Putting older maps online opens up possibilities that would likely stun the old cartographers.
While most of the hacks in this book focus on how to create and use maps that reflect the world as it is now, there are lots of reasons to look back at older maps. Apart from the remarkable cartography and design of many of the best older maps, these maps can help us see what features of our world mapmakers considered important before the advent of superhighways, or even canals and railroads.
The David Rumsey Map Collection (http://www.davidrumsey.com), which began as a physical map collection 20 years ago, offers over 10,000 maps that visitors can explore online. Casual visitors can zoom in to appreciate fine detail, while other users can overlay these maps with more recent ones, using the combination to evaluate change over time.
The site offers several options for browsing, from a simple in-brower viewer, to a separate Java client application, to a set of tools for integrating the maps with GIS data. One of those tools even lets you visit the map in three dimensions. For starters, the insight Browser, as shown in Figure 3-3, is probably the easiest to use, though it requires that pop-up ad blocking be turned off. (I switched browsers rather than tinker with settings.)
Figure 3-3. Opening the collection with the insight Browser
You can wander through all 10,000 maps, or you can search using the options on the lefthand side. I chose to search by State/Province, picked New York from the list, and clicked past the first 100 maps before finding the one I was looking for, in the top left corner of the selection shown in Figure 3-4. Double-clicking on the selected map brings up another window displaying the map and navigation details, as shown in Figure 3-5. Zooming in to a portion of the map where my house now stands, as shown in Figure 3-6, I can see the creek, with sawmills marked by Xs and other mills as circles on Xs, along with the beginnings of the local road system.
Figure 3-4. Maps of upstate New York from 1829
Figure 3-5. An 1829 map of Tompkins County, New York, with options for exploring it
Figure 3-6. Zoomed in on an 1829 map to see the detail available
Most of what you'll want to do in this mode is zoom in and out. The printer button prints a small version of the map on ordinary paper; it's not going to let you take a full image with all the details in the map.
While you can spend hours looking over old maps, the site has a few wilder features to offer as well, notably its 3-D viewing experience at http://davidrumsey.com/GIS/3d.htm. You'll want broadband network access and a reasonably fast computer to use this feature. It crashed my old 600 MHz ThinkPad but ran fine on a 1.8 GHz eMachines with 384 MB of RAM.
The Yosemite Valley map is the most developed of the six currently available maps, as it starts from an 1883 survey map of the valley and also permits an overlay with much more recent U.S. Geological Survey maps. Using the mouse, arrow keys, and spacebar, you can swoop through the valley, enjoying the detail of the maps, and you can also choose how much of the new map you see through the old map. It's hard to demonstrate the feeling the viewer provides in a book, but Figure 3-7 will give you some idea of what to expect as you explore the valley.
Figure 3-7. Looking over the Yosemite Valley, through a 3-D rendering of an 1883 map
You can also change the view from 1883 to the present using the Z, X, C, V, and B keys. Figures Figure 3-8 through Figure 3-10 show a similar part of the map at different settings.
Figure 3-8. Looking over the Yosemite Valley from Sentinel Dome, using just the 1883 map
Figure 3-9. Looking over the Yosemite Valley from Sentinel Dome, using both the 1883 map and the USGS map
Figure 3-10. Looking over the Yosemite Valley from Sentinel Dome, using just the USGS map
While the 3-D maps are stunning, the collection also offers 2-D maps that combine historical maps with more recent ones through a GIS viewer. Whether you want to explore technical possibilities or stock your wish list with data and tools, the David Rumsey Collection is a fine place to start!