Cartographic Accuracy

I realize that there are some spelling mistakes and some of the 16xx terms aren’t quite right but hey, that’s what this kinda of peer review is for. Right and yes its still incomplete..

Essay on “Cartographic Accuracy”

Abstract:

With the arrival of Grantville in 1631, among the host of things that came with it was a penchant for accuracy by the up-timers. This penchant has been seen in most of the goings on of the town and its people and has begun to carry over to the local down-timers that have come to expect the near wondrous measurements demonstrated by the up-timers. Maps are no exception the majority of the maps that would have come through with Grantville are mostly large scale maps (i.e. greater than 1:1,000,000). These maps can be found in the Goodes World Atlas, the Rand McNally Atlas and the various maps found in the many encyclopedias in the town. Another series of maps, those of National Geographic, also fall in this category. These large well-made maps are most easily compared to the work of Mercator and Anders Bureus. These maps generally define what large scale maps should be to the majority of the worlds populace. They are almost unusable for the purposes of Grantville. The Atlas’s of Goodes and McNally are equally of little use for the common use of the people of Grantville or its leaders. Equally important is the equipment that has been brought back with them. Transits, stadia rods, tapes, and surveyor levels pretty much round out the available equipment.

Ability and knowledge

In the universe of 16xx there exist a small but able group of cartographers. These people are scattered throughout the nations of Europe and are mainly involved in creating large scale maps of various nations and coastlines. By today’s standards and the standards of the up-timers these maps are pitiful. That is not say that there are not redeeming features of them or that they time that their creators took was wasted, just that the difference in accuracy and the difference of knowledge between the times is quite significant and can not be underestimated.

For the sake of the USE the principle characters of note are Anders Bureus, Lenart Tortelson, Olaf Hansson Svart, and Johann Bureus. These members constitute not all of the major cartographers, but the most important. In my research and those of others there are at least 20 other cartographers either mentioned by full name or in part. The abilities of these men are actually quite good for their time, their mid to small level maps are actually quite accurate, given the equipment of the day¹. Against modern maps these hold up to an error of about one foot in five hundred of being accurate. Given the size of the maps this is almost an acceptable error for modern times.

Under the administration of Anders and his brother Johann, Swedish cartography became quite systematic and relied heavily on actual measured distances. They are considered to some of the first to attempt thematic and topographic mapping, and their maps were used up until the early nineteenth century, because of this, despite an error in longitude. The basis for these maps was an almost fanatical devotion to detail and training. The existing records point to a methodical and detailed record of measurements and this is borne out in the latitudinal direction of the 1626 map of Sweden. The longitudinal error came from Ptolemaic sources. These sources are the same ones that convinced many that Columbus could have sailed to India from Spain with running into the pesky Americas.

The transition to modern methods should be quite easy. Much of the need to convince the survey crews to take records has already been hammered in, all that remains is to teach the updated means of surveying and record keeping.

Locally there are two or three surveyors, only one with his books². These books, while important to the high school, are not as important as the knowledge in these gentlemen’s heads. They know tricks and shortcuts to surveying in difficult terrain and it is vitally important that their head be picked clean. Additionally their familiarity with the current Swedish methods of chain and rod and their current knowledge of transit and stadia means that they should be able to teach the down-timers very quickly on the use of the up-time equipment. They should also be able to convince the surveyors why they need to concentrate solely on surveying and leave the placement of points to the professional cartographers.

Equipment:

When asked what equipment was available in Grantville at the time of the fold, a list of items was forwarded to me. These items included one transit, a level, two stadia rods, a hand full of chains and several tapes³. Additionally another one or two transits maybe found stored in the attics around town. The most import of these items is the transit. This instrument is used to site and calculate distances, angles, and elevations. It is the single most important tool of a surveyor and by extension is quite important for cartographers. Because of its importance the instrument should be duplicated as soon as humanly possible. However there are some problems with this. After talking with various members of the board and with members of the Wisconsin DNR and the University of Wisconsin-Madison Cartographic department it became clear that the abilities of Grantville are not up to the task of replicating a modern transit. They are however, capable of replicating a transit of the 1930’s with some difficulty. This means that measurements of down to the second of arc are impossible. The closest accuracy one will achieve is to the half minute or third of a minute.

Reproduction of the transit will be the most important thing in updating the surveying and cartographic fields. The problem is that none of the equipment in Grantville can cut and mark the verniers. In the up time this equipment was owned by half a dozen companies owning maybe a dozen machines. So the odds that one of these machines came through is vanishingly small to the point of zero and as I understand it, none of the machines in the shops are designed with this kind of demarcation in mind. What they can do is cut the circular plates for the artisans that will mark and assemble the transits. Additional to the verniers is the telescope. This should be a times seven or eight with the minimum acceptable multiplier a times four. A rifle scope should be sacrificed (if one hasn’t been already), in the interests of duplication.

