratic principles and improve economic conditions.  The IAGS was just one of many programs created as part of this effort.  One extremely important benefit the IAGS provided back to the US was that we were able to get American personnel on the ground in these countries to make detailed evaluations of local conditions (after all, that's what surveyors and cartographers do, right?) and we got maps that were created to US standards for vast areas of Central and South America.

According to all the accounts I've read and my own direct experience with the IAGS in Central and South America, the program was a great success. The goals of the IAGS were warmly embraced by most countries, who realized they utterly lacked the resources and training needed to map their own territories. IAGS liasion personnel were permanently assigned to each country, working out of the US embassies, and developed deep and lasting ties with government, military and business leaders.  IAGS personnel were very highly regarded in most countries, and I've heard more than one old-timer talk about how whenever they flew into a country to work and the local customs agents saw the distinctive IAGS logo on their luggage they were swiftly and courteously passed through customs without inspection or interrogation.

My introduction to the IAGS came when I attended the Defense Mapping School's Mapping, Charting & Geodesy Officer's Course at Fort Belvior, Virginia back in 1982.  By then the IAGS had been, or was in the process of transforming into, the Defense Mapping Agency International Division (I'm running on memory here, so please forgive any errors). However, the IAGS logo was visible throughout the building, and we received a short orientation brief on IAGS operations.  My next contact came in 1990 while working in Honduras as part of an airfield construction task force.  My team's job was to conduct route reconnaissance and terrain evaluation of large sections of southern Honduras.  We made contact with the Honduran IAGS liaison officer, Emory Phlegar.  Emory was a long time IAGS hand who had 'gone native' - he married into Honduran society and seemed to know everyone and everything that was going on in that small, poor country.  He provided us a wealth of information and with a simple phone call opened a number of doors for us with the Honduran Instituto Goegrafico Nacional (National Geographic Institute).

Three years later I was stationed at Fort Clayton, Panama, and headed up the geographic analysis team supporting US Army South and US Southern Command.  This job put me in close and frequent contact with the last remnant of the IAGS in the old Canal Zone. Southern Command and the Defense Mapping Agency (DMA) ran a joint map warehouse on Albrook Air Force Station.  The Air Force took care of ordering, stocking and issuing standard US maps to all US military operating in Central and South America.  In the same building the Defense Mapping Agency ran a small but very interesting and critical 'local products' warehouse that received and stocked maps printed by the different countries who had been part of the IAGS.  By agreement, DMA received 100 copies of every map printed by the participating countries. Quite often these maps were the only representation of Central and South American land areas available to the US military, and we relied heavily on this map supply. In fact my unit acquired an early large format Xerox copier specifically to make copies of these maps for Army use so as not to draw down the limited stock kept by DMA.

Additionally, DMA continued to operate a topographic and survey instrument repair shop out of the building.  This was a one man show, employing an instrument repairman who fixed or calibrated any equipment that had been loaned to countries participating in the IAGS.  Much of the loaned equipment was simply too big to pack up and send back to Albrook to be worked on, so this lone repairman spent a lot of time on the road traveling from country to country repairing equipment.  Most of what he worked on was obsolete by US standards, but was still perfectly serviceable and suitable to the Latin American countries that couldn't afford anything more modern. As such, his workshop at Albrook was a fascinating mix of spare parts bins and machine tools.  Since he dealt with a lot of obsolete equipment I'm sure he had the skills and equipment needed to fabricate any broken or worn part.

Unfortunately there is very little information about the IAGS on the web.  Not even Wikipedia has a dedicated page, and only catalogs indirect references to the agency. This is a shame, because the IAGS was a landmark cooperative effort that yielded enormous benefit for all countries involved, and its story needs to be out there for everyone to read. Somebody at the National Geospatial-Intelligence Agency (the successor to the Defense Mapping Agency) or the Corps of Engineers needs to write up a short history of the IAGS and its accomplishments while the participants are still around to tell their stories.

But for now it is You Tube to the rescue!  I found this film, part of the Army's 'Big Picture' series, covering IAGS operations:



Enjoy!

Brian

Which Way North? (Part II) - The Pocket Transit

In Which Way North? (Part I) we discussed the history of the magnetic compass and talked a bit about magnetic declination.  Now let's start looking at some specific compass designs and discuss why they were important.

To start we'll look at a compass design that is uniquely American and was born of the late 19th Century explosion of mining and mineral exploration in the US.  This compass was originally conceived to fit a very specific need, but it was so well designed and executed that it found use in a wide variety of applications and industries.  It continues to be produced today, over 100 years since its introduction and little changed from its original design.

The Brunton Pocket Transit was patented in 1894 by David Brunton, a Colorado mining engineer.  Brunton was frustrated by the number of survey instruments a mining engineer and geologist had to carry around with him (and I say 'him' because mining engineering and field geology was an exclusively male profession well into the 20th Century).  In the late 1800s it was not unusual for engineers and geologists doing basic exploratory mineral mapping to lug around full sized survey transits, surveying compasses, tripods, clinometers, and plane tables. These instruments offered a high level of accuracy that simply wasn't needed for exploratory surveys.  As an engineer himself Brunton realized that what was needed a portable device that allowed field survey personnel to do fast and accurate exploratory quality surveys without being burdened down by equipment that was heavy, expensive and difficult to set up and use.  These men were in the business of discovering, verifying and mapping mineral deposits that covered vast areas.  Huge sums of money were at stake as mining and mineral companies scrambled to secure valuable leases on the stuff that was fueling America's exploding industrial economy - timber, gold, silver, coal, iron ore, chromium, nickel, bauxite, petroleum and dozens of other minerals that were key to America's growth.  Field engineers and geologists needed to move fast, do rough mapping and get that information back to the office for the development of lease maps and boundary descriptions.  They didn't need to be burdened with heavy, sensitive and fragile survey gear if that level of accuracy wasn't required.  David Brunton recognized the problem and set to work developing a solution.

What Brunton came up with as a pocket-sized device that incorporated an accurate magnetic compass with a sighting vane, a clinometer, a level and a large mirror with a sight line.  Housed in a machined aluminum case (still an expensive material in the late 1800s), it was rugged, reliable and useful.

Brunton named his instrument the 'Pocket Transit', a lofty title for a fairly rudimentary mapping device.  But the name served its intended purpose; in the mind of the engineer and geologist it set the device apart from the common handheld compass.  Here was a professional instrument that offered a level of accuracy and functionality not found elsewhere.

Brunton's 1894 model Pocket Transit

Brunton had more than marketing on his side.  The Pocket Transit actually delivered where it mattered - in the field and in the hands of engineers and geologists across North America.  It delivered all the functionality and accuracy needed to get the job done.  It ended up being the perfect device for the job at hand.

Demand for Brunton's device increased steadily and improvements were introduced.  An additional bubble level and a cover mounted peep sight were added in 1912.  In the same year Brunton introduced modifications to the case that allowed mounting the instrument on a non-magnetic tripod or jacobs staff.  (It's interesting that in his 1894 patent application Brunton derided other compass designs that needed to be tripod mounted, but in the 1912 patent application he discusses tripod mounting like it's the greatest idea since sliced bread.)  Somewhere between 1894 and 1912 the Pocket Transit acquired the ability to pre-set magnetic declination by use of an adjustment screw on the side of the case.  By 1926 Brunton's design had fully matured with the addition of a bullseye level for improved leveling and the addition a percent grade scale to the clinometer.  From this point forward it was minor improvements in materials, manufacturing techniques and the added availability of different compass ring layouts (degrees, quadrants, mils, etc.)

A 1926 patent model of the Brunton  Pocket Transit.
Note the round level and the percent grade indices
at the bottom of the clinometer scale.  This is the basic
design still in production today.

One of the reasons Brunton's pocket transit was
so damned useful is that he made it a complete package.
Early in the production of the pocket transit Brunton started
engraving sine and tangent tables on the lid.  Using these
tables in conjunction with the clinometer an engineer could
quickly and accurately determine heights of objects like trees
or cliff faces.  To this day Brunton includes the sine and
tangent tables on the lids of all pocket transits.
So damned useful!

From the beginning David Brunton licensed the Colorado instrument maker William Ainsworth & Sons to produce the pocket transit.  After Brunton's death in 1927 Ainsworth purchased the manufacturing rights to Brunton's designs and continued manufacturing and improving the Pocket Transit through the late 1960s.  In 1972 the production rights and the Brunton name were purchased by the Brunton Company of Riverton, Wyoming.  The Brunton Company continues to manufacture this basic design.

The Brunton design was so well thought out that engineers and geologists quickly developed field techniques keyed to the Pocket Transit's unique layout and construction.  The best example is the determination of the strike and dip of rock formations.  Most sedimentary and metamorphic rock formations are not horizontal.  They were all deposited in horizontal layers but over geological time (i.e., millions of years) those horizontal layers have been warped and deformed by pressure and other geological forces.  One of the keys to understanding these forces is mapping the strike (the horizontal angle of deformity) and dip (the vertical angle of deformity) of individual rock layers.  Before the Brunton Pocket Transit the measurement of strike and dip was a clumsy process involving two separate devices - a field compass (often a fairly large and somewhat fragile device) and a clinometer.  With the Brunton the process is quick and simple - open the instrument and lay it horizontally against the rock formation.  Keeping the edge of the instrument in contact with the rock face rotate it up and down slightly until the circular level is centered.  Note the magnetic azimuth as indicated by the compass needle.  That is your strike.  Score a line on the rock face horizontal to the pocket transit using a piece of chalk or small piece of rock and remove the pocket transit.  Make another score mark that is perpendicular to the horizontal mark you just made (your mark should look like a 'T').  Place the Pocket Transit along this perpendicular mark and measure the angle of slope using the built in clinometer.  This is your dip.  It takes longer to describe than it does to do it in the field.  This is the standard measurement technique for strike and dip, and every college and university geology department in North America teaches it as part of their field geology curriculum.

From the University of Calgary website.  Measuring the strike
of a rock formation using a Brunton Pocket Transit.

From the University of Calgary website.  Measuring the dip of
a rock formation using the Brunton Pocket Transit.

My introduction to the Brunton Pocket Transit came in the mid-1970s while studying geology in college.  We learned strike and dip measurement techniques early on in the field methods class, and later during our summer field geology course we ranged across the southwestern United States, making thousands of strike and dip measurements in an effort to understand the geologic processes that formed the unique landscape of that region.  I saw the Pocket Transit as a useful but fairly limited device, suited only to the field geologist.  Years later while attending a course at the Defense Mapping School at Fort Belvior, Virginia, our class got an intensive block of instruction on the use of the Pocket Transit not just for strike and dip measurement but for height determination, precise azimuth determination, basic plane table survey work and rough site layout.  I finally saw the full potential of the Pocket Transit and purchased my first one soon after.  That Pocket Transit has seen service in Kuwait, Honduras, Panama, Germany, Bosnia, Korea and across the US.  It has been a constant companion on hundreds of field surveys, assisting with tasks like mapping out refugee camps on the Empire Range area of the Panama Canal Zone, measuring road grades along the Pan-American Highway in Honduras and fixing North Korean observation point locations along the Korean DMZ.

The Brunton Pocket Transit doesn't measure horizontal angles as well as a conventional transit, it doesn't measure vertical angles angles as well as a theodolite, sextant or even an Abney hand level.  If you need to shoot azimuths using handheld techniques the Army lensatic compass is a better tool.  However, the Pocket Transit does all of these tasks well enough, and puts everything needed into a compact, easy to carry package that really does fit into your pocket.  (In his patent application David Brunton noted that the instrument fits nicely into a vest pocket - therefore the name pocket transit).

Let's have a look at some Brunton Pocket Transit variations (click on the pictures for an enlarged view):

This is a modern incarnation of the Pocket Transit - a glass filled composite
body version.  This particular Pocket Transit is almost 20 years old
and has been used around the world, and it still looks new.

This is a particularly nice WWII era Pocket Transit manufactured in 1943.
This model is graduated in mils (6400 mils in a circle).  Designated the
M-2 Compass, it was designed for use by artillery troops who need a more
discreet subdivision of the circle for accurate artillery gun laying and spotting.
A variation of this model is still used by the US Army and USMC today.

An early induction dampened model graduated in degrees

A nice post-war model graduated in quadrants instead of degrees.
Most early Pocket Transits were sold with the quadrant setup rather than
degrees.  The use of quadrants was the accepted method of noting direction
within the engineering and geology community up through the 1970s.  Brunton
still sells a modern version of this layout, but it really is useless for general
navigation purposes.  If you want to do land navigation with a Pocket
Transit get the model laid out in degrees!

As you can tell, I think the Brunton Pocket Transit is a nifty little tool.  But it is not a novelty, not something to be put on a shelf to be admired.  The Pocket Transit is designed and built to be used.  It represents American ingenuity at its best.  From 1894 on the Pocket Transit ended up being used in all corners of the United States, doing useful, often rough duty helping to map American and her natural resources.  Rugged, reliable, useful.  American to the core!

Brian

In writing this blog post I relied heavily on several sources that I feel need to be acknowledged.

First is William Hudson's excellent website About Brunton Pocket Transits.  Mr. Hudson's site is the most complete compilation of information about Pocket Transits on the web, and should be the starting point for anyone interested in finding out more about these great little devices.  Thanks you Mr. Hudson.

Next is Dr. Peter H. von Bitter's article The Brunton Pocket Transit, A One Hundred Year Old North American Invention.  Originally written in 1995 for the journal of the History of the Earth Sciences Society to celebrate the 100 year anniversary of the invention of the Brunton Pocket Transit, von Bitter's article forms an excellent short history of the man David Brunton and his famous invention.  Thank you Dr. von Bitter.

Although not source, there is an scanned copy of a 1913 Ainsworth bulletin available on the the Surveying Antiques website.  This bulletin describes the various ways to hold and use the Pocket Transit and is an interesting overview of the instrument and its uses.