Currently the best lenses are made in Amsterdam. However a surveyors telescope is not a simple refractive tube. It uses two lenses and a pair of prisms to do the focusing, enlarging, and area gathering. The lenses would most likely have a bit of color distortion because of the impurities in the glass and the correction for this wasn’t discovered until the late nineteenth century. I do not know if there is anyone in the town that would know how to work around this, however it’s not important. It is mentioned because of its likely occurrence. The prisms will represent the biggest problem in the construction of the telescope. They are essentially the same prisms placed 180 degrees opposite of one another. They have to be practically the same prism for them to revert the image and NOT have a great deal of distortion. Because of the detail of this the best method is probably batch creation with hand polishing for minor correction and hope that somewhere in the batch exist two prisms that can be used with each other. If a four piece telescope is not pursued a simple two piece can be used, but the disadvantages are great. It will most likely be capable only of about four to six times, as that is all that is practical for the focal length, it will suffer from a restricted point of view. Galileos’ telescope was restricted to a fifteen minute field of vision. This could make it time consuming to find a person in the field and will mean that extra care will have to be taken to get the tripod FIRMLY planted in the ground as it will amplify any user unsteadiness. I am not certain as too the extent of the “wobble” but there would be an exaggerated one in this type of scope as opposed to the 4 piece version.

As mentioned before the one third minute or half minute transits are at the maximum extent of what could be produced down-time. The accompanying stadia rods are easy enough to manufacture and can be replicated fairly quickly.

Tapes are currently beyond the ability of the current infrastructure to produce. Once rolled metal for hacksaw blades becomes possible it will be possible to begin production of these items.

The continuance of chains as a useful surveying tool is limited. They are tricky to use and even today when they are used they are inevitably checked against a tape. The main problem with them is that even good surveyors continually screw up with them. For best use they must be held perfectly taunt and flat from anywhere between shoulder and knee height. As soon as transits become available in numbers chains should be relegated to the surveyors pack⁴ and used as a last resort.

Personnel, Training and Outfitting

Personnel for this survey can come from multiple sources. Existing agencies in Germany and Sweden could be trained the easiest. Few up-timers would needed for this project mostly for training and for the occasional jaunt in the field with a survey team just to verify the numbers, but by and large the actual survey can be held to down-timers trained on the new equipment.

Training should begin with the Swedish Field Army, specifically it’s engineering corp. This agency because of the need for accurate measurements, spotting, and general usefulness of the army would be the first area that the down-timers could see the benefits of the heightened accuracy. A sizable engineering corps usually accompanies all fortifications, field camps and military movements so these would be some of the first places to test the new methods. The Geologic Field Camp would be the best place to start their training, assuming that there is room in the classes for about a dozen more people for each session. However because the transit is the key to all of this it is not necessary that training of surveyors begin immediately. The down-time construction of a transit will probably take about 2 years. With the couple that would be available to ready crews a full scale training regime could actually wait till the second year of production so to facilitate a supply of equipment to be used.

Once trained each crew should have a horse a person or donkey cart and a pair horses, three to six stadia rods, one transit in a shock resistant case, a pack of notebooks, if available a tape, chains, three or four plumb-bobs and several guns. This last item can be relaxed in areas where they aren’t needed but I am going to assume that for the most part that Germany has a whole is still unsettled and it doesn’t hurt for the crews to be able to fend off brigands and thieves.

Expenses-Equipment:

While first in priority, I am dealing with the expenses last. The survey already exists in a myriad of forms throughout the 16xx universe. There are surveyors and runners and bad maps and cartography throughout the whole of Europe and the rest of the world. The practical upshot of this is that the current batch of surveyors only needs to be retrained. While the class size is small for the field camp, after five years there should be enough data from trained personnel to actually start a school of map design and production. What this means of course is that up-front costs of the Survey are in fact limited to just retraining.

Costs of the construction of the transits would probably run in the $2,000 to $4,000 range. Discussions with board members have assured me that there is in fact enough knowledge for them to be built, but that in fact the price will be high. Even if the first dozen fail, I doubt that the cost of the transit will be more than $4000 dollars. The nature of transits, there will be little recovery of costs of quantity, and it is likely that after the first dozen of so the cost will only drop by about ten percent. This is a large amount of capital to be laid out on a small piece of equipment.

Incidental costs of the stadia rods, tapes, chains and supplies to keep the surveyors in the field will add up to the cost of the transit in most cases. There are few people that would want to put up this kind of money, especially when the old methods pioneered by the Romans have worked for so long. Because of politics that means that only those currently allied with the USE and Sweden are available to get money from. Several obvious sources, excluding national treasuries, would be the Bureus brothers, the cartographers of Holland, some of the larger towns, and the occasional family that is involved in surveying. This is not a large pool of funds and in fact is probably smaller still as both the Swedish and USE treasuries are at the breaking point trying to fight the 30 Years War.

The Map Survey:

Once crews are trained, outfitted, and are comfortable with the equipment that they are now responsible for a starting point must be acted on. For my money all towns of significance should be surveyed. Ideally starting with Grantville and then moving to Jena and to other local towns. A buffer of five miles should be surveyed around the outside of the town. When the crew completes its’ survey the teams path to the next town should be surveyed as it goes. Major towns, cities, and crossroads should be the first order of business, followed by systematic survey of the national boarder with the closest of the towns. Every effort should be made to place important physical features in a 10-mile swath of the surveyor’s path. These paths should be well surveyed. If an adile table and operator can be spared a quick map of important areas in the path could be done.

Once a group of survey books is completed they will be sent to the nearest office for transcribing to paper or velum. Points of interest, on features or natural oddities should be referenced as well to form the most accurate picture of the landscape for the transcriber. Once transcribed the points can be connected or interpreted to